Q-Values for (α,p) Reactions on Aluminum and Boron by Means of Photographic Emulsions

Abstract

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.

An Analysis of the Energy Levels of the Mirror Nuclei,C13andN13

“…18 A complete survey of these and earlier B(a, p) investigations has been given by Slatis, Hjalmar, and Carlsson. 48 A 3.8-Mev gamma-ray has been observed with 1.4-Mev…”

“…Because they are not easily interpreted, we list the more recent Q values [41][42][43][44][45] in Table I. Reference 41 used magnetic analysis of the particle groups, the others range measurements.…”

“…The radiative width, coI\ 66 of the pi level, as measured by Van Patter 29 as well as by Seagrave, 61 is 1.3 ev. Assuming that a twobody interaction is involved between the odd proton and the core and neglecting possible interaction effects, 67 the width for a p%-*p\ transition is given by 68 coI\= (2/9)(hvneVhc)(McT 2 (gs-gi) 2 x 2 , (44) where g 8 , gi are the spin and orbital g factors, and x(^ 1) measures the extent of overlap of the radial wave functions. With g s = 5.58, gz=0.96, hv=3.52, we find x=0.90.…”