Speaker
Description
The discrepancy between observations from γ-ray astronomy of the 60Fe/26Al γ-ray flux ratio and recent calculations is an unresolved puzzle in nuclear astrophysics. The stellar β-decay rate of 59Fe is one of the major nuclear uncertainties impeding us from a precise prediction. Due to contributions from thermally populated low-lying states in 59Fe, the total β-decay rate in a typical 60Fe-synthesis environment is about two orders of magnitude larger than the terrestrial one. Since direct measurement of the β-decay rates from excited states of 59Fe is not possible, we used the 59Co(t,3He)59Fe charge-exchange reaction to measure its inverse transition and the β-decay rate of 59Fe is then obtained by applying the detailed balance theory. The new stellar decay rate of 59Fe is a factor of 3.5 +/- 1.1 larger than the currently adopted rate at T = 1.2 GK. Stellar evolution calculations show that the 60Fe production yield of an 18 solar mass star is decreased significantly by 40% when using the new rate. Our result eliminates one of the major nuclear uncertainties in the predicted yield of 60Fe and alleviates the existing discrepancy of the 60Fe/26Al ratio.
| Length of presentation requested | Oral presentation: 17 min + 3 min questions |
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| Please select between one and three keywords related to your abstract | Nuclear physics - experimental |
