There is a discrepancy in the electron excitation cross section for electric quadrupole transitions between Sneddon and Touschek, who obtain essentially the same result for both electric quadrupole and magnetic dipole transitions, and Wick. We have also calculated this and agree with Wick's result. TABLE I. Hourly rate of coincidences.

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T HE energy of the Y-rays emitted by natural radioactive K 40 was measured by the absorption method, with copper and lead used as absorbers. We found an energy of 1.5 Mev in accord with the value 1.54 Mev obtained by Warner and Hirzel. 1 This energy, however, is a little higher than the upper limit 1.35 Mev of the continuous /3-spectrum 2 and so it seemed difficult to associate this 7-ray with the /3-transitions. On the other hand, positron emission or i£-capture could take place to account for the great abundance of A 40 . Evidence for a i£-capture process was given 3 recently, and no positron activity has been detected. We undertook fi-y coincidences to show that the 7-rays should be associated with the i^-capture process. Measurements were taken with a precision of 1 percent, and no coincidences were obtained. These experiments show that no 7-rays can be associated with the ^-transitions and that, therefore, the nucleus of Ca 40 is not left in an excited state, showing that the disintegration scheme proposed by Warner and Hirzel is a correct one.

about 15/1, while the corresponding ratio of meson intensity is only 2/1.Hence we may say that it appears almost certain that high energy nucleons and

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