Resistive Plate Chambers (RPCs), used for the Muon Spectrometer of the ALICE experiment at CERN LHC, are currently operated in maxi-avalanche mode with a low threshold value and without amplification in the front-end electronics. RPC detectors have shown a good operation stability with the current gas mixture during the entire Run 1 (2010$-$2013) and the ongoing Run 2 (2015$-$2018) at the LHC. The gas mixture is made up of $C_{2}H_{2}F_{4}$, $SF_{6}$ and $iC_{4}H_{10}$. Since the first two gases have high Global Warming Potentials (GWPs), there is the risk that they will be phased out of production in the next years, due to the recent restrictions and regulations of the European Union. Therefore, finding a new eco-friendly gas mixture has become extremely important in order to reduce the emissions of greenhouse gases. In addition, the present $iC_{4}H_{10}$ contribution makes the current gas mixture flammable. Non-flammable components, or at least in non-flammable concentrations, would be advisable to make the operation of detectors simpler and safer. In order to identify a gas mixture suited to cope with the requirements of the ALICE Muon Identifier in the forthcoming High-Luminosity runs, a dedicated experimental set-up has been used to carry out R&D studies on promising gas mixtures with small-size RPCs. Hydrofluoroolefins ($HFOs$) are appropriate candidates to replace the $C_{2}H_{2}F_{4}$ thanks to their very low GWPs, especially $HFO1234ze$ which is not flammable at room temperature. Several tests on $HFO$-based mixtures with addition of various gases are ongoing and encouraging results have already been obtained. Furthermore, the use of $CO_{2}$ as a quencher has been studied as it might represent a valid solution to avoid flammability of the mixture. Finally, medium-term stability of detectors exposed to the cosmic-ray flux will be shown in this paper.
Experience gained about Resistive Plate Chambers ageing from the ALICE Muon TRigger/IDentifier detector
ALICE μ子鉴别器由72个单间隙酚醛树脂电阻板室组成，自2009年以来一直在使用四氟乙烷/异丁烷/六氟化硫混合气体的最大雪崩模式（鉴别阈值：7 mV，无放大）下运行，计数率为数十Hz/cm ^2。在这次演讲中，RPC系统的长期性能和稳定性将在效率，暗电流和暗速率方面进行讨论。将对探测器上观察到的潜在老化迹象进行评估，并总结最常见的硬件问题。
ALICE μ子触发器目前由一个探测器产生，该探测器目前由72个以最大雪崩模式运行的胶木单间隙电阻板室组成，排列在四个5.5x6.5平方米的探测平面上。为了满足即将从2021年开始的LHC高亮度运行的要求，其中ALICE将以连续模式读出，μ子触发器将成为μ子标识符，并将进行重大升级。在当前设置中，来自约21k条的信号由2400个非放大前端（FEE）卡区分，其阈值由外部模拟电压提供（每个腔室侧一个）。所有这些卡将被配备有前置放大级的鉴别器所取代，这将允许降低探测器的操作高压，从而延长其寿命。此外，它们的参考阈值将通过无线（和每个腔室侧链接的I2C）传递，允许在单个卡级别调整值。此外，24个暴露最多的室将被更换为新的，配备高质量（即更光滑的表面）电木层压板。报告了在测试台和探测器上使用的新FEE卡以及在新RPC室（带有宇宙射线）上进行的测试。
Characterization of tetrafluoropropene-based gas mixtures for the Resistive Plate Chambers of the ALICE muon spectrometer
欧洲核子研究中心大型强子对撞机ALICE实验的μ子识别系统是基于电阻板室（RPC）探测器。这些RPC在所谓的最大雪崩模式下使用由正乙烷（C $_{2}$ H $_{2}$ F $_{4}$）、六氟化硫（SF $_{6}$）和异丁烷（i-C $_{4}$ H $_{10}$）制成的气体混合物操作。所有这些成分都是温室气体：特别是前两种气体，由于欧洲联盟最近的条例，已经逐步停止生产，其成本正在逐步增加。因此，为了减少RPC操作对环境的影响，并且出于经济原因，寻找新的生态友好的气体混合物变得极其重要。由于类似的化学结构，氢氟烯烃似乎是替代C $_{2}$ H $_{2}$ F $_{4}$的合适的候选物，这是由于它们非常低的GWP，尤其是具有商品名HFO 1234 ze的正丙烯（C $_{3}$ H $_{2}$ F $_{4}$）。为了确定符合未来几年ALICE环境运行要求的环保气体混合物，已经建立了一个专门的实验装置，对有前途的气体混合物进行研发研究。测量已经进行了一个小尺寸的RPC配备了前端的电子设备，提供信号放大，开发ALICE操作在高亮度后，LHC长2002。本文讨论了添加CO $_{2}$的HFO 1234 ze基混合物，以及i-C $_{4}$ H $_{10}$和SF $_{6}$在这种混合物中作为猝灭剂的作用。
Design and performance of a large-area scintillator-based chamber for the MID subsystem of ALICE 3
Instituto de Física, Universidad Nacional Autónoma de México（墨西哥国立自治大学物理研究所）；Instituto Tecnológico de Culiacán, Tecnológico Nacional de México（库利亚坎理工学院，墨西哥科技学院）；Chicago State University（芝加哥州立大学）；Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México（墨西哥国立自治大学核科学研究所）；Centro de Investigación y Estudios Avanzados（高级研究与创新中心）；Universidad Autónoma de Sinaloa（锡那罗亚自治大学）；Czech Technical University in Prague（布拉格捷克理工大学）；Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla（普埃布拉自治大学物理数学科学学院）
