Carbon $^{14}$C and Tritium as possible background sources in XENON1T

TL;DR

This study investigates how carbon-14 and tritium could serve as background sources in the XENON1T dark matter detector, analyzing their spectral distortions and estimating impurity levels through simulations and experimental comparison.

Contribution

It provides a detailed simulation-based analysis of carbon-14 and tritium backgrounds, including their spectral effects and impurity level estimations in the XENON1T experiment.

Findings

Carbon-14 in dust particles can contribute to low-energy background spectrum.

Tritium spectrum is distorted by threshold effects and dust interactions.

Estimated activity level of carbon-14 is about 1500 decays per ton per year.

Abstract

In this work, carbon $^{14}$C and Tritium were considered as possible background source in the XENON1T experiment. The simulation results show that if $^{14}$C is located in dust particles with a characteristic size of tens of micrometers, then its beta spectrum is softened and can contribute to the low-background part of the spectrum (up to 20 keV) of the XENON1T experiment. In addition, it has been shown that the tritium spectrum is also significantly distorted due to the threshold effect and the form in which tritium is living in xenon. Comparison of the simulation results with experimental data allowed us to estimate the activity level of $^{14}$C at about 1500 decays / t / year, which gives the level of organic impurities containing $^{14}$C at the level of 2x10$^{-13}$ g/g. In the case of tritium background, spectrum distortions are already caused by nanoparticles. Wherein the shape of the spectrum from tritium sitting on the surface of the dust fits better into the experimental data than the spectrum from pure tritium. In addition, since the dust absorbs part of the decays, the total amount of tritium in xenon can be several times greater than assuming a background from pure tritium in xenon (the factor strongly depends on the size of the dust particles).