Search for High Energy Gamma-ray Sources in the Southern Sky

大麦哲伦星云中的超新星1987A为研究年轻超新星的粒子发射和电磁辐射提供了第一次机会。位于膨胀喷发中心的一颗快速旋转的磁化中子星可能是超高能宇宙射线的强大来源。佐藤指出，高能伽马射线可能是由中子星加速的强子与超新星抛射物碰撞产生的衰变子产生的。我们在新西兰的黑桦林(海拔1640米，41ﾟ45‘S，173ﾟ47’E)安装了伽马射线探测器。计数器阵列由76个闪烁探测器组成。观察工作于1987年10月13日开始。根据1987-1991年的资料，得到SN1987A(100TeV)超高能伽马射线通量的上限为4×10~(-14)cm~(-2)。用三个切伦科夫反射镜和数据对SN1987A发射的3TeV以上的伽马射线进行了探测，给出了5×10~(-12)cm~(-1)~(-2)的通量上限。1988年1月14日和15日的数据被发现具有对应于(1.9&lt；正负&gt；0.5)x10^-11&gt；cm；-2&gt；sec^&lt；-1&gt；的流量的超额计数。观测到的超额时间与银河卫星探测到的X射线耀斑时间一致。最近，我们从南方天体包括Cen A、Vela X-1、Cen X-3、Cir X-1以及麦哲伦星云中的几个天体寻找到了超高能伽马射线。所有这些来源都没有显示出明显的过度事件。观测仍在进行中。月球被用来通过其阴影效应来测量探测器的角分辨率。人们发现，月球中心的事件密度低于月球方向附近的事件密度。

The supernova 1987A in the Large Magellanic Cloud has provided the first opportunity to study the emission of particles and electromagnetic radiation from a young supernova. A rapidly rotating, magnetized neutron star at the center of the expanding ejecta may be a powerful source of ultra high-energy (UHE) cosmic rays. H. Sato has pointed out that high energy gamma-rays may be produced from the decay pions generated by the collisions of hadrons accelerated by the neutron star with supernova ejecta. We installed gamma-ray detectors at the Black Birch in New Zealand (1640 m above sea level, 41ﾟ45'S, 173ﾟ47'E). The counter array consists of 76 scintillation detectors. The observations started on 13 October 1987. An upper limit on tile flux of UHE gamma-rays from SN1987A (>100 TeV) was obtained to be 4X10^<-14> cm^<-2> sec^<-1> from the data of 1987-1991. gamma-rays above 3 TeV emitted by SN1987A have been searched for using three, Cerenkov mirrors and data give an upper bound on the flux of 5X10^<-12> cm^<-2> sec^<-1>. Data on January 14 and 15 1988 were found to have excess counts corresponding to a flux of (1.9<plus-minus>0.5)X10^<-11> cm^<-2> sec^<-1>. The observed time of the excess coincides with the time of X-ray flare detected by the Ginga Satellite.Recently, we have searched for UHE gamma-ray from Southern objects including Cen A, Vela X-1, Cen X-3, Cir X-1 and also several objects in the Magellanic Clouds. None of these sources shows significant excess events. The observation is still being carried out.The moon was used to measure the angular resolution of the detector through its shadowing effect. The density of the events at the center of the moon has been found to be lower than event density near direction of the moon.