Galactic Confinement Time of Iron-Group Cosmic Rays Derived from theM54nChronometer

Autor:	M. R. Dragowsky, D. E. Digregorio, Yuen-Dat Chan, M. C. P. Isaac, K. Zaerpoor, A. O. Macchiavelli, Eric B. Norman, Kenneth S. Krane, Ruth-Mary Larimer, M. M. Hindi, R. W. MacLeod, P. Miocinovic
Rok vydání:	1997
Předmět:	Physics Iron group Isotope Marine chronometer law General Physics and Astronomy Cosmic ray Gammasphere Positron emission Astrophysics Beta decay Galaxy law.invention
Zdroj:	Physical Review Letters. 79:4306-4309
ISSN:	1079-7114 0031-9007
DOI:	10.1103/physrevlett.79.4306
Popis:	The {beta} -decay half-life of {sup 54}Mn is needed to employ this isotope as a cosmic ray chronometer. We have determined the partial half-life of {sup 54}Mn for positron emission by counting a highly purified 35-{mu}Ci source of {sup 54}Mn in GAMMASPHERE to search for the astrophysically interesting {beta}{sup +} decay branch through the observation of coincident positron-annihilation {gamma} rays. A careful analysis of 97hours of source counting and 61hours of background shows a net signal of 24{plus_minus}10 back-to-back 511-511keV coincident events. Based on this result, the branch for this decay mode is (2.2{plus_minus}0.9){times}10{sup {minus}7}{percent} . The implications of this result for the {sup 54}Mn cosmic-ray chronometer problem are discussed. {copyright} {ital 1997} {ital The American Physical Society}
Databáze:	OpenAIRE
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