Discovery of the neutron

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nuclei in number equal to the atomic mass. But since each hydrogen nucleus had charge +1, the nucleus required a smaller number of "internal electrons" each of charge −1 to give the nucleus its correct total charge. The mass of protons is about 1800 times greater than that of electrons, so the mass of the electrons is incidental in this computation. Such a model was consistent with the scattering of alpha particles from heavy nuclei, as well as the charge and mass of the many isotopes that had been identified. There were other motivations for the proton–electron model. As noted by Rutherford at the time, "We have strong reason for believing that the nuclei of atoms contain electrons as well as positively charged bodies...", namely, it was known that

1569:, Enrico Fermi and his team bombarded heavier elements with neutrons and found the products to be radioactive. By 1934 they had used neutrons to induce radioactivity in 22 different elements, many of these elements of high atomic number. Noticing that other experiments with neutrons at his laboratory seemed to work better on a wooden table than a marble table, Fermi suspected that the protons of the wood were slowing the neutrons and so increasing the chance for the neutron to interact with nuclei. Fermi therefore passed neutrons through paraffin wax to slow them and found that the radioactivity of some bombarded elements increased by a factor of tens to hundreds. The 607:

mass 4. In a 1919 paper, Rutherford had reported the apparent discovery of a new doubly charged particle of mass 3, denoted the X++, interpreted to consist of three protons and a closely bound electron. This result suggested to Rutherford the likely existence of two new particles: one of two protons with a closely bound electron, and another of one proton and a closely bound electron. The X++ particle was later determined to have mass 4 and to be just a low-energy alpha particle. Nevertheless, Rutherford had conjectured the existence of the deuteron, a +1 charge particle of mass 2, and the neutron, a neutral particle of mass 1. The former is the nucleus of

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quantum mechanical system," he still assumed the presence of nuclear electrons. In particular, Heisenberg assumed the neutron was a proton–electron composite, for which there is no quantum mechanical explanation. Heisenberg had no explanation for how lightweight electrons could be bound within the nucleus. Heisenberg introduced the first theory of nuclear exchange forces that bind the nucleons. He considered protons and neutrons to be different quantum states of the same particle, i.e., nucleons distinguished by the value of their nuclear

1047: 1589: 951: 1526: 6214: 1699: 943:), an unusually penetrating radiation was produced. Beryllium produced the most intense radiation. Polonium is highly radioactive, producing energetic alpha radiation, and it was commonly used for scattering experiments at the time. Alpha radiation can be influenced by an electric field, because it is composed of charged particles. The observed penetrating radiation was not influenced by an electric field, however, so it was thought to be 248: 842:

continuous energy distribution seemed to indicate that energy was not conserved by this "nuclear electrons" process. Indeed, in 1929 Bohr proposed to modify the law of energy conservation to account for the continuous energy distribution. The proposal earned the support of Werner Heisenberg. Such considerations were apparently reasonable, inasmuch as the laws of quantum mechanics had so recently overturned the laws of classical mechanics.

1597: 1135: 736:, the director of Utrecht's Physical Laboratory, showed that the spin of nitrogen nucleus must be equal to one. However, if the nitrogen-14 (N) nucleus was composed of 14 protons and 7 electrons, an odd number of spin-1/2 particles, then the resultant nuclear spin should be half-integer. Kronig therefore suggested that perhaps "protons and electrons do not retain their identity to the extent they do outside the nucleus". 5177:

excuse to postpone putting the piece of lead in its place. when finally, with some reluctance, I was going to put it in place, I said to myself: 'No, I do not want this piece of lead here; what I want is a piece of paraffin'. It was just like that with no advance warning, no conscious prior reasoning. I immediately took some odd piece of paraffin and placed it where the piece of lead was to have been.

528:, could be explained in terms of the 1913 Bohr model, with reasonable extra assumptions about atomic structure in other elements. Moseley's result, by Bohr's later account, not only established atomic number as a measurable experimental quantity, but gave it a physical meaning as the positive charge on the atomic nucleus. The elements could be ordered in the 458:

atoms, and therefore the single atom's mass is less than the sum of the hydrogen atom masses. Aston's work on isotopes won him the 1922 Nobel Prize in Chemistry for the discovery of isotopes in a large number of non-radioactive elements, and for his enunciation of the whole number rule. Noting Aston's recent discovery of nuclear binding energy, in 1920

830:, implies that an electron confined to a region the size of an atomic nucleus typically has a kinetic energy of about 40 MeV, which is larger than the observed energy of beta particles emitted from the nucleus. Such energy is also much larger than the binding energy of nucleons, which Aston and others had shown to be less than 9 MeV per nucleon. 489:. At that time, the positions of the elements in the periodic table were not known to have any physical significance. If the elements were ordered based on increasing atomic mass, however, periodicity in chemical properties was exhibited. Exceptions to this periodicity were apparent, however, such as cobalt and nickel. 1438:, depending on the precise value used for the deuteron mass. The mass of the neutron was too large to be a proton–electron composite, and the neutron was therefore identified as an elementary particle. Chadwick and Goldhaber predicted that a free neutron would be able to decay into a proton, electron, and neutrino ( 22: 1675:

Hahn and his collaborators had detected the splitting of uranium nuclei, made unstable by neutron absorption, into lighter elements. Meitner and Frisch also showed that the fission of each uranium atom would release about 200 MeV of energy. The discovery of fission electrified the global community of

1006:

had already conducted experiments on disintegrating light elements using alpha radiation from polonium. They had also developed more accurate and efficient methods for detecting, counting, and recording the ejected protons. Chadwick repeated the creation of the radiation using beryllium to absorb the

598:

at the Royal Society entitled the "Nuclear Constitution of Atoms", a summary of recent experiments on atomic nuclei and conclusions as to the structure of atomic nuclei. By 1920, the existence of electrons within the atomic nucleus was widely assumed. It was assumed the nucleus consisted of hydrogen

504:

of the atom with the visiting Bohr. The model accounted for the electromagnetic emission spectrum from the hydrogen atom, and Moseley and Bohr wondered if the electromagnetic emission spectra of heavier elements such as cobalt and nickel would follow their ordering by weight, or by their position in

1119:

particle. The theory preserved the principle of conservation of energy, which had been thrown into question by the continuous energy distribution of beta particles. The basic theory for beta decay proposed by Fermi was the first to show how particles could be created and destroyed. It established a

606:

In that lecture, Rutherford conjectured the existence of new particles. The alpha particle was known to be very stable, and it was assumed to retain its identity within the nucleus. The alpha particle was presumed to consist of four protons and two closely bound electrons to give it +2 charge and

532:

in order of atomic number, rather than atomic weight. The result tied together the organization of the periodic table, the Bohr model for the atom, and Rutherford's model for alpha scattering from nuclei. It was cited by Rutherford, Bohr, and others as a critical advance in understanding the nature

312:

to a high angle. The scattering indicated that some of the alpha particles ricocheted back from a small, but dense, component inside the atoms. Based on these measurements, by 1911 it was apparent to Rutherford that the atom consisted of a small, massive nucleus with positive charge surrounded by a

1553:

The discovery of the neutron immediately gave scientists a new tool for probing the properties of atomic nuclei. Alpha particles had been used over the previous decades in scattering experiments, but such particles, which are helium nuclei, have +2 charge. This charge makes it difficult for alpha

1423:

refer to the deuteron, proton, or neutron mass, and "b.e." is the binding energy. The masses of the deuteron and proton were known; Chadwick and Goldhaber used values 2.0142 Da and 1.0081&nbap;Da, respectively. They found that the neutron's mass was slightly greater than the mass of the

1014:

Following the Paris experiment, he aimed the radiation at paraffin wax, a hydrocarbon high in hydrogen content, hence offering a target dense with protons. As in the Paris experiment, the radiation energetically scattered some of the protons. Chadwick measured the range of these protons, and also

954:

A schematic diagram of the experiment used to discover the neutron in 1932. At left, a polonium source was used to irradiate beryllium with alpha particles, which induced an uncharged radiation. When this radiation struck paraffin wax, protons were ejected. The protons were observed using a small

1015:

measured how the new radiation impacted the atoms of various gases. Measurements of the recoil energy showed that the mass of the radiation particles must be similar to the mass of the proton: the new radiation could not consist of gamma rays. Uncharged particles with about the same mass as the

5176:

One day, as I came to the laboratory, it occurred to me that I should examine the effect of placing a piece of lead before the incident neutrons. Instead of my usual custom, I took great pains to have the piece of lead precisely machined. I was clearly dissatisfied with something; I tried every

1066:

had proposed proton–neutron models for the nucleus. Heisenberg's landmark papers approached the description of protons and neutrons in the nucleus through quantum mechanics. While Heisenberg's theory for protons and neutrons in the nucleus was a "major step toward understanding the nucleus as a

841:

at the Cavendish Laboratory measured the energies of β-decay electrons. They found that the distribution of energies from any particular radioactive nuclei was broad and continuous, a result that contrasted notably with the distinct energy values observed in alpha and gamma decay. Further, the

457:

had been known since 1905, Aston and others quickly realized that the mass discrepancy is due to the binding energy of atoms. When the contents of a number of hydrogen atoms are bound into a single atom, the single atom's energy must be less than the sum of the energies of the separate hydrogen

363:

independently found in 1913 that an element undergoing alpha decay will produce an element two places to the left in the periodic system and an element undergoing beta decay will produce an element one place to the right in the periodic system. Also, those radioelements that reside in the same

1357:

In this reaction, the resulting proton and neutron have about equal kinetic energy, since their masses are about equal. The kinetic energy of the resulting proton could be measured (0.24 MeV), and therefore the deuteron's binding energy could be determined (2.6 MeV − 2(0.24 MeV) =

779:

showed that a composite system with an odd number of spin-1/2 particles must obey Fermi statistics; a system with an even number of spin-1/2 particle obeys Bose statistics. If the nitrogen nucleus had 21 particles, it should obey Fermi statistics, contrary to fact. Thus, Heitler and Herzberg

716:

of atomic spectra was inconsistent with the proton–electron hypothesis. This structure is caused by the influence of the nucleus on the dynamics of orbiting electrons. The magnetic moments of supposed "nuclear electrons" should produce hyperfine spectral line splittings similar to the

232:

in 1914. These radiations had also been identified as emanating from atoms, hence they provided clues to processes occurring within atoms. Conversely, the radiations were also recognized as tools that could be exploited in scattering experiments to probe the interior of atoms.

476:

Rutherford and others had noted the disparity between the mass of an atom, computed in atomic mass units, and the approximate charge required on the nucleus for the Rutherford model to work. The required charge of the atomic nucleus was usually about half its atomic mass.

1146:

explored a model for a composite neutron to account for its great penetrating power through matter and its electrical neutrality, for example. The issue was a legacy of the prevailing view from the 1920s that the only elementary particles were the proton and electron.

277:

radiation, the emission of a fast electron from the nucleus (the accompanying antineutrino is omitted). In the Rutherford model for the nucleus, a red sphere was a proton with positive charge, and a blue sphere was a proton tightly bound to an electron, with no net

1554:

particles to overcome the Coulomb repulsive force and interact directly with the nuclei of atoms. Since neutrons have no electric charge, they do not have to overcome this force to interact with nuclei. Almost coincident with their discovery, neutrons were used by

1624:, furthered the research begun by Fermi and his team when they bombarded uranium with neutrons. Between 1934 and 1938, Hahn, Meitner, and Strassmann found a great number of radioactive transmutation products from these experiments, all of which they regarded as 700:

Throughout the 1920s, physicists assumed that the atomic nucleus was composed of protons and "nuclear electrons". Under this hypothesis, the nitrogen-14 (N) nucleus would be composed of 14 protons and 7 electrons, so that it would have a net charge of +7

1088:

If the proton–neutron model for the nucleus resolved many issues, it highlighted the problem of explaining the origins of beta radiation. No existing theory could account for how electrons, or positrons, could emanate from the nucleus. In 1934,

1181:. If greater than the combined masses, then the neutron was elementary like the proton. The question was challenging to answer because the electron's mass is only 0.05% of the proton's, hence exceptionally precise measurements were required. 849:

to interpret. Many theories were invented to explain how the above arguments could be wrong. In his 1931 monograph, Gamow summarized all these contradictions, marking the statements regarding electrons in the nucleus with warning symbols.

5287:

Hahn, O.; Strassmann, F. (10 February 1939). "Proof of the Formation of Active Isotopes of Barium from Uranium and Thorium Irradiated with Neutrons; Proof of the Existence of More Active Fragments Produced by Uranium Fission".

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units and a mass of 14 atomic mass units. This nucleus would also be orbited by another 7 electrons, termed "external electrons" by Rutherford, to complete the N atom. However problems with the hypothesis soon became apparent.

1472:

Soon after the discovery of the neutron, indirect evidence suggested the neutron had an unexpected non-zero value for its magnetic moment. Attempts to measure the neutron's magnetic moment originated with the discovery by

1120:

general, basic theory for the interaction of particles by weak or strong forces. While this influential paper has stood the test of time, the ideas within it were so new that when it was first submitted to the journal

1558:, Chadwick's colleague and protege, in scattering experiments with nitrogen. Feather was able to show that neutrons interacting with nitrogen nuclei scattered to protons or induced nitrogen to disintegrate to form 1517:

from studies of the hyperfine structure of atomic spectra. By the late 1930s accurate values for the magnetic moment of the neutron had been deduced by the Rabi group using measurements employing newly developed

1074:

The proton–neutron model explained the puzzle of dinitrogen. When N was proposed to consist of 3 pairs each of protons and neutrons, with an additional unpaired neutron and proton each contributing a spin of

615:. The mass of the hypothetical neutral particle would be little different from that of the proton. Rutherford determined that such a zero-charge particle would be difficult to detect by available techniques. 975:-containing compound, it ejected protons of very high energy (5 MeV). This observation was not in itself inconsistent with the assumed gamma ray nature of the new radiation, but that interpretation ( 1628:. Transuranic nuclides are those that have an atomic number greater than uranium (92), formed by neutron absorption; such nuclides are not naturally occurring. In July 1938, Meitner was forced to escape 1058:, it was quickly accepted that the atomic nucleus is composed of protons and neutrons, although the precise nature of the neutron was initially unclear. Within months after the discovery of the neutron, 1050:

Models depicting the nucleus and electron energy levels in hydrogen, helium, lithium, and neon atoms. In reality, the diameter of the nucleus is about 100,000 times smaller than the diameter of the atom.

4426: 130:

The uncharged neutron was immediately exploited as a new means to probe nuclear structure, leading to such discoveries as the creation of new radioactive elements by neutron irradiation (1934) and the

521:. Indeed, Moseley introduced this nomenclature. Moseley found that the frequencies of the radiation were related in a simple way to the atomic number of the elements for a large number of elements. 3195:

George Gamow "Constitution of Atomic Nuclei and Radioactivity". (The International Series of Monographs on Physics.) Pp.viii + 114.(Oxford: Clarendon Press; London: Oxford University Press, 1931.)

1676:

atomic physicists and the public. In their second publication on nuclear fission, Hahn and Strassmann predicted the existence and liberation of additional neutrons during the fission process.

979:) had a logical problem. From energy and momentum considerations, a gamma ray would have to have impossibly high energy (50 MeV) to scatter a massive proton. In Rome, the young physicist 308:, or the Geiger–Marsden experiment, these measurements made the extraordinary discovery that although most alpha particles passing through a thin gold foil experienced little deflection, a few 1085: ħ in the same direction for a total spin of 1 ħ, the model became viable. Soon, neutrons were used to naturally explain spin differences in many different nuclides in the same way. 983:

declared that the manner in which the new radiation interacted with protons required a neutral particle as heavy as a proton, but declined to publish his result despite the encouragement of

684:, then at the Institute for Theoretical Physics in Copenhagen, did not mention the neutron. At the time of their 1932 measurements in Paris that would lead to the discovery of the neutron, 450:.). Significantly, the one exception to this rule was hydrogen itself, which had a mass value of 1.008. The excess mass was small, but well outside the limits of experimental uncertainty. 1109:, or electromagnetic radiation, were similarly created and destroyed in atomic processes. Ivanenko had suggested a similar analogy in 1932. Fermi's theory requires the neutron to be a spin- 3529:

In 1930 Bothe, in collaboration with H. Becker, bombarded beryllium of mass 9 (and also boron and lithium) with alpha rays derived from polonium, and obtained a new form of radiation ...

4729:"Über die magnetische Ablenkung von Wasserstoffmolekülen und das magnetische Moment des Protons. II / Magnetic Deviation of Hydrogen Molecules and the Magnetic Moment of the Proton. I." 4681:"Über die magnetische Ablenkung von Wasserstoffmolekülen und das magnetische Moment des Protons. I / Magnetic Deviation of Hydrogen Molecules and the Magnetic Moment of the Proton. I." 317:. The concentrated atomic mass was required to provide the observed deflection of the alpha particles, and Rutherford developed a mathematical model that accounted for the scattering. 146:

by the end of World War II. Both the proton and the neutron were presumed to be elementary particles until the 1960s, when they were determined to be composite particles built from

1799:. By this model, particles such as the proton and neutron were not elementary, but composed of various configurations of a small number of other truly elementary particles called 2429:

Strömholm, D. and Svedberg, T. (1909) "Untersuchungen über die Chemie der radioactiven Grundstoffe II." (Investigations into the chemistry of the radioactive elements, part 2),

556:'s research work on determining the radioactive decay chains of radium and uranium by precise chemical separation was interrupted. Meitner spent much of the war working as a 3637: 1522:

techniques. The large value for the proton's magnetic moment and the inferred negative value for the neutron's magnetic moment were unexpected and raised many questions.

4245: 1733: 1184:

The difficulty of making the measurement is illustrated by the wide-ranging values for the mass of the neutron obtained from 1932 to 1934. The accepted value today is

1170:

in 1933, the primary question was the mass of the neutron relative to the proton. If the neutron's mass was less than the combined masses of a proton and an electron (

4253: 4185: 1807:. The quark model received experimental verification beginning in the late 1960s and finally provided an explanation for the neutron's anomalous magnetic moment. 1640:, and she was able to secure a new position in Sweden. The decisive experiment on 16–17 December 1938 (using a chemical process called "radium–barium–mesothorium 799:

process. Apparently, an electron could not be confined within a nucleus by any potential well. The meaning of this paradox was intensely debated at the time.

5960: 1002:, Chadwick quickly performed a series of experiments showing that the gamma ray hypothesis was untenable. The previous year, Chadwick, J.E.R. Constable, and 795:, this clear and precise paradox suggested that an electron approaching a high potential barrier has a high probability of passing through the barrier by a 3771: 1989: 1493:

had independently deduced that the magnetic moment of the neutron was negative and unexpectedly large by measuring the magnetic moments of the proton and

5061: 618:

About the time of Rutherford's lecture, other publications appeared with similar suggestions of a proton–electron composite in the nucleus, and in 1921

216:

rays, which possessed even more penetrating power. These radiations were soon identified with known particles: beta rays were shown to be electrons by

6024: 5697: 6059: 5741: 4895: 1585:

that he was originally planning to put a piece of lead there, but an inexplicable, intuitive feeling made him put a paraffin in the spot instead.

5991: 1142:

The question of whether the neutron was a composite particle of a proton and an electron persisted for a few years after its discovery. In 1932

759:

molecules. While the lines for both diatomic molecules showed alternation in intensity between light and dark, the pattern of alternation for H

1652:. By January 1939 Hahn had concluded that what they had thought were transuranic nuclides were instead much lighter nuclides, such as barium, 6235: 5775: 5650: 838: 3279:

During the 1920s physicists came to accept the view that matter is built of only two kinds of elementary particles, electrons and protons.

775:

showed that the hydrogen nuclei obey Fermi statistics and the nitrogen nuclei obey Bose statistics. However, a then unpublished result of

5663: 1575:"for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of 1573:

for interaction with nuclei is much larger for slow neutrons than for fast neutrons. In 1938 Fermi received the Nobel Prize in Physics

462:

suggested that stars may obtain their energy by fusing hydrogen (protons) into helium and that the heavier elements may form in stars.

5724: 3032:

Harkins, William (1921). "The constitution and stability of atomic nuclei. (A contribution to the subject of inorganic evolution.)".

947:. The radiation was more penetrating than any gamma rays known, and the details of experimental results were difficult to interpret. 1234:

resolved the issue by reporting the first accurate measurement of the mass of the neutron. They used the 2.6 MeV gamma rays of

6034: 5948: 845:

While all these considerations did not "prove" an electron could not exist in the nucleus, they were confusing and challenging for

791:

in 1928, presented further quantum mechanical objections to the notion of an electron confined within a nucleus. Derived from the

158:

At the start of the 20th century, the vigorous debate as to the existence of atoms had not yet been resolved. Philosophers such as

3206: 721:, but no such effects were observed. It seemed that the magnetic moment of the electron vanished when it was within the nucleus. 6169: 6095: 3541:

Bothe, W.; Becker, H. (1930). "Künstliche Erregung von Kern-γ-Strahlen" [Artificial excitation of nuclear γ-radiation].

1562:

with the emission of an alpha particle. Feather was therefore the first to show that neutrons produce nuclear disintegrations.

751:

in 1929 were inconsistent with the statistics expected from the proton–electron hypothesis. Rasetti obtained band spectra for H

3586:

Becker, H.; Bothe, W. (1932). "Die in Bor und Beryllium erregten γ-Strahlen" [Γ-rays excited in boron and beryllium].

104:

had been identified as the charge on the nucleus. Throughout the 1920s, the nucleus was viewed as composed of combinations of

6090: 5491: 5448: 5373: 5130: 4270: 3497: 3149: 2321: 2270: 2236: 2194: 1999: 1030:" for nuclear physics in the Cavendish Laboratory, with discoveries of the neutron, artificial nuclear disintegration by the 1644:") produced puzzling results: what they had understood to be three isotopes of radium were instead consistently behaving as 6102: 5847: 5814: 802:

By about 1930 it was generally recognized that it was difficult to reconcile the proton–electron model for nuclei with the

5425:. Guide to the Enrico Fermi Collection, Special Collections Research Center, University of Chicago Library. Archived from 6192: 6159: 5418: 485:, was not half of the atomic weight for elements, but instead was exactly equal to the element's ordinal position in the 5965: 5402: 5004: 4582: 4532: 4161: 3861: 3731: 3451: 3356:

Klein, O. (1929). "Die Reflexion von Elektronen an einem Potentialsprung nach der relativistischen Dynamik von Dirac".

3313: 3174: 2891: 2779: 2412: 2137: 2091: 1933: 351:

was studying chemistry related problems on radioactive materials. Soddy had worked with Rutherford on radioactivity at

284:

shows beta decay of a free neutron as it is understood today; an electron and antineutrino are created in this process.

6323: 6305: 5862: 5837: 5712: 5702: 5692: 5188:

Chandrasekhar, S., Enrico Fermi: Collected Papers (Chicago: University of Chicago Press, 1962), Vol. II, pp. 926-927.

4905: 4612: 3687: 3341: 3211: 2822: 2755: 2631: 2294: 368:. For his study of radioactivity and the discovery of isotopes, Soddy was awarded the 1921 Nobel Prize in Chemistry. 242: 3635:[Emission of high-speed protons by hydrogenated substances under the influence of very penetrating γ-rays]. 3633:"Émission de protons de grande vitesse par les substances hydrogénées sous l'influence des rayons γ très pénétrants" 359:, had been identified between uranium and lead, although the periodic table only allowed for 11 elements. Soddy and 6042: 5753: 5643: 3920: 1715: 2501: 2456: 2381: 5998: 5936: 5770: 5736: 5333: 3779: 1724:

to the United States. Large numbers of scientists were migrating to the United States to escape the troubles and

803: 569: 5095: 3703: 2795: 6287: 6252: 5867: 5765: 4123: 4115: 2597: 2066: 1745: 1031: 1019:

matched the properties Rutherford described in 1920 and which had later been called neutrons. Chadwick won the

676:

Rutherford's conjecture and the hypothetical "neutron" were not widely accepted. In his 1931 monograph on the

5073: 1767:

The discoveries of the neutron and positron in 1932 were the start of the discoveries of many new particles.

6174: 5955: 5921: 5874: 2799: 1533:) in the courtyard of Rome University's Physics Institute in Via Panisperna, about 1934. From Left to right: 305: 57: 208:, which differed in their ability to penetrate, or travel into, ordinary objects or gases. Two years later, 5943: 5916: 5894: 5852: 5748: 1720:

The discovery of nuclear fission at the end of 1938 marked a shift in the centers of nuclear research from

1467: 780:

concluded: "the electron in the nucleus ... loses its ability to determine the statistics of the nucleus."

442:, which he took to have a mass of exactly 16. (Today the whole-number rule is expressed in multiples of an 364:

places in the periodic system are chemically identical. Soddy called these chemically identical elements

166:

denied that atoms were real, viewing them as a convenient mathematical construct, while scientists such as

1195:. In Chadwick's 1932 paper reporting on the discovery, he estimated the mass of the neutron to be between 6217: 6187: 5970: 5931: 5879: 5636: 217: 1787:

were discovered. A classification scheme for organizing all these particles, proposed independently by

6047: 5909: 5799: 5719: 4971: 1582: 1519: 3902: 580: 6154: 6123: 6003: 5899: 5794: 3513: 1800: 1209:. By bombarding boron with alpha particles, Frédéric and Irène Joliot-Curie obtained a high value of 4732: 4684: 4047: 4002: 3957: 3588: 3543: 3358: 2844: 6179: 6008: 5926: 5904: 5758: 5588:

Gell, Y.; Lichtenberg, D. B. (1969). "Quark model and the magnetic moments of proton and neutron".

1685: 493: 289: 4922: 3405: 2444:. London, England: J. M. Dent & Sons, p. 141. (Cameron also anticipated the displacement law.) 6085: 5787: 5729: 5707: 5290: 1570: 1451: 740: 454: 116:

known at the time, but that model presented several experimental and theoretical contradictions.

3632: 2262: 2256: 1736:). The new centers of nuclear research were the universities in the United States, particularly 328:

for electrons orbiting the nucleus in 1913 and this eventually lead to an atomic model based on

6300:, William R. Shea, ed. Dordrecht, Holland: D. Riedel Publishing Company. pp. 19–67, 1983. 4153: 3105: 3067: 3034: 2930: 2695: 2487: 2346: 1958: 1875:. Such a momentum implies that the electron has a (relativistic) kinetic energy of about 40MeV. 1863:

in the order of 5×10cm, the uncertainty principle would require an electron to have a momentum

1703: 1681: 1178: 1094: 1020: 995: 834: 517:

line, was related to the element's position in the periodic table, that is, its atomic number,

478: 127:

in 1932 and the determination that it was a new elementary particle, distinct from the proton.

93: 5365: 5359: 3305: 3297: 1481:

that the proton had an anomalously large magnetic moment. By 1934 groups led by Stern, now in

6080: 6075: 6029: 5886: 5685: 1953: 1783:

were discovered in 1950. Throughout the 1950s and 1960s, a large number of particles called

1741: 1177:), then the neutron could be a proton-electron composite because of the mass defect from the 994:

at the Cavendish Laboratory also did not believe the gamma ray hypothesis since it failed to

348: 309: 4966: 4489:

Breit, G.; Rabi, I.I. (1934). "On the interpretation of present values of nuclear moments".

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to search for the neutron. The experiments continued throughout the 1920s without success.

5680: 5599: 5518: 5299: 5253: 5209: 5013: 4939: 4862: 4825: 4790: 4776: 4741: 4693: 4643: 4541: 4500: 4456: 4398: 4360: 4312: 4262: 4218: 4056: 4011: 3966: 3870: 3816: 3740: 3597: 3552: 3460: 3420: 3367: 3254: 3006: 2997: 2964: 2900: 2541: 2355: 2146: 2100: 1677: 1625: 964: 689: 666: 197: 33: 5545: 8: 6133: 5200: 5064:[Influence of hydrogenous substances on the radioactivity produced by neutrons]. 4728: 4680: 3136:. Sources in the History of Mathematics and Physical Sciences. Vol. 6. p. 105. 2022: 1737: 1534: 1530: 1243: 713: 113: 5603: 5522: 5303: 5257: 5213: 5017: 4943: 4866: 4851:

Rabi, I.I.; Kellogg, J.M.; Zacharias, J.R. (1934). "The magnetic moment of the deuton".

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Rabi, I.I.; Kellogg, J.M.; Zacharias, J.R. (1934). "The magnetic moment of the proton".

4794: 4745: 4697: 4647: 4545: 4504: 4460: 4402: 4364: 4316: 4266: 4222: 4060: 4015: 3970: 3874: 3820: 3744: 3601: 3556: 3464: 3424: 3371: 3258: 3010: 2968: 2904: 2845:"This Month in Physics History: May 1932: Chadwick reports the discovery of the neutron" 2545: 2359: 2185:

Stuewer, Roger H. (1983). "The Nuclear Electron Hypothesis". In Shea, William R. (ed.).

2150: 2104: 1991:

Theoretical concepts in physics: an alternative view of theoretical reasoning in physics

1216:, while Ernest Lawrence's team at the University of California measured the small value 6311: 6128: 5809: 5659: 5615: 5590: 5391: 5315: 5269: 5239: 4757: 4709: 4661: 4330: 4146: 4072: 4027: 3982: 3834: 3613: 3568: 3383: 3270: 2672: 2664: 2620: 2567: 2225: 1922: 976: 744: 725: 541: 224:

in 1907; and gamma rays were shown to be electromagnetic radiation, that is, a form of

5530: 5221: 2338: 662:

in connection with the atom can be found in the literature as early as 1899, however.

394:

at the Cavendish Laboratory in 1919. He was able then to separate the two isotopes of

6319: 6301: 6283: 6266: 6248: 6236:

Annotated bibliography for neutrons from the Alsos Digital Library for Nuclear Issues

6199: 6118: 5804: 5782: 5672: 5619: 5487: 5480: 5398: 5369: 5167: 5136: 5126: 5119: 4901: 4761: 4713: 4608: 4602: 4578: 4571: 4157: 4141: 4119: 4111: 4076: 4031: 3986: 3683: 3617: 3572: 3493: 3387: 3337: 3309: 3274: 3170: 3145: 2775: 2751: 2729: 2723: 2676: 2627: 2593: 2559: 2408: 2317: 2290: 2266: 2232: 2190: 2062: 1995: 1929: 1753: 1486: 1231: 1151: 1059: 1003: 702: 506: 505:

the periodic table. In 1913–1914 Moseley tested the question experimentally by using

435: 391: 376: 352: 329: 193: 167: 119:

The essential nature of the atomic nucleus was established with the discovery of the

49: 5319: 2571: 1046: 371: 6338: 6293: 6138: 5607: 5526: 5355: 5307: 5273: 5261: 5244: 5217: 5049: 5021: 4947: 4870: 4833: 4798: 4749: 4701: 4665: 4651: 4634: 4549: 4508: 4464: 4406: 4368: 4334: 4320: 4303: 4226: 4064: 4019: 3974: 3878: 3838: 3824: 3807: 3748: 3605: 3560: 3468: 3428: 3375: 3262: 3137: 3114: 3076: 3043: 3014: 2972: 2908: 2704: 2656: 2549: 2532: 2363: 2154: 2108: 2027: 1963: 1788: 1621: 1576: 1167: 1121: 772: 733: 630:

was adopted for the hydrogen nucleus. Neutron was apparently constructed from the

595: 525: 471: 459: 443: 360: 171: 85: 53: 5456: 3706:. American Institute of Physics, Niels Bohr Library and Archives. 25 February 1971 6275: 6258: 5509: 5242:(1939). "Disintegration of Uranium by Neutrons: A New Type of Nuclear Reaction". 4930: 4853: 4781: 4491: 4447: 4209: 3134:

Wolfgang Pauli Wissenschaftlicher Briefwechsel mit Bohr, Einstein, Heisenberg u.a

2955: 1669: 1510: 1163: 1063: 1027: 980: 944: 796: 619: 529: 344: 189: 185: 163: 131: 73: 5628: 5057: 3656: 3141: 1538: 6164: 5826: 5567: 5053: 5045: 4891: 4348: 2524: 2477:

Aston, Francis William. Mass spectra and isotopes. London: Edward Arnold, 1942.

1757: 1711: 1661: 1649: 1555: 1546: 1542: 1239: 999: 991: 867: 792: 768: 748: 639: 545: 486: 386:

on the deflection of positively charged atoms by electric and magnetic fields,

341: 301: 297: 256: 236: 229: 143: 138:

atoms by neutrons (1938). The discovery of fission led to the creation of both

124: 77: 65: 45: 25: 5426: 4372: 3118: 3080: 3047: 3018: 2708: 2367: 1967: 1823:

Hans Bethe discusses Chadwick and Goldhaber's work on deuteron disintegration.

1822: 1816: 1604:. The heavy nuclide fragments into lighter components and additional neutrons. 728:

in 1928, Kronig learned of a surprising aspect of the rotational spectrum of N

6332: 5171: 4204: 3334:

The Age of Innocence: Nuclear Physics between the First and Second World Wars

3245: 1954:"The Scattering of α and β Particles by Matter and the Structure of the Atom" 1780: 1641: 1588: 1498: 1490: 1434: 1427: 1361: 1219: 1212: 1205: 1198: 1191: 1173: 1143: 950: 859: 784: 776: 718: 600: 497: 387: 383: 177: 139: 101: 97: 5140: 4951: 3432: 1525: 6240: 5235: 5041: 5026: 4999: 4874: 4837: 4802: 4554: 4527: 4512: 4468: 4230: 3883: 3856: 3753: 3726: 3660: 3473: 3446: 2977: 2950: 2913: 2886: 2563: 2159: 2132: 2113: 2086: 1792: 1729: 1725: 1668:

immediately and correctly interpreted these observations as resulting from

1633: 1629: 1613: 1514: 1459: 1455: 1159: 1090: 984: 968: 709: 681: 549: 548:

was interned in Germany for the duration of the war, 1914–1918. In Berlin,

221: 209: 6270: 4604:

Lawrence and his Laboratory: A History of the Lawrence Berkeley Laboratory

1648:. Radium (atomic number 88) and barium (atomic number 56) are in the same 1365:). The neutron's mass could then be determined by the simple mass balance 767:. After carefully analyzing these experimental results, German physicists 524:

Within a year it was noted that the equation for the relation, now called

438:, that the masses of all the particles have whole number relationships to 5062:"Azione di sostanze idrogenate sulla radioattività provocata da neutroni" 1796: 1665: 1601: 1255: 788: 665:

Rutherford and Chadwick immediately began an experimental program at the

612: 537: 293: 89: 61: 5155: 5040: 1497:. Values for the magnetic moment of the neutron were also determined by 5611: 5311: 4753: 4705: 4294: 4068: 4023: 3978: 3609: 3564: 3379: 2733: 2590:

H.G.J. Moseley: The Life and Letters of an English Physicist, 1887–1915

1760:, exploiting the enormous energy released by the fission of uranium or 1749: 1482: 1474: 1439: 1306: 1155: 1150:

The nature of the neutron was a primary topic of discussion at the 7th

589: 510: 501: 325: 321: 159: 4410: 3447:"Bakerian Lecture – A new mass-spectrograph and the whole number rule" 3266: 2668: 2488:"Atomic Weights and the International Committee — A Historical Review" 536:

Further research in atomic physics was interrupted by the outbreak of

21: 5568:"An SU(3) Model for Strong Interaction Symmetry and its Breaking: II" 5449:"Fermi at Columbia: The Manhattan Project and the First Nuclear Pile" 5423:

The University of Chicago Library: Digital Activities and Collections

5265: 4656: 4629: 4325: 4298: 4152:. Bristol and Philadelphia: Institute of Physics Publishing. p. 3829: 3802: 2554: 2031: 1761: 1698: 1653: 1637: 1617: 1506: 1502: 1463: 1281: 1224: 875: 846: 670: 608: 557: 553: 447: 439: 252: 213: 201: 16:

Scientific background leading to the discovery of subatomic particles

4630:"A nuclear photo-effect: disintegration of the diplon by gamma rays" 3100: 3062: 2928:

Rutherford, E. (1919). "Collision of α particles with light atoms".

2690: 2502:"The Nobel Prize in Chemistry 1922: Francis W. Aston – Biographical" 2426:

Others had also suggested the possibility of isotopes; for example:

2189:. Dordrecht, Holland: D. Riedel Publishing Company. pp. 19–67. 1744:

where Enrico Fermi had relocated, and a secret research facility at

44:

and its properties was central to the extraordinary developments in

3630: 2849: 2660: 2457:"The Nobel Prize in Chemistry 1921: Frederick Soddy – Biographical" 2020:

Squires, Gordon (1998). "Francis Aston and the mass spectrograph".

1494: 1235: 1102: 1035: 972: 871: 648: 365: 355:. By 1910, about 40 different radioactive elements, referred to as 314: 247: 220:

in 1902; alpha rays were shown to be helium ions by Rutherford and

205: 109: 2772:

Quantum Generations: A History of Physics in the Twentieth Century

2382:"The Nobel Prize in Chemistry 1921 – Frederick Soddy Biographical" 1817:

Ernest Rutherford summarizes the state of nuclear physics in 1935.

1596: 1134: 5546:"An SU(3) Model for Strong Interaction Symmetry and its Breaking" 5507:

Gell-Mann, M. (1964). "A Schematic Model of Baryons and Mesons".

4445:

Kurie, F.N.D. (1933). "The Collisions of Neutrons with Protons".

4183:

Iwanenko, D. (1932). "Sur la constitution des noyaux atomiques".

3063:"Attempts to detect the presence of neutrons in a discharge tube" 1478: 1332: 1068: 921: 863: 565: 514: 513:

line in the X-ray spectrum of a particular element, known as the

340:

Concurrent with the work of Rutherford, Geiger, and Marsden, the

320:

While the Rutherford model was largely ignored at the time, when

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Feather, N. (1960). "A history of neutrons and nuclei. Part 1".

3132:

Pauli, W. (1985). "Das Jahr 1932 die Entdeckung des Neutrons".

1847: 1843: 1784: 1721: 1657: 1645: 1609: 1106: 1016: 695: 654: 181: 105: 5096:"The Nobel Prize in Physics 1938: Enrico Fermi – Biographical" 1702:

The first atomic bomb was exploded in the Manhattan Project's

5334:"The Nobel Prize in Chemistry 1944: Otto Hahn – Biographical" 3097:

of the word proton for the hydrogen nucleus in a footnote to

1804: 1559: 898: 631: 561: 225: 147: 48:

in the first half of the 20th century. Early in the century,

2403:

Choppin, Gregory; Liljenzin, Jan-Olov; Rydberg, Jan (2013),

237:

Gold foil experiment and the discovery of the atomic nucleus

174:

saw that physical theories required the existence of atoms.

28:

at the 1933 Solvay Conference. Chadwick had discovered the

3680:

The Neutron and the Bomb: A Biography of Sir James Chadwick

1776: 1772: 1768: 1756:. This wartime project was focussed on the construction of 1566: 1166:, Fermi, Chadwick, and others. As posed by Chadwick in his 395: 69: 4045:

Heisenberg, W. (1933). "Über den Bau der Atomkerne. III".

3778:. American Institute of Physics. 2011–2014. Archived from 1689:"for his discovery of the fission of heavy atomic nuclei." 300:

in a series of experiments to determine what happens when

5361:

Hitler's uranium club: the secret recordings at Farm Hall

4000:

Heisenberg, W. (1932). "Über den Bau der Atomkerne. II".

481:

boldly hypothesized that the required charge, denoted by

4389:

Wilson, Fred L. (1968). "Fermi's Theory of Beta Decay".

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Biographical Memoirs of the National Academy of Sciences

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Heisenberg, W. (1932). "Über den Bau der Atomkerne. I".

3724: 2314:

Inward bound: of matter and forces in the physical world

622:, an American chemist, named the uncharged particle the 3725:

Chadwick, J.; Constable, J.E.R.; Pollard, E.C. (1931).

2647:

Heilbron, John (1966), "The Work of H. G. J. Moseley",

2402: 1592:

Lise Meitner and Otto Hahn in their laboratory in 1913.

967:

in Paris showed that if this unknown radiation fell on

2622:

Niels Bohr's Times: In Physics, Philosophy, and Polity

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Iwanenko, D. (1932). "Neutronen und kernelektronen".

3638:

Comptes Rendus des Séances de l'Académie des Sciences

3243:

Brown, Laurie M. (1978). "The idea of the neutrino".

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Nuclear fission caused by absorption of a neutron by

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Friedlander, G.; Kennedy, J.W.; Miller, J.M. (1964)

2948: 2339:"On the Constitution of Atoms and Molecules, Part I" 5121:

Enrico Fermi: And the Revolutions in Modern physics

3704:"Oral History Interview: Norman Feather, Session I" 2261:, Addison Wesley, Reading, Massachusetts, pp. 2126: 2124: 6282:, Berkeley, University of California Press, 1996. 5479: 5390: 5118: 4570: 4207:; Condon, E.U. (1932). "The Spin of the Neutron". 4186:Comptes Rendus de l'Académie des Sciences de Paris 4145: 4135: 4133: 4131: 2802:, Niels Bohr Library and Archives. 31 October 1962 2619: 2307: 2305: 2224: 1921: 1126:in 1933 it was rejected as being too speculative. 564:technician near the Austrian front, while Hahn, a 465: 5658: 5354: 5000:"The Collisions of Neutrons with Nitrogen Nuclei" 4627: 2887:"Bakerian Lecture: Nuclear Constitution of Atoms" 2289:(illustrated ed.), Oxford University Press, 2130: 955:ionization chamber. Adapted from Chadwick (1932). 6330: 3487: 3406:"Nuclear Physics A. Stationary States of Nuclei" 2774:(Reprint ed.). Princeton University Press. 2287:Radioactivity: A History of a Mysterious Science 2121: 1994:. Cambridge University Press. pp. 377–378. 990:On hearing of the Paris results, Rutherford and 5587: 4890: 4139: 4128: 4110:, Cambridge University Press, Cambridge, 1995, 2796:"Oral History Interview: Niels Bohr, Session I" 2302: 2061:, Dover Publications, Mineola, New York, 2011, 1445: 678:Constitution of Atomic Nuclei and Radioactivity 5286: 3663:, 25 July 2006, Access date: 16 November 2017. 3631:Joliot-Curie, Irène; Joliot, Frédéric (1932). 3327: 3325: 3204: 2927: 2884: 2222: 1951: 1684:in March 1939. In 1945 Hahn received the 1944 1154:held in October 1933, attended by Heisenberg, 5644: 5506: 5500: 5234: 5198:Hahn, O. (1958). "The Discovery of Fission". 5153: 4964: 4774: 4726: 3169:, Bristol: Adam Hilger Ltd (published 1984), 3060: 2949:Urey, H.; Brickwedde, F.; Murphy, G. (1932). 2316:(Reprint ed.). Oxford: Clarendon Press 1987: 1097:, in which the neutron decays to a proton by 874:fell on certain light elements, specifically 153: 4562: 4293: 4203: 3896: 3894: 2990: 2988: 2691:"The High Frequency Spectra of the Elements" 2617: 2227:Lise Meitner and the dawn of the nuclear age 1947: 1945: 1680:and his team proved this phenomenon to be a 1026:The year 1932 was later referred to as the " 696:Problems of the nuclear electrons hypothesis 6265:, Publisher, North-Holland Pub. Co., 1966. 5559: 5537: 4997: 4678: 4148:The Origin of the Concept of Nuclear Forces 4108:Early Quantum Electrodynamics: A Sourcebook 3850: 3848: 3585: 3540: 3403: 3322: 3300:. In French, A. P.; Kennedy, P. J. (eds.). 2994: 2613: 2611: 2609: 2583: 2581: 1752:, established in 1942, the new home of the 1734:Jewish scientists and the Manhattan Project 1093:published his classic paper describing the 853: 509:techniques. He found that the most intense 324:joined Rutherford's group he developed the 292:between 1908 and 1913, Rutherford directed 5651: 5637: 4044: 3999: 3954: 3727:"Artificial disintegration by α-particles" 3291: 3289: 3287: 2015: 2013: 2011: 1230:In 1935 Chadwick and his doctoral student 200:distinguished two types of radioactivity, 92:had been determined to be (approximately) 6318:, The University of Chicago Press, 1997. 6298:Otto Hahn and the Rise of Nuclear Physics 6247:, Oxford: Oxford University Press, 1986. 5565: 5543: 5453:Columbia University Department of Physics 5382: 5191: 5025: 4886: 4884: 4655: 4553: 4488: 4427:Physikalische Zeitschrift der Sowjetunion 4384: 4382: 4324: 3945:(2nd edition), Wiley, pp. 22–23 and 38–39 3891: 3882: 3828: 3752: 3673: 3671: 3669: 3481: 3472: 3131: 2985: 2976: 2912: 2880: 2878: 2876: 2874: 2872: 2763: 2725:Moseley and the numbering of the elements 2553: 2522: 2187:Otto Hahn and the Rise of Nuclear Physics 2158: 2112: 2080: 2078: 2076: 2074: 1942: 6296:, "The Nuclear Electron Hypothesis". In 6263:Weak interactions and nuclear beta decay 5388: 4528:"The passage of neutrons through matter" 4484: 4482: 4480: 4478: 4423: 4182: 4089:Iwanenko, D.D., The neutron hypothesis, 3854: 3845: 3800: 3794: 3399: 3397: 3238: 3236: 3234: 3198: 3191: 3189: 3187: 3185: 2646: 2606: 2587: 2578: 2525:"The Internal Constitution of the Stars" 2336: 2084: 1697: 1595: 1587: 1524: 1133: 1129: 1101:an electron and a (as yet undiscovered) 1045: 949: 603:was electrons emitted from the nucleus. 579: 370: 335: 313:much larger cloud of negatively charged 304:scatter from metal foil. Now called the 246: 20: 5471: 4353:International Journal of Modern Physics 4243: 4178: 4176: 3438: 3331: 3295: 3284: 3054: 3031: 2837: 2820: 2721: 2688: 2254: 2250: 2248: 2184: 2180: 2178: 2176: 2174: 2172: 2170: 2053: 2051: 2049: 2047: 2045: 2043: 2041: 2019: 2008: 1915: 1913: 1911: 1764:through neutron-based chain reactions. 862:and his collaborator Herbert Becker in 6331: 5477: 5116: 5110: 4920: 4881: 4600: 4594: 4525: 4519: 4388: 4379: 3666: 3164: 3098: 3093:Rutherford reported acceptance by the 2869: 2284: 2278: 2218: 2216: 2214: 2212: 2210: 2208: 2206: 2071: 1909: 1907: 1905: 1903: 1901: 1899: 1897: 1895: 1893: 1891: 1842:The atomic number and atomic mass for 1105:. The paper employed the analogy that 866:, Germany found that if the energetic 712:pointed out in 1926 that the observed 5632: 5125:. New York: Oxford University Press. 4475: 4444: 4438: 3766: 3764: 3696: 3677: 3444: 3394: 3355: 3304:. Harvard University Press. pp. 3242: 3231: 3182: 2769: 2750:(8th ed.), Courier Corporation, 2374: 2330: 1032:Cockcroft–Walton particle accelerator 806:of quantum mechanics. This relation, 575: 6103:Noisy intermediate-scale quantum era 5197: 4965:Tamm, I.Y.; Altshuler, S.A. (1934). 4844: 4809: 4628:Chadwick, J.; Goldhaber, M. (1934). 4568: 4347: 4173: 3488:Kenneth S. Krane (5 November 1987). 2745: 2431:Zeitschrift für anorganischen Chemie 2405:Radiochemistry and Nuclear Chemistry 2311: 2245: 2167: 2131:Chadwick, J.; Goldhaber, M. (1935). 2038: 1919: 1829: 732:. The precision measurement made by 540:. Moseley was killed in 1915 at the 4991: 4768: 4720: 3900: 3657:Ettore Majorana: genius and mystery 3158: 2921: 2437:: 197–206; see especially page 206. 2258:Introduction to High Energy Physics 2203: 1928:. Oxford: Oxford University Press. 1888: 1850:they are respectively 28 and 58.68. 1846:are respectively 27 and 58.97, for 1042:Proton–neutron model of the nucleus 13: 6229: 5486:. New York: Simon & Schuster. 5005:Proceedings of the Royal Society A 4958: 4914: 4672: 4607:. University of California Press. 4577:. University of California Press. 4533:Proceedings of the Royal Society A 4351:(2012). "Fermi's β-Decay Theory". 3935: 3862:Proceedings of the Royal Society A 3761: 3732:Proceedings of the Royal Society A 3452:Proceedings of the Royal Society A 2892:Proceedings of the Royal Society A 2592:. University of California Press. 2440:Cameron, Alexander Thomas (1910). 2231:. Basel, Switzerland: Birkhäuser. 2138:Proceedings of the Royal Society A 2092:Proceedings of the Royal Society A 14: 6350: 5222:10.1038/scientificamerican0258-76 3803:"Possible Existence of a Neutron" 3514:"The Nobel Prize in Physics 1954" 3212:New Scientist and Science Journal 3167:Cambridge Physics in the Thirties 3101:"XXIV. The constitution of atoms" 2821:Reynosa, Peter (7 January 2016). 243:Rutherford scattering experiments 68:. In this model, atoms had their 32:the year before while working at 6213: 6212: 5581: 5441: 5411: 5364:. New York: Copernicus. p. 5348: 5326: 5280: 5228: 4967:"Magnetic Moment of the Neutron" 4775:Esterman, I.; Stern, O. (1934). 4727:Esterman, I.; Stern, O. (1933). 4168:heisenberg proton neutron model. 3298:"Niels Bohr and Nuclear Physics" 3165:Hendry, John, ed. (1984-01-01), 2407:(4th ed.), Academic Press, 2133:"A nuclear photoelectric effect" 1716:Timeline of particle discoveries 1620:, together with their assistant 1138:Seventh Solvay Conference, 1933. 692:were unaware of the conjecture. 626:. About that same time the word 6280:Lise Meitner: A Life in Physics 5393:Einstein: His Life and Universe 5182: 5147: 5088: 5034: 4777:"Magnetic moment of the deuton" 4621: 4573:Lise Meitner: A Life in Physics 4417: 4341: 4287: 4237: 4197: 4100: 4083: 4038: 3993: 3948: 3913: 3857:"Bakerian Lecture.–The Neutron" 3718: 3649: 3624: 3579: 3534: 3506: 3349: 3125: 3087: 3025: 2942: 2814: 2788: 2739: 2715: 2682: 2640: 2516: 2494: 2480: 2471: 2449: 2420: 2396: 1853: 1836: 1779:were discovered in 1947, while 1579:brought about by slow neutrons" 804:Heisenberg uncertainty relation 466:Atomic number and Moseley's law 306:Rutherford gold foil experiment 4679:Frisch, R.; Stern, O. (1933). 3404:Bethe, H.; Bacher, R. (1936), 3302:Niels Bohr: A Centenary Volume 2951:"A Hydrogen Isotope of Mass 2" 1981: 180:was discovered in 1896 by the 1: 5531:10.1016/S0031-9163(64)92001-3 5482:The Making of the Atomic Bomb 4359:(3, 4): 1230005-1–1230005-7. 2800:American Institute of Physics 2689:Moseley, Henry G. J. (1913). 1882: 1795:in 1964, became known as the 1693: 544:, while Rutherford's student 76:concentrated in a very small 4900:. Harvard University Press. 4246:"Robert F. Bacher 1905–2004" 3490:Introductory Nuclear Physics 2059:Neutrons, Nuclei, and Matter 1581:. Later, Fermi recounted to 1529:Fermi and his students (the 1468:Discovery of nuclear fission 1446:Neutron physics in the 1930s 1023:in 1935 for this discovery. 763:is opposite to that of the N 743:of diatomic molecules using 7: 6025:Cosmic microwave background 4998:Feather, N. (1 June 1932). 4897:Rabi, Scientist and Citizen 3901:Ley, Willy (October 1966). 3682:. Oxford University Press. 3336:, Oxford University Press, 3142:10.1007/978-3-540-78801-0_3 2626:. Oxford University Press. 2255:Perkins, Donald H. (1982), 1672:, a term coined by Frisch. 1369: 1250: 10: 6355: 5575:CERN Report No.8419/TH.412 5553:CERN Report No.8182/TH.401 5154:Chandrasekhar, S. (1984). 4972:Doklady Akademii Nauk SSSR 3943:Nuclear and Radiochemistry 3776:Rutherford's Nuclear World 3296:Stuewer, Roger H. (1985). 1962:. Series 6 (21): 669–688. 1771:were discovered in 1936. 1728:in Europe and the looming 1709: 1520:nuclear magnetic resonance 1449: 1054:Given the problems of the 658:). References to the word 594:In 1920 Rutherford gave a 587: 469: 240: 154:Discovery of radioactivity 56:of the atom, based on the 6208: 6147: 6111: 6068: 6017: 5981: 5825: 5671: 5389:Isaacson, Walter (2007). 4373:10.1142/S0217751X12300050 3413:Reviews of Modern Physics 3119:10.1080/14786442108636219 3081:10.1080/14786442108633801 3048:10.1080/14786442108633770 3019:10.1080/00107516008202611 2823:"An Ode to Henry Moseley" 2709:10.1080/14786441308635052 2523:Eddington, A. S. (1920). 2368:10.1080/14786441308634955 2285:Malley, Marjorie (2011), 1968:10.1080/14786440508637080 1810: 1664:. Meitner and her nephew 1238:-208 (Tl) (then known as 375:Replica of Aston's third 88:had been discovered, the 5478:Rhodes, Richard (1986). 5397:. Simon & Schuster. 5156:"The Pursuit of Science" 3905:. For Your Information. 3801:Chadwick, James (1932). 2588:Heilbron, J. L. (1974). 2087:"Existence of a Neutron" 2085:Chadwick, James (1932). 1825:(2 min., Web of Stories) 1819:(7 min., Nobelprize.org) 1686:Nobel Prize in Chemistry 854:Discovery of the neutron 741:rotational energy levels 611:, discovered in 1931 by 568:, worked on research in 494:University of Manchester 290:University of Manchester 74:positive electric charge 42:discovery of the neutron 6160:Chandrasekhar–Eddington 6086:Golden age of cosmology 6018:On specific discoveries 5966:Lorentz transformations 5291:Die Naturwissenschaften 4952:10.1103/PhysRev.43.1001 4526:Massey, H.S.W. (1932). 3903:"The Delayed Discovery" 3433:10.1103/RevModPhys.8.82 3332:Stuewer, Roger (2018), 3205:Crowther, J.G. (1971). 2885:Rutherford, E. (1920). 2722:Bernard, Jaffe (1971), 2223:Rife, Patricia (1999). 1952:Rutherford, E. (1911). 1859:In a nucleus of radius 1612:, the collaboration of 1452:Nucleon magnetic moment 590:Discovery of the proton 533:of the atomic nucleus. 455:mass-energy equivalence 434:. Aston discovered the 6091:Medieval Islamic world 5834:Computational physics 5776:Variational principles 5703:Electrical engineering 5066:La Ricerca Scientifica 5027:10.1098/rspa.1932.0113 4875:10.1103/PhysRev.46.163 4838:10.1103/PhysRev.46.157 4803:10.1103/PhysRev.45.739 4733:Zeitschrift für Physik 4685:Zeitschrift für Physik 4555:10.1098/rspa.1932.0195 4513:10.1103/PhysRev.46.230 4469:10.1103/PhysRev.44.463 4297:; Peierls, R. (1934). 4231:10.1103/PhysRev.41.683 4048:Zeitschrift für Physik 4003:Zeitschrift für Physik 3958:Zeitschrift für Physik 3907:Galaxy Science Fiction 3884:10.1098/rspa.1933.0152 3754:10.1098/rspa.1931.0017 3589:Zeitschrift für Physik 3544:Zeitschrift für Physik 3474:10.1098/rspa.1927.0106 3359:Zeitschrift für Physik 3207:"Rutherford the Great" 3106:Philosophical Magazine 3068:Philosophical Magazine 3061:Glasson, J.L. (1921). 3035:Philosophical Magazine 2978:10.1103/PhysRev.39.164 2931:Philosophical Magazine 2914:10.1098/rspa.1920.0040 2696:Philosophical Magazine 2347:Philosophical Magazine 2312:Pais, Abraham (2002). 2160:10.1098/rspa.1935.0162 2114:10.1098/rspa.1932.0112 1988:Longair, M.S. (2003). 1959:Philosophical Magazine 1920:Pais, Abraham (1986). 1707: 1605: 1593: 1550: 1179:nuclear binding energy 1139: 1051: 1021:Nobel Prize in Physics 956: 585: 479:Antonius van den Broek 382:Building from work by 379: 285: 37: 6081:Golden age of physics 6076:Copernican Revolution 5072:(7–8). Archived from 4921:Bacher, R.F. (1933). 4601:Seidel, R.W. (1989). 3855:Chadwick, J. (1933). 3445:Aston, F. W. (1927). 2770:Kragh, Helge (2002). 2618:Abraham Pais (1991). 1742:University of Chicago 1701: 1599: 1591: 1528: 1137: 1130:Nature of the neutron 1095:process of beta decay 1056:proton–electron model 1049: 953: 583: 374: 349:University of Glasgow 336:Discovery of isotopes 250: 192:materials. In 1898, 188:, while working with 24: 6184:Relativity priority 6039:Subatomic particles 5999:Loop quantum gravity 5988:Quantum information 5937:Quantum field theory 5737:Gravitational theory 5419:"About Enrico Fermi" 5117:Cooper, Dan (1999). 4244:Whaling, W. (2009). 2998:Contemporary Physics 1740:in New York and the 739:Observations of the 724:While on a visit to 667:Cavendish Laboratory 228:, by Rutherford and 198:Cavendish Laboratory 114:elementary particles 58:gold foil experiment 34:Cavendish Laboratory 6148:Scientific disputes 6134:Via Panisperna boys 6035:Gravitational waves 5982:Recent developments 5713:Maxwell's equations 5604:1969NCimA..61...27G 5523:1964PhL.....8..214G 5429:on 26 November 2012 5304:1939NW.....27...89H 5258:1939Natur.143..239M 5214:1958SciAm.198b..76H 5201:Scientific American 5018:1932RSPSA.136..709F 4944:1933PhRv...43.1001B 4867:1934PhRv...46..163R 4830:1934PhRv...46..157R 4795:1934PhRv...45..739S 4746:1933ZPhy...85...17E 4698:1933ZPhy...85....4F 4648:1934Natur.134..237C 4569:Sime, R.L. (1996). 4546:1932RSPSA.138..460M 4505:1934PhRv...46..230B 4461:1933PhRv...44..463K 4403:1968AmJPh..36.1150W 4365:2012IJMPA..2730005Y 4317:1934Natur.133..532B 4267:2009BMNAS2009....1W 4223:1932PhRv...41..683G 4061:1933ZPhy...80..587H 4016:1932ZPhy...78..156H 3971:1932ZPhy...77....1H 3909:. pp. 116–127. 3875:1933RSPSA.142....1C 3821:1932Natur.129Q.312C 3745:1931RSPSA.130..463C 3602:1932ZPhy...76..421B 3557:1930ZPhy...66..289B 3465:1927RSPSA.115..487A 3425:1936RvMP....8...82B 3372:1929ZPhy...53..157K 3259:1978PhT....31i..23B 3099:Masson, O. (1921). 3095:British Association 3011:1960ConPh...1..191F 2969:1932PhRv...39..164U 2905:1920RSPSA..97..374R 2546:1920Natur.106...14E 2360:1913PMag...26....1B 2151:1935RSPSA.151..479C 2105:1932RSPSA.136..692C 2023:Dalton Transactions 1738:Columbia University 1531:Via Panisperna boys 714:hyperfine structure 542:Battle of Gallipoli 96:of the mass of the 6312:Sin-Itiro Tomonaga 6193:General relativity 6188:Special relativity 6129:Oxford Calculators 5956:Special relativity 5875:General relativity 5660:History of physics 5612:10.1007/BF02760010 5591:Il Nuovo Cimento A 5566:Zweig, G. (1964). 5544:Zweig, G. (1964). 5459:on 29 October 2017 5312:10.1007/BF01488988 4754:10.1007/BF01330774 4706:10.1007/bf01330773 4069:10.1007/BF01335696 4024:10.1007/BF01337585 3979:10.1007/BF01342433 3923:. Nobel Foundation 3782:on 21 October 2014 3678:Brown, A. (1997). 3610:10.1007/BF01336726 3565:10.1007/BF01390908 3380:10.1007/BF01339716 2746:Born, Max (2013), 2703:(156): 1024–1034. 2490:. 26 January 2004. 1708: 1606: 1594: 1551: 1140: 1052: 977:Compton scattering 961:Irène Joliot-Curie 957: 745:Raman spectroscopy 726:Utrecht University 686:Irène Joliot-Curie 586: 576:Rutherford nucleus 570:poison gas warfare 500:discussed the new 446:(amu) relative to 380: 332:by the mid-1920s. 286: 257:nucleus of an atom 52:developed a crude 38: 6316:The Story of Spin 6226: 6225: 6200:Transfermium Wars 6119:Harvard Computers 5944:Subatomic physics 5917:Quantum mechanics 5853:Superconductivity 5844:Condensed matter 5673:Classical physics 5493:978-0-671-44133-3 5375:978-0-387-95089-1 5356:Bernstein, Jeremy 5132:978-0-19-511762-2 5076:on 17 August 2021 4789:(10): 761(A109). 4642:(3381): 237–238. 4411:10.1119/1.1974382 4397:(12): 1150–1160. 4311:(3362): 532–533. 4055:(9–10): 587–596. 3499:978-0-471-80553-3 3267:10.1063/1.2995181 3151:978-3-540-13609-5 2825:. Huffington Post 2337:Bohr, N. (1913). 2323:978-0-19-851997-3 2272:978-0-201-05757-7 2238:978-0-8176-3732-3 2196:978-90-277-1584-5 2026:(23): 3893–3900. 2001:978-0-521-52878-8 1830:Explanatory notes 1754:Manhattan project 1577:nuclear reactions 1412: 1411: 1358:2.1 MeV, or 1353: 1352: 1244:photodisintegrate 1232:Maurice Goldhaber 1152:Solvay Conference 1071:quantum numbers. 1060:Werner Heisenberg 1007:alpha particles: 703:elementary charge 646:(by imitation of 584:Ernest Rutherford 507:X-ray diffraction 453:Since Einstein's 436:whole number rule 392:mass spectrograph 377:mass spectrometer 353:McGill University 330:quantum mechanics 194:Ernest Rutherford 168:Arnold Sommerfeld 94:integer multiples 86:chemical elements 50:Ernest Rutherford 6346: 6294:Roger H. Stuewer 6216: 6215: 6139:Women in physics 5891:Nuclear physics 5815:Perpetual motion 5749:Material science 5693:Electromagnetism 5653: 5646: 5639: 5630: 5629: 5624: 5623: 5585: 5579: 5578: 5572: 5563: 5557: 5556: 5550: 5541: 5535: 5534: 5504: 5498: 5497: 5485: 5475: 5469: 5468: 5466: 5464: 5455:. Archived from 5445: 5439: 5438: 5436: 5434: 5415: 5409: 5408: 5396: 5386: 5380: 5379: 5352: 5346: 5345: 5343: 5341: 5336:. Nobelprize.org 5330: 5324: 5323: 5284: 5278: 5277: 5266:10.1038/143239a0 5232: 5226: 5225: 5195: 5189: 5186: 5180: 5179: 5166:(3/4): 410–420. 5151: 5145: 5144: 5124: 5114: 5108: 5107: 5105: 5103: 5098:. Nobelprize.org 5092: 5086: 5085: 5083: 5081: 5060:(October 1934). 5038: 5032: 5031: 5029: 5012:(830): 709–727. 4995: 4989: 4988: 4986: 4984: 4962: 4956: 4955: 4927: 4918: 4912: 4911: 4888: 4879: 4878: 4848: 4842: 4841: 4813: 4807: 4806: 4772: 4766: 4765: 4724: 4718: 4717: 4676: 4670: 4669: 4659: 4657:10.1038/134237a0 4625: 4619: 4618: 4598: 4592: 4591: 4576: 4566: 4560: 4559: 4557: 4540:(835): 460–469. 4523: 4517: 4516: 4486: 4473: 4472: 4442: 4436: 4435: 4421: 4415: 4414: 4386: 4377: 4376: 4345: 4339: 4338: 4328: 4326:10.1038/133532a0 4291: 4285: 4284: 4282: 4281: 4275: 4269:. Archived from 4250: 4241: 4235: 4234: 4201: 4195: 4194: 4180: 4171: 4170: 4151: 4137: 4126: 4104: 4098: 4087: 4081: 4080: 4042: 4036: 4035: 4010:(3–4): 156–164. 3997: 3991: 3990: 3952: 3946: 3939: 3933: 3932: 3930: 3928: 3917: 3911: 3910: 3898: 3889: 3888: 3886: 3852: 3843: 3842: 3832: 3830:10.1038/129312a0 3798: 3792: 3791: 3789: 3787: 3768: 3759: 3758: 3756: 3739:(814): 463–489. 3722: 3716: 3715: 3713: 3711: 3700: 3694: 3693: 3675: 3664: 3653: 3647: 3646: 3628: 3622: 3621: 3583: 3577: 3576: 3538: 3532: 3531: 3526: 3524: 3510: 3504: 3503: 3485: 3479: 3478: 3476: 3459:(772): 487–514. 3442: 3436: 3435: 3410: 3401: 3392: 3391: 3353: 3347: 3346: 3329: 3320: 3319: 3293: 3282: 3281: 3240: 3229: 3228: 3226: 3224: 3202: 3196: 3193: 3180: 3179: 3162: 3156: 3155: 3129: 3123: 3122: 3113:(242): 281–285. 3091: 3085: 3084: 3058: 3052: 3051: 3029: 3023: 3022: 2992: 2983: 2982: 2980: 2946: 2940: 2939: 2925: 2919: 2918: 2916: 2899:(686): 374–400. 2882: 2867: 2866: 2864: 2862: 2841: 2835: 2834: 2832: 2830: 2818: 2812: 2811: 2809: 2807: 2792: 2786: 2785: 2767: 2761: 2760: 2743: 2737: 2736: 2719: 2713: 2712: 2686: 2680: 2679: 2644: 2638: 2637: 2625: 2615: 2604: 2603: 2585: 2576: 2575: 2557: 2555:10.1038/106014a0 2540:(2653): 233–40. 2529: 2520: 2514: 2513: 2511: 2509: 2504:. Nobelprize.org 2498: 2492: 2491: 2484: 2478: 2475: 2469: 2468: 2466: 2464: 2459:. Nobelprize.org 2453: 2447: 2424: 2418: 2417: 2400: 2394: 2393: 2391: 2389: 2384:. Nobelprize.org 2378: 2372: 2371: 2343: 2334: 2328: 2327: 2309: 2300: 2299: 2282: 2276: 2275: 2252: 2243: 2242: 2230: 2220: 2201: 2200: 2182: 2165: 2164: 2162: 2145:(873): 479–493. 2128: 2119: 2118: 2116: 2099:(830): 692–708. 2082: 2069: 2055: 2036: 2035: 2032:10.1039/a804629h 2017: 2006: 2005: 1985: 1979: 1978: 1976: 1974: 1949: 1940: 1939: 1927: 1917: 1876: 1867:of the order of 1857: 1851: 1840: 1789:Murray Gell-Mann 1781:lambda particles 1622:Fritz Strassmann 1535:Oscar D'Agostino 1437: 1430: 1370: 1364: 1349: 1347: 1346: 1339: 1338: 1324: 1322: 1321: 1314: 1313: 1298: 1296: 1295: 1288: 1287: 1273: 1271: 1270: 1263: 1262: 1251: 1223:using their new 1222: 1215: 1208: 1201: 1194: 1189: 1176: 1168:Bakerian Lecture 1118: 1117: 1113: 1084: 1083: 1079: 1013: 1010: 959:Two years later 942: 941: 940: 933: 932: 919: 918: 917: 910: 909: 896: 895: 894: 887: 886: 829: 825: 824: 820: 787:, discovered by 773:Gerhard Herzberg 734:Leonard Ornstein 596:Bakerian lecture 511:short-wavelength 460:Arthur Eddington 444:atomic mass unit 433: 432: 431: 424: 423: 415: 414: 413: 406: 405: 390:built the first 361:Kazimierz Fajans 276: 275: 274: 267: 266: 172:Ludwig Boltzmann 6354: 6353: 6349: 6348: 6347: 6345: 6344: 6343: 6329: 6328: 6276:Ruth Lewin Sime 6259:Herwig Schopper 6232: 6230:Further reading 6227: 6222: 6204: 6175:Joule–von Mayer 6143: 6107: 6064: 6013: 5977: 5868:Big Bang theory 5821: 5720:Fluid mechanics 5667: 5657: 5627: 5586: 5582: 5570: 5564: 5560: 5548: 5542: 5538: 5510:Physics Letters 5505: 5501: 5494: 5476: 5472: 5462: 5460: 5447: 5446: 5442: 5432: 5430: 5417: 5416: 5412: 5405: 5387: 5383: 5376: 5353: 5349: 5339: 5337: 5332: 5331: 5327: 5285: 5281: 5233: 5229: 5196: 5192: 5187: 5183: 5152: 5148: 5133: 5115: 5111: 5101: 5099: 5094: 5093: 5089: 5079: 5077: 5039: 5035: 4996: 4992: 4982: 4980: 4963: 4959: 4931:Physical Review 4925: 4919: 4915: 4908: 4892:Rigden, John S. 4889: 4882: 4854:Physical Review 4849: 4845: 4818:Physical Review 4814: 4810: 4782:Physical Review 4773: 4769: 4725: 4721: 4677: 4673: 4626: 4622: 4615: 4599: 4595: 4585: 4567: 4563: 4524: 4520: 4492:Physical Review 4487: 4476: 4448:Physical Review 4443: 4439: 4422: 4418: 4387: 4380: 4349:Yang, Chen Ning 4346: 4342: 4292: 4288: 4279: 4277: 4273: 4248: 4242: 4238: 4210:Physical Review 4202: 4198: 4181: 4174: 4164: 4138: 4129: 4105: 4101: 4088: 4084: 4043: 4039: 3998: 3994: 3953: 3949: 3940: 3936: 3926: 3924: 3919: 3918: 3914: 3899: 3892: 3853: 3846: 3799: 3795: 3785: 3783: 3770: 3769: 3762: 3723: 3719: 3709: 3707: 3702: 3701: 3697: 3690: 3676: 3667: 3654: 3650: 3629: 3625: 3584: 3580: 3539: 3535: 3522: 3520: 3512: 3511: 3507: 3500: 3486: 3482: 3443: 3439: 3408: 3402: 3395: 3354: 3350: 3344: 3330: 3323: 3316: 3294: 3285: 3241: 3232: 3222: 3220: 3203: 3199: 3194: 3183: 3177: 3163: 3159: 3152: 3130: 3126: 3092: 3088: 3059: 3055: 3030: 3026: 2993: 2986: 2956:Physical Review 2947: 2943: 2926: 2922: 2883: 2870: 2860: 2858: 2843: 2842: 2838: 2828: 2826: 2819: 2815: 2805: 2803: 2794: 2793: 2789: 2782: 2768: 2764: 2758: 2744: 2740: 2720: 2716: 2687: 2683: 2645: 2641: 2634: 2616: 2607: 2600: 2586: 2579: 2527: 2521: 2517: 2507: 2505: 2500: 2499: 2495: 2486: 2485: 2481: 2476: 2472: 2462: 2460: 2455: 2454: 2450: 2425: 2421: 2415: 2401: 2397: 2387: 2385: 2380: 2379: 2375: 2341: 2335: 2331: 2324: 2310: 2303: 2297: 2283: 2279: 2273: 2253: 2246: 2239: 2221: 2204: 2197: 2183: 2168: 2129: 2122: 2083: 2072: 2056: 2039: 2018: 2009: 2002: 1986: 1982: 1972: 1970: 1950: 1943: 1936: 1918: 1889: 1885: 1880: 1879: 1858: 1854: 1841: 1837: 1832: 1813: 1758:nuclear weapons 1718: 1696: 1678:Frédéric Joliot 1670:nuclear fission 1632:persecution in 1470: 1448: 1432: 1425: 1422: 1408: 1396: 1378: 1359: 1345: 1343: 1342: 1341: 1337: 1335: 1334: 1333: 1331: 1320: 1318: 1317: 1316: 1312: 1309: 1308: 1307: 1305: 1294: 1292: 1291: 1290: 1286: 1284: 1283: 1282: 1280: 1269: 1267: 1266: 1265: 1261: 1258: 1257: 1256: 1254: 1217: 1210: 1203: 1196: 1187: 1185: 1171: 1164:Ernest Lawrence 1132: 1115: 1111: 1110: 1081: 1077: 1076: 1064:Dmitri Ivanenko 1044: 1028:annus mirabilis 1011: 1008: 996:conserve energy 981:Ettore Majorana 971:, or any other 965:Frédéric Joliot 945:gamma radiation 939: 937: 936: 935: 931: 928: 927: 926: 925: 916: 914: 913: 912: 908: 905: 904: 903: 902: 893: 891: 890: 889: 885: 882: 881: 880: 879: 868:alpha particles 856: 822: 818: 817: 807: 766: 762: 758: 754: 731: 698: 690:Frédéric Joliot 620:William Harkins 592: 578: 530:periodic system 474: 468: 430: 428: 427: 426: 422: 420: 419: 418: 417: 412: 410: 409: 408: 404: 402: 401: 400: 399: 345:Frederick Soddy 338: 302:alpha particles 279: 273: 271: 270: 269: 265: 263: 262: 261: 260: 245: 239: 218:Walter Kaufmann 186:Henri Becquerel 164:Wilhelm Ostwald 156: 144:nuclear weapons 17: 12: 11: 5: 6352: 6342: 6341: 6327: 6326: 6309: 6291: 6273: 6256: 6238: 6231: 6228: 6224: 6223: 6221: 6220: 6209: 6206: 6205: 6203: 6202: 6197: 6196: 6195: 6190: 6182: 6180:Shapley–Curtis 6177: 6172: 6170:Leibniz–Newton 6167: 6165:Galileo affair 6162: 6157: 6151: 6149: 6145: 6144: 6142: 6141: 6136: 6131: 6126: 6121: 6115: 6113: 6109: 6108: 6106: 6105: 6100: 6099: 6098: 6088: 6083: 6078: 6072: 6070: 6066: 6065: 6063: 6062: 6060:Speed of light 6057: 6056: 6055: 6050: 6045: 6037: 6032: 6027: 6021: 6019: 6015: 6014: 6012: 6011: 6006: 6004:Nanotechnology 6001: 5996: 5995: 5994: 5985: 5983: 5979: 5978: 5976: 5975: 5974: 5973: 5968: 5963: 5953: 5952: 5951: 5941: 5940: 5939: 5934: 5929: 5924: 5914: 5913: 5912: 5907: 5902: 5897: 5889: 5884: 5883: 5882: 5872: 5871: 5870: 5865: 5857: 5856: 5855: 5850: 5842: 5841: 5840: 5831: 5829: 5827:Modern physics 5823: 5822: 5820: 5819: 5818: 5817: 5812: 5807: 5802: 5795:Thermodynamics 5792: 5791: 5790: 5780: 5779: 5778: 5773: 5763: 5762: 5761: 5756: 5746: 5745: 5744: 5734: 5733: 5732: 5727: 5717: 5716: 5715: 5710: 5705: 5700: 5690: 5689: 5688: 5677: 5675: 5669: 5668: 5656: 5655: 5648: 5641: 5633: 5626: 5625: 5580: 5558: 5536: 5517:(3): 214–215. 5499: 5492: 5470: 5440: 5410: 5404:978-0743264747 5403: 5381: 5374: 5347: 5325: 5279: 5227: 5190: 5181: 5146: 5131: 5109: 5087: 5068:(in Italian). 5033: 4990: 4957: 4913: 4906: 4880: 4843: 4808: 4767: 4740:(1–2): 17–24. 4719: 4671: 4620: 4613: 4593: 4584:978-0520089068 4583: 4561: 4518: 4474: 4437: 4416: 4378: 4340: 4299:"The Neutrino" 4286: 4236: 4217:(5): 683–685. 4196: 4172: 4163:978-0750303736 4162: 4142:Rechenberg, H. 4127: 4099: 4082: 4037: 3992: 3947: 3934: 3912: 3890: 3844: 3793: 3760: 3717: 3695: 3688: 3665: 3655:Zichichi, A., 3648: 3623: 3578: 3533: 3518:nobelprize.org 3505: 3498: 3480: 3437: 3419:(82): 82–229, 3393: 3348: 3342: 3321: 3315:978-0674624160 3314: 3283: 3230: 3197: 3181: 3176:978-0852747612 3175: 3157: 3150: 3124: 3086: 3053: 3024: 3005:(3): 191–203. 2984: 2963:(1): 164–165. 2941: 2920: 2868: 2836: 2813: 2787: 2781:978-0691095523 2780: 2762: 2756: 2748:Atomic Physics 2738: 2714: 2681: 2661:10.1086/350143 2655:(3): 336–364, 2639: 2632: 2605: 2598: 2577: 2515: 2493: 2479: 2470: 2448: 2446: 2445: 2442:Radiochemistry 2438: 2419: 2414:978-0124058972 2413: 2395: 2373: 2329: 2322: 2301: 2295: 2277: 2271: 2244: 2237: 2202: 2195: 2166: 2120: 2070: 2037: 2007: 2000: 1980: 1941: 1935:978-0198519973 1934: 1886: 1884: 1881: 1878: 1877: 1852: 1834: 1833: 1831: 1828: 1827: 1826: 1820: 1812: 1809: 1712:Chicago Pile-1 1695: 1692: 1682:chain reaction 1650:chemical group 1556:Norman Feather 1547:Franco Rasetti 1543:Edoardo Amaldi 1513:(1934) in the 1511:S.A. Altshuler 1447: 1444: 1420: 1414: 1413: 1410: 1409: 1406: 1401: 1398: 1394: 1389: 1386: 1383: 1380: 1376: 1355: 1354: 1351: 1350: 1344: 1336: 1329: 1326: 1319: 1310: 1303: 1300: 1293: 1285: 1278: 1275: 1268: 1259: 1246:the deuteron. 1131: 1128: 1043: 1040: 1009:Be + He (α) → 1000:Norman Feather 998:. Assisted by 992:James Chadwick 938: 929: 915: 906: 892: 883: 855: 852: 793:Dirac equation 769:Walter Heitler 764: 760: 756: 752: 749:Franco Rasetti 729: 697: 694: 601:beta radiation 577: 574: 546:James Chadwick 487:periodic table 470:Main article: 467: 464: 429: 421: 411: 403: 337: 334: 298:Ernest Marsden 272: 264: 241:Main article: 238: 235: 230:Edward Andrade 190:phosphorescent 155: 152: 125:James Chadwick 66:Ernest Marsden 46:atomic physics 26:James Chadwick 15: 9: 6: 4: 3: 2: 6351: 6340: 6337: 6336: 6334: 6325: 6324:9780226807942 6321: 6317: 6313: 6310: 6307: 6306:90-277-1584-X 6303: 6299: 6295: 6292: 6289: 6285: 6281: 6277: 6274: 6272: 6268: 6264: 6260: 6257: 6254: 6250: 6246: 6242: 6239: 6237: 6234: 6233: 6219: 6211: 6210: 6207: 6201: 6198: 6194: 6191: 6189: 6186: 6185: 6183: 6181: 6178: 6176: 6173: 6171: 6168: 6166: 6163: 6161: 6158: 6156: 6155:Bohr–Einstein 6153: 6152: 6150: 6146: 6140: 6137: 6135: 6132: 6130: 6127: 6125: 6122: 6120: 6117: 6116: 6114: 6110: 6104: 6101: 6097: 6094: 6093: 6092: 6089: 6087: 6084: 6082: 6079: 6077: 6074: 6073: 6071: 6067: 6061: 6058: 6054: 6051: 6049: 6046: 6044: 6041: 6040: 6038: 6036: 6033: 6031: 6028: 6026: 6023: 6022: 6020: 6016: 6010: 6009:String theory 6007: 6005: 6002: 6000: 5997: 5993: 5990: 5989: 5987: 5986: 5984: 5980: 5972: 5969: 5967: 5964: 5962: 5959: 5958: 5957: 5954: 5950: 5947: 5946: 5945: 5942: 5938: 5935: 5933: 5930: 5928: 5925: 5923: 5920: 5919: 5918: 5915: 5911: 5908: 5906: 5903: 5901: 5898: 5896: 5893: 5892: 5890: 5888: 5885: 5881: 5878: 5877: 5876: 5873: 5869: 5866: 5864: 5861: 5860: 5858: 5854: 5851: 5849: 5846: 5845: 5843: 5839: 5836: 5835: 5833: 5832: 5830: 5828: 5824: 5816: 5813: 5811: 5808: 5806: 5803: 5801: 5798: 5797: 5796: 5793: 5789: 5786: 5785: 5784: 5781: 5777: 5774: 5772: 5769: 5768: 5767: 5764: 5760: 5759:Metamaterials 5757: 5755: 5752: 5751: 5750: 5747: 5743: 5740: 5739: 5738: 5735: 5731: 5728: 5726: 5723: 5722: 5721: 5718: 5714: 5711: 5709: 5706: 5704: 5701: 5699: 5696: 5695: 5694: 5691: 5687: 5684: 5683: 5682: 5679: 5678: 5676: 5674: 5670: 5665: 5661: 5654: 5649: 5647: 5642: 5640: 5635: 5634: 5631: 5621: 5617: 5613: 5609: 5605: 5601: 5597: 5594:. Series 10. 5593: 5592: 5584: 5576: 5569: 5562: 5554: 5547: 5540: 5532: 5528: 5524: 5520: 5516: 5512: 5511: 5503: 5495: 5489: 5484: 5483: 5474: 5458: 5454: 5450: 5444: 5428: 5424: 5420: 5414: 5406: 5400: 5395: 5394: 5385: 5377: 5371: 5367: 5363: 5362: 5357: 5351: 5335: 5329: 5321: 5317: 5313: 5309: 5305: 5301: 5297: 5293: 5292: 5283: 5275: 5271: 5267: 5263: 5259: 5255: 5252:(3615): 239. 5251: 5247: 5246: 5241: 5240:Frisch, O. R. 5237: 5231: 5223: 5219: 5215: 5211: 5207: 5203: 5202: 5194: 5185: 5178: 5173: 5169: 5165: 5161: 5157: 5150: 5142: 5138: 5134: 5128: 5123: 5122: 5113: 5097: 5091: 5075: 5071: 5067: 5063: 5059: 5055: 5051: 5050:B. Pontecorvo 5047: 5043: 5037: 5028: 5023: 5019: 5015: 5011: 5007: 5006: 5001: 4994: 4978: 4974: 4973: 4968: 4961: 4953: 4949: 4945: 4941: 4937: 4933: 4932: 4924: 4917: 4909: 4907:9780674004351 4903: 4899: 4898: 4893: 4887: 4885: 4876: 4872: 4868: 4864: 4860: 4856: 4855: 4847: 4839: 4835: 4831: 4827: 4823: 4819: 4812: 4804: 4800: 4796: 4792: 4788: 4784: 4783: 4778: 4771: 4763: 4759: 4755: 4751: 4747: 4743: 4739: 4735: 4734: 4730: 4723: 4715: 4711: 4707: 4703: 4699: 4695: 4692:(1–2): 4–16. 4691: 4687: 4686: 4682: 4675: 4667: 4663: 4658: 4653: 4649: 4645: 4641: 4637: 4636: 4631: 4624: 4616: 4614:9780520064263 4610: 4606: 4605: 4597: 4590: 4586: 4580: 4575: 4574: 4565: 4556: 4551: 4547: 4543: 4539: 4535: 4534: 4529: 4522: 4514: 4510: 4506: 4502: 4498: 4494: 4493: 4485: 4483: 4481: 4479: 4470: 4466: 4462: 4458: 4454: 4450: 4449: 4441: 4433: 4429: 4428: 4420: 4412: 4408: 4404: 4400: 4396: 4392: 4385: 4383: 4374: 4370: 4366: 4362: 4358: 4354: 4350: 4344: 4336: 4332: 4327: 4322: 4318: 4314: 4310: 4306: 4305: 4300: 4296: 4290: 4276:on 2014-05-31 4272: 4268: 4264: 4260: 4256: 4255: 4247: 4240: 4232: 4228: 4224: 4220: 4216: 4212: 4211: 4206: 4200: 4192: 4188: 4187: 4179: 4177: 4169: 4165: 4159: 4155: 4150: 4149: 4143: 4140:Brown, L.M.; 4136: 4134: 4132: 4125: 4121: 4117: 4113: 4109: 4106:Miller A. I. 4103: 4096: 4092: 4086: 4078: 4074: 4070: 4066: 4062: 4058: 4054: 4050: 4049: 4041: 4033: 4029: 4025: 4021: 4017: 4013: 4009: 4005: 4004: 3996: 3988: 3984: 3980: 3976: 3972: 3968: 3965:(1–2): 1–11. 3964: 3960: 3959: 3951: 3944: 3938: 3922: 3916: 3908: 3904: 3897: 3895: 3885: 3880: 3876: 3872: 3869:(846): 1–25. 3868: 3864: 3863: 3858: 3851: 3849: 3840: 3836: 3831: 3826: 3822: 3818: 3815:(3252): 312. 3814: 3810: 3809: 3804: 3797: 3781: 3777: 3773: 3767: 3765: 3755: 3750: 3746: 3742: 3738: 3734: 3733: 3728: 3721: 3705: 3699: 3691: 3689:9780198539926 3685: 3681: 3674: 3672: 3670: 3662: 3658: 3652: 3644: 3641:(in French). 3640: 3639: 3634: 3627: 3619: 3615: 3611: 3607: 3603: 3599: 3595: 3592:(in German). 3591: 3590: 3582: 3574: 3570: 3566: 3562: 3558: 3554: 3550: 3547:(in German). 3546: 3545: 3537: 3530: 3519: 3515: 3509: 3501: 3495: 3491: 3484: 3475: 3470: 3466: 3462: 3458: 3454: 3453: 3448: 3441: 3434: 3430: 3426: 3422: 3418: 3414: 3407: 3400: 3398: 3389: 3385: 3381: 3377: 3373: 3369: 3365: 3361: 3360: 3352: 3345: 3343:9780192562906 3339: 3335: 3328: 3326: 3317: 3311: 3307: 3303: 3299: 3292: 3290: 3288: 3280: 3276: 3272: 3268: 3264: 3260: 3256: 3252: 3248: 3247: 3246:Physics Today 3239: 3237: 3235: 3218: 3214: 3213: 3208: 3201: 3192: 3190: 3188: 3186: 3178: 3172: 3168: 3161: 3153: 3147: 3143: 3139: 3135: 3128: 3120: 3116: 3112: 3108: 3107: 3102: 3096: 3090: 3082: 3078: 3074: 3070: 3069: 3064: 3057: 3049: 3045: 3041: 3037: 3036: 3028: 3020: 3016: 3012: 3008: 3004: 3000: 2999: 2991: 2989: 2979: 2974: 2970: 2966: 2962: 2958: 2957: 2952: 2945: 2937: 2933: 2932: 2924: 2915: 2910: 2906: 2902: 2898: 2894: 2893: 2888: 2881: 2879: 2877: 2875: 2873: 2856: 2852: 2851: 2846: 2840: 2824: 2817: 2801: 2797: 2791: 2783: 2777: 2773: 2766: 2759: 2757:9780486318585 2753: 2749: 2742: 2735: 2731: 2728:, Doubleday, 2727: 2726: 2718: 2710: 2706: 2702: 2698: 2697: 2692: 2685: 2678: 2674: 2670: 2666: 2662: 2658: 2654: 2650: 2643: 2635: 2633:0-19-852049-2 2629: 2624: 2623: 2614: 2612: 2610: 2601: 2595: 2591: 2584: 2582: 2573: 2569: 2565: 2561: 2556: 2551: 2547: 2543: 2539: 2535: 2534: 2526: 2519: 2503: 2497: 2489: 2483: 2474: 2458: 2452: 2443: 2439: 2436: 2432: 2428: 2427: 2423: 2416: 2410: 2406: 2399: 2383: 2377: 2369: 2365: 2361: 2357: 2354:(151): 1–24. 2353: 2349: 2348: 2340: 2333: 2325: 2319: 2315: 2308: 2306: 2298: 2296:9780199766413 2292: 2288: 2281: 2274: 2268: 2264: 2260: 2259: 2251: 2249: 2240: 2234: 2229: 2228: 2219: 2217: 2215: 2213: 2211: 2209: 2207: 2198: 2192: 2188: 2181: 2179: 2177: 2175: 2173: 2171: 2161: 2156: 2152: 2148: 2144: 2140: 2139: 2134: 2127: 2125: 2115: 2110: 2106: 2102: 2098: 2094: 2093: 2088: 2081: 2079: 2077: 2075: 2068: 2064: 2060: 2054: 2052: 2050: 2048: 2046: 2044: 2042: 2033: 2029: 2025: 2024: 2016: 2014: 2012: 2003: 1997: 1993: 1992: 1984: 1969: 1965: 1961: 1960: 1955: 1948: 1946: 1937: 1931: 1926: 1925: 1916: 1914: 1912: 1910: 1908: 1906: 1904: 1902: 1900: 1898: 1896: 1894: 1892: 1887: 1874: 1870: 1866: 1862: 1856: 1849: 1845: 1839: 1835: 1824: 1821: 1818: 1815: 1814: 1808: 1806: 1802: 1798: 1794: 1790: 1786: 1782: 1778: 1774: 1770: 1765: 1763: 1759: 1755: 1751: 1747: 1743: 1739: 1735: 1731: 1727: 1723: 1717: 1713: 1705: 1700: 1691: 1690: 1687: 1683: 1679: 1673: 1671: 1667: 1663: 1659: 1655: 1651: 1647: 1643: 1642:fractionation 1639: 1635: 1631: 1627: 1623: 1619: 1615: 1611: 1603: 1598: 1590: 1586: 1584: 1583:Chandrasekhar 1580: 1578: 1572: 1571:cross section 1568: 1563: 1561: 1557: 1548: 1544: 1540: 1536: 1532: 1527: 1523: 1521: 1516: 1512: 1508: 1504: 1500: 1499:Robert Bacher 1496: 1492: 1488: 1484: 1480: 1476: 1469: 1465: 1461: 1457: 1453: 1443: 1441: 1436: 1429: 1419: 1405: 1402: 1399: 1393: 1390: 1387: 1384: 1381: 1375: 1372: 1371: 1368: 1367: 1366: 1363: 1348: 1330: 1327: 1323: 1304: 1301: 1297: 1279: 1276: 1272: 1253: 1252: 1249: 1248: 1247: 1245: 1241: 1237: 1233: 1228: 1226: 1221: 1214: 1207: 1200: 1193: 1182: 1180: 1175: 1169: 1165: 1161: 1157: 1153: 1148: 1145: 1144:Harrie Massey 1136: 1127: 1125: 1124: 1108: 1104: 1100: 1096: 1092: 1086: 1072: 1070: 1065: 1061: 1057: 1048: 1039: 1037: 1033: 1029: 1024: 1022: 1018: 1005: 1001: 997: 993: 988: 986: 982: 978: 974: 970: 966: 962: 952: 948: 946: 923: 900: 877: 873: 870:emitted from 869: 865: 861: 860:Walther Bothe 851: 848: 843: 840: 836: 835:Charles Ellis 831: 828: 815: 811: 805: 800: 798: 797:pair creation 794: 790: 786: 785:Klein paradox 781: 778: 777:Eugene Wigner 774: 770: 750: 746: 742: 737: 735: 727: 722: 720: 719:Zeeman effect 715: 711: 707: 704: 693: 691: 687: 683: 679: 674: 672: 668: 663: 661: 657: 656: 651: 650: 645: 641: 637: 633: 629: 625: 621: 616: 614: 610: 604: 602: 597: 591: 582: 573: 571: 567: 563: 559: 555: 551: 547: 543: 539: 534: 531: 527: 526:Moseley's law 522: 520: 516: 512: 508: 503: 499: 498:Henry Moseley 495: 490: 488: 484: 480: 473: 472:Moseley's law 463: 461: 456: 451: 449: 445: 441: 437: 397: 393: 389: 388:Francis Aston 385: 384:J. J. Thomson 378: 373: 369: 367: 362: 358: 357:radioelements 354: 350: 346: 343: 333: 331: 327: 323: 318: 316: 311: 307: 303: 299: 295: 291: 283: 258: 254: 249: 244: 234: 231: 227: 223: 219: 215: 211: 207: 203: 199: 195: 191: 187: 183: 179: 178:Radioactivity 175: 173: 169: 165: 161: 151: 149: 145: 141: 140:nuclear power 137: 133: 128: 126: 122: 117: 115: 111: 107: 103: 102:atomic number 99: 98:hydrogen atom 95: 91: 90:atomic masses 87: 83: 79: 75: 71: 67: 63: 59: 55: 51: 47: 43: 35: 31: 27: 23: 19: 6315: 6297: 6279: 6262: 6245:Inward Bound 6244: 6241:Abraham Pais 6124:The Martians 6052: 5788:Spectroscopy 5730:Aerodynamics 5708:Field theory 5598:(1): 27–40. 5595: 5589: 5583: 5574: 5561: 5552: 5539: 5514: 5508: 5502: 5481: 5473: 5461:. Retrieved 5457:the original 5452: 5443: 5431:. Retrieved 5427:the original 5422: 5413: 5392: 5384: 5360: 5350: 5338:. Retrieved 5328: 5298:(6): 89–95. 5295: 5289: 5282: 5249: 5243: 5230: 5205: 5199: 5193: 5184: 5175: 5163: 5159: 5149: 5120: 5112: 5100:. 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Retrieved 3517: 3508: 3489: 3483: 3456: 3450: 3440: 3416: 3412: 3366:(3–4): 157. 3363: 3357: 3351: 3333: 3301: 3278: 3250: 3244: 3223:27 September 3221:. Retrieved 3219:(3): 464–466 3216: 3210: 3200: 3166: 3160: 3133: 3127: 3110: 3109:. Series 6. 3104: 3094: 3089: 3075:(250): 596. 3072: 3066: 3056: 3042:(249): 305. 3039: 3033: 3027: 3002: 2996: 2960: 2954: 2944: 2935: 2929: 2923: 2896: 2890: 2859:. Retrieved 2854: 2848: 2839: 2827:. Retrieved 2816: 2804:. Retrieved 2790: 2771: 2765: 2747: 2741: 2724: 2717: 2700: 2694: 2684: 2652: 2648: 2642: 2621: 2589: 2537: 2531: 2518: 2506:. Retrieved 2496: 2482: 2473: 2461:. Retrieved 2451: 2441: 2434: 2430: 2422: 2404: 2398: 2386:. Retrieved 2376: 2351: 2345: 2332: 2313: 2286: 2280: 2257: 2226: 2186: 2142: 2136: 2096: 2090: 2058: 2021: 1990: 1983: 1971:. Retrieved 1957: 1924:Inward Bound 1923: 1872: 1868: 1864: 1860: 1855: 1838: 1793:George Zweig 1766: 1726:antisemitism 1719: 1704:Trinity test 1688: 1674: 1634:Nazi Germany 1614:Lise Meitner 1607: 1574: 1564: 1552: 1539:Emilio Segrè 1515:Soviet Union 1471: 1460:Lise Meitner 1456:Enrico Fermi 1433:1.0090 1426:1.0084 1417: 1415: 1403: 1391: 1373: 1360:0.0023 1356: 1229: 1218:1.0006 1183: 1172:1.0078 1160:Lise Meitner 1149: 1141: 1122: 1098: 1091:Enrico Fermi 1087: 1073: 1055: 1053: 1025: 1004:E.C. Pollard 989: 985:Enrico Fermi 969:paraffin wax 958: 857: 844: 832: 826: 813: 809: 801: 782: 738: 723: 710:Ralph Kronig 708: 699: 682:George Gamow 677: 675: 664: 659: 653: 647: 643: 635: 627: 623: 617: 605: 593: 560:and medical 550:Lise Meitner 535: 523: 518: 491: 482: 475: 452: 381: 356: 342:radiochemist 339: 319: 287: 281: 222:Thomas Royds 210:Paul Villard 176: 157: 129: 118: 41: 39: 18: 6048:Higgs boson 5463:24 November 5433:24 November 5340:18 November 5236:Meitner, L. 5102:18 November 4391:Am. J. Phys 4097:(1932) 798. 3927:18 November 3710:16 November 2861:16 November 2829:16 November 2508:18 November 2388:5 September 1973:15 November 1797:quark model 1666:Otto Frisch 1630:antisemitic 1626:transuranic 1602:uranium-235 1477:in 1933 in 1211:1.012 1204:1.008 1197:1.005 789:Oskar Klein 613:Harold Urey 558:radiologist 538:World War I 294:Hans Geiger 259:indicating 212:discovered 80:. By 1920, 62:Hans Geiger 6288:0520208609 6253:0198519974 6069:By periods 5887:Geophysics 5859:Cosmology 5054:F. Rasetti 4983:30 January 4861:(3): 163. 4824:(3): 157. 4499:(3): 230. 4455:(6): 463. 4434:: 820–822. 4280:2015-03-21 4193:: 439–441. 4124:0521568919 4116:0521568919 2806:25 October 2734:B009I5KZGM 2599:0520023757 2067:0486482383 2057:Byrne, J. 1883:References 1750:New Mexico 1746:Los Alamos 1710:See also: 1694:After 1939 1662:platinoids 1660:and light 1636:after the 1501:(1933) at 1487:I. I. Rabi 1483:Pittsburgh 1475:Otto Stern 1450:See also: 1440:beta decay 1385:b.e. 1240:thorium C" 1156:Niels Bohr 1034:, and the 847:physicists 839:W. Wooster 588:See also: 502:Bohr model 326:Bohr model 322:Niels Bohr 202:alpha rays 184:scientist 160:Ernst Mach 112:, the two 100:, and the 6271:644015779 6112:By groups 6096:Astronomy 5932:Molecules 5766:Mechanics 5681:Astronomy 5620:123822660 5208:(2): 76. 5172:0026-4695 5080:16 August 5046:E. Amaldi 4762:186232193 4714:120793548 4295:Bethe, H. 4077:126422047 4032:186221789 3987:186218053 3786:19 August 3618:121188471 3573:122888356 3492:. Wiley. 3388:121771000 3275:121080564 3253:(9): 23. 2857:(5). 2007 2677:144765815 1762:plutonium 1654:lanthanum 1638:Anschluss 1618:Otto Hahn 1549:and Fermi 1507:I.Y. Tamm 1503:Ann Arbor 1464:Otto Hahn 1225:cyclotron 876:beryllium 858:In 1930, 833:In 1927, 671:Cambridge 634:root for 609:deuterium 554:Otto Hahn 448:carbon-12 440:oxygen-16 315:electrons 310:scattered 253:schematic 206:beta rays 110:electrons 6333:Category 6218:Category 6043:timeline 6030:Graphene 5992:timeline 5961:timeline 5949:timeline 5922:timeline 5863:timeline 5848:timeline 5838:timeline 5800:timeline 5771:timeline 5754:timeline 5742:timeline 5725:timeline 5698:timeline 5686:timeline 5664:timeline 5358:(2001). 5320:33512939 5141:39508200 5058:E. Segrè 5042:E. 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Discovery of the neutron

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