The Phase-2 upgrade of the Large Hadron Collider (LHC) to High-Luminosity LHC (HL-LHC) allows an increase in the operational luminosity value by a factor of 5–7 that will result in delivering 3000 fb⁻¹ or more integrated luminosity. Due to high luminosity, the number of interactions per bunch crossings (pileup) will increase up to a value of 140–200. To cope with high pileup rates, a precision minimum ionising particles (MIPs) timing detector (MTD) with a time resolution of $\sim$30–40 ps and hermetic coverage up to a pseudo-rapidity of $\left|\eta \right|=3$ is proposed by the Compact Muon Solenoid (CMS) experiment. An endcap part ($1.6<\left|\eta \right|<3$) of the MTD, called the endcap timing layer, will be based on low-gain avalanche detector (LGAD) technology. LGADs provide a good timing resolution due to a combination of a fast signal rise time and high signal-to-noise ratio. The performance of the ETL depends on optimising the crucial features of the sensors, namely; gain, signal homogeneity, fill factor, leakage current, uniformity of multiple-pad sensors and long term stability. The paper mainly focuses on the study of the fill factor of LGADs with varying temperature and irradiation at varying proton fluences as these sensors will be operated at low temperatures and are subjected to a high radiation environment.

The 3.1 production of LGADs from Hamamatsu Photonics K.K. (HPK) includes 2x2 sensors with different structures, in particular, different values of narrower inactive region widths between the pads, called the no-gain region. In this paper, the term interpad-gap is used instead of no-gain region in order to follow the conventional terminology. These sensors have been designed to study their fill factor, which is the ratio of the area within the active region (gain region) to the total sensor area. A comparative study on the dependence of breakdown voltage with the interpad-gap width for the sensors has been carried out. Using infrared light (as the electron–hole pair creation by IR laser mimics closely to the traversing of MIPs) from the Scanning-Transient Current Technique (Scanning-TCT) set-up shows that the fill factor does not vary significantly with a variation in temperature and irradiation at high proton fluences.

将大型强子对撞机（LHC）升级为高亮度LHC（HL-LHC）的第二阶段，可使工作亮度值增加5-7倍，这将导致交付3000 fb ^-1或更高的集成度亮度。由于具有较高的发光度，每个束交叉（堆积）的相互作用数将增加到140-200。为了应对高堆积率，时间分辨率为的精密最小电离粒子（MIP）定时检测器（MTD）$〜$30–40 ps，并且气密覆盖范围高达伪快速 $\left|\eta \right|=3$由紧凑型介电螺线管（CMS）实验提出。端盖部分（$\mathrm{1个}。6<\left|\eta \right|<3$称为端盖定时层的MTD）将基于低增益雪崩检测器（LGAD）技术。由于快速的信号上升时间和高的信噪比相结合，LGAD提供了良好的时序分辨率。ETL的性能取决于优化传感器的关键功能，即：增益，信号均匀性，填充因子，泄漏电流，多焊盘传感器的均匀性和长期稳定性。由于这些传感器将在低温下运行并处于高辐射环境下，因此本文主要研究温度和质子注量变化下辐照的LGAD的填充因子。

3.1由Hamamatsu Photonics KK（HPK）生产的LGAD包括2x2传感器，它们具有不同的结构，尤其是焊盘之间较窄的无效区域宽度的不同值，称为无增益区域。在本文中，为了遵循常规术语，使用术语焊盘间间隙代替无增益区域。这些传感器的设计目的是研究其填充系数，即有效区域（增益区域）内的面积与传感器总面积之比。进行了击穿电压与传感器间间隙宽度的依赖性的比较研究。