论文标题
寻找环保气体混合物中的爱丽丝电阻板室
Searching for an eco-friendly gas mixture for the ALICE Resistive Plate Chambers
论文作者
论文摘要
爱丽丝RPC的混合物为89.7％$ c_ {2} h_ {2} f_ {4} $，10％i- $ c_ {4} h_ {10} $和0.3％$ $ sf_ {6} $。 $ c_ {2} h_ {2} f_ {4} $和$ sf_ {6} $是具有较高全球变暖潜力（GWP）的氟化温室气体。新的欧盟法规已实施了F-Gas的生产和使用的渐进阶段，目的是在2014年在2030年将其排放量减少三分之二。尽管这些法规排除了研究活动，但该法规的排除量也将不可避免地提高其价格，而CERN也旨在减少其排放量。由于这些原因，至关重要的是要在LHC长时间关闭3时找到RPC的更环保的气体混合物，可预见到2026年。由于$ C_ {2} H_ {2} h_ {2} f_ {4} $是混合物GWP的主要贡献者，它是一种大型的R＆d Cropsion，它替换为R＆D的过程，它替换为IT替换IT替换IT tetra terra。 （$ c_ {3} h_ {2} f_ {4} $），由于其与$ c_ {2} h_ {2} h_ {2} f_ {4} $的化学相似性及其低gwp（大约7）。宇宙射线的初步测试在探测器性能方面显示出令人鼓舞的结果。下一步是研究使用这些新的气体混合物（老化研究）运行的RPC的长期行为。由于这是所有（而且不仅）LHC实验的一个值得关注的主题，因此设置了一个协作Ecogas@gif ++，以进行联合研究。除其他外，在CERN的Gamma辐射设施中安装了一个小型的爱丽丝RPC，在那里它们暴露于一个强大的辐射场，来自12.5 TBQ $^{137} $ CS源，这使一个人可以在相对较短的时间内模拟多年的操作。该设施在一年中的特定时间还提供了一个MUON光束，可用于研究辐射期间和之后的检测器性能（例如效率和簇尺寸）。
The ALICE RPCs are operated with a mixture of 89.7% $C_{2}H_{2}F_{4}$, 10% i-$C_{4}H_{10}$ and 0.3% $SF_{6}$. $C_{2}H_{2}F_{4}$ and $SF_{6}$ are fluorinated greenhouse gases with a high Global Warming Potential (GWP). New European Union regulations have imposed a progressive phase-down of the production and usage of F-gases, aiming to cut down their emission by two thirds in 2030 with respect to 2014. Even though research activities are excluded from these regulations, the phase-down will inevitably increase their price and CERN is also aiming to cut down on its emissions. For these reasons it is crucial to find a more eco-friendly gas mixture for RPCs by the time of the LHC long shutdown 3, foreseen in 2026. Since $C_{2}H_{2}F_{4}$ is the main contributor to the mixture GWP, an extensive R&D process has started to replace it with tetrafluoropropene ($C_{3}H_{2}F_{4}$), due to its chemical similarity with $C_{2}H_{2}F_{4}$ and its low GWP (around 7). Preliminary tests with cosmic rays have shown promising results in terms of detector performance. The next step is to study the long-term behavior of RPCs operated with these new gas mixtures (aging studies). Since this is a subject of interest for all (and not only) the LHC experiments, a collaboration, ECOgas@GIF++, was setup to carry out joint studies. Among others, a small ALICE-like RPC was installed at the Gamma Irradiation Facility at CERN, where they are exposed to a strong radiation field, coming from a 12.5 TBq $^{137}$Cs source, which allows one to simulate many years of operation in a relatively short time. The facility also provides a muon beam at specific times of the year, which can be used to study the detector performance (e.g. efficiency and cluster size) during and after irradiation.
