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The AMoRE-II experiment will search for the 0νββ decay of 100Mo nuclei using molybdate crystal scintillators, operating at milli-Kelvin (mK) temperatures, with a total of 80 kg of 100Mo. The background goal for the experiment is 10–4 counts/keV/kg/year in the region of interest around the 0νββ decay Q-value of 3,034 keV. To achieve this level, the rate of background signals arising from emissions produced by decays of radioactive impurities in the detector and shielding materials must be strictly controlled. To do this, concentrations of such impurities are measured and are controlled through materials selection and purification. In this paper, we describe the design and the construction materials used to build the AMoRE-II detector and shielding system, including active and passive shielding, the cryostat, and the detector holders and instrumentation, and we report on measurements of radioactive impurities within candidate and selected materials.

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 $$^{100}$$ 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 $$\alpha $$ α 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 $$\alpha $$ α energy spectra fitted with the corresponding simulated spectra for six crystal detectors, where sources of background contributions could be identified through high energy $$\alpha $$ α peaks and continuum parts in the energy spectrum for both internal and surface contaminations. We determine the low-energy contributions from internal and surface $$\alpha $$ α contaminations by extrapolating from the $$\alpha $$ α background fitting model.

Abstract The advanced molybdenum-based rare process experiment (AMoRE) aims to search for neutrinoless double beta decay ($$0\nu \beta \beta $$ 0νββ ) of $$^{100}$$ 100 Mo with $$\sim 100\,\hbox {kg}$$ ∼100kg of $$^{100}$$ 100 Mo-enriched molybdenum embedded in cryogenic detectors with a dual heat and light readout. At the current, pilot stage of the AMoRE project we employ six calcium molybdate crystals with a total mass of 1.9 kg, produced from $$^{48}$$ 48 Ca-depleted calcium and $$^{100}$$ 100 Mo-enriched molybdenum ($$^{48{{\text {depl}}}}\hbox {Ca}^{100}\hbox {MoO}_{4}$$ 48deplCa100MoO4 ). The simultaneous detection of heat (phonon) and scintillation (photon) signals is realized with high resolution metallic magnetic calorimeter sensors that operate at milli-Kelvin temperatures. This stage of the project is carried out in the Yangyang underground laboratory at a depth of 700 m. We report first results from the AMoRE-Pilot $$0\nu \beta \beta $$ 0νββ search with a 111 kg day live exposure of $$^{48{{\text {depl}}}}\hbox {Ca}^{100}\hbox {MoO}_{4}$$ 48deplCa100MoO4 crystals. No evidence for $$0\nu \beta \beta $$ 0νββ decay of $$^{100}$$ 100 Mo is found, and a upper limit is set for the half-life of $$0\nu \beta \beta $$ 0νββ of $$^{100}$$ 100 Mo of $$T^{0\nu }_{1/2} > 9.5\times 10^{22}~\hbox {years}$$ T1/20ν>9.5×1022years at 90% C.L. This limit corresponds to an effective Majorana neutrino mass limit in the range $$\langle m_{\beta \beta }\rangle \le (1.2-2.1)\,\hbox {eV}$$ ⟨mββ⟩≤(1.2-2.1)eV .

The Multivariate Exponentially Weighted Moving Average (MEWMA) control chart is an effective tool for monitoring small shifts in the mean vector of multiple correlated variables over time. The traditional MEWMA control charts are not appropriate when dealing with data that has indeterminacy. For the purpose of dealing with indeterminate data, we present a novel Neutrosophic MEWMA Control Chart that incorporates bootstrap control limits in this research. A simulation study is conducted to compare the performance of the proposed method with the neutrosophic Hotelling T2 control chart. The study considered Alarm Rate (AR) and Average Run Length (ARL) have been used as the performance evaluation metrics. Finally, an illustrative example from the chemical industry was used to demonstrate the application of the proposed chart. It is considered that the proposed chart can be effectively applied to a wide range of manufacturing processes, providing significant benefits in process monitoring and control.