A buffer-free concept bubble chamber for PICO dark matter searches
Abstract
In this paper, we report on the successful operation at Drexel University of the PICO collaboration's first CF buffer-free prototype fluorocarbon bubble chamber. Previous PICO bubble chambers have produced world-leading WIMP search results with fluorocarbon target fluids, separated from the steel bellows by a buffer layer of water. Surface tension effects at the jar walls and liquid-liquid interface lead to a class of background events which have nuclear-recoil-like acoustic signatures and thus contaminate the WIMP-like signal region in analysis. Thus new bubble chambers are to be constructed "right-side-up", meaning that the jar of CF is above the bellows with no water inside the inner vessel. The Drexel Bubble Chamber (DBC), runs successfully at and below the nuclear recoil thresholds used by PICO for WIMP searches, including thresholds as low as 1.19 keV. We have demonstrated sensitivity to Cs gammas and spontaneous fission neutrons from Cm, and acoustic alpha discrimination is demonstrated to be possible although the observed rate of alpha decays is very low. Position reconstruction from stereoscopic imaging allows for basic analysis cuts for calibration data. The successful construction and operation of this prototype confirm the effectiveness of the right-side-up design, which will be used in future dark matter searches such as PICO-40L and PICO-500.
Cite
@article{arxiv.1905.07367,
title = {A buffer-free concept bubble chamber for PICO dark matter searches},
author = {Matthew Bressler and Peter Campion and V. Scott Cushman and Alexander Morrese and Johannes M. Wagner and Salvatore Zerbo and Russell Neilson and Mike Crisler and C. Eric Dahl},
journal= {arXiv preprint arXiv:1905.07367},
year = {2019}
}
Comments
For v2: figures updated for clarity and readability, some text updated with better explanations and references added. Results unchanged For v3: Bibliography formatting updated