Search for exotic physics in double-$β$ decays with GERDA Phase II
The GERDA collaboration, M. Agostini, A. Alexander, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, S. Belogurov, A. Bettini, L. Bezr… 展开作者
The GERDA collaboration, M. Agostini, A. Alexander, G. Araujo, A. M. Bakalyarov, M. Balata, I. Barabanov, L. Baudis, C. Bauer, S. Belogurov, A. Bettini, L. Bezrukov, V. Biancacci, E. Bossio, V. Bothe, R. Brugnera, A. Caldwell, C. Cattadori, A. Chernogorov, T. Comellato, V. D'Andrea, E. V. Demidova, A. Di Giacinto, N. Di Marco, E. Doroshkevich, F. Fischer, M. Fomina, A. Gangapshev, A. Garfagnini, C. Gooch, P. Grabmayr, V. Gurentsov, K. Gusev, J. Hakenmüller, S. Hemmer, W. Hofmann, J. Huang, M. Hult, L. V. Inzhechik, J. Janicskó Csáthy, J. Jochum, M. Junker, V. Kazalov, Y. Kermaïdic, H. Khushbakht, T. Kihm, K. Kilgus, I. V. Kirpichnikov, A. Klimenko, K. T. Knöpfle, O. Kochetov, V. N. Kornoukhov, P. Krause, V. V. Kuzminov, M. Laubenstein, M. Lindner, I. Lippi, A. Lubashevskiy, B. Lubsandorzhiev, G. Lutter, C. Macolino, B. Majorovits, W. Maneschg, L. Manzanillas, G. Marshall, M. Miloradovic, R. Mingazheva, M. Misiaszek, M. Morella, Y. Müller, I. Nemchenok, L. Pandola, K. Pelczar, L. Pertoldi, P. Piseri, A. Pullia, C. Ransom, L. Rauscher, M. Redchuk, S. Riboldi, N. Rumyantseva, C. Sada, S. Sailer, F. Salamida, S. Schönert, J. Schreiner, M. Schütt, A. -K. Schütz, O. Schulz, M. Schwarz, B. Schwingenheuer, O. Selivanenko, E. Shevchik, M. Shirchenko, L. Shtembari, H. Simgen, A. Smolnikov, D. Stukov, A. A. Vasenko, A. Veresnikova, C. Vignoli, K. von Sturm, T. Wester, C. Wiesinger, M. Wojcik, E. Yanovich, B. Zatschler, I. Zhitnikov, S. V. Zhukov, D. Zinatulina, A. Zschocke, A. J. Zsigmond, K. Zuber, G. Zuzel
A search for Beyond the Standard Model double-$β$ decay modes of $^{76}$Ge has been performed with data collected during the Phase II of the GERmanium Detector Array (GERDA) experiment, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). Improved limits on the decays involving Majorons have been obtained, compared to previous experiments with $^{76}$Ge, with half-life values on the order of 10$^{23}$ yr. For the first time with $^{76}$Ge, limits on Lorentz invariance violation effects in double-$β$ decay have been obtained. The isotropic coefficient $\mathring{a}_\text{of}^{(3)}$, which embeds Lorentz violation in double-$β$ decay, has been constrained at the order of $10^{-6}$ GeV. We also set the first experimental limits on the search for light exotic fermions in double-$β$ decay, including sterile neutrinos.
Results on neutrinoless double beta decay from GERDA Phase I
锗探测器阵列（GERDA）是用于探测$^{76}$ Ge的无中微子双β（0 $νββ$）衰变的探测器，它安装在意大利INFN的国立大萨索实验室（LNGS）。本文介绍了GERDA的探测原理和探测器设置。并对GERDA第一阶段的主要物理结果进行了讨论。它们包括测量2 $νββ$衰变的半衰期、能谱的背景分解和根据信号的脉冲形状辨别背景的技术。在本文的最后一部分，我们估计了0-$νββ$的半衰期（$T^{0ν}_{1/2} >2.1\cdot 10^{25}$ yr at 90% C. L.）并与前人的结果进行了比较。来自第一阶段的GERDA数据强烈反对最近基于海德堡-莫斯科实验数据发现0 $νββ$的说法。
Limit on the Radiative Neutrinoless Double Electron Capture of $^{36}$Ar from GERDA Phase I
无中微子双电子俘获是一个过程，如果被发现，将提供轻子数破坏和中微子马约拉纳性质的证据。利用意大利INFN Gran Sasso实验室锗探测器阵列（GERDA）第一阶段实验的数据，用安装在液氩中的锗探测器对$^{36}$ Ar的无中微子双电子俘获进行了研究。没有观察到信号，并建立了$^{36}$ Ar的辐射无中微子双电子捕获半衰期的实验下限：$T_{1/2} > $ 3.6 $\times$ 10 $^{21}$ yr，90% C. I.
Pulse shape discrimination studies with a Broad-Energy Germanium detector for signal identification and background suppression in the GERDA double beta decay experiment
Final Results of GERDA on the Search for Neutrinoless Double-$β$ Decay
锗探测器阵列（GERDA）实验寻找$^{76}$ Ge的轻子数破坏的无中微子双$β$（$0νββ$）衰变，其发现将在宇宙学和粒子物理学中产生深远的影响。通过在有源液氩屏蔽中操作富含$^{76}$ Ge的裸锗二极管，GERDA在信号区实现了前所未有的低本底指数$5.2\times10^{-4}$计数/（keV $\cdot$ kg $\cdot$ yr），并满足了在无本底状态下收集100 kg $\cdot$ yr暴露量的设计目标。当结合第一阶段的结果时，在127.2 kg $\cdot$/年的总暴露量后未观察到信号。$^{76}$ Ge中$0νββ$衰变半衰期的限值设定为90% C.L.时的$T_{1/2}>1.8\times10^{26}$年，这与假定没有信号时的灵敏度一致。
Design and Performance of the GERDA Low-Background Cryostat for Operation in Water
在寻找$^{76}$ Ge的无中微子双β衰变过程中，在INFN国立大萨索实验室进行的锗探测器阵列（GERDA）实验在感兴趣的区域获得了远低于10 $^{-3}$ cts/（keV $\cdot$ kg $\cdot$ yr）的前所未有的低本底。它利用了第一次实现的一种新的屏蔽概念的基础上，一个大型低温恒温器充满了液体惰性气体，浸没在水箱。锗探测器无需在液氩中封装即可工作。氩气和水将实验室和低温恒温器构造材料的环境背景屏蔽到可忽略的水平。在此期间，各种实验都采用了同样的方法。本文概述了64 m $^3$液氩低温恒温器及其相关基础设施的设计和运行经验。讨论包括与水箱中大型低温恒温器的操作相关的具有挑战性的安全问题。
Improved limit on neutrinoless double beta decay of $^{76}$Ge from GERDA Phase II
GERDA实验研究了$^{76}$ Ge（$^{76}$ Ge $\rightarrow$ $^{76}$ Se +2 e $^-$）的轻子数违反无中微子双β衰变的情况，该双β衰变是在液态氩中用富集的$^{76}$ Ge部分操作裸Ge二极管。BEGe型探测器的曝光量比我们以前发布的数据增加了三倍。BEGe探测器的特点是通过对探测器信号的时间曲线进行分析，可以实现出色的背景抑制。在分析窗口中，已达到$1.0_{-0.4}^{+0.6}\cdot10^{-3}$ cts/（keV $\cdot$ kg $\cdot$ yr）的背景水平;如果归一化为能量分辨率，则这是任何0 $νββ$实验中达到的最低水平。未观察到信号，新的90% C.L.结合我们以前的数据，确定了$8.0\cdot10^{25}$年半衰期的下限。假设无信号，预期灵敏度中位数为$5.8\cdot10^{25}$年。
Feasibility study of the observation of the neutrino accompanied double beta-decay of Ge-76 to the 0+(1) excited state of Se-76 using segmented germanium detectors
Double beta decay experiments: beginning of a new era
本文对双β衰变过程的实验研究现状进行了综述。最敏感的实验结果进行了讨论，并讨论了有效马约拉纳中微子质量（$<m_ν>) are given. New results on two neutrino double beta decay are presented. The special attention is given to new current experiments with mass of studied isotopes more than 100 kg, EXO--200 and KamLAND--Zen. These experiments open a new era in research of double beta decay. In the second part of the review prospects of search for neutrinoless double beta decay in new experiments with sensitivity to $ <m_v> $ at the level of $ \sim 0.01-0.1$ eV的现代限制值。给出了最有前景的项目（CUORE、GERDA、MAJORANA、SuperNEMO、EXO、KamLAND-Zen、SNO+）的参数和特性。
