Monday, September 30, 2013

The 6Li(22Ne,26Mg)d α-transfer experiment for the study of low-energy resonances in 22Ne(α,γ)26Mg

Shuya Ota (Japan Atomic Energy Agency, Tokai, Ibaraki, Japan)

The slow neutron-capture process (s-process) is responsible for creating about half of the elements heavier than iron that are observed in the solar system. The 22Ne(α,n)25Mg (α-particle-capture on 22Ne and neutron emission) reaction is expected to be an important source of neutrons for the s-process and the reaction rate largely influences the synthesis of nuclides during the s-process.

A variety of attempts to experimentally determine the reaction rate in the energy range of 400-1000 keV α-particles in laboratory system, corresponding to the s-process temperatures in the stars (0.2-0.3 GK), has been made. These include direct 22Ne(α,n)25Mg measurements and indirect measurements via 26Mg(γ,n)25Mg, 25Mg(n,γ)26Mg, 26Mg(γ,γ')26Mg, 26Mg(p,p'γ)26Mg, and 22Ne(6Li,d)26Mg α-transfer reactions. However, ambiguities of important low-energy resonances in 26Mg produced by α + 22Ne have remained the longstanding problem.

To solve the problem, we studied the 6Li(22Ne,26Mg)d α-transfer experiment. The experiments were performed using a 22Ne beam from JAEA (Japan Atomic Energy Agency)-Tokai 20 MV Tandem accelerator. The results showed successful coincidences of Mg and deuteron ions and the obtained reaction yield was in good agreement with the expected value [1, 2]. In the present seminar, our experimental techniques will be introduced and the results from the experiment will be discussed.

[1] S. Ota et al., Proceedings of Science (NIC XII) 221 (2012).

[2] S. Ota et al., European Physical Journal web of conference (INPC 2013, submitted)