232 research outputs found
Monte Carlo Simulation Variance Reduction Techniques for Photon Transport in Liquid Xenon Detectors
Monte Carlo simulations are a crucial tool for the analysis and prediction of
various background components in liquid xenon (LXe) detectors. With improving
shielding in new experiments, the simulation of external backgrounds, such as
induced by gamma rays from detector materials, gets more computationally
expensive. We introduce and validate an accelerated Monte Carlo simulation
technique for photon transport in liquid xenon detectors. The method simulates
photon-induced interactions within a defined geometry and energy range with
high statistics while interactions outside of the region of interest are not
simulated directly but are taken into account by means of probability weights.
For a simulation of gamma induced backgrounds in an exemplary detector geometry
we achieve a three orders of magnitude acceleration compared to a standard
simulation of a current ton-scale LXe dark matter experiment
Radon daughter removal from PTFE surfaces and its application in liquid xenon detectors
Long-lived radon daughters are a critical background source in experiments
searching for low-energy rare events. Originating from radon in ambient air,
radioactive polonium, bismuth and lead isotopes plate-out on materials that are
later employed in the experiment. In this paper, we examine cleaning procedures
for their capability to remove radon daughters from PTFE surfaces, a material
often used in liquid xenon TPCs. We found a large difference between the
removal efficiency obtained for the decay chains of Rn and Rn,
respectively. This indicates that the plate-out mechanism has an effect on the
cleaning success. While the long-lived Rn daughters could be reduced by
a factor of ~2, the removal of Rn daughters was up to 10 times more
efficient depending on the treatment. Furthermore, the impact of a nitric acid
based PTFE cleaning on the liquid xenon purity is investigated in a small-scale
liquid xenon TPC
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