2024 APS April Meeting
Wednesday–Saturday, April 3–6, 2024;
Sacramento & Virtual
Session N00: Poster Session II (2:00PM - 4:00PM PT) & Coffee Break VI (2:00PM - 2:30PM PT)
2:00 PM,
Friday, April 5, 2024
SAFE Credit Union Convention Center
Room: Exhibit Hall A, Floor 1
Abstract: N00.00018 : Dark Matter Induced Neutron Production Search limits Using a Pb-Target*
Abstract
Presenter:
David S Koltick
(Purdue University)
Authors:
David S Koltick
(Purdue University)
Haichuan Cao
(Purdue University)
For this study indirect search Dark Matter (DM) - Matter (M) cross section limits are set based on neutron production data collected by the NMDS-II detector at 1166 m.w.e., by transforming the cosmic ray induced neutron production number spectrum data collected at 583 m.w.e., as background, to the deeper level underground, based on GEANT4 cosmic ray simulations at the two depths. The NMDS-II detector collected 6504 hrs data when located at 583 m.w.e. and 1440 hrs at 1166 m.w.e.. The detector consists of a 30 cm cube Pb-target surrounded by a He-3 detector system consisting of 60 individual detectors. The systems single particle detection efficiency is 23.2 +- 1.2% measured using a calibrated Cf-252 source. The neutron production in the 30 cm cube lead target is estimated to be muon induced for approximately 50% of the events and by muon induced shower neutrons for approximately 50% the events, in which the muon does not pass through the target. The highest neutron multiplicity event, observed at 583 m.w.e., produced approximately 233 neutrons. The neutron multiplicity, n, distribution, fits well to a power law k x n^{-p}. For the simulation at 583 m.w.e., p=2.37 +- 0.01 and for the data collected at 583 m.w.e, p=2.36 +- 0.10. At 1166 m.w.e., p=2.31 +- 0.01 for the simulation and for the collected data set with only 6 events having observed multiplicity above 5, yields p=2.50 +- 0.35 estimated using the Maximum Likelihood method. At 583 m.w.e., 392 events were collected above multiplicity 5 observed neutrons. When projected to 1166 m.w.e. 12.1 +- 4.4 background events are expected compared to the 6 events collected. The difference -6.1 +- 5.1 events indicates that no excess DM events were collected. From this, using either a proton-Pb spallation model or a pion fireball model to account for the DM energy deposition, and assuming 2.3 events as the 90% confidence limit for no observed events, the search limits are 1.1 x 10^{-44}cm^{-2} for 10 GeV deposited energy, 1.9 x 10^{-45}cm^{-2} at 1 GeV and 3.0 x 10^{-45}cm^{-2} for 500 MeV deposited energy and no acceptance at 100 MeV.
*Funded in part by U.S. Department of Energy DE-SC0007884 and the Department of Physics and Astronomy at Purdue University and TechSource Inc.