Eur. Phys. J. C (2022) 82: 1140
https://doi.org/10.1140/epjc/s10052-022-11104-3

Regular Article - Experimental Physics

Alpha backgrounds in the AMoRE-Pilot experiment

¹ JSC FOMOS-Materials, 107023, Moscow, Russia
² Department of Physics, Kyungpook National University, 41566, Daegu, Korea
³ Physikalisch-Technische Bundesanstalt, 38116, Braunschweig, Germany
⁴ Institute for Nuclear Research of NASU, 03028, Kyiv, Ukraine
⁵ Nakhon Pathom Rajabhat University, 73000, Nakhon Pathom, Thailand
⁶ Department of Physics, Soongsil University, 06978, Seoul, Korea
⁷ Department of Physics and Astronomy, Seoul National University, 08826, Seoul, Korea
⁸ Department of Physics, Institut Teknologi Bandung, 40132, Bandung, Indonesia
⁹ Kirchhoff-Institute for Physics, 69120, Heidelberg, Germany
¹⁰ Baksan Neutrino Observatory of INR RAS, 361609, Kabardino-Balkaria, Russia
¹¹ Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Science, 630090, Novosibirsk, Russia
¹² Department of Physics, Chung-Ang University, 06911, Seoul, Korea
¹³ Department of Physics and Research Institute for Natural Science, Hanyang University, 04763, Seoul, Korea
¹⁴ Center for Underground Physics, Institute for Basic Science (IBS), 34126, Daejeon, Korea
¹⁵ Semyung University, 27136, Jecheon, Korea
¹⁶ Department of Physics, Kohat University of Science and Technology, Khyber Pakhtunkhwa 26000, Kohat, Pakistan
¹⁷ Department of Physics and Astronomy, Sejong University, 05006, Seoul, Korea
¹⁸ University of Science and Technology (UST), 34113, Daejeon, Korea
¹⁹ National Research Nuclear University MEPhI, 115409, Moscow, Russia
²⁰ Korea Research Institute of Standards and Science, 34113, Daejeon, Korea
²¹ Tsinghua University, 100084, Beijing, China
²² V.N. Karazin Kharkiv National University, 61022, Kharkiv, Ukraine
²³ Department of Accelerator Science, Korea University, 30019, Sejong, Korea
²⁴ Department of Physics, Abdul Wali Khan University, 23200, Mardan, Pakistan
²⁵ University of Mataram, 83121, Mataram Nusa Tenggara Bar., Indonesia
²⁶ Department of Physics, Universitas Negeri Padang, 25131, Padang, Indonesia

^ab ejjeon@ibs.re.kr

Received: 16 July 2021
Accepted: 5 December 2022
Published online: 16 December 2022

Abstract

The Advanced Mo-based Rare process Experiment (AMoRE)-Pilot experiment is an initial phase of the AMoRE search for neutrinoless double beta decay of ${}^{100}$Mo, with the purpose of investigating the level and sources of backgrounds. Searches for neutrinoless double beta decay generally require ultimately low backgrounds. Surface $\alpha$ decays on the crystals themselves or nearby materials can deposit a continuum of energies that can be as high as the Q-value of the decay itself and may fall in the region of interest (ROI). To understand these background events, we studied backgrounds from radioactive contaminations internal to and on the surface of the crystals or nearby materials with Geant4-based Monte Carlo simulations. In this study, we report on the measured $\alpha$ energy spectra fitted with the corresponding simulated spectra for six crystal detectors, where sources of background contributions could be identified through high energy $\alpha$ peaks and continuum parts in the energy spectrum for both internal and surface contaminations. We determine the low-energy contributions from internal and surface $\alpha$ contaminations by extrapolating from the $\alpha$ background fitting model.