Experimental Test of Parity Conservation in Beta Decay

The branching ratio of the two modes of decay of Fm'", i.e., E.C./n, was found to be about 8.5—which gives 89.5% decay by electron capture and 10.5% by alpha emission. It was not possible to measure the cross section for the Cf'"(n, 3n)Fm'" reaction because Fm'" could also be produced from other californium isotopes in the target. A previous publication4 on a possible identification of the Fm'" gave the values of 6.85&0.04 Mev for the alpha-particle energy, and a half-life &10 days. It is a pleasure to thank the crew of the 60-inch cyclotron for their extremely careful and skillful operation of the machine during the bombardment. We wish to thank Professor Glenn T. Seaborg for his continued interest. * On leave from the Israel Atomic Energy Commission, Weizmann Institute of Science, Rehovoth, Israel. 'Thompson, Ghiorso, Harvey, and Choppin, Phys. Rev. 93, 908 (1954). ~ Harvey, Chetham-Strode, Ghiorso, Choppin, and Thompson, Phys. Rev. 104, 1315 (1956). 'Thompson, Harvey, Choppin, and Seaborg, J. Am. Chem. Soc. 76, 6229 (1954); Choppin, Harvey, and Thompson, J. Inorg. and Nuclear Chem. 2, 66 (1956). 4 Friedman, Gindler, Barnes, Sjoblom, and Fields, Phys. Rev. 102, 585 (1956).