Beta Decay

C.S. Wu and S.A. Moszkowski
Sep 1 1966

Wu's more distant review of the He6 events


Evidence for V—A Interaction. Suddenly many doors swung open to lead to the determination of the β interactions.

The early experimental results indicated that a is close to +1/3, favoring a tensor interaction. However, more recent experiments (He-58; Al-59), whose arrangements are shown in

Prove. Inclusively that coefficient a in Gamow-Teller is negative, being in fact close to the expected value of -1/3 for the axial-vector form. This result has been confirmed by the Oak Ridge group (Jo-63) with a more refined setup

The Beta-Spectrum of He6

C. S. Wu, B. M. Rustad, V. Perez-Mendez, and L. Lidofsky
Physical Review
Aug 5 1952

Used Columbia spectrometer to calculate revised comparative lifetime of He6


The end point together with tg=0.823 yields the ft value of He' of 815~70 sec.' Moszkowski4 estimated the relative contribution of P and G —T interactions by equating ft M ' for the H3—He3 and He6—Li6 transitions. Using the old He6 "ft"value he obtained E=Cg'/CG'=0. 11~0.45, which leads to the conclusion of the insignificant role of the F interaction in beta-decay.

If one repeats the calculation of Moszkowski using the new ft values for He6 one obtains K&1.4&0.7 which completely alters the picture. The recent finding of the C' —8"* and 0'4 —N'4* transitions which should be allowed and favored 0—0 transitions, demonstrates that the presence of the Fermi interaction in the beta-process is definitely necessary.

Electron-Neutrino Angular Correlation in the Positron Decay of Argon 35

W. B. Herrmannsfeldt, D. R. Maxson, P. Stahelin, and J. S. Allen
Physical Review Letters
May 28 1957

The first experiment with contadictory results from He-6
. Paper cites Kistner-Schwarzschild-Rustad paper on suitability of A35 for correlation experiment.


In view of this rather unexpected result, a review of the existing data on the angular correlation coefficient of the positron emitter Ne19 may be interesting. For comparison with the A35 results, the experimental values and the theoretical limits of X for Ne" are plotted in the lower half of Fig. 2. It is evident, that in the case of Ne", the experimental values of A.

Determination of the Gamow-Teller Beta-Decay Interaction From the Decay of Helium-6

W. B. Herrmannsfeldt, R. L. Burman, P. Stahelin, J. S. Allen, and T. H. Braid
Physical Review Letters
Jun 23 1958

Directly contradictory results


The electron-neutrino angular correlation coefficient has been measured for the negatron decay of He6 using the same apparatus x previously employed to determine the angular correlations in the positron decays of A35 and Ne19. He6 decays with a half-life' of 0.85 sec by beta-particle emission to Li6 with a maximum beta energy of 3.5 Mev and a spin change delta I = 1 with no change in the nuclear parity. x Thus, He6 obeys only the rules for allowed Gamow-Teller decay and the angular correlation coefficient lambda.


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