EDITOR 641impurities. The third source was prepared by means of a thenoyl trifluoracetone (TTA) extraction 4 of scandium. Sources were deposited upon a cellophane foil 0.001 inch thick.The results of the spectrometer studies are given by the momentum spectrum in Fig. 1. Since only the high energy spectrum is of interest, the low energy group of Sc 46 is not shown. However, normalization of the three sources was made by comparing counting rates across the peak of this low energy, high intensity group. Statistical errors are no larger than the size of the marker which indicates the position of the experimental point. The arrows indicate experimental data taken 72 days and 112 days after initiation of the study with appropriate normalization by means of the peak counting rate of the lower energy beta-spectrum. This indicates that the higher energy group decays with the same half-life as does the lower energy group, this being 84 days, in good agreement with the accepted value for Sc 46 . Since there is little difference in the shapes of the spectra obtained from all three sources and since the half-life is the same as that associated with Sc 46 , it would appear that the recorded electrons are not produced by an impurity.The results are not in agreement with those previously reported by Peacock and Wilkinson. 2 The maximum energy appears here to be about 1.2±0.1 Mev. Nothing above background counting could be observed at energies higher than 1.2 Mev. A Fermi-Kurie plot of the data shows a convexity toward the energy axis. This was expected since a thick source (3-6 mg/cm 2 ) was necessary in order to obtain an appreciable counting rate over background for the higher energy group. Since it is conceivable that the radiation observed could be caused by Compton electrons ejected as secondary electrons from the source by the 0.89-and 1.12-Mev gamma-rays, it was decided to cover the source with an aluminum foil having a thickness approximately equal to that of the source. If the higher energy electrons were purely secondary Compton electrons one would expect an increase in counting rate over the higher energy group of approximately fifty percent. Although the spectrum in Fig. 1 does show a definite increase in counting rate when the source is covered, it amounts only to about 15 percent. It would therefore appear that, although part of the electron radiation is caused by secondary electrons ejected from the source by the Compton process, at least a part really belong to a high energy beta-group. This real group of higher energy beta-particles appears not to exceed 0.5 percent of the total number of such particles from Sc 46 . * Assisted by the joint program of the ONR and AEC.
EDITOR 1429 dependence of gamma-transition lifetime on nucleon configuration. The data presented in Fig. 1 show that there is, in fact, some evidence to this effect.In Fig. 1, the values of the matrix elements \M | 2 for all the evaluable E3 transitions of the 7/2+<=^> § type are plotted against a number n, representing the complexity of the nucleon configuration. For odd-proton nuclei (open circle points), n is the number of protons coupling to form the 7/2+state, and for odd-neutron nuclei (full circle points) n is the number of neutron holes in the configuration forming the 7/2+state. Reasonable estimates of n can be arrived at in the case of g 9 /2 proton and neutron configurations by consideration of the energy systematics of the 7/2 +levels. 4 For the cases of Os 191 , W 183 , and W 185 , however, the nvalues for the inn holes can be regarded as no more than judicious shell-theory guesses. It is apparent from the plot that \M\ 2 increases steeply with n and at approximately the same rate for odd protons of the g 9 /2 shell, and for odd neutrons of both the g 9 /2 and iu/2 sub-shells. To indicate the odd-proton variation, the Rh 105 and Ag 107 points have been joined by a line because these isomers have equal neutron numbers. There appears to be some evidence from the plot that there is a systematic effect of adding pairs of neutrons and protons. The departure of Kr 79 from the general trend may be due to experimental inaccuracy.Since the factors involved in the estimates 2 of transition probabilities are the same for both odd-proton and odd-neutron transitions and since the single nucleon p\ states are common to all transitions, the differences of \M\ 2 should be attributed to the differences of nucleon electric moment of the 7/2+states. It is not surprising that the electric moment of the odd-proton 7/2 states should increase with increasing numbers of protons in the outer-shell configurations. It is also reasonable to expect that an increasing number of neutrons in the outer shell configurations should tend to crowd protons into the core, thus affecting the electric moment in an inverse manner to the odd-proton states. This is equivalent to saying that for odd-neutron states the electric moment should increase with the number of neutron holes in the configuration.If the argument for the variation of \M\ 2 with configuration complexity be accepted for the E3 transitions, it may be conversely argued that the constancy of \M | 2 for the M4: transitions also indicates relatively pure configurations. Analysis of the M\ cases makes this indeed appear so, for there are only two cases (Ag 110 and In 110 ) which have \M| 2 values departing significantly from the mean, and these configurations are, in fact, the only ones which are not describable in terms of a single nucleon. It may well be, therefore, that large departures of \M\ 1 values from the mean value for a particular multipole transition are associated either with departures of one or both of the states from single nucleon configurations or alternatively w...
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