In situ measurement of the electron drift velocity for upcoming directional Dark Matter detectors

J. Billard (1) , F. Mayet (1) , G. Bosson (1) , O. Bourrion (1) , O. Guillaudin (1) , J. Lamblin (1) , J.P. Richer (1) , Q. Riffard (1) , D. Santos (1) , F. J. Iguaz , Lena Lebreton (2) , D. Maire (2)

1 LPSC - Laboratoire de Physique Subatomique et de Cosmologie
2 IRSN/PRP-HOM/SDE/LMDN - Laboratoire de Métrologie et de Dosimétrie des Neutrons

The knowledge of the electron drift velocity is a key issue for directional detection of galactic Dark Matter as it is used for the 3D track reconstruction. The aim of this paper is to present a dedicated method for the measurement of the electron drift velocity with the MIMAC detector, using a pure CF4 gas and a CF4 + CHF3 gas mixture. This new measurement method uses high energy alpha tracks from a collimated source and includes a profile likelihood method associated to a modeling of the signal induced on the grid. In particular, we show that adding CHF3 allows us to lower the electron drift velocity while keeping almost the same Fluorine content of the gas mixture. We show that the drift velocity at 50 mbar is reduced by a factor of about 5 when considering 30% of CHF3, allowing to improve the three-dimensional track reconstruction.

Domaines: Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]; Instrumentations et Détecteurs [physics.ins-det]; Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]

J. Billard, F. Mayet, G. Bosson, O. Bourrion, O. Guillaudin, et al.. In situ measurement of the electron drift velocity for upcoming directional Dark Matter detectors. 2024. ⟨in2p3-00821779⟩