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arXiv · 1906.04712

Modeling emission of acoustic energy during bubble expansion in PICO bubble chambers

Tetiana Kozynets·Scott Fallows·Carsten B. Krauss
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Abstract

The PICO experiment uses bubble chambers filled with superheated C$_3$F$_8$ for spin-dependent WIMP dark matter searches. One of the main sources of background in these detectors is alpha particles from decays of environmental $^{222}\mathrm{Rn}$, which nucleate bubbles that are visually indistinguishable from WIMP candidate events. Alpha-induced bubbles can be discriminated acoustically, because the signal from alpha events is consistently larger in magnitude than that from nuclear recoil/WIMP-like events. By studying the dynamics of bubbles nucleated by these two types of ionizing radiation from the first stages of their growth, we present a physical model for the acoustic discrimination for the first time. The distribution of acoustic energies that we generate for a simulated sample of bubble nucleations by alpha particles and nuclear recoils is compared directly to the experimental data.

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Tetiana Kozynets, Scott Fallows, Carsten B. Krauss. 2019-09-08. Modeling emission of acoustic energy during bubble expansion in PICO bubble chambers. https://doi.org/10.1103/physrevd.100.052001

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