GERDA collaboration, Matteo Agostini, Alexander M. Bakalyarov, Marco Balata, Igor Barabanov, Laura Baudis, Christian Bauer, Enrico Bellotti, Sergej Belogurov, A… 展开作者
GERDA collaboration, Matteo Agostini, Alexander M. Bakalyarov, Marco Balata, Igor Barabanov, Laura Baudis, Christian Bauer, Enrico Bellotti, Sergej Belogurov, Alessandro Bettini, Leonid Bezrukov, Dariusz Borowicz, Elisabetta Bossio, Vikas Bothe, Victor Brudanin, Riccardo Brugnera, Allen Caldwell, Carla Cattadori, Andrey Chernogorov, Tommaso Comellato, Valerio D'Andrea, Elena V. Demidova, Natalia Di Marco, Alexander Domula, Evgenyi Doroshkevich, Viacheslav Egorov, Felix Fischer, Maria Fomina, Albert Gangapshev, Alberto Garfagnini, Chris Gooch, Peter Grabmayr, Valery Gurentsov, Konstantin Gusev, Janina Hakenmüller, Sabine Hemmer, Roman Hiller, Werner Hofmann, Mikael Hult, Lev V. Inzhechik, Jozsef Janicskó Csáthy, Josef Jochum, Matthias Junker, Vladimir Kazalov, Yoann Kermaïdic, Thomas Kihm, Igor V. Kirpichnikov, Alexander Klimenko, Raphael Kneißl, Karl T. Knöpfle, Oleg Kochetov, Vasily N. Kornoukhov, Patrick Krause, Valery V. Kuzminov, Matthias Laubenstein, Andrea Lazzaro, Manfred Lindner, Ivano Lippi, Alexey Lubashevskiy, Bayarto Lubsandorzhiev, Guillaume Lutter, Carla Macolino, Bela Majorovits, Werner Maneschg, Michael Miloradovic, Rizalina Mingazheva, Marcin Misiaszek, Pavel Moseev, Igor Nemchenok, Krysztof Panas, Luciano Pandola, Krysztof Pelczar, Luigi Pertoldi, Paolo Piseri, Alberto Pullia, Chloe Ransom, Stefano Riboldi, Nadezda Rumyantseva, Cinzia Sada, Francesco Salamida, Stefan Schönert, Jochen Schreiner, Mario Schütt, Ann-Katrin Schütz, Oliver Schulz, Mario Schwarz, Bernhard Schwingenheuer, Oleg Selivanenko, Egor Shevchik, Mark Shirchenko, Hardy Simgen, Anatoly Smolnikov, Danila Stukov, Laura Vanhoefer, Andrey A. Vasenko, Anna Veresnikova, Chiara Vignoli, Katharina von Sturm, Thomas Wester, Christoph Wiesinger, Marcin Wojcik, Evgeny Yanovich, Birgit Zatschler, Igor Zhitnikov, Sergey V. Zhukov, Daniya Zinatulina, Andreas Zschocke, Anna J. Zsigmond, Kai Zuber, Grzegorz Zuzel
The GERmanium Detector Array (GERDA) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta ($0νββ$) decay of $^{76}$Ge. The technological challenge of GERDA is to operate in a "background-free" regime in the region of interest (ROI) after analysis cuts for the full 100$\,$kg$\cdot$yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around $Q_{ββ}$ for the $0νββ$ search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos ($2νββ$) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for GERDA Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of $16.04^{+0.78}_{-0.85} \cdot 10^{-3}\,$cts/(kg$\cdot$keV$\cdot$yr) for the enriched BEGe data set and $14.68^{+0.47}_{-0.52} \cdot 10^{-3}\,$cts/(kg$\cdot$keV$\cdot$yr) for the enriched coaxial data set. These values are similar to the one of Gerda Phase I despite a much larger number of detectors and hence radioactive hardware components.
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。
Isotopically modified Ge detectors for {\sc Gerda}: from production to operation
\textsc{Gerda}实验通过新颖的脉冲形状鉴别（PSD）技术来搜索无中微子双β（$0νβ$ β $) decay of $ ^{76} $Ge using high-purity germanium detectors made of material enriched in $ ^{76} $Ge. For Phase II of the experiment a sensitivity for the half life $ T_{1/2} ^{0ν}\，\，\sim 2 \cdot 10^{26} $ yr is envisioned. Modified Broad Energy Germanium detectors (BEGe) with thick n$ ^+ $ electrodes provide the capability to efficiently identify and reject background events, while keeping a large acceptance for the $ 0νβ $beta$ -衰变信号。生产厚窗口BEGe型探测器的\textsc{Gerda}实验的可行性证明了通过测试所有的生产步骤，从采购的同位素改性锗工作BEGe探测器。对\textsc{Gerda} Phase II原型BEGe探测器的光谱…
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。
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.
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。
