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Discovery of the neutron
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James Chadwick at the 1933 Solvay Conference. Chadwick had discovered the neutron the year before while working at Cavendish Laboratory.
The discovery of the neutron and its properties was central to the extraordinary developments in atomic physics that occurred in the first half of the 20th century. Early in the century, Ernest Rutherford developed a crude model for the atom,[1]:188 [2] based on the gold foil experiment of Hans Geiger and Ernest Marsden. In this model, atoms had their mass and positive electric charge concentrated in a very small nucleus.[3] By 1920 chemical isotopes had been discovered, the atomic masses had been determined to be integer multiples of the mass of the hydrogen atom,[4] and the atomic number had been identified as the charge on the nucleus.[5]:§1.1.2 Throughout the 1920s, the nucleus was viewed as composed of combinations of protons and electrons, the two elementary particles known at the time, but that model presented several experimental and theoretical contradictions.[1]:298
The essential nature of the atomic nucleus was established with the discovery of the neutron by James Chadwick in 1932[6] and the determination that it was a new elementary particle, distinct from the proton.[7][8]:55
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 fission of uranium atoms by neutrons (1938).[9] The discovery of fission led to the creation of both nuclear power and weapons by the end of World War II. Both the proton and neutron were presumed to be elementary particles until the 1960s when they were determined to be composite particles built from quarks.[10]
Contents
[hide]
1 Gold foil experiment
2 Discovery of isotopes
3 Atomic number and Moseley's law
4 Rutherford atom
5 Problems of the nuclear electrons hypothesis
6 Discovery of the neutron
7 Proton–neutron model of the nucleus
8 The nature of the neutron
9 Neutron physics in the 1930s
10 After 1939
11 Videos
12 References
13 Further reading
Gold foil experiment[edit]
See also: Atomic theory and Plum pudding model
A schematic of the nucleus of an atom indicating
β−
radiation, the emission of a fast electron from the nucleus (the accompanying antineutrino is omitted). In the Rutherford model for the nucleus, red spheres were protons with positive charge and blue spheres were protons tightly bound to an electron with no net charge.
The inset shows beta decay of a free neutron as it is understood today; an electron and antineutrino are created in this process.
At the start of the 20th century, the vigorous debate as to the existence of atoms had not yet been resolved. Philosophers such as Ernst Mach and Wilhelm Ostwald denied that atoms were real, viewing them as a convenient mathematical construct, while scientists such as Arnold Sommerfeld and Ludwig Boltzmann saw that physical theories required the existence of atoms.[9]:§1 Radioactivity had been recently discovered in uranium and thorium. Ernest Rutherford had separated radioactivity into three types: alpha, beta, and gamma rays, depending on their ability to penetrate, or travel into, ordinary objects or gases.[11] These radiations were soon identified with known particles: alpha rays were shown to be helium ions by Rutherford and Thomas Royds in 1907;[12] beta rays were shown to be electrons by Henri Becquerel in 1900; and gamma rays were shown to be electromagnetic radiation, that is, a form of light, in 1914.[1]:62 These radiations had also been identified as emanating from atoms, hence they provided clues as 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.
At the University of Manchester between 1908 and 1913, Rutherford directed Hans Geiger and Ernest Marsden in a series of experiments to determine what happens when alpha particles scatter from metal foil. Now called the Rutherford gold foil experiment, or the Geiger–Marsden experiment, these measurements made the extraordinary discovery that alpha particles would occasionally scatter to high angle when passing through a thin gold foil. The scattering indicated that the alpha particles were reflecting from a small, but dense, component of 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 much larger cloud of negatively charged electrons.[2] The concentrated atomic mass was required to provide the observed reflection of the alpha particles, and Rutherford developed a mathematical model that accounted for the scattering.[2]
The Rutherford model was very influential, motivating the Bohr model for electrons orbiting the nucleus in 1913[13] and eventually leading to quantum mechanics by the mid-1920s.
Discovery of isotopes[edit]
Concurrent with the work of Rutherford, Geiger, and Marsden, the radiochemist Frederick Soddy at the University of Glasgow was studying radioactive decay chains of uranium. Soddy had been a student of Rutherford. Soddy's study indicated about 40 different radioactive elements, referred to as radioelements, between uranium and lead, although the periodic table only allowed for 11 elements.[14] By 1913 Soddy had determined that several of these elements had identical chemical properties but different atomic weights. He called these chemically similar elements isotopes.[15][16] For his study of radioactivity and the discovery of isotopes, Soddy was awarded the 1921 Nobel Prize in Chemistry.[17]
Replica of Aston's third mass spectrometer
Building from work by J. J. Thomson on the deflection of positively charged atoms by electric and magnetic fields, Francis Aston built the first mass spectrograph at the Cavendish Laboratory in 1919.[4] His aim was to try to separate the two isotopes of neon, which he was able to easily do. Aston discovered that the masses of all the particles are whole numbers, called the whole number rule, that is, the masses of all the isotopes are whole number multiples of the mass of the hydrogen atom.[18] Aston arbitrarily computed his masses relative to oxygen-16, which he took to have a mass of exactly 16. (Today the atomic mass unit (amu) is relative to carbon-12.[19]) Ironically, 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 experimental uncertainty. Aston and others quickly realized that the discrepancy is due to the binding energy of atoms, that is, the mass of a number of hydrogen atoms bound into a single atom must be less than the sum of the masses of the separate hydrogen atoms. Additional work determined the nuclide binding energies. Aston's work on isotopes garnered 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. [20] Noting Aston's recent discovery of nuclear binding energy, in 1920 Arthur Eddington suggested that stars may obtain their energy by fusing hydrogen (protons) into helium and that the heavier elements may form in stars.[21][22]
Atomic number and Moseley's law[edit]
Main article: Moseley's law
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. In 1911 Antonius van den Broek made the then bold suggestion that the required charge, denoted Z, was not half of the atomic weight for elements, but instead was exactly equal to the element's atomic number, or place in the periodic table.[1]:5 At that time the positions of the elements in the table were not known to have any physical significance, except as a way to order the elements in particular sequences with similar chemical properties.
At the University of Manchester in 1913 Henry Moseley discussed the new Bohr model of the atom with the visiting Bohr.[23] The model accounted for the electromagnetic emission spectrum from the hydrogen atom, and Moseley 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 the periodic table. In 1913-1914 Moseley tested the question experimentally by using x-ray diffraction techniques. He found that the most intense short-wavelength line in the x-ray spectrum of a particular element, known as the K-alpha line, was related to the element's position in the periodic table, that is, its atomic number, Z. Indeed, Moseley introduced this nomenclature.[5]:§1.1.2 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.[24]
Within a year it was noted that the equation for the relation, now called Moseley's law, 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 periodic system 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 of the atomic nucleus.[25]
Further research in atomic physics was interrupted by the outbreak of World War I. Moseley was killed in 1915 at the Battle of Gallipoli,[26] while Rutherford's student James Chadwick was interned in Germany for the duration of the war, 1914-1918.[27] In Berlin, Lise Meitner and Otto Hahn's work on determining the radioactive decay chains of radium and uranium by precise chemical separation was interrupted.[9]:§4 Meitner spent much of the war working as a radiologist and medical X-ray technician near the Austrian front, while Hahn, a chemist, worked on research in poison gas warfare.
Rutherford atom[edit]
Ernest Rutherford
See also: Discovery of the proton
In 1920 Rutherford gave a Bakerian lecture at the Royal Society entitled the "Nuclear Constitution of Atoms", a summary of what was then known about the nucleus of the atom.[28][8]:23 By 1920, the existence of electrons within the atomic nucleus was widely assumed. It was assumed the nucleus consisted of hydrogen nuclei in number equal to the atomic mass. But since each hydrogen 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...",[28] namely, it was known that beta radiation was electrons emitted from the nucleus.[8]:21
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 mass 4. In a 1919 paper,[29] 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.[8]:25 Nevertheless, Rutherford had conjectured[28] the existence of the neutron, a neutral particle of mass 1, and the deuteron, a +1 charge particle of mass 2. The latter is the nucleus of deuterium, discovered in 1931 by Harold Urey.[30] 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.
By 1921 Rutherford had named the uncharged particle the neutron,[31] while about that same time the word proton was adopted for the hydrogen nucleus.[32] Neutron was apparently constructed from the Latin root for neutral and the Greek ending -on (by imitation of electron and proton).[33][34] References to the word neutron in connection with the atom can be found in the literature as early as 1899, however.[35]
Rutherford and Chadwick immediately began an experimental program to search for the neutron at the Cavendish Laboratory in Cambridge.[31][8]:27 The experiments continued throughout the 1920s without success.[6]
Rutherford's conjecture was not widely accepted. In his 1931 textbook on the Constitution of Atomic Nuclei and Radioactivity, George Gamow, then at the Institute for Theoretical Physics in Copenhagen, did not mention the neutron.[36] At the time of their 1932 measurements in Paris that would lead to the discovery of the neutron, Irène Joliot-Curie and Frédéric Joliot were unaware of the conjecture.[37]
Problems of the nuclear electrons hypothesis[edit]
Throughout the 1920s, physicists assumed that the atomic nucleus was composed of protons and "nuclear electrons".[8]:29–32[38][39] Under this hypothesis, the nitrogen-14 (14N) nucleus would be composed of 14 protons and 7 electrons, so that it would have a net charge of +7 elementary charge units and a mass of 14 atomic mass units. The nucleus was also orbited by another 7 electrons, termed "external electrons" by Rutherford,[28] to complete the 14N atom. Obvious problems with the hypothesis became apparent, however.
Ralph Kronig pointed out in 1926 that the observed hyperfine structure 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 Zeeman effect, but no such effects were observed.[40][8]:34 It appeared as if the magnetic moment of the electron disappeared when it was within the nucleus.
Observations of the energy levels of molecules by Franco Rasetti in 1929 were inconsistent with the nuclear spin expected from proton–electron hypothesis.[8]:35[41] Molecular Raman spectroscopy of dinitrogen (14N2) showed that transitions originating from even-numbered rotational levels are more intense than those from odd levels, hence the even levels are more populated.[1] According to quantum mechanics and the Pauli exclusion principle, the spin of the 14N nucleus is therefore an integer multiple of ħ (the reduced Planck constant).[42][43] Yet both protons and electrons carry an intrinsic spin of ½ ħ, and there is no way to arrange an odd number (14 protons + 7 electrons = 21) of spins ±½ ħ to give a spin that is an integer multiple of ħ.
The Klein paradox,[44] discovered by Oskar Klein in 1928, presented further quantum mechanical objections to the notion of an electron confined within a nucleus.[40] Derived from the Dirac equation, this clear and precise paradox showed that a high-energy electron approaching a potential barrier has a high probability of passing through the barrier, or escaping, by transforming to a particle of negative mass. 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.[40]
By about 1930 it was generally recognized that it was difficult to reconcile the proton–electron model for nuclei with the Heisenberg uncertainty relation of quantum mechanics.[40][1]:299 This relation, Δx⋅Δp ≥ ½ħ, implies that an electron confined to a region the size of an atomic nucleus has an expected kinetic energy of 10–100 MeV.[1][45][46] This energy is larger than the observed energy of beta particles emitted from the nucleus.[1] The expected electron energy is also larger than the binding energy of nucleons, which Aston and others had shown to be less than 9 MeV per nucleon.[47]
While all these considerations did not "prove" an electron could not exist in the nucleus, they were challenging for physicists to interpret. In his 1931 textbook, Gamow summarized all these contradictions. Adding to the confusion in interpretation, the continuous energy distribution of beta decay electrons seemed to indicate that energy was not conserved by this "nuclear electrons" process. Indeed, Bohr, Gamow, Heisenberg and others considered the possibility that the laws of quantum mechanics were not applicable inside the nucleus.[8]:40[36] Such considerations were apparently reasonable, inasmuch as the laws of quantum mechanics had so recently overturned the laws of classical mechanics. The contradictions were mysterious and troublesome,[38] until it was realized that there are no electrons in the nucleus.
Discovery of the neutron[edit]
In 1930, Walther Bothe and Herbert Becker in Giessen, Germany found that if the energetic alpha particles emitted from polonium fell on certain light elements, specifically beryllium (9
4Be
), boron (11
5B
), or lithium (7
3Li
), an unusually penetrating radiation was produced. Beryllium produced the most intense such radiation. Polonium is highly radioactive, producing energetic alpha radiation. Polonium was commonly used for such scattering experiments at the time.[36]:99–110 Since the observed radiation was not influenced by an electric field (neutrons have no charge), it was thought to be gamma radiation. The radiation was more penetrating than any gamma rays known, and the details of experimental results were difficult to interpret.[48][49][36]
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 ionization chamber. Adapted from Chadwick (1932).[6]
Two years later Irène Joliot-Curie and Frédéric Joliot in Paris showed that if this unknown radiation fell on paraffin wax, or any other hydrogen-containing compound, it ejected protons of very high energy (5 MeV).[50] This observation was not in itself inconsistent with the assumed gamma ray nature of the new radiation, but that interpretation (Compton scattering) 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.[5]:§1.3.1 In Rome, the young physicist Ettore Majorana declared that the manner in which the new radiation interacted with protons required a new neutral particle.[51]
On hearing of the Paris results, neither Rutherford nor James Chadwick at the Cavendish Laboratory believed the gamma ray hypothesis.[52] Assisted by Norman Feather,[53] Chadwick quickly performed a series of experiments showing that the gamma ray hypothesis was untenable. The previous year, Chadwick, J.E.R. Constable, and E.C. Pollard had already conducted experiments on disintegrating light elements using alpha radiation from polonium.[54] 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 and aimed the radiation at paraffin following the Paris experiment. Paraffin wax is a hydrocarbon high in hydrogen content, hence offers a target dense with protons; since neutrons and protons have almost equal mass, protons scatter energetically from neutrons. Chadwick measured the range of these protons, and also measured how the new radiation impacted the atoms of various gases.[55] He found that the new radiation consisted of not gamma rays, but uncharged particles with about the same mass as the proton. These particles were neutrons.[56][6][57][15] Chadwick won the Nobel Prize in Physics for this discovery in 1935.[58]
The year 1932 was later referred to as the "annus mirabilis" for nuclear physics in the Cavendish Laboratory,[55] with discoveries of the neutron, artificial nuclear disintegration by the Cockcroft–Walton particle accelerator, and the positron.
Proton–neutron model of the nucleus[edit]
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.
Given the problems of the proton–electron model,[38][39] 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, Werner Heisenberg[59][60][61][15] and Dmitri Ivanenko[62] had proposed proton–neutron models for the nucleus.[63] 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 quantum mechanical system,"[64] 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 isospin quantum numbers.
The proton–neutron model explained the puzzle of dinitrogen. When 14N was proposed to consist of 3 pairs each of protons and neutrons, with an additional unpaired neutron and proton each contributing a spin of 1⁄2 ħ in the same direction for a total spin of 1 ħ, the model became viable.[65][66][67] Soon, neutrons were used to naturally explain spin differences in many different nuclides in the same way.
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,[68] could emanate from the nucleus. In 1934, Enrico Fermi published his classic paper describing the process of beta decay, in which the neutron decays to a proton by creating an electron and a (as yet undiscovered) neutrino.[69] The paper employed the analogy that photons, or electromagnetic radiation, were similarly created and destroyed in atomic processes. Ivanenko had suggested a similar analogy in 1932.[65][70] Fermi's theory requires the neutron to be a spin-½ 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 general, basic theory for the interaction of particles by weak or strong forces.[69] 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 Nature in 1933 it was rejected as being too speculative.[64]
The nature of the neutron[edit]
Seventh Solvay Conference, 1933.
The question of whether the neutron was a composite particle of a proton and an electron persisted for a few years after its discovery.[71][72] In 1932 Harrie Massey explored a model for a composite neutron to account for its great penetrating power through matter and its electrical neutrality,[73] for example. The issue was a legacy of the prevailing view from the 1920s that the only elementary particles were the proton and electron. The nature of the neutron was a primary topic of discussion at the 7th Solvay Conference held in October 1933, attended by Heisenberg, Niels Bohr, Lise Meitner, Ernest Lawrence, Fermi, Chadwick, and others.[64][74] As posed by Chadwick in his Bakerian Lecture 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 (7000100780000000000♠1.0078 u), then the neutron could be a proton-electron composite because of the mass defect from the binding energy. If greater than the combined masses, then the neutron was elementary like the proton.[57] 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.
The difficulty of making the measurement is illustrated by the wide-ranging values for the mass of the neutron obtained from 1932-1934. The accepted value today is 7000100865999999999♠1.00866 u. In Chadwick's 1932 paper reporting on the discovery, he estimated the mass of the neutron to be between 7000100499999999999♠1.005 u and 7000100800000000000♠1.008 u.[52] By bombarding boron with alpha particles, Frédéric and Irène Joliot-Curie obtained a high value of 7000101200000000000♠1.012 u, while Ernest Lawrence's team at the University of California measured the small value 7000100060000000000♠1.0006 u using their new cyclotron.[75]
In 1935 Chadwick and his doctoral student Maurice Goldhaber resolved the issue by reporting the first accurate measurement of the mass of the neutron. They used the 2.6 MeV gamma rays of Thallium-208 (208Tl) (then known as thorium C") to photodisintegrate the deuteron[76]
2
1D
+
γ
→ 1
1H
+
n
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) = 2.1 MeV, or 6997230000000000000♠0.0023 u). The neutron's mass could then be determined by the simple mass balance
md + b.e. = mp + mn
where md,p,n 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 u and 1.0081 u, respectively. They found that the neutron's mass was slightly greater than the mass of the proton 7000100840000000000♠1.0084 u or 7000100899999999999♠1.0090 u, depending on the precise value used for the deuteron mass.[7] The mass of the neutron was too large to be a proton-electron composite, and the neutron was therefore identified as an elementary particle.[52] Ironically, in support of Fermi's theory, Chadwick and Goldhaber predicted that a free neutron would be able to decay into a proton, electron, and neutrino (beta decay).
Neutron physics in the 1930s[edit]
See also: Neutron magnetic moment, Enrico Fermi, Lise Meitner, and Otto Hahn
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 Otto Stern in 1933 in Hamburg that the proton had an anomalously large magnetic moment.[77][78] By 1934 groups led by Stern, now in Pittsburgh, and I. I. Rabi in New York had independently deduced that the magnetic moment of the neutron was negative and unexpectedly large by measuring the magnetic moments of the proton and deuteron.[72][79][80][81][82] Values for the magnetic moment of the neutron were also determined by Robert Bacher[83] (1933) at Ann Arbor and I.Y. Tamm and S.A. Altshuler[72][84] (1934) in the Soviet Union 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 nuclear magnetic resonance techniques.[82] 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.[72]
Fermi and his students (the Via Panisperna boys) in the courtyard of Rome University's Physics Institute in Via Panisperna, about 1934. From Left to right: Oscar D'Agostino, Emilio Segrè, Edoardo Amaldi, Franco Rasetti and Fermi
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 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 its discovery, neutrons were used by Norman Feather, Chadwick's colleague and protege, in scattering experiments with nitrogen.[85] Feather was able to show that neutrons interacting with nitrogen nuclei scattered to protons or induced nitrogen to disintegrate to form boron with the emission of an alpha particle. Feather was therefore the first to show that neutrons produce nuclear disintegrations.
In Rome, Enrico Fermi bombarded heavier elements with neutrons and found the products to be radioactive. By 1934 Fermi 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 bombarded elements increased by a hundredfold. The cross section for interaction with nuclei is much larger for slow neutrons than for fast neutrons. In 1938 Fermi received the Nobel Prize in Physics "for his demonstrations of the existence of new radioactive elements produced by neutron irradiation, and for his related discovery of nuclear reactions brought about by slow neutrons".[86][87]
Lise Meitner and Otto Hahn in their laboratory in 1913.[9]
Nuclear fission caused by absorption of a neutron by uranium-235. The heavy nuclide fragments into lighter components and additional neutrons.
In Berlin, the collaboration of Lise Meitner and Otto Hahn, together with their assistant Fritz Strassmann, 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 transuranic.[88] 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 antisemitic persecution in Nazi Germany after the Anschluss, 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 fractionation") produced puzzling results: what they had understood to be three isotopes of radium were instead consistently behaving as barium.[9] Radium (atomic number 88) and barium (atomic number 56) are in the same chemical group. By January 1939 Hahn had concluded that what they had thought were transuranic nuclides were instead much lighter nuclides, such as barium, lanthanum, cerium and light platinoids. Meitner and her nephew Otto Frisch immediately and correctly interpreted these observations as resulting from nuclear fission, a term coined by Frisch.[89] 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 atomic physicists and the public.[9] In their second publication on nuclear fission, Hahn and Strassmann predicted the existence and liberation of additional neutrons during the fission process.[90] Frédéric Joliot and his team proved this phenomenon to be a chain reaction in March 1939. In 1945 Hahn received the 1944 Nobel Prize in Chemistry "for his discovery of the fission of heavy atomic nuclei."[91][92]
After 1939[edit]
The Trinity test of the Manhattan Project in 1945 was the first atomic bomb.
See also: Chicago Pile-1 and Timeline of particle discoveries
The discovery of nuclear fission at the end of 1938 marked a shift in the centers of nuclear research from Europe to the United States. Large numbers of scientists were migrating to the United States to escape the troubles and antisemitism in Europe and the looming war[93]:407–410 (See Jewish scientists and the Manhattan Project). The new centers of nuclear research were the universities in the United States, particularly Columbia University in New York and the University of Chicago where Enrico Fermi had relocated,[94][95] and a secret research facility at Los Alamos, New Mexico, established in 1942, the new home of the Manhattan project.[96] This wartime project was focussed on the construction of nuclear weapons, exploiting the enormous energy released by the fission of uranium or plutonium through neutron-based chain reactions.
The discoveries of the neutron and positron in 1932 were the start of the discoveries of many new particles. Muons were discovered in 1936. Pions and kaons were discovered in 1947, while lambda particles were discovered in 1950. Throughout the 1950s and 1960s, a large number of particles called hadrons were discovered. A classification scheme for organizing all these particles, proposed independently by Murray Gell-Mann[97] and George Zweig[98][99] in 1964, became known as the quark model. 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 partons or quarks. The quark model received experimental verification beginning in the late 1960s and finally provided an explanation for the neutron's anomalous magnetic moment.[100][10]
Videos[edit]
Ernest Rutherford summarizes the state of nuclear physics in 1935. (7 min., Nobelprize.org)
Hans Bethe discusses Chadwick and Goldhaber's work on deuteron disintegration. (2 min., Web of Stories)
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^ Jump up to: a b c d e f Rife, Patricia (1999). Lise Meitner and the dawn of the nuclear age. Basel, Switzerland: Birkhäuser. ISBN 0-8176-3732-X.
^ Jump up to: a b Perkins, Donald H. (1982), Introduction to High Energy Physics, Addison Wesley, Reading, Massachusetts, pp. 201–202, ISBN 0-201-05757-3
Jump up ^ Rutherford distinguished and named α and β rays on page 116 of: Rutherford, E. (1899) "Uranium radiation and the electrical conduction produced by it," Philosophical Magazine, Series 5, vol. 47, no. 284, 109–163. Rutherford named γ rays on page 177 of: Rutherford, E. (1903) "The magnetic and electric deviation of the easily absorbed rays from radium," Philosophical Magazine, Series 6, vol. 5, no. 26, 177–187.
Jump up ^ Rutherford, E.; Royds, T. (1908) "Spectrum of the radium emanation," Philosophical Magazine, Series 6, vol. 16, 313–317.
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^ Jump up to: a b c Ley, Willy (October 1966). "The Delayed Discovery". For Your Information. Galaxy Science Fiction. pp. 116–127.
Jump up ^ Others had also suggested the possibility of isotopes; for example:
Strömholm, D. and Svedberg, T. (1909) "Untersuchungen über die Chemie der radioactiven Grundstoffe II." (Investigations into the chemistry of the radioactive elements, part 2), Zeitschrift für anorganischen Chemie, 63: 197–206; see especially page 206.
Cameron, Alexander Thomas (1910). Radiochemistry. London, England: J. M. Dent & Sons, p. 141. (Cameron also anticipated the displacement law.)
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^ Jump up to: a b Glasson, J.L. (1921). "Attempts to detect the presence of neutrons in a discharge tube". Philosophical Magazine. 42 (250): 596. doi:10.1080/14786442108633801.
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Jump up ^ Pauli, W. (1985). "Das Jahr 1932 Die Entdeckung des Neutrons". Wolfgang Pauli Wissenschaftlicher Briefwechsel mit Bohr, Einstein, Heisenberg u.a. Sources in the History of Mathematics and Physical Sciences. 6. p. 105. doi:10.1007/978-3-540-78801-0_3. ISBN 978-3-540-13609-5.
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^ Jump up to: a b c d Gamow G. (1931) Constitution of Atomic Nuclei and Radiation, Oxford: Clarendon Press
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^ Jump up to: a b c Brown, Laurie M. (1978). "The idea of the neutrino". Physics Today. 31 (9): 23. Bibcode:1978PhT....31i..23B. doi:10.1063/1.2995181.
^ Jump up to: a b Friedlander, G.; Kennedy, J.W.; Miller, J.M. (1964) Nuclear and Radiochemistry (2nd edition), Wiley, pp. 22–23 and 38–39
^ Jump up to: a b c d Stuewer, Roger H. (1985). "Niels Bohr and Nuclear Physics". In French, A. P.; Kennedy, P. J. Niels Bohr: A Centenary Volume. Harvard University Press. pp. 197–220. ISBN 0674624165.
Jump up ^ Interview with Franco Rasetti Judith R. Goodstein, Caltech Oral History Project (1982)
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Jump up ^ Shultis, J. Kenneth; Faw, Richard E. (2007), Fundamentals of Nuclear Science and Engineering, CRC, 2nd edition, ISBN 1420051369
Jump up ^ In a nucleus of diameter R in the order of 10 fm, the uncertainty principle would require an electron to have a momentum p of the order of h/R. Such a momentum implies that the electron has a (relativistic) kinetic energy of 10–100 MeV.
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Jump up ^ Joliot-Curie, Irène; Joliot, Frédéric (1932). "Émission de protons de grande vitesse par les substances hydrogénées sous l'influence des rayons γ très pénétrants" [Emission of high-speed protons by hydrogenated substances under the influence of very penetrating γ-rays]. Comptes Rendus des Séances de l'Académie des Sciences (in French). 194: 273.
Jump up ^ Zichichi, A., Ettore Majorana: genius and mystery, CERN Courier, 25 July 2006, Access date: 16 November 2017.
^ Jump up to: a b c Brown, A. (1997). The Neutron and the Bomb: A Biography of Sir James Chadwick. Oxford University Press. ISBN 9780198539926.
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Jump up ^ Chadwick, James (1932). "Possible Existence of a Neutron". Nature. 129 (3252): 312. Bibcode:1932Natur.129Q.312C. doi:10.1038/129312a0.
^ Jump up to: a b Chadwick, J. (1933). "Bakerian Lecture.–The Neutron". Proceedings of the Royal Society A. 142 (846): 1–25. Bibcode:1933RSPSA.142....1C. doi:10.1098/rspa.1933.0152.
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Jump up ^ Heisenberg, W. (1932). "Über den Bau der Atomkerne. I". Zeitschrift für Physik. 77: 1–11. Bibcode:1932ZPhy...77....1H. doi:10.1007/BF01342433.
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^ Jump up to: a b Iwanenko, D. (1932). "Sur la constitution des noyaux atomiques". Comptes Rendus de l'Académie des Sciences de Paris. 195: 439–441.
Jump up ^ Bacher, R.F.; Condon, E.U. (1932). "The Spin of the Neutron". Physical Review. 41 (5): 683–685. Bibcode:1932PhRv...41..683G. doi:10.1103/PhysRev.41.683.
Jump up ^ Whaling, W. (2009). "Robert F. Bacher 1905–2004" (PDF). Biographical Memoirs of the National Academy of Sciences. Archived (PDF) from the original on 2014-05-31.
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^ Jump up to: a b Wilson, Fred L. (1968). "Fermi's Theory of Beta Decay". Am. J. Phys. 36 (12): 1150–1160. Bibcode:1968AmJPh..36.1150W. doi:10.1119/1.1974382.
Jump up ^ Iwanenko, D. (1932). "Neutronen und kernelektronen". Physikalische Zeitschrift der Sowjetunion. 1: 820–822.
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^ Jump up to: a b c d Breit, G.; Rabi, I.I. (1934). "On the interpretation of present values of nuclear moments". Physical Review. 46 (3): 230. Bibcode:1934PhRv...46..230B. doi:10.1103/PhysRev.46.230.
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Jump up ^ Sime, R.L. (1996). Lise Meitner: A Life in Physics. University of California Press. ISBN 0520089065.
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Jump up ^ Frisch, R.; Stern, O. (1933). "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." Zeitschrift für Physik. 84: 4–16. Bibcode:1933ZPhy...85....4F. doi:10.1007/bf01330773.
Jump up ^ Esterman, I.; Stern, O. (1933). "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." Zeitschrift für Physik. 85: 17–24. Bibcode:1933ZPhy...85...17E. doi:10.1007/BF01330774.
Jump up ^ Esterman, I.; Stern, O. (1934). "Magnetic moment of the deuton". Physical Review. 45 (10): 761(A109). Bibcode:1934PhRv...45..739S. doi:10.1103/PhysRev.45.739.
Jump up ^ Rabi, I.I.; Kellogg, J.M.; Zacharias, J.R. (1934). "The magnetic moment of the proton". Physical Review. 46 (3): 157. Bibcode:1934PhRv...46..157R. doi:10.1103/PhysRev.46.157.
Jump up ^ Rabi, I.I.; Kellogg, J.M.; Zacharias, J.R. (1934). "The magnetic moment of the deuton". Physical Review. 46 (3): 163. Bibcode:1934PhRv...46..163R. doi:10.1103/PhysRev.46.163.
^ Jump up to: a b Rigden, John S. (2000). Rabi, Scientist and Citizen. Harvard University Press. ISBN 9780674004351.
Jump up ^ Bacher, R.F. (1933). "Note on the Magnetic Moment of the Nitrogen Nucleus". Physical Review. 43 (12): 1001. Bibcode:1933PhRv...43.1001B. doi:10.1103/PhysRev.43.1001. Retrieved 10 February 2015.
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Jump up ^ Cooper, Dan (1999). Enrico Fermi: And the Revolutions in Modern physics. New York: Oxford University Press. ISBN 0-19-511762-X. OCLC 39508200.
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Further reading[edit]
Annotated bibliography for neutrons from the Alsos Digital Library for Nuclear Issues
Abraham Pais, Inward Bound, Oxford: Oxford University Press, 1986. ISBN 0198519974.
Herwig Schopper, Weak interactions and nuclear beta decay, Publisher, North-Holland Pub. Co., 1966. OCLC 644015779
Ruth Lewin Sime, Lise Meitner: A Life in Physics, Berkeley, University of California Press, 1996. ISBN 0520208609.
Roger H. Stuewer, "The Nuclear Electron Hypothesis". In Otto Hahn and the Rise of Nuclear Physics, William R. Shea, ed. Dordrecht, Holland: D. Riedel Publishing Company. pp. 19–67, 1983. ISBN 90-277-1584-X.
Sin-Itiro Tomonaga, The Story of Spin, The University of Chicago Press, 1997. ISBN 9780226807942
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2018 Major League Baseball season
From Wikipedia, the free encyclopedia
Jump to: navigation, search
2018 MLB season
League
Major League Baseball
Sport
Baseball
Duration
March 29 – October 31, 2018[1]
Number of games
162
Number of teams
30
Regular season
League Postseason
World Series
MLB seasons
← 2017
2019 →
The 2018 Major League Baseball season began on March 29, 2018, and is scheduled to end on September 30. The postseason will begin on October 2. The 2018 World Series is set to begin on October 23, and a potential Game 7 is scheduled on October 31.[2]
The 2018 MLB Draft will be held from June 4 to 6 in Secaucus, New Jersey.
The 89th Major League Baseball All-Star Game will be held on July 17 at Nationals Park, the home of the Washington Nationals.
Contents
[hide]
1 Schedule
2 Rule changes
3 Standings
3.1 Division
4 Managerial changes
4.1 General managers
4.1.1 Offseason
4.2 Field managers
4.2.1 Offseason
4.2.2 In–season
5 League leaders
5.1 American League
5.2 National League
6 Milestones
6.1 Batters
6.2 Pitchers
6.2.1 No-hitters
6.2.2 Other pitching accomplishments
7 Uniforms
7.1 Wholesale changes
7.2 Alternate changes
7.3 Anniversaries and special events
7.4 Other uniforms
7.5 Throwbacks
8 Broadcast rights
8.1 Television
8.1.1 National
8.2 Radio
8.2.1 Local
8.2.2 National
8.3 Digital
9 Retired numbers
10 See also
11 References
12 External links
Schedule[edit]
As has been the case since 2013, all teams will play their four division opponents 19 times each for a total of 76 games. They will play six or seven games against each of the other 10 same-league opponents for a total of 66 games, and 20 inter-league games. The primary inter-league match-ups are AL East vs NL East, AL Central vs NL Central, and AL West vs NL West. Since "natural rivalry" matchups are part of the three-year divisional rotation, the schedule format for interleague games will be different from previous years. The 20 interleague games each team will play will consist of two three-game series (one home, one away) against its natural rival (total of six games), two two-game series (one home, one away) against each team for two other opponents (total of eight games), and a single three-game series against each team for the last two (one home, one away; total of six games).
Under the new collective bargaining agreement reached in December 2016, the regular season has been extended to 187 days in order to add four additional off-days for all teams. All teams were scheduled to play Opening Day, March 29–the earliest domestic start of a regular season in MLB history. There will no longer be a Sunday-night game on the final Sunday before the All-Star Game. A single, nationally televised afternoon game will be played on the Thursday after the All-Star Game (which for 2018, will be played between the St. Louis Cardinals and Chicago Cubs), before all other teams return from break the next day.[3][4][5]
The Minnesota Twins and the Cleveland Indians played a two-game series at Hiram Bithorn Stadium in San Juan, Puerto Rico on April 17 and 18,[6] while the Los Angeles Dodgers and San Diego Padres will play a three-game series at Estadio de Béisbol Monterrey in Monterrey, Mexico from May 4 to 6.[7] The Little League Classic game at BB&T Ballpark in Williamsport, Pennsylvania, coinciding with the Little League World Series, will return to the schedule. It will be played between the Philadelphia Phillies and the New York Mets on August 19.[8]
Rule changes[edit]
Beginning in the 2018 season, MLB implemented new pace of play rules, which include limiting the amount of mound visits for each team to six visits per nine innings. Teams will receive an additional visit for every extra inning played.[9]
Standings[edit]
Division[edit]
American League
National League
v
t
e
American League East
W
L
Pct.
GB
Home
Road
Boston Red Sox 19 5 0.792 — 8–1 11–4
New York Yankees 15 9 0.625 4 11–5 4–4
Toronto Blue Jays 14 10 0.583 5 8–5 6–5
Tampa Bay Rays 10 13 0.435 8½ 6–7 4–6
Baltimore Orioles 6 19 0.240 13½ 3–9 3–10

v
t
e
American League Central
W
L
Pct.
GB
Home
Road
Cleveland Indians 13 10 0.565 — 7–4 6–6
Detroit Tigers 10 13 0.435 3 6–7 4–6
Minnesota Twins 8 12 0.400 3½ 5–3 3–9
Chicago White Sox 6 16 0.273 6½ 2–10 4–6
Kansas City Royals 5 18 0.217 8 1–10 4–8

v
t
e
American League West
W
L
Pct.
GB
Home
Road
Houston Astros 17 9 0.654 — 7–5 10–4
Los Angeles Angels 16 9 0.640 ½ 5–7 11–2
Seattle Mariners 14 10 0.583 2 5–5 9–5
Oakland Athletics 13 12 0.520 3½ 8–6 5–6
Texas Rangers 9 17 0.346 8 4–12 5–5

v
t
e
National League East
W
L
Pct.
GB
Home
Road
New York Mets 15 8 0.652 — 7–4 8–4
Philadelphia Phillies 15 9 0.625 ½ 10–3 5–6
Atlanta Braves 14 10 0.583 1½ 8–4 6–6
Washington Nationals 11 14 0.440 5 3–7 8–7
Miami Marlins 7 17 0.292 8½ 3–9 4–8

v
t
e
National League Central
W
L
Pct.
GB
Home
Road
St. Louis Cardinals 15 9 0.625 — 7–5 8–4
Milwaukee Brewers 16 10 0.615 — 8–6 8–4
Pittsburgh Pirates 14 11 0.560 1½ 7–5 7–6
Chicago Cubs 12 10 0.545 2 4–4 8–6
Cincinnati Reds 5 20 0.200 10½ 3–9 2–11

v
t
e
National League West
W
L
Pct.
GB
Home
Road
Arizona Diamondbacks 17 7 0.708 — 9–3 8–4
Colorado Rockies 14 12 0.538 4 5–7 9–5
Los Angeles Dodgers 11 12 0.478 5½ 7–8 4–4
San Francisco Giants 11 13 0.458 6 5–5 6–8
San Diego Padres 9 17 0.346 9 4–10 5–7

Managerial changes[edit]
General managers[edit]
Offseason[edit]
Team
Former GM
Reason For Leaving
New GM
Story/Accomplishments
Atlanta Braves
John Coppolella Resigned Alex Anthopoulos John Coppolella resigned from the Braves on October 2, 2017, because of a Major League Baseball investigation.[10] On November 12, 2017, Alex Anthopoulos was hired as the new general manager of the team.[11] On November 21, 2017, Coppolella was banned for life from baseball as a result of the investigation.
Field managers[edit]
Offseason[edit]
Team
Former manager
Reason for leaving
New manager
Story/Accomplishments
Detroit Tigers
Brad Ausmus Contract not renewed Ron Gardenhire The Tigers announced on September 22, 2017, that Ausmus' contract would not be renewed. Ausmus compiled a 314–332 (.486) record in four years as manager with one playoff appearance.[12] The Tigers hired former Minnesota Twins manager Ron Gardenhire on October 19, 2017. As the Twins' manager from 2002 to 2014 he compiled a record of 1068–1039 (.507), and 6–21 (.222) in six post-season appearances. He also won AL Manager of the Year in 2010.[13]
Philadelphia Phillies
Pete Mackanin Reassigned Gabe Kapler It was announced on October 1, 2017, that Mackanin would be removed as manager but he managed the final three games of the 2017 season. Mackanin had a record of 174–238 (.422) in his two and a half seasons as manager with no playoff appearances. It was also announced he would remain with the organization as a special assistant to the general manager.[14] On October 29, 2017, the Phillies announced the hire of former Dodgers' Director of Development Gabe Kapler. He has no previous major league managerial or coaching experience.[15]
New York Mets
Terry Collins Retired Mickey Callaway Collins announced on October 1, 2017, that he would retire after the last game of the season. He will move to the Mets' front office. Collins finished with a 551–583 (.486) record in seven years with club, with two playoff appearances in 2015 and 2016, where they lost to the Kansas City Royals in the World Series and lost the Wild Card to the San Francisco Giants in the following season.[16] The Mets named Cleveland Indians pitching coach Mickey Callaway as their new manager on October 22, 2017. Callaway has no previous managerial experience.[17]
Boston Red Sox
John Farrell Fired Alex Cora Farrell was fired on October 11, 2017. Farrell during his five years as manager compiled a 432–378 (.533) record and earned three division titles in 2013, 2016 and 2017. He led the Red Sox to the 2013 World Series title.[18] Houston Astros bench coach Alex Cora was named manager on October 22, 2017, and formally assumed the role after the Astros' win in the 2017 World Series.[19] He has no previous managerial experience.
Washington Nationals
Dusty Baker Contract not renewed Dave Martinez The Nationals announced on October 20, 2017, that Baker would not be returning for the 2018 season. Baker led the Nationals to the postseason in each of his two seasons with the club but couldn't get past the NLDS. The Nationals were 192–132 (.593) under Baker.[20] The Nationals hired Dave Martinez to be their new manager on October 29, 2017. Martinez was previously the bench coach for the Chicago Cubs, and has no managerial experience.[21]
New York Yankees
Joe Girardi Aaron Boone The Yankees announced on October 26, 2017, that Girardi would not return for the 2018 season. Girardi led the Yankees to three division titles and one World Series championship during his ten years of managing the club. The Yankees were 910–710 (.562) under Girardi.[22] On December 1, 2017, radio announcer Aaron Boone was hired as the team's new manager.[23] He has no previous coaching or managerial experience.
In–season[edit]
Team
Former manager
Interim manager
Reason for leaving
New manager
Story/Accomplishments
Cincinnati Reds Bryan Price Jim Riggleman Fired TBA Price was fired after starting the season with a 3–15 (.167). In four seasons, Price finished with a 279–387 (.419) record with no playoff appearances. Bench coach Jim Riggleman was selected as the interim manager. His previous managerial experience includes stints with the Padres, Cubs, Mariners, and Nationals. He has been a Manager in the Reds' minor league system since 2012.[24]
League leaders[edit]
Updated through April 26
American League[edit]
Hitting leaders
Stat
Player
Total
AVG Didi Gregorius (NYY) .354
HR Mike Trout (LAA) 10
RBI Didi Gregorius (NYY) 29
R Mookie Betts (BOS) 25
H Jed Lowrie (OAK) 37
SB Dee Gordon (SEA) 9
Pitching leaders
Stat
Player
Total
W 4 tied with 4
L Kendall Graveman (OAK) 5
ERA Sean Manaea (OAK) 1.23
K Gerrit Cole (HOU) 49
IP Justin Verlander (HOU) 39.2
SV Edwin Díaz (SEA) 11
National League[edit]
Hitting leaders
Stat
Player
Total
AVG Tommy Pham (STL) .355
HR Ozzie Albies (ATL)
Charlie Blackmon (COL)
Bryce Harper (WAS) 8
RBI Javier Baez (CHC) 24
R Ozzie Albies (ATL) 24
H Ozzie Albies (ATL)
DJ Lemahieu (COL)
Dansby Swanson (ATL)
30
SB Trea Turner (WAS) 10
Pitching leaders
Stat
Player
Total
W Max Scherzer (WAS) 5
L Jon Gray (COL)
Clayton Kershaw (LAD) 4
ERA Johnny Cueto (SF) 0.35
K Max Scherzer (WAS) 57
IP Max Scherzer (WAS) 39.0
SV Wade Davis (COL)
Jeurys Familia (NYM) 9
Milestones[edit]
Batters[edit]
George Springer (HOU):
With his Opening Day lead-off home run on March 29 against the Texas Rangers, Springer became the first player in Major League history to lead off back-to-back seasons with a home run.[25]
Joe Panik (SF):
Became the first player in Major League history to hit a home run in consecutive 1–0 victories by his team.[26]
Adrian Beltre (TEX):
With a second-inning double on April 5 against the Oakland Athletics, Beltre became the all-time leader in hits by a player from Latin America. Beltre, from the Dominican Republic, passed Rod Carew of Panama with the 3,054th hit in his career.[27]
Joe Mauer (MIN):
Recorded his 2,000th career hit with a single in the seventh inning against the Chicago White Sox on April 12. He became the 287th player to reach this mark.[28]
Miguel Cabrera (DET):
Recorded his 550th career double in the seventh inning against the Baltimore Orioles on April 19. He became the 30th player to reach this mark.
Ryan Braun (MIL):
Recorded his 1,000th career RBI with a pinch-hit home run in the sixth inning against the Miami Marlins on April 19. He became the 285th player to reach this mark.[29]
Pitchers[edit]
No-hitters[edit]
Sean Manaea (OAK):
Threw his first career no-hitter by defeating the Boston Red Sox 3–0 on April 21. Manaea walked two and threw one wild pitch, throwing 108 pitches, 75 for strikes, and striking out ten. One other runner reached on an error. There was also a controversial call in which a runner was called out for exiting the base path near first base, after having originally been called safe.[30]
Other pitching accomplishments[edit]
Max Scherzer (WAS):
Became the second pitcher in the live-ball era (since 1920) to pitch a shutout, strike out at least 10 batters and steal a base in the same game by accomplishing this feat on April 9 against the Atlanta Braves. He joins Nolan Ryan who did this against the Pittsburgh Pirates on May 16, 1984.[31]
Roberto Osuna (TOR):
On April 10, at the age of 23 years and 62 days, Osuna became the youngest pitcher in Major League history to acquire his 100th career save. Osuna was over a year younger than the previous record holder Francisco Rodríguez. Rodríguez had accomplished the feat at the age of 24 years and 246 days.[32]
Uniforms[edit]
Wholesale changes[edit]
The Detroit Tigers modified the Olde English D on the home jersey to match the D on the cap. This is the first major change to the Tigers' home jersey since 1934 (not counting the hiatus in 1960). [33]
The Cleveland Indians have confirmed this will be final season using the Chief Wahoo logo on its uniforms. It will be replaced at the start of the 2019 season.[34]
Alternate changes[edit]
The Oakland Athletics added a kelly green alternate jersey to commemorate the franchise's 50th anniversary in Oakland. The uniforms are used during every Friday home game.[35]
The Washington Nationals added a second navy blue jersey to commemorate the team's hosting of the 2018 All-Star Game. The uniform features the script "Nationals" in white with red trim and numerals in red with white trim. [36]
Both the Cincinnati Reds and the Pittsburgh Pirates replaced their camouflage uniforms with new white alternate jerseys featuring olive and military green logos, letters and numbers.[37][38]
Anniversaries and special events[edit]
The following teams will wear commemorative patches for special occasions:[citation needed]
Team
Special occasion
All Teams "MSD" patch in memory of the victims of the Stoneman Douglas High School shooting (February 23)
#42 patch for Jackie Robinson Day (April 15)
Pink ribbons for breast cancer awareness (May 12–13, Mother's Day weekend)
"Play Ball" patch in partnership with USA Baseball and USA Softball (June 2–3)
Blue ribbons for prostate cancer awareness (June 16–17, Father's Day weekend)
Players Weekend (August 24–26)
Gold ribbons for childhood cancer awareness (August 31)
Atlanta Braves 50th anniversary of the assassination of Reverend Martin Luther King, Jr. (April 4)[39]
Arizona Diamondbacks 20th anniversary of the franchise
Chicago Cubs "MSD" patch in memory of the victims of the Stoneman Douglas High School shooting (March 29)
Colorado Rockies 25th anniversary of the franchise
Houston Astros 2017 World Series Championship (April 2)
Kansas City Royals 50th season of the franchise
Los Angeles Dodgers 60th anniversary in Los Angeles
Miami Marlins 25th anniversary of the franchise (began as the Florida Marlins)
“MSD” patch in memory of the victims of the Stoneman Douglas High School shooting (March 29-April 1)
New York Mets Autograph patch in memory of Rusty Staub
Oakland Athletics 50th anniversary in Oakland
San Francisco Giants 60th anniversary in San Francisco
Tampa Bay Rays 20th anniversary of the franchise (originally Devil Rays)
Toronto Blue Jays #32 patch in memory of Roy Halladay
Washington Nationals 2018 All Star Game
Other uniforms[edit]
The Astros wore gold-lettered uniforms at their home opener April 2 and April 3 to mark them winning the 2017 World Series title.[40]
Players, managers and coaches wore #42 on April 15, the 71st anniversary of Jackie Robinson's debut in the majors.[41]
The Orioles wore special caps and green uniforms on April 22, Earth Day.[42]
The Royals will wear an alternate uniform with a crown atop the R, and a cap with a crown instead of the "KC", on June 30 in Seattle.[43]
Throwbacks[edit]
The Phillies will wear their 1980s powder blue uniforms for select Thursday home games.[44]
The Athletics and White Sox wore 1968 throwbacks April 17 to mark the 50th anniversary of the Athletics' first season in Oakland.[45]
The Tigers and Royals will wear Negro Leagues throwbacks May 6. The Tigers will wear the uniforms of the Detroit Stars, and the Royals will wear the uniforms of the Kansas City Monarchs.[46]
The Marlins will wear 1993 throwbacks June 8-10 to mark their 25th anniversary.[47]
The Mariners will mark the 20th anniversary of their 1998 "Turn Ahead the Clock" promotion by wearing the uniforms from that game June 30 against Kansas City.[48]
The Rays wore throwbacks from their inaugural season on March 31 against the Boston Red Sox. They will wear these throwbacks again on June 9 against the Seattle Mariners, June 23rd against the New York Yankees and on September 8th against the Baltimore Orioles.
Broadcast rights[edit]
Television[edit]
National[edit]
This is the fifth year of the current eight-year deals with Fox Sports, ESPN and TBS. Fox will air eight weeks of baseball on Saturday Nights leading up to the 2018 Major League Baseball All-Star Game which will also air on Fox. Fox will then televise Saturday afternoon games for the last four weeks of the regular season. FS1 will televise games on Tuesday and on Saturdays both during the afternoon and night. ESPN will televise games on its flagship telecast Sunday Night Baseball as well as Monday and Wednesday Nights. TBS will televise Sunday afternoon games for the last 13 weeks of the regular season. Fox and ESPN Sunday Night Baseball telecasts will be exclusive; all other national telecasts will be subject to local blackout.
TBS will televise the American League Wild Card Game, Division Series and Championship Series. ESPN will televise the National League Wild Card. Fox Sports 1 and MLB Network will televise the National League Division Series. Fox and Fox Sports 1 will televise the National League Championship Series. The World Series will air exclusively on Fox for the 19th consecutive year.
Radio[edit]
Local[edit]
The Minnesota Twins will return to Entercom's WCCO/Minneapolis after twelve years on KSTP, followed by the Twins-owned FM station KQGO;[49] WCCO has been the flagship for the Twins' network for 46 of the team's 58 years of existence. Entercom will also take over all existing play-by-play contracts from their newly acquired stations from CBS Radio after the two companies merged their radio assets on November 17, 2017.
The Chicago White Sox will have a new flagship station in Tribune Broadcasting's WGN/Chicago, after Cumulus Media asked to void their agreement to carry the team's games on WLS as part of its Chapter 11 bankruptcy filing, and Cumulus ending several high-profile talent and sports rights agreements due to their cost. The deal allows WGN to return to MLB play-by-play after a three-year hiatus after the end of their long association with the Chicago Cubs, who moved to WBBM in the 2015 season, then WSCR in 2016. WGN had previously carried White Sox broadcasts from 1927 until 1943.[50][51][52]
The San Diego Padres will have a new flagship station, as they moved from Entercom's KBZT to KEGY (FM), the latter of which flipped from contemporary hit radio to hot talk branded as "97.3 The Machine".[53][54][55][56][57][58][59]
National[edit]
ESPN Radio will air its 21st season of national coverage, including Sunday Night Baseball, Saturday games, Opening Day and holiday games, the All-Star Game, and Home Run Derby, and the entire Major League Baseball postseason.
Digital[edit]
Nine regular season games will be broadcast exclusively in the United States on Facebook Watch, beginning with the April 4 game between the New York Mets and Philadelphia Phillies.[60]
Retired numbers[edit]
Roy Halladay had his #32 retired posthumously by the Toronto Blue Jays on March 29.[61]
Barry Bonds will have his #25 retired by the San Francisco Giants on August 11.[62]
Jack Morris will have his #47 retired by the Detroit Tigers on August 12.[63]
Alan Trammell will have his #3 retired by the Detroit Tigers on August 26.[63]
See also[edit]
2018 in baseball
2018 Nippon Professional Baseball season
References[edit]
Jump up ^ October 31 is the date of a potential Game 7 of the World Series. The earliest the season can end is October 27.
Jump up ^ Newman, Mark. "2018 Major League Baseball schedule released". Major League Baseball. Retrieved 16 September 2017.
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Jump up ^ Jackson, Shane. "Indians, Twins to play in Puerto Rico in 2018". MLB.com. MLB Advanced Media. Retrieved 27 September 2017.
Jump up ^ Shaikin, Bill. "Dodgers and Padres set for Mexico series in May". Los Angeles Times. Retrieved 2017-11-13.
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Jump up ^ Gelb, Matt. "Phillies fire Pete Mackanin as manager". Philadelphia Inquirer. Retrieved September 30, 2017.
Jump up ^ "Phillies tap Dodgers exec Gabe Kapler as next manager". espn.com. ESPN. Retrieved 30 October 2017.
Jump up ^ DiComo, Anthony (October 1, 2017). "Collins resigns, set to move to front-office role". MLB.com.
Jump up ^ "Indians pitching coach Mick Callaway to be Mets' new manager". espn.com. ESPN. Retrieved 22 October 2017.
Jump up ^ Browne, Ian (October 11, 2017). "Red Sox dismiss Farrell after five seasons". MLB.com.
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Jump up ^ "Dusty Baker won't return as Nationals manager". espn.com. ESPN. Retrieved 20 October 2017.
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Jump up ^ Hoch, Bryan (October 26, 2017). "Girardi out as Yankees manager after 10 years". MLB.com. MLB. Retrieved October 26, 2017.
Jump up ^ "Aaron Boone become next manager of the New York Yankees/". ESPN.com. ESPN. December 1, 2017. Retrieved December 1, 2017.
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Jump up ^ https://www.yahoo.com/sports/george-springer-pulls-off-opening-day-feat-youve-never-seen-230711723.html
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Jump up ^ "Detroit Tigers Honor Club Heritage with Unified Olde English 'D' on Caps and Home Jerseys". MLB.com. Retrieved March 19, 2018.
Jump up ^ "Cleveland Indians removing Chief Wahoo logo from uniforms starting in 2019 season". www.cincinnati.com. January 29, 2018.
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Jump up ^ Merkin, Scott (17 November 2017). "Twins radio broadcasts set to return to WCCO". MLB.com. Retrieved 18 November 2017.
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Jump up ^ Rosenthal, Phil (18 January 2018). "WLS-AM parent company asks court to end 'unprofitable' White Sox, Bulls deals". Chicago Tribune. Retrieved 31 January 2018.
Jump up ^ Castle, George (14 February 2018). "WGN-Radio and 720 signal best possible 2018 home for White Sox". Chicago Baseball Museum. Retrieved 17 February 2018.
Jump up ^ "As Padres Move To KEGY, Format Flip Expected". Inside Radio. Retrieved 2018-02-21.
Jump up ^ Acee, Kevin. "Padres announce new radio home, spring broadcast schedule". San Diego Union-Tribune. Retrieved 2018-02-21.
Jump up ^ "San Diego Padres Make 97.3 KEGY Its New Home Ahead of Flip". RadioInsight. Retrieved 2018-02-21.
Jump up ^ Lin, Dennis. "Controversial radio host Dan Sileo will not be involved with Padres". Los Angeles Times. Retrieved 2018-02-18.
Jump up ^ "Former ALT 105 hosts of morning show Kevin Klein Live relocate to revive program in San Diego". SFGate. Retrieved 2018-03-03.
Jump up ^ "97.3 The Machine San Diego Debuts". RadioInsight. 2018-03-01. Retrieved 2018-03-02.
Jump up ^ "KEGY (Energy 97.3)/San Diego Turns Off The Top 40, Rocks Out In Prep For New Format". All Access. Retrieved 2018-03-02.
Jump up ^ DiComo, Anthony (April 3, 2018). "PHI-NYM airs exclusively on Facebook on Wed". MLB.com. Retrieved April 3, 2018.
Jump up ^ Blue Jays retiring No. 32 for Roy Halladay. MLB.com. Published on February 12, 2018. Retrieved on February 12, 2018
Jump up ^ Shea, John (February 6, 2018). "Giants retiring Barry Bonds' jersey number: 25". San Francisco Chronicle. Retrieved February 6, 2018.
^ Jump up to: a b Tigers to retire Trammell's No. 3, Morris' No. 47. MLB.com. Published on December 17, 2017. Retrieved on January 25, 2018.
External links[edit]
2018 Major League Baseball season schedule
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