Search for cosmic-ray anti-protons produced through Hawking radiation of primordial black holes

这个项目的目的是利用气球携带的设备搜索通过大气层顶部原始黑洞的霍金辐射产生的宇宙射线反质子。这项实验的关键是一台能够测量低于1GeV霍金辐射特性的低能反质子的装置，以及为了改善统计数据而在南极洲进行的长时间飞行。我们已经开发了飞行时间(TOF)计数器和中等飞行时间计数器以及相关的读出电子学。TOF计数器用于区分反质子和电子。安装在中央跟踪器和低温恒温器之间的小缝隙中的中TOF计数器用于触发无法穿透超导线圈的低能粒子。2004年12月，Bess-Polar光谱仪从南极洲的麦克默多基地发射升空。在8.5天的飞行中，总共记录了432次反质子事件。反质子的数量是前一次飞行的4倍。我们首次测量到0.2GeV以下的反质子。实验中得到的能谱与二次产生模型一致，我们没有发现来自霍金辐射的反质子的证据。

The purpose of this program is to search for cosmic-ray antiprotons produced through Hawking radiation of primordial black holes at the top of the atmosphere by using a balloon-borne apparatus. Keys to this experiment are an apparatus capable of measuring low energy antiprotons below 1 GeV characteristic of Hawking radiation and a long duration flight at Antarctica to improve statistics.We have developed time-of-flight (TOF) counters and middle-TOF counters and related read-out electronics. The TOF counters are used to distinguish antiprotons from electron. The middle-TOF counters installed in a small gap between a central tracker and a cryostat are used to trigger low energy particles that cannot penetrate a superconducting coil.In December 2004, the BESS-Polar spectrometer was launched from McMurdo base in Antarctica. A total of 432 antiproton events were recorded in a 8.5 day flight. The number of antiprotons was 4 times larger than previous flight. We have measured antiprotons below 0.2 GeV for the first time. The energy spectrum obtained in this experiment is consistent with a secondary production model and we found no evidence for the antiprotons from Hawking radiation.