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S3o "smeared out" as a result of th" participating excited stateSo The same will be true if the reactions leading to changes in mass ntunber take place in the regions of the beta unstable nuclei on the slopes of the energy valley, as is assumei in the neutron capture theory of the formation of the elements (Alpher and Herman, 1950, 195l» 1953)o The sum rule of isobar abundances In the A 100 region the isobar irlth the highest neutron excess, is almost always the most abundant one- The abundance of the isobar with the lower neutron excess, the so called "shielded" isobar is only of a comparable magnitude, if this isobar has a considerably greater binding energy than the unshielded oneo In most of these cases the value for the sum of the abx\ndanc9 of the two isobars agrees with an interoolated value between the valxsss of the unshielded isobar existing at the aaes nuitbers A - 2 and k 4- 2o The distribution gives tha impression, as if, in this mass range, the shielded nuclei have formed fi'om their shielding isobars after the mass distribution was established6 It can be shown, however, that such transmutation can not have occtjrred by tro sob^qtient /S" decays froa a thermally excited levelc On© can show this by considering the isobaric pair Tn*ê.Sn^^ for which the following information is available: Ratio of abundance IrT^/Sr^^ = 10o5o Excited level in In^^^ J 0o335 Mev » E*o Half life on this state: 4o5 hourso Partial half life for the beta decay of this state 70 hourso Spins of In^^ in the excited and noonnal states are 9/2 and -|« The mnriber of In^^ nuclei in the excited state, N*, at a temperature T will be N* W « g/g* jj e '^ From the above experimental data one finds that natural indium cannot liave been at a temrieratu3?e T for more with kT eacpresaad in M®Va
5u« This means that the In^^^ in natuire cannot have been subject to a higher temperature then about 0.3 Mev a k'V for more then a few days, or else a larger iwoportion of the nuclei of mass ll5 "would be present in the form of Sn ô By comparing this result with available data on excited states one finds that it is not possible to account for "Wie abundance of the shielded nuclear species by assuming beta decay from thermally excited levels hiêr than the ground state of the intermediate odd-odd isobar- According to the neutron capture theory, shielded nuclei will f oi*m in the later stage of the neutaran build up when the rate of the neutron capture processes beccîes smaller than the average rate of beta decay, so that the build up takes place in the stable nuclei regiono They will then form from sufficiently long lived or stable odd A nuclei by (?p^) and subsequi&nt beta decay of iisB odd-odd nucleic These abundances, however, cannot recdily be expected to follow the pattern required hy the sua rules- Light isotopes in the higher mass region The neutron capture theory dcBS not account for the existence of the t3rpe of shielded nuclei that have a lower binding energy than their shielding isobars and are on the p side of the energy valley. The abundance of these species is in general about ten times sraallar than that of the energetically favoured type of shielded nuclideso Their abundance is not correlated with their relative binding enexîeso One can inomediately see this from the fact that in a number of elenents the abundance of th«i lightest isotope is higher than that of the second lightesto This is the ease for Mo, Hu, Cd, Sn, Xe, and BEO In the case of Ce and Ry the lightest isotope is only slightly less abundant than the second liglitesto The lightest isotqpe, of course, always has a smaller
Page 1 and 2:
05" 9003'9 ,^ r.V- ou 15 -^ CBNTiJA
Page 3 and 4:
DISCLAIMER Portions of this documen
Page 5 and 6:
o which states that the elements wi
Page 7 and 8: inattention will be drawn to any ev
Page 9 and 10: 6 the proportions 10:1:2- The Nodda
Page 11 and 12: 8 Just in the case of these element
Page 13 and 14: 10 spectral lines on the temperatur
Page 15 and 16: 12 have studied the iron sulfide fr
Page 17 and 18: 14 the proportion of the three phas
Page 19 and 20: 16 by more than a factor of 10, e.g
Page 21 and 22: 18 million times smaller than that
Page 23 and 24: 20 as occurs at other points in the
Page 25 and 26: 22 220 ppm relative to silicon equa
Page 27 and 28: 24 abundances, R, and column three
Page 29 and 30: 26o The heavier rare gases^ Bie rar
Page 31 and 32: 28, the amount is very constant nea
Page 33 and 34: 30o valueso This ratio is 300 hy we
Page 35 and 36: greater constancy in the copper dat
Page 37 and 38: 33 o mass curve we natst assun® ab
Page 39 and 40: 35. Noddack*s value of 1.86 for the
Page 41 and 42: 37 value. Undoubtedly a marked decr
Page 43 and 44: 3Bo meteorites. We have selected a
Page 45 and 46: 40 than that given by Noddack (1955
Page 47 and 48: 42 The average is secured by assumi
Page 49 and 50: 44 these data all appear to be doub
Page 51 and 52: 46 ppm are not presented with great
Page 53 and 54: 48 We adopt values for u235, u^^°
Page 55 and 56: 50 the elements were formed at leas
Page 57: i»2o for the sum of isobaric abund
Page 61 and 62: :>6„ of the neutron excess number
Page 63 and 64: dance values fitting into the trend
Page 65 and 66: OUo 56 56 The hjalf life of m , whi
Page 67 and 68: TABLE II 6 Atomic Abundances of the
Page 69 and 70: TABLE II continued 3 45 Rh 1.3 3,5
Page 71 and 72: TABLE III Element A N I Log H H 1 H
Page 73 and 74: 21 22 23 24 25 26 27 28 29 Sc Ti V
Page 75 and 76: TABLE III Continued 5 37 Rb p- 37.
Page 77 and 78: 52 55 5^ 55 56 57 58 Te I Xe Cs Bn
Page 79 and 80: 67 Ho 68 Er 71 Lu 72 Hf 73 Ta 74 W
Page 81: TABLE III Continued 11 122 124 40 4
Page 86 and 87: Blbliography-2 Pellenberger, Th.v.,
Page 88 and 89: Pinson, W.H., Ahrens, L.H. and Fran
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