First measurement of ²⁵Al+p resonant scattering relevant to the astrophysical reaction ²²Mg(α,p)²⁵Al

Abstract

Type I X-ray bursts (XRBs) are the most frequently observed thermonuclear explosions in nature. The 22Mg(α,p)25Al reaction plays a critical role in XRB models. However, experimental information is insufficient to deduce a precise 22Mg(α,p)25Al reaction rate for the respective XRB temperature range. A new measurement of 25Al+p resonant scattring was performed up to the astrophysically interested energy region of 22Mg(α,p)25Al. Several resonances were observed in the excitation functions, and their level properties have been determined based on an R-matrix analysis. In particular, proton widths and spin-parities of four natural-parity resonances above the α threshold of 26Si, which can contribute the reaction rate of 22Mg(α,p)25Al, were first experimentally determined.

RIB induced reactions: Studying astrophysical reactions with low-energy RI beam at CRIB

“…To study the reactions of two unstable particles ( 7 Be and n), we applied the Trojan horse method (THM, see References in [6,8]), which is an indirect method to study a 2body reaction via a 3-body reaction measurement under a quasi-free kinematical condition. The 7 Be(n, α) 4 He reaction had been measured with the THM in a previous work [8], and our new work expanded the sensitivity also to the 7 Be(n, p 0 ) 7 Li and 7 Be(n, p 1 ) 7 Li * reactions, by achieving a sufficient energy resolution to separate the contributions of these two reactions. √ E cm of the 7 Be(n, p 0 ) 7 Li, 7 Be(n, p 1 ) 7 Li * and 7 Be(n, α) 4 He reactions in [6] are shown as open red circles, blue triangles, green squares, respectively.…”

“…The primordial production of light nuclides is well described with the standard model of Big Bang nucleosynthesis (BBN), however, the 7 Li/H abundance remains overestimated by a factor of 3-4, known as the cosmological lithium problem. We have studied the 7 Be(n, p 0 ) 7 Li, 7 Be(n, p 1 ) 7 Li * and 7 Be(n, α) 4 He reactions, which may affect the primordial 7 Li abundance [6].…”

“…The primordial production of light nuclides is well described with the standard model of Big Bang nucleosynthesis (BBN), however, the 7 Li/H abundance remains overestimated by a factor of 3-4, known as the cosmological lithium problem. We have studied the 7 Be(n, p 0 ) 7 Li, 7 Be(n, p 1 ) 7 Li * and 7 Be(n, α) 4 He reactions, which may affect the primordial 7 Li abundance [6]. To study the reactions of two unstable particles ( 7 Be and n), we applied the Trojan horse method (THM, see References in [6,8]), which is an indirect method to study a 2body reaction via a 3-body reaction measurement under a quasi-free kinematical condition.…”

“…The typical intensity of the RI beam at CRIB is 10 4 -10 6 pps. The maximum intensity attained was 2-3 × 10 8 pps by the 7 Be beam produced with a cryogenic target system, in which the target gas can be cooled down to about 90 K [4]. One problem in producing such intense RI beams with a gas target is the density-reduction effect.…”

“…We introduce below two latest works at CRIB [6,7], in which RI-involving astrophysical reactions were indirectly studied at astrophysical energies.…”