Medipix and Timepix devices, installed in the ATLAS cavern, have provided valuable complementary luminosity information. Results are presented from measurements with the Timepix3 (TPX3) detectors. In contrast with previously employed frame-based data acquisition, the TPX3 detector remains active continuously, sending information on the pixel hits as they occur. The hit- and cluster-counting methods were used for the luminosity determination of the Large Hadron Collider (LHC) proton–proton collisions. The LHC luminosity versus time is determined using these two methods and fits to a simple model, which incorporates luminosity reduction from the single bunch and beam–beam interactions. The precision of the luminosity determination could be improved by counting the number of clusters, instead of just pixel hits. The internal precision and long-term stability of the TPX3 luminosity measurements are below 0.5%. TPX3, owing to its 1.56-ns time-tagging, is able to resolve the time structure of the luminosity due to the collisions of the individual proton bunches when integrated over an LHC fill.

中文翻译：

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Timepix3 在 ATLAS 实验中测定 13 TeV 质子-质子碰撞的光度

安装在 ATLAS 洞穴中的 Medipix 和 Timepix 设备提供了有价值的补充光度信息。结果来自 Timepix3 (TPX3) 检测器的测量结果。与之前采用的基于帧的数据采集相比，TPX3 检测器持续保持活动状态，在像素命中发生时发送有关像素命中的信息。命中计数和簇计数方法用于确定大型强子对撞机 (LHC) 质子-质子碰撞的光度。LHC 光度与时间的关系是使用这两种方法确定的，并适合一个简单的模型，该模型结合了来自单束和光束相互作用的光度降低。通过计算簇的数量，而不仅仅是像素命中，可以提高亮度确定的精度。TPX3 光度测量的内部精度和长期稳定性低于 0.5%。TPX3 由于其 1.56 ns 的时间标记，能够解析由于单个质子束在 LHC 填充上集成时的碰撞而导致的光度的时间结构。