Modeling of GERDA Phase II data
Creators: name: GERDA Collaboration
name: Agostini, Matteo
name: Bakalyarov, Alexander M.
name: Balata, Marco
name: Barabanov, Igor
name: Baudis, Laura
name: Bauer, Christian
name: Bellotti, Enrico
name: Belogurov, Sergej
name: Bettini, Alessandro
name: Bezrukov, Leonid
name: Borowicz, Dariusz
name: Bossio, Elisabetta
name: Bothe, Vikas
name: Brudanin, Victor
name: Brugnera, Riccardo
name: Caldwell, Allen
name: Cattadori, Carla
name: Chernogorov, Andrey
name: Comellato, Tommaso
name: D'Andrea, Valerio
name: Demidova, Elena V.
name: Di Marco, Natalia
name: Domula, Alexander
name: Doroshkevich, Evgenyi
name: Egorov, Viacheslav
name: Fischer, Felix
name: Fomina, Maria
name: Gangapshev, Albert
name: Garfagnini, Alberto
name: Gooch, Chris
name: Grabmayr, Peter
name: Gurentsov, Valery
name: Gusev, Konstantin
name: Hakenmüller, Janina
name: Hemmer, Sabine
name: Hiller, Roman
name: Hofmann, Werner
name: Hult, Mikael
name: Inzhechik, Lev V.
name: Csáthy, Jozsef Janicskó
name: Jochum, Josef
name: Junker, Matthias
name: Kazalov, Vladimir
name: Kermaïdic, Yoann
name: Kihm, Thomas
name: Kirpichnikov, Igor V.
name: Klimenko, Alexander
name: Kneißl, Raphael
name: Knöpfle, Karl T.
name: Kochetov, Oleg
name: Kornoukhov, Vasily N.
name: Krause, Patrick
name: Kuzminov, Valery V.
name: Laubenstein, Matthias
name: Lazzaro, Andrea
name: Lindner, Manfred
name: Lippi, Ivano
name: Lubashevskiy, Alexey
name: Lubsandorzhiev, Bayarto
name: Lutter, Guillaume
name: Macolino, Carla
name: Majorovits, Bela
name: Maneschg, Werner
name: Miloradovic, Michael
name: Mingazheva, Rizalina
name: Misiaszek, Marcin
name: Moseev, Pavel
name: Nemchenok, Igor
name: Panas, Krysztof
name: Pandola, Luciano
name: Pelczar, Krysztof
name: Pertoldi, Luigi
name: Piseri, Paolo
name: Pullia, Alberto
name: Ransom, Chloe
name: Riboldi, Stefano
name: Rumyantseva, Nadezda
name: Sada, Cinzia
name: Salamida, Francesco
name: Schönert, Stefan
name: Schreiner, Jochen
name: Schütt, Mario
name: Schütz, Ann-Katrin
name: Schulz, Oliver
name: Schwarz, Mario
name: Schwingenheuer, Bernhard
name: Selivanenko, Oleg
name: Shevchik, Egor
name: Shirchenko, Mark
name: Simgen, Hardy
name: Smolnikov, Anatoly
name: Stukov, Danila
name: Vanhoefer, Laura
name: Vasenko, Andrey A.
name: Veresnikova, Anna
name: Vignoli, Chiara
name: von Sturm, Katharina
name: Wester, Thomas
name: Wiesinger, Christoph
name: Wojcik, Marcin
name: Yanovich, Evgeny
name: Zatschler, Birgit
name: Zhitnikov, Igor
name: Zhukov, Sergey V.
name: Zinatulina, Daniya
name: Zschocke, Andreas
name: Zsigmond, Anna J.
name: Zuber, Kai
name: Zuzel, Grzegorz
Publisher: name: arXiv
Year: 2019
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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.