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

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.

arXiv comment13 pages, 14 figures

References in corpus (8)

• scikit-image: Image processing in Python
• Dark Matter Search Results from the Complete Exposure of the PICO-60 C${}_3$F${}_8$ Bubble Chamber
• Dark Matter Search Results from the PICO-60 C${}_3$F${}_8$ Bubble Chamber
• Final Analysis and Results of the Phase II SIMPLE Dark Matter Search
• Shifted forces in molecular dynamics
• Discrimination of nuclear recoils from alpha particles with superheated liquids
• Direct Simulations of Homogeneous Bubble Nucleation: Agreement with CNT and no Local Hot Spots
• Molecular dynamics simulations of bubble nucleation in dark matter detectors

Cited by in corpus (3)

• Data-Driven Modeling of Electron Recoil Nucleation in PICO C${}_3$F${}_8$ Bubble Chambers
• A buffer-free concept bubble chamber for PICO dark matter searches
• Model for bubble nucleation efficiency of low-energy nuclear recoils in bubble chambers for dark matter detection