Results are tabulated of the radioactivities produced by 4 Mev protons in targets of 7N, gO, 2oCa, 24O, 27C0, 3oZn, 34Se, 42M0, 46Pd, 48Cd, 49ln. In most cases the reactions are of the p-n type, and lead to isotopes which emit either + or -electrons. A detailed study was made of O, Zn and Se. The reaction 0 18 (p,n)F 18 (107 min.) shows a threshold at 2.56 Mev and a positron energy of 0.74 Mev in good agreement with the energy relations. The cross section for the reaction at 4 Mev is about 2X10 -25 cm 2 and there is a resonance maximum at 3.55 Mev. The cross section for the reaction 0 16 (p,y)F 17 is 4000 times smaller. The isomeric Br 80 periods (17.4 min. and 4.45 hr.) are observed in the reaction Se 80 (p,n)Br 80 . At 4 Mev the ratio of the short to long period activities for infinite bombardment is about 15 but the thresholds are at about 3.0 and 3.2 Mev, respectively. The cross section for the reaction is about 0.6 X 10~2 6 cm 2 at 4 Mev.
Indium activated by 7.2-Mev protons exhibits two activities, one due to In 115 * and one due to Sn 113 . The other two activities previously reported have been shown to be due to impurities. Sn 113 has a half-life of about 100 days and decays by i£-electron capture emitting In K x-rays. An active In of 105 ±10 min. half-life with a y-ray of 0.39 Mev has been chemically separated from an aged Sn 113 sample. An exactly similar In has been formed by proton bombardment of Cd which suggests the assignment of this activity to an excited state of stable In 113 . The absence of Cd K x-rays indicates that In 113 * decays to In 113 with the emission of the 0.39-Mev 7-ray. In addition bombarded Cd shows the expected In isotopes In 111 20 min. (+), In 114 48 days ( -) and In 116 54 min. (-). A positron emitter of 65±5 min. half-life with a maximum positron energy of 1.6±0.3 Mev is found and tentatively assigned to In 110 . Activities of 72 sec. ( -) and 2.7±0.2 days ( -) the latter accompanied by y-rays of 170 and 250 kev are ascribed to isomeric states of In 112 .
which is the product of a deuteron plane wave and the wave function \pi(p) of the initial nucleus. In the Butler theory, 4 one effectively does the same thing but for the exclusion of the range of integration r n^r o, where ro is the range of the interaction N between the picked-up neutron and the target nucleus. 5 As remarked in reference 2, both approaches neglect the reaction effects of the various outgoing waves on the stripping process. In this letter, we report on calculations taking into account one of the most important of such effects, namely, the reaction of the proton outgoing wave itself. It is more convenient to consider the matrix element I= (d\N-\~P\ty) for the time-reversed process T&ziP, d)3ti. Both matrix elements are related in a well-known fashion. ^ is the exact wave function for a stationary state of collision p-^rSlz. An approximate value for/ is obtained by:(a) neglecting V in the Schrodinger equation for "*"; (b) replacing P everywhere by a fixed average potential (P with the effect that ^ becomes the product of ^2 by a proton plane wave plus a wave elastically scattered by potential (P.Then, using the Schrodinger equation, one gets for / an expression amenable to computation. In approximation (a), one treats the formation of the deuteron as a perturbation, as was already done in the Born approach. Approximation (b) still takes correctly into account the reaction effect of the elastically scattered wave provided 0, in agreement with Newns' prediction. 9 (4) In the (d, py) angular correlation, although the over-all anisotropy remains as important as in the Butler theory, the actual shape of the distribution ...
Positive-pion proton differential cross sections have been measured at 41.5 Mev for six angles. The angles in the center-of-mass system are 53°, 69.1°, 100.4°, 128°, 141.7°, and 163.5° and the corresponding cross sections in mb/sterad in the center-of-mass system are 0.252±0.020, 0.354±0.025, 0.777±0.038, 1.145 ±0.067, 1.495±0.084, and 1.750=1=0.110. Negative pion elastic cross sections have been measured for the first five of the above angles and are, respectively, in mb/sterad in the cm. system: 0.338=b0.047, 0.281 ±0.038, 0.148±0.029, 0.112±0.042, and 0.085±0.25. Phase-shift analyses of these data and those of other authors lead to the following expressions for the low-energy behavior of the T = f phases: 0:31^= -(0.0418 ±0.004V, a 3 *=-(0.1145±0.0026)? 7 , and co\.a zz N = ^ (0.0877±0.0014)/[co*(l-co*/2.17)].
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