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arXiv 2402.06830physics.ins-dethep-exnucl-ex
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PIKACHU项目的首项研究:用于搜寻$^{160}$Gd双β衰变的高纯度Gd$_3$Ga$_3$Al$_2$O$_{12}$:Ce晶体的研发与评估

First Study of the PIKACHU Project: Development and Evaluation of High-Purity Gd$_3$Ga$_3$Al$_2$O$_{12}$:Ce Crystals for $^{160}$Gd Double Beta Decay Search

Takumi Omori, Takashi Iida, Azusa Gando, Keishi Hosokawa, Kei Kamada, Keita Mizukoshi, Yasuhiro Shoji, Masao Yoshino, Ken-Ichi Fushimi, Hisanori Suzuki, Kotaro Takahashi

AI总结:

PIKACHU项目研发高纯度Ce掺杂GAGG单晶以搜寻$^{160}$Gd双β衰变,通过改进材料纯化提升了探测灵敏度,为精确测量半衰期和揭示中微子马约拉纳特性提供了可行方案。

摘要:

揭示无中微子双β衰变(0$ν$2$β$)对于确认中微子的马约拉纳特性至关重要。0$νββ$的衰变率在理论上存在不确定性,受核矩阵元影响且在不同核素间存在差异。为降低这种不确定性,精确测量不同核素中发射中微子的双β衰变(2$ν$2$β$)的半衰期是必不可少的。我们启动了PIKACHU(Pure Inorganic scintillator experiment in KAmioka for CHallenging Underground sciences)项目,以制造高纯度Ce掺杂的Gd$_3$Ga$_3$Al$_2$O$_{12}$(GAGG)单晶,并用其研究$^{160}$Gd的双β衰变。两种理论模型对$^{160}$Gd中2$ν$2$β$核矩阵元计算的预测在半衰期估计上存在显著差异,相差约一个数量级。如果较低的半衰期估计成立,与先前使用Ce掺杂Gd$_2$SiO$_5$(GSO)晶体的研究相比,探测$^{160}$Gd中的2$ν$2$β$可能会实现灵敏度提升略超一个数量级。通过对原材料的精细纯化与筛选,我们成功研发出纯度超越以往标准的GAGG晶体。我们对这些晶体的实验表明,达到超越早期研究的灵敏度是可行的。本文讨论了高纯度GAGG晶体的持续研发与闪烁体性能评估,以及PIKACHU实验的未来展望。

英文摘要:

Uncovering neutrinoless double beta decay (0$ν$2$β$) is crucial for confirming neutrinos' Majorana characteristics. The decay rate of 0$νββ$ is theoretically uncertain, influenced by nuclear matrix elements that vary across nuclides. To reduce this uncertainty, precise measurement of the half-life of neutrino-emitting double beta decay (2$ν$2$β$) in different nuclides is essential. We have launched the PIKACHU (Pure Inorganic scintillator experiment in KAmioka for CHallenging Underground sciences) project to fabricate high-purity Ce-doped Gd$_{3}$Ga$_{3}$Al$_{2}$O$_{12}$ (GAGG) single crystals and use them to study the double beta decay of $^{160}$Gd. Predictions from two theoretical models on nuclear matrix element calculations for 2$ν$2$β$ in $^{160}$Gd show a significant discrepancy in estimated half-lives, differing by approximately an order of magnitude. If the lower half-life estimation holds true, detecting 2$ν$2$β$ in $^{160}$Gd could be achievable with a sensitivity enhancement slightly more than an order of magnitude compared to prior investigations using Ce-doped Gd$_2$SiO$_5$ (GSO) crystal. We have successfully developed GAGG crystals with purity levels surpassing previous standards through refined purification and selection of raw materials. Our experiments with these crystals indicate the feasibility of reaching sensitivities exceeding those of earlier studies. This paper discusses the ongoing development and scintillator performance evaluation of High-purity GAGG crystals, along with the anticipated future prospects of the PIKACHU experiment.

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