Recombination in Liquid Argon with ProtoDUNE

The ProtoDUNE single phase liquid argon time projection chamber is a prototype for the first far detector module of the Deep Underground Neutrino Experiment (DUNE). It has an active volume of 7.2 m x 6.1 m x 7.0 m and incorporates full-sized components designed for the far detector. Its first physics run took place in a mixed particle beam with momenta in the range 0.3 GeV/c to 7 GeV/c at the CERN Neutrino Platform in 2018-2019. In this talk I will present the first results of a liquid argon recombination measurement using stopping protons in ProtoDUNE.

In the Jaffé columnar ionization theory a charged particle traversing a medium creates a cylindrical column of ions along its path. Recombination of electrons with this population of ions leads to a non-linear relationship between the deposited energy and the collected charge. There are two leading models to parameterize the effects of recombination, Birks’ model and the Modified Box model. I will compare the ProtoDUNE data to each of these models to extract best fit parameters and make a comparison to previous results from ICARUS, ArgoNEUT and MicroBooNE.