Central exclusive processes can be studied in CMS by combining the information of the central detector with the Precision Proton Spectrometer (PPS). PPS detectors, placed symmetrically at more than 200 m from the interaction point, can detect the scattered protons that survive the interaction. PPS has taken data at high luminosity while fully integrated in the CMS experiment. The total amount of collected data corresponds to more than 100 fb$^{-1}$ during the LHC Run 2. PPS consists of 3D silicon tracking stations as well as timing detectors that measure both the position and direction of protons and their time-of-flight with high precision. The detectors are hosted in special movable vacuum chambers, the Roman Pots, which are placed in the primary vacuum of the LHC beam pipe. The sensors reach a distance of few mm from the beam. Detectors have to operate in vacuum and must be able to sustain highly non-uniform irradiation: sensors used in Run 2 have accumulated an integrated dose with a local peak of $\sim 5 \cdot 10^{15}$ protons/cm$^2$. The timing system is made with high purity scCVD diamond sensors. A new architecture with two diamond crystals read out in parallel by the same electronic channel has been used to enhance the detector performance. In this paper, after a general overview of the PPS detector, we describe the timing system in detail. The sensor and the dedicated amplification chain are described, together with the signal digitization technique. Performance of the detector in Run 2 is reported. Recently the sensors used in Run 2 have been tested for efficiency and timing performance in a dedicated test beam at DESY. Preliminary results on radiation damage are reported. Important upgrades of the timing system are ongoing for the LHC Run 3, with the goal of reaching an ultimate timing resolution better than 30 ps; they are also discussed here.

中文翻译：

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CMS 精密质子光谱仪计时系统：运行 2 中的性能、未来升级和传感器辐射硬度研究

通过将中央探测器的信息与精密质子光谱仪 (PPS) 相结合，可以在 CMS 中研究中央专属过程。PPS 探测器对称放置在距离相互作用点 200 米以上的地方，可以探测在相互作用中幸存下来的散射质子。PPS 以高亮度采集数据，同时完全集成到 CMS 实验中。LHC Run 2 期间收集的数据总量对应于 100 多个 fb$^{-1}$。PPS 由 3D 硅跟踪站以及测量质子的位置和方向及其时间的定时探测器组成 -高精度飞行。探测器位于特殊的可移动真空室 Roman Pots 中，该真空室放置在 LHC 束管的初级真空中。传感器到达距离光束几毫米的距离。探测器必须在真空中运行，并且必须能够承受高度不均匀的辐射：运行 2 中使用的传感器累积了一个局部峰值为 $\sim 5 \cdot 10^{15}$ protons/cm$^ 的积分剂量2美元。计时系统由高纯度 scCVD 金刚石传感器制成。由同一电子通道并行读取两个金刚石晶体的新架构已被用于提高检测器性能。在本文中，在对 PPS 检测器进行总体概述之后，我们详细描述了计时系统。介绍了传感器和专用放大链，以及信号数字化技术。报告了运行 2 中检测器的性能。最近，运行 2 中使用的传感器在 DESY 的专用测试光束中进行了效率和计时性能测试。报告了辐射损伤的初步结果。LHC Run 3 的计时系统正在进行重要升级，目标是达到优于 30 ps 的终极计时分辨率；他们也在这里讨论。