翻訳と辞書 Words near each other ・ Isochoric ・ Isochoric process ・ Isochorismatase ・ Isochorismate lyase ・ Isochorismate synthase ・ Isoamyl acetate ・ Isoamyl alcohol ・ Isoamylase ・ Isoanala ・ Isoantibodies ・ Isoantigen ・ Isoaspartate ・ Isoazimuthal ・ Isobar ・ Isobar (company) ・ Isobar (nuclide) ・ Isobar Australia ・ Isobaric ・ Isobaric counterdiffusion ・ Isobaric labeling ・ Isobaric loudspeaker ・ Isobaric process ・ Isobaric tag for relative and absolute quantitation ・ IsoBase ・ Isobe Station ・ Isobe Station (Gunma) ・ Isobe, Mie ・ Isobel ・ Isobel (disambiguation) ・ Isobel (song) Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Isobar (nuclide) ： ウィキペディア英語版 Isobar (nuclide) Isobars are atoms (nuclides) of different chemical elements that have the same number of nucleons. Correspondingly, isobars differ in atomic number (or number of protons) but have the same mass number. An example of a series of isobars would be 40S, 40Cl, 40Ar, 40K, and 40Ca. The nuclei of these nuclides all contain 40 nucleons; however, they contain varying numbers of protons and neutrons.〔Sprawls (1993)〕 The term "isobars" (originally "isobares") for nuclides was suggested by Alfred Walter Stewart in 1918.〔http://jnm.snmjournals.org/content/19/6/581.full.pdf〕 It is derived from the Greek word ''isos'', meaning "equal" and ''baros'', meaning "weight".〔(Etymology Online )〕 == Mass == The same mass number does not imply neither the same mass of nuclei, nor equal atomic masses of corresponding nuclides. From the Weizsäcker's formula for the mass of a nucleus : $m(A,Z)\; =\; Z\; m\_p\; +\; N\; m\_n\; -\; a\_\; A\; +\; a\_\; A^\; +\; a\_\; \backslash frac\; \backslash frac\; -\; \backslash delta(A,Z)$ where mass number  equals to the sum of atomic number  and number of neutrons , and , , , , , are constants, one can see that the mass depends on and non-linearly, even for a constant mass number. For odd , it is admitted that and the mass dependence on  is convex (or on  or , it does not matter for a constant ). This explains that beta-decay is energetically favorable for neutron-rich nuclides, and positron decay is favorable for strongly neutron-deficient nuclides. Both decay modes do not change the mass number, hence an original nucleus and its daughter nucleus are isobars. In both aforementioned cases, a heavier nucleus decays to its lighter isobar. For even  the  term has the form: :$\backslash delta(A,Z)\; =\; (-1)^Z\; a\_P\; A^$ where is another constant. This term, subtracted from the mass expression above, is positive for even-even nuclei and negative for odd-odd nuclei. This means that even-even nuclei, which have not a strong neutron excess or neutron deficiency, have higher binding energy than their odd-odd isobar neighbors. It implies that even-even nuclei are (relatively) lighter and more stable. The difference is especially strong for small . This effect is also predicted (qualitatively) by other nuclear models and has important consequences. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Isobar (nuclide)」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.