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arXiv 0911.5580astro-ph.IM
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空气切伦科夫望远镜立体系统的单个电磁子级联的背景

The background from single electromagnetic subcascades for a stereo system of air Cherenkov telescopes

Dorota Sobczynska

摘要:

MAGIC实验是一个非常大的成像空气切伦科夫望远镜,对低能(E <100 GeV)VHE伽马射线敏感,自2004年以来一直在运行。人们发现,在100 GeV以下,IACT中的伽马/强子分离变得更加困难[Albert et al 2008]由两台大型望远镜组成的系统最终可能会被包含来自仅一个电磁子级联或两个伽马子级联的切伦科夫光的强子事件触发,这些子级联是单个pi^0衰变的产物。这可能是实验灵敏度在100 GeV以下下降的原因。本文用蒙特卡罗模拟研究了两台MAGIC望远镜在立体模式下的系统。探测到的图像具有与初级伽马射线相似的形状,并且它们具有小尺寸(主要低于400个光电子(p.e.))其对应于低于100 GeV的初级伽马射线的能量。来自单个或两个电磁子级联的背景集中在200 GeV以下的能量。最后,将背景事件的数量与蟹状星云的VHE伽马射线过量事件的数量进行比较。所研究的背景在250 p.e.以下的尺寸的简单切割中幸存。因此实验的灵敏度在较低的能量下恶化。

英文摘要:

The MAGIC experiment, a very large Imaging Air Cherenkov Telescope (IACT) with sensitivity to low energy (E < 100 GeV) VHE gamma rays, has been operated since 2004. It has been found that the gamma/hadron separation in IACTs becomes much more difficult below 100 GeV [Albert et al 2008] A system of two large telescopes may eventually be triggered by hadronic events containing Cherenkov light from only one electromagnetic subcascade or two gamma subcascades, which are products of the single pi^0 decay. This is a possible reason for the deterioration of the experiment's sensitivity below 100 GeV. In this paper a system of two MAGIC telescopes working in stereoscopic mode is studied using Monte Carlo simulations. The detected images have similar shapes to that of primary gamma-rays and they have small sizes (mainly below 400 photoelectrons (p.e.)) which correspond to an energy of primary gamma-rays below 100 GeV. The background from single or two electromagnetic subcascdes is concentrated at energies below 200 GeV. Finally the number of background events is compared to the number of VHE gamma-ray excess events from the Crab Nebula. The investigated background survives simple cuts for sizes below 250 p.e. and thus the experiment's sensitivity deteriorates at lower energies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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