重离子碰撞中接近π介子阈能的光子产生
核实验
2008-11-26 v2
摘要
我们报道了在Ar+Ca于180A MeV能量下的反应中硬光子(Eg>30 MeV)的测量,该能量处来自π0介子衰变的光子占主导。利用TAPS谱仪同时对光子能谱和用于识别π0的光子-光子符合进行测量,实现了π0贡献的扣除。所得光子能谱呈指数形状,其反斜率为E0=(53±0.03(统计)-5+8(系统)) MeV。光子多重性等于(1.21±0.03(统计)+0.3-0.2(系统))10E0^-2,比由现有系统学外推的值大约高一个数量级。这种硬光子产生的增强归因于次级np碰撞对总光子产额的贡献显著增大。我们得出结论:在180A MeV的Ar+Ca反应中,平均而言,对硬光子产生有贡献的np碰撞数目比首次机会np碰撞数目大7倍。
引用
@article{arxiv.nucl-ex/9910006,
title = {Photon production in heavy-ion collisions close to the pion threshold},
author = {G. Martinez and L. Aphecetche and Y. Charbonnier and H. Delagrange and D. d'Enterria and T. Matulewicz and Y. Schutz and R. Turrisi and M. Appenheimer and V. Metag and R. Novotny and H. Stroeher and A. R. Wolf and M. Wolf and J. Weiss and R. Averbeck and S. Hlavavc and R. Holzmann and F. Lefevre and R. S. Simon and R. Stratmann and F. Wissmann and M. Hoefman and M. J. van Goethem and H. Loehner and R. W Ostendorf and R. H. Siemssen and P. Vogt and H. W. Wilschut and J. Diaz and A. Marin and A. Kugler and P. Tlusty and V. Wagner and A. Doeppenschmidt},
journal= {arXiv preprint arXiv:nucl-ex/9910006},
year = {2008}
}
备注
15 pages, 4 figures, references added