Gallacher D, de St Croix A, Bron S, Rebeiro B M, McElroy T, Al Kharusi S, Brunner T, Chambers C, Chana B, Charlesworth Z, Egan E, Francesconi M, Galli L, Giampa P, Goeldi D, Lavoie S, Lefebvre J, Li X, Malbrunot C, Margetak P, Massacret N, Nowicki S C, Rasiwala H, Raymond K, Retière F, Rottoo S, Rudolph L, Shang X, Tétrault M A, Totev T, Viel S, Viet N V H
Physics Department, McGill University, Montreal, QC H3A 2T8 Canada.
TRIUMF, Vancouver, BC V6T 2A3 Canada.
Eur Phys J C Part Fields. 2025;85(6):692. doi: 10.1140/epjc/s10052-025-14381-w. Epub 2025 Jun 24.
The Light-only Liquid Xenon experiment (LoLX) employs a small-scale detector equipped with 96 Hamamatsu VUV4 silicon photomultipliers (SiPMs) submerged in 5 kg of liquid xenon (LXe) to perform characterization measurements of light production, transport and detection in xenon. In this work, we perform a novel measurement of the "external cross-talk" (ExCT) of SiPMs, where photons produced in the avalanche escape the device and produce correlated signals on other SiPMs. SiPMs are the photodetector technology of choice for next generation rare-event search experiments; understanding the sources and effects of correlated noise in SiPMs is critical for producing accurate estimates of detector performance and sensitivity projections. We measure the probability to observe ExCT through timing correlation of detected photons in low-light conditions within LoLX. Measurements of SiPM ExCT are detector dependent; thus the ExCT process is simulated and modelled using the Geant4 framework. Utilizing simulations, we determine the average transport and detection efficiency for ExCT photons within LoLX, a necessary input to extract the true ExCT probability and detector independent photon emission intensity. For an applied overvoltage of 4 V and 5 V, we measure a mean number of photons emitted into LXe per avalanche of and respectively. Using an optical model to describe photon transmission through the SiPM surface, this corresponds to an estimated photon yield inside the bulk silicon of and photons per avalanche. The relative increase in intensity of SiPM ExCT emission between 4 and 5 V is consistent with expectation for the linear increase of gain with respect to overvoltage.
纯光液态氙实验（LoLX）采用了一个配备96个滨松VUV4硅光电倍增管（SiPM）的小型探测器，该探测器浸没在5千克液态氙（LXe）中，用于对氙中的光产生、传输和探测进行特性测量。在这项工作中，我们对SiPM的“外部串扰”（ExCT）进行了一项新颖的测量，即雪崩中产生的光子逸出器件并在其他SiPM上产生相关信号的情况。SiPM是下一代稀有事件搜索实验首选的光电探测器技术；了解SiPM中相关噪声的来源和影响对于准确估计探测器性能和灵敏度预测至关重要。我们通过在LoLX的低光条件下检测到的光子的时间相关性来测量观察到ExCT的概率。SiPM ExCT的测量取决于探测器；因此，使用Geant4框架对ExCT过程进行了模拟和建模。利用模拟，我们确定了LoLX内ExCT光子的平均传输和探测效率，这是提取真实ExCT概率和与探测器无关的光子发射强度所需的输入。对于施加的4V和5V过电压，我们分别测量了每次雪崩发射到LXe中的平均光子数为 和 。使用光学模型来描述光子通过SiPM表面的传输，这对应于估计在块状硅内部每次雪崩产生 和 个光子的光子产额。4V和5V之间SiPM ExCT发射强度的相对增加与增益相对于过电压的线性增加的预期一致。
