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Title ImagePublic Abstract


DE-SC0019057: Measurement of Coherent Elastic Neutrino-Nucleus Scattering with Germanium Detectors at the SNS

Award Status: Active
  • Institution: North Carolina State University, Raleigh, NC
  • UEI: U3NVH931QJJ3
  • DUNS: 042092122
  • Most Recent Award Date: 01/18/2022
  • Number of Support Periods: 3
  • PM: Crawford, Glen
  • Current Budget Period: 06/01/2020 - 09/30/2023
  • Current Project Period: 06/01/2018 - 09/30/2023
  • PI: Green, Matthew
  • Supplement Budget Period: N/A

Public Abstract

Project Title: Measurement of Coherent Elastic Neutrino-Nucleus Scattering with Germanium Detectors at the SNS
M. P. Green, Principle Investigator, North Carolina State University

2701 Sullivan Drive, Admin III, Suite 240, Raleigh, NC 27695-7514

Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) is scattering process in which a neutrino interacts coherently with an entire nucleus. While the coherence of the process leads to a large cross section enhancement with increasing neutron number (proportional to the square of the number of neutrons in the nucleus), the low momentum transfer results in difficult-to-detect low energy nuclear recoils. The COHERENT Collaboration has combined state-of-the-art low-threshold detector technology with the intense flux of neutrinos generated at Oak Ridge National Laboratory's Spallation Neutron Source (SNS) to detect CEvNS for the first time, and is developing it as a tool for searches for physics beyond the Standard Model, including Non-Standard Neutrino Interactions (NSIs), oscillations into sterile neutrinos, nuclear form factors, neutrino charge radii, and magnetic moments. The SNS combines neutrino energies that are ideally-suited for CEvNS detection with a time structure that enables powerful background reduction. The simultaneous deployment of multiple detectors with differing neutron numbers is critical for initial studies of this process. 

P-Type Point-Contact (PPC) germanium detectors are well-matched to the problem of detecting CEvNS recoils; they combine low energy thresholds, excellent energy resolution, a well-understood quenching factor, and low intrinsic backgrounds. The COHERENT Collaboration aims to deploy a 10kg array of on-hand PPC detectors at the SNS for an initial measurement of CEvNS in germanium; this will allow for a cost-effective measurement of CEvNS with an $N$ that is complementary to other existing or planned COHERENT detector subsystems with lower systematic uncertainties.  

The research program detailed in this proposal aims to:

  • Assess the internal backgrounds in PPC detectors housed in vendor cryostats, and modify as necessary to reduce internal backgrounds;
  • Design, fabricate and assemble a shielding package at the SNS that will allow detection of CEvNS at the SNS with a PPC array;
  • Deploy a fully-operational 10-kg array of PPC germanium detectors at the SNS using on-hand detectors and DAQ hardware procured with NC State startup funds;
  • Measure the SNS CEvNS recoil spectrum in germanium.   Use the measured recoil spectrum in a combined analysis with the other COHERENT detector subsystems to observe the N2 cross section dependence and constrain Non-Standard neutrino Interactions.

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