Germanium detector simulations for nEXO

The nEXO experiment is being designed to observe the neutrinoless double-beta decay of Xe-136. Should this decay be observed, the neutrino and antineutrino would have to be the same particle. This would be only the second truly unexpected discovery in particle physics in several generations and only possible because of the first one: that neutrinos have mass (2015 Nobel Prize).

In order to observe this exceedingly rare decay, nEXO must start with an exceedingly low background. Since background gamma-ray radiation is most difficult to shield at these energies, the detector must be made of exceedingly low radioactivity materials. To ensure this, we will assay every part and material that will go into this massive experiment. One of our best tools to determine gamma-ray background contribution from prospective materials is direct gamma-ray counting with a high purity germanium spectrometer. To understand the efficiency of this device to a wide array of sample materials and geometry, we use a detailed simulation including the detector geometry and all of the relevant physics processes available in the Geant4 simulation toolkit.

Software:

This simulation uses CERN's Geant4 simulation toolkit to generate simulated radioactive decays in the sample material, propagation of the resulting radiation, and the energy deposition of this radiation in a simulation of our detector. The simulation stores the generated data using CERN's ROOT modular analysis toolkit, that we also use to process and analyze the data from the real detector. We need a specific version of Geant 4: Geant 4.9.6 and ROOT: 5.34.

Participants:

Lead PI: Ryan MacLellan

Students:

Thakur Bhatta

Logan J Hissong, Added on LCC cluster, 03/02/2023

Grants:

Publications:

Patents:

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