论文标题
蜡烛探测器能量分辨率的研究
A study on energy resolution of CANDLES detector
论文作者
论文摘要
在中微子双β衰减（$0νββ$）实验中，能量分辨率对于区分$0νββ$和背景事件很重要。低能能力光谱仪（蜡烛）对中微子和暗物质进行研究的钙含钙的$^{48} $ CA的$0νββ$使用CAF $ _2 $闪烁体作为检测器和来源。光电层管（PMTS）收集闪烁光子。在$^{48} $ CA的Q值下，当前的能量分辨率（2.6％）超过了光电子数量的理想统计波动（1.6％）。由于CAF $ _2 $的长衰减常数为1000 ns，因此使用4000 NS内的信号积分来计算能量。基线波动（$σ_{基线} $）累积在信号集成中，从而降低了能量分辨率。本文在蜡烛检测器中研究$σ_{基线} $，该$^{48} $ CA的Q值将分辨率严重降低了1％。为避免$σ_ {\ rm基线} $，可以使用光子计数来获取每个PMT中的光电子数；但是，每个PMT的显着光电信号重叠概率会导致计数中缺少光电子，并减少能量分辨率。 “部分光子计数”减少$σ_{基线} $，并最大程度地减少光电子损失。我们在1460.8 keV（$^$^{40} $ k）上获得了4.5-4.0％的提高能源分辨率，在2614.5 keV（$γ$ -RARE of $^{208} $ TL）中获得了3.3-2.9％的提高能源分辨率。估计Q值的能量分辨率估计将从2.6％提高到2.2％，并且$^{48} $ CA的$0νββ$半衰期的检测器敏感性可以提高1.09倍。
In a neutrinoless double-beta decay ($0νββ$) experiment, energy resolution is important to distinguish between $0νββ$ and background events. CAlcium fluoride for studies of Neutrino and Dark matters by Low Energy Spectrometer (CANDLES) discerns the $0νββ$ of $^{48}$Ca using a CaF$_2$ scintillator as the detector and source. Photomultiplier tubes (PMTs) collect scintillation photons. At the Q-value of $^{48}$Ca, the current energy resolution (2.6%) exceeds the ideal statistical fluctuation of the number of photoelectrons (1.6%). Because of CaF$_2$'s long decay constant of 1000 ns, a signal integration within 4000 ns is used to calculate the energy. The baseline fluctuation ($σ_{baseline}$) is accumulated in the signal integration, thus degrading the energy resolution. This paper studies $σ_{baseline}$ in the CANDLES detector, which severely degrades the resolution by 1% at the Q-value of $^{48}$Ca. To avoid $σ_{\rm baseline}$, photon counting can be used to obtain the number of photoelectrons in each PMT; however, a significant photoelectron signal overlapping probability in each PMT causes missing photoelectrons in counting and reduces the energy resolution. "Partial photon counting" reduces $σ_{baseline}$ and minimizes photoelectron loss. We obtain improved energy resolutions of 4.5-4.0% at 1460.8 keV ($γ$-ray of $^{40}$K), and 3.3-2.9% at 2614.5 keV ($γ$-ray of $^{208}$Tl). The energy resolution at the Q-value is estimated to be improved from 2.6% to 2.2%, and the detector sensitivity for the $0νββ$ half-life of $^{48}$Ca can be improved by 1.09 times.
