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Title: Beta-ray branching and half-lives of /sup 12/B and /sup 12/N

Journal Article · · Phys. Rev., C; (United States)

The ratio of /sup 12/B and /sup 12/N ..beta..-ray branches to the 4.44-MeV excited state of /sup 12/C was measured by detecting ..beta.. rays in a 4..pi.. plastic scintillator and ..gamma.. rays in two Ge(Li) detectors. Activities were made in the /sup 11/B(d,p)/sup 12/B and /sup 10/B(/sup 3/He,n)/sup 12/N reactions using a chopped Van de Graaff beam. Data were stored in two successive computer time bins of two half-lives each in order to establish by subtraction the shape of the short-lived ..beta..-ray spectrum and its net number of counts. The ratio of these branches was found to be /sup 12/N//sup 12/B = 1.56 +- 0.05. A measurement of the /sup 12/B absolute ..beta..-ray branch to the 4.44-MeV state via ..beta..-..gamma.. coincidences using an NaI(Tl) detector for the ..gamma.. rays gave a value of 1.276 +- 0.050%. Half-lives, obtained by multiscaling ..beta..-ray counts, were found to be 20.20 +- 0.02 msec for /sup 12/B and 11.000 +- 0.016 msec for /sup 12/N. The mirror asymmetries derived from these results are delta = +0.044 +- 0.034 for the decay to the 4.44-MeV state of /sup 12/C and delta = +0.129 +- 0.008 for the branch to the ground state.

Research Organization:
Brookhaven National Laboratory, Upton, New York 11973
OSTI ID:
5075644
Journal Information:
Phys. Rev., C; (United States), Vol. 17:1
Country of Publication:
United States
Language:
English