[Bubble] Nucleation efficiency of nuclear recoils in bubble chambers

[Jay Benesch]

https://arxiv.org/abs/2111.01175

Nucleation efficiency of nuclear recoils in bubble chambers
Daniel Durnford, Marie-Cécile Piro

     Bubble chambers using liquid xenon (and liquid argon) have been 
operated (resp. planned) by the Scintillating Bubble Chamber (SBC) 
collaboration for GeV-scale dark matter searches and CEνNS from 
reactors. This will require a robust calibration program of the 
nucleation efficiency of low-energy nuclear recoils in these target 
media. Such a program has been carried out by the PICO collaboration, 
which aims to directly detect dark matter using C3F8 bubble chambers. 
Neutron calibration data from mono-energetic neutron beam and Am-Be 
source has been collected and analyzed, leading to a global fit of a 
generic nucleation efficiency model for carbon and fluorine recoils, at 
thermodynamic thresholds of 2.45 and 3.29keV. Fitting the 
many-dimensional model to the data (34 free parameters) is a non-trivial 
computational challenge, addressed with a custom Markov Chain Monte 
Carlo approach, which will be presented. Parametric MC studies 
undertaken to validate this methodology are also discussed. This fit 
paradigm demonstrated for the PICO calibration will be applied to 
existing and future scintillating bubble chamber calibration data.

Comments: 	6 pages, 3 figures
Subjects: 	Instrumentation and Methods for Astrophysics (astro-ph.IM); 
Instrumentation and Detectors (physics.ins-det)