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arXiv 0908.2507physics.ins-dethep-ex
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ATLAS监控的超级大型强子对撞机漂移管室

ATLAS monitored drift tube chambers for super-LHC

Albert Engl, Otmar Biebel, Ralf Hertenberger, Alexander Mlynek, Thomas A. Mueller, Felix Rauscher

摘要:

在欧洲核子研究中心的大型强子对撞机(LHC)的高亮度升级之后,ATLAS μ子光谱仪预计将在伽马和中子的背景速率增加10倍的情况下工作。这是具有挑战性的,因为预计光谱仪的动量分辨率为10%。这需要80 μ m的μ子漂移管的单管分辨率。在1000 Hz/cm 2左右的背景速率下,空间电荷效应将导致缓慢和非线性的AR:CO2 = 93:7气体混合物中漂移管空间分辨率的劣化。这是以前的实验研究伽马和低能量中子。几乎没有关于快中子的信息。因此,我们组织我们的研究在以下几个方面:-我们调查了11 MeV中子的ATLAS MDT室的位置分辨率的影响。在4和16 kHz/cm 2之间的通量密度,几乎没有影响的位置分辨率被发现,它降低了只有10 μ m的检测效率只有4*10-4。- 我们研究了惰性气体混合物的牢度和线性的位置漂移时间(r-t)关系。在最大漂移时间减少2倍的情况下,可以使用当前的硬件和电子设备。在我们的实验研究中,我们使用了慕尼黑的宇宙射线设施。两种气体混合物显示出与标准气体几乎相同的位置分辨率。- 对于光谱仪区域的最高背景率,我们促成了新开发的15毫米漂移管的调查。位置分辨率已被测量为0和1400 Hz/cm 2之间的伽马背景率的函数。- 加菲尔德模拟已被执行,以模拟由于伽马辐照的空间电荷效应。结果将提交标准几何形状以及新的15毫米漂移管。

英文摘要:

After the high-luminosity upgrade of the Large Hadron Collider (LHC) at CERN, the ATLAS muon spectrometer is expected to work at 10 times increased background rates of gammas and neutrons. This is challenging as the momentum resolution of the spectrometer is expected to be 10 %. This requires a single tube resolution of the muon drift tubes of 80 mum. At background rates around 1000 Hz/cm2 space charge effects will lead in the slow and non-linear AR:CO2 = 93:7 gas mixture to a degradation of the drift-tube spatial resolution. This was studied before experimentally for gammas and low energetic neutrons. Almost no information exists for fast neutrons. Therefore, we organized our studies under the following aspects: - We investigated the influence of 11 MeV neutrons on the position resolution of ATLAS MDT chambers. At flux densities between 4 and 16 kHz/cm2, almost no influence on the position resolution was found, it degrades by only 10 mum at a detection efficiency of only 4*10-4. - We investigated inert gas mixtures on fastness and linearity of their position-drifttime (r-t) relation. At a reduction of the maximum drift time by a factor of 2, the use of the present hardware and electronics might be possible. For our experimental studies we used our Munich cosmic ray facility. Two gas mixtures show almost identical position resolution as the standard gas. - For spectrometer regions of highest background rates we contributed to the investigation of newly developed 15 mm drift tubes. Position resolutions have been measured as a function of gamma background rates between 0 and 1400 Hz/cm2. - Garfield simulations have been performed to simulate space charge effects due to gamma irradiation. Results will be presented for the standard geometry as well as for the new 15 mm drift tubes.

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