Bemmerer D, Confortola F, Costantini H, Formicola A, Gyürky Gy, Bonetti R, Broggini C, Corvisiero P, Elekes Z, Fülöp Zs, Gervino G, Guglielmetti A, Gustavino C, Imbriani G, Junker M, Laubenstein M, Lemut A, Limata B, Lozza V, Marta M, Menegazzo R, Prati P, Roca V, Rolfs C, Alvarez C Rossi, Somorjai E, Straniero O, Strieder F, Terrasi F, Trautvetter H P
Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Padova, via Marzolo 8, 35131 Padova, Italy.
Phys Rev Lett. 2006 Sep 22;97(12):122502. doi: 10.1103/PhysRevLett.97.122502. Epub 2006 Sep 19.
The nuclear physics input from the 3He(alpha,gamma)7Be cross section is a major uncertainty in the fluxes of 7Be and 8B neutrinos from the Sun predicted by solar models and in the 7Li abundance obtained in big-bang nucleosynthesis calculations. The present work reports on a new precision experiment using the activation technique at energies directly relevant to big-bang nucleosynthesis. Previously such low energies had been reached experimentally only by the prompt-gamma technique and with inferior precision. Using a windowless gas target, high beam intensity, and low background gamma-counting facilities, the 3He(alpha,gamma)7Be cross section has been determined at 127, 148, and 169 keV center-of-mass energy with a total uncertainty of 4%. The sources of systematic uncertainty are discussed in detail. The present data can be used in big-bang nucleosynthesis calculations and to constrain the extrapolation of the 3He(alpha,gamma)7Be astrophysical S factor to solar energies.
来自³He（α，γ）⁷Be截面的核物理输入，是太阳模型预测的太阳中⁷Be和⁸B中微子通量以及大爆炸核合成计算中得到的⁷Li丰度的主要不确定因素。本工作报道了一项使用活化技术的新的精密实验，该实验的能量与大爆炸核合成直接相关。此前，只有通过瞬发γ技术才能在实验中达到如此低的能量，且精度较低。利用无窗气体靶、高束流强度和低本底γ计数设备，在质心能量为127、148和169 keV时测定了³He（α，γ）⁷Be截面，总不确定度为4%。详细讨论了系统不确定度的来源。目前的数据可用于大爆炸核合成计算，并用于限制³He（α，γ）⁷Be天体物理S因子向太阳能的外推。
