Cosmic-ray half-life of56Ni
| Autor: | K. Zaerpoor, Y. D. Chan, M. R. Dragowsky, M. C. P. Isaac, K. S. Krane, R.-M. Larimer, A. O. Macchiavelli, R. W. Macleod, E. B. Norman |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Physical Review C. 59:3393-3396 |
| ISSN: | 1089-490X 0556-2813 |
| DOI: | 10.1103/physrevc.59.3393 |
| Popis: | The positron decay partial half-life of {sup 56}Ni is needed to employ this isotope as a cosmic-ray chronometer. We conducted an experiment by counting a purified 2.8-{mu}Ci source of {sup 56}Ni in GAMMASPHERE in order to search for the {beta}{sup +}-decay branch of this isotope. A plastic scintillator was used to measure the energy of positrons in coincidence with the positron-annihilation {gamma} rays and the characteristic 158-keV {gamma} ray line. A careful analysis of 96 h of source counting shows no net signal and results in an upper limit of 77 counts of 511-511-158 keV plus scintillator coincident events. From this result we establish a 1{sigma} upper limit on the branch for this decay mode to be (6.3{times}10{sup {minus}5}){percent}. The discrepancy between the outcome of this experiment and previous measurements of this branch and the implications of this result for the {sup 56}Ni cosmic-ray chronometer problem are discussed. {copyright} {ital 1999} {ital The American Physical Society} |
| Databáze: | OpenAIRE |
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