Observation of Cosmic-Ray Antiprotons by Emulsion Chamber

低能反质子的观测将对宇宙学和宇宙射线的传播产生深远的影响。特别是在能量小于300 Mev的能量范围内，二次反质子的产生受到运动极限的抑制，反质子的丰度是解决这个问题的关键。能量小于1GeV的反质子-质子比(P/P)的实验结果已经被几位作者报道，P/P的上限为2.8×10~(-5)~(-5)。然而，这些都是相互矛盾的，给现有的宇宙学模型、封闭星系模型和漏盒模型等提出了问题。我们在这个能区寻找反质子的实验是用1987年8月从加拿大萨斯喀彻温省阿尔伯特王子气球送来的乳胶堆进行的。截止能量为170 MeV。这架飞机在37公里的高空暴露了大约22.5小时。INCED…反质子的检测更多的宇宙射线粒子在乳化液堆叠中形成“恒星”。其中，乳化液中的反质子停顿呈现出特征图案；恰好在顶点之前发生弯曲。静态pp湮没的分支率数据表明，90%以上的湮没产生2个以上的带电介子。所以我们定义了反质子候选者，它显示了顶点附近的‘弯曲’，带有2个以上的带电粒子。当我们做显微镜检查时，要在许多带电轨迹和背景中获得反质子候选者有两个过程。首先，我们用显微镜扫描乳剂，并进行自动图像处理，从背景中选择带电轨迹。在该过程中，通过在250倍下改变焦距获得的12张图像经过背景缩减处理，并重建为一幅带有带电轨迹的图像。结果(1)我们发展了先进的图像处理技术，用于扫描乳剂中的带电粒子并重建轨迹。(2)我们扫描的乳剂的总体积为1.18厘米~3。我们得到了次级粒子的数目分布和弯曲事件中次级粒子的数目分布。我们还没有得到反质子候选粒子。我们通过模拟得到了初级宇宙线粒子在堆栈中的行为。通过与模拟的比较，我们可以预期在170 Mev到300 Mev能区的p/p比为2.6×10~(-5)。较少

The observation of the low-energy antiprotons would have profound implications for cosmology and propagation of the cosmic rays. Especially in the energy range less than 300 Mev, production of secondary antiproton is suppressed in a gaeactic space by the kinematical limit and the abundance of antiproton present us the key to the problem. The experimental results of antiproton-proton ratio (P/P) for energies less than 1 GeV have been already reported by several authors and the upper limit of P/P is 2.8X10^<-5>. However, those are inconsistent with each other and present us problems to current cosmological models, closed galaxy model and leaky-box model and other models. Our experiment to search for antiprotons in this energy region has been carried out with the emulsion stack flown by the balloon from Prince Albert, Saskatchewan, Canada in August 1987. Cut-off energy is 170 MeV. The exposure by the flight achieved about 22.5 hours at an altitude of 37 km.Detection of antiprotonThe incid … More ent cosmic ray particles make 'stars' in the emulsion stack. Among them, the antiproton stop in the emulsion shows the characteristic pattern ; 'bend' just before the vertex point. The data of branching ratios for pp annihilation at rest shows that over ninety percent of annihilation produce more than 2 charged pions. So we define the antiproton candidate that shows the 'bend' near the vertex with more than 2 charged particles. When we make an microscope examination, there are two processes to get the antiproton candidate among many charged tracks and background. At first, we scan a emulsion by microscope with automatic image processing and select the charged tracks from background. In this process, 12 pictures, obtained by changing a focus under 250 magnifications, are processed by background reduction and are reconstructed to one image with charged tracks. The second, this imageis reprocessed with Hough-transformation and the antiproton candidates selected by its pattern.result(1) We developed the advanced image processing technique to scan charged particles in emulsion and reconstructed tracks.(2) The total volume of emulsion in which we have scanned is 1.18 cm3. We have number distribution of secondary particles and the number distribution of secondary particles in 'bend' events. We have not obtained antiproton candidate.We get result the behavior of primary cosmic ray particles in the stack by simulation. We can expect the p/p ratio in the energy region between 170 Mev and 300 Mev to 2.6X10^<-5> by the comparison with simulation. Less