Design and Simulation of a Calibration Source for the Deep Underground Neutrino Experiment (DUNE) at Sanford Lab

Author: James Haiston, Department of Physics

Co-Author: Jason Stock

Co-Author: Madan Timalsina

Mentor & Co-Author: Dr. Juergen Reichenbacher, Department of Physics

The far detector of the Deep Underground Neutrino Experiment (DUNE) will be located at the Sanford Underground Research Facility (SURF) in Lead, SD, while neutrinos to be probed will travel from the 1300 km distant accelerator at Fermilab in Chicago. DUNE’s underground detector will be comprised of 4 individual 10 kton liquid argon time projection chamber (TPC) modules. The first module is scheduled to be operational in 2024.

In order to expand DUNE’s science goal to probe extra-terrestrial neutrino sources, it is important to understand the detector response to low low-energy neutrino events from supernova explosions and the sun. The development of a calibration source, which can mimic such low-energy events is hereby crucial. Our design of a calibration source and deployment system can inject single 9 MeV gamma-rays into the DUNE TPC that mimic short tracks from solar or supernovae neutrinos and probe the trigger efficiency.

The physics of the source design requires it to be bulky in order to have enough moderator material to be able to thermalize neutrons, so that the desired 58Ni(n, γ)59Ni nuclear reaction can produce gamma-rays with 9 MeV energy. This energy is not only required to mimic the topology of supernova and solar neutrino events, but also to penetrate the DUNE TPC from outside of its field cage. Moreover, there are engineering requirements for such a calibration source, as the source must be able to endure cryogenic temperatures (87 K), it must not float, and it must fit easily through the sealable flanges, which limit its diameter to 20 cm.

In addition to the mechanical deployment scheme, computer simulation studies are presented that demonstrate the effectiveness of such a calibration source deployment in DUNE. In further simulations we optimized the configuration of nickel rods inside our Delrin moderator with a Cf-252 neutron source.