New libraries for simulating neutron scattering in dark matter detector calibrations

Abstract

Dark matter detectors require calibrations of their energy scale and efficiency to detect nuclear recoils in the $1-50$ keV range. Most calibrations use neutron scattering and require MCNP or Geant4 simulations of neutron propagation through the detector. For most nuclei heavier than ${}^{16}$O, these simulations' libraries ignore the contribution of resolved resonances to the neutron elastic differential cross-section. For many isotopes and neutron energies of importance to dark matter detection, this invalid assumption can severely distort simulated nuclear recoil spectra. The correct angular distributions can be calculated from the resonance parameters using R-matrix formalism. A set of neutron scattering libraries with high resolution angular distributions for MCNP and Geant4 of ${}^{19}$F, ${}^{40}$Ar, ${}^{50,52}$Cr, ${}^{56}$Fe, ${}^{136}$Xe, and ${}^{206,207,208}$Pb is presented. An MCNPX library for simulating the production of low-energy neutrons in the ${}^9$Be$(\gamma ,n{)}^8$Be reaction is also presented. Example dark matter detector calibrations are simulated with the new libraries showing how detector sensitivity could be overestimated by factors of two by relying on existing MCNP and Geant4 libraries.

4 pages, 3 figures

References in corpus (1)

• First dark matter search results from a 4-kg CF${}_3$I bubble chamber operated in a deep underground site

Cited by in corpus (9)

• 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-2L C${}_3$F${}_8$ Bubble Chamber
• Measurement of the ionization produced by sub-keV silicon nuclear recoils in a CCD dark matter detector
• Measurement of the low-energy quenching factor in germanium using an ${}^{88}$Y/Be photoneutron source
• Nuclear-recoil energy scale in CDMS II silicon dark-matter detectors
• A reanalysis of radioisotope measurements of the ${}^9$Be$(\gamma ,n{)}^8$Be cross-section
• Measurement of the scintillation efficiency for nuclear recoils in liquid argon under electric fields up to 3 kV/cm
• Determining the bubble nucleation efficiency of low-energy nuclear recoils in superheated C${}_3$F${}_8$ dark matter detectors
• Geant4 simulation of the moderating neutrons spectrum