| Autor: |
J. R. Leslie, H. Schmeing, H. B. Mak, J.S. Forster, E. Hagberg, J.C. Hardy, T. K. Alexander, I. Neeson, I. S. Towner, V.T. Koslowsky, G.C. Ball, G.R. Dyck |
| Rok vydání: |
1994 |
| Předmět: |
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| Zdroj: |
Nuclear Physics A. 571:555-568 |
| ISSN: |
0375-9474 |
| Popis: |
A search for Gamow-Teller decay branches of 39Ca to excited states in 39K was conducted with a large HPGe detector which observed the decays of 39Ca samples delivered by a helium-jet transport system. A pair of plastic scintillators in front of the HPGe detector were used to reject events due to bremsstrahlung from the 39Ca positrons. With this setup, weak γ-rays could be observed with a degree of sensitivity not previously achieved. The l- forbidden 1 d 3 2 → 2 s 1 2 transition to the first excited state in 39K, was observed with a branching ratio of (2.50 ± 0.27) × 10−5. This result agrees with but is more accurate than the only previous measurement. Thus, the ratio of the l-forbidden Gamow-Teller and isovector M1 matrix elements in mass-39 nuclei continues to disagree with theoretical values obtained by Towner and Khanna from calculations involving core-polarization and meson-exchange currents. This leaves very few possibilities to explain the discrepancy between theory and experiment. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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