APS » PROLA » Phys. Rev. Lett. » Volume 79 » Issue 22

Phys. Rev. Lett. 79, 4306 - 4309 (1997)

Galactic Confinement Time of Iron-Group Cosmic Rays Derived from the 54Mn Chronometer

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K. Zaerpoor1, Y. D. Chan2, D. E. DiGregorio3, M. R. Dragowsky1, M. M. Hindi4, M. C. P. Isaac2, K. S. Krane1, R. M. Larimer2, A. O. Macchiavelli2, R. W. Macleod2, P. Miocinovic5, and E. B. Norman2
1Physics Department, Oregon State University, Corvallis, Oregon 97331
2Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
3Laboratorio TANDAR-Comision Nacional de Energia Atomica, Buenos Aires, 1429 Argentina
4Physics Department, Tennessee Technological University, Cookeville, Tennessee 38505
5Physics Department, University of California, Berkeley, California 94720

 See Also: Erratum

Received 29 July 1997

The β-decay half-life of 54Mn is needed to employ this isotope as a cosmic ray chronometer. We have determined the partial half-life of 54Mn for positron emission by counting a highly purified 35-μCi source of 54Mn in GAMMASPHERE to search for the astrophysically interesting β+ decay branch through the observation of coincident positron-annihilation γ rays. A careful analysis of 97 hours of source counting and 61 hours of background shows a net signal of 24±10 back-to-back 511-511 keV coincident events. Based on this result, the branch for this decay mode is (2.2±0.9)×10-7%. The implications of this result for the 54Mn cosmic-ray chronometer problem are discussed.


©1997 The American Physical Society

URL: http://link.aps.org/abstract/PRL/v79/p4306
DOI: 10.1103/PhysRevLett.79.4306
PACS: 98.70.Sa, 26.40.+r, 27.40.+z

See Also

Erratum: K. Zaerpoor, Y. D. Chan, D. E. DiGregorio, M. R. Dragowsky, M. M. Hindi, M. C. Isaac, K. S. Krane, R. M. Larimer, A. O. Macchiavelli, R. W. Macleod, P. Miocinovic, and E. B. Norman, Erratum: Galactic Confinement Time of Iron-Group Cosmic Rays Derived from the 54Mn Chronometer [Phys. Rev. Lett. 79, 4306 (1997)], Phys. Rev. Lett. 82, 2219 (1999)

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