Public Abstract

DE-SC0022167: Design of a Cryogenic Scintillation Neutrino Detector at the Spallation Neutron Source

Award Status: Expired

Institution: University of South Dakota, Vermillion, SD
UEI: U9EDNSCHTBE7
DUNS: 929930808

Most Recent Award Date: 09/17/2022
Number of Support Periods: 1
PM: Crawford, Glen

Current Budget Period: 04/01/2021 - 11/30/2022
Current Project Period: 04/01/2021 - 11/30/2022
PI: Liu, Jing

Supplement Budget Period: N/A

Public Abstract

We propose to verify the feasibility of using a cryogenic scintillating crystal based neutrino detector at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory, for the detection of low-mass dark matter particles and non-standard neutrino interactions (NSIs), as part of the detector R&D effort of the COHERENT experiment. The main objectives are to verify that the high light yield of undoped CsI crystals measured above 13 keV at 77 K still holds down to the desired energy threshold, to measure nuclear quenching factor of undoped cryogenic CsI at the Triangle Universities Nuclear Laboratory, and to switch light sensors from photomultiplier tubes (PMTs) to silicon photomultiplier (SiPM) arrays. In 2017, the COHERENT collaboration detected neutrinos emitted from the SNS through a long-seeking physics process named coherent elastic neutrino-nucleus scatterings (CEvNS) using a 14 kg CsI(Na) detector. A PMT was used as the light sensor in that detector. A serious background limiting the detector sensitivity was the Cherenkov radiation emitted from the PMT quartz window by charged particles. The switch from PMTs to SiPM arrays is used to completely eliminate this background, since SiPM arrays do not have a quartz window. In order to reduce the high dark count rate of SiPMs at room temperature, they need to be cooled, by liquid nitrogen for convenience. The cryogenic operation calls for undoped CsI/NaI instead of doped ones, since the former at 77 Kelvin have about twice higher light yields than the latter at 300 Kelvin. Compared to the original COHERENT CsI(Na) detector, the combination of the high photon-detection efficiency of SiPMs and the high light yield of undoped crystals at 77 Kelvin, leads to at least an order of magnitude increase of the detectable CEvNS events, given a similar exposure. If successful, the proposed study will be followed by the design of a 10 kg prototype detector operating at the SNS. Its sensitivities to the proposed dark matter and NSI searches have been proven to be very competitive in two published scientific papers.

We propose to verify the feasibility of using a cryogenic scintillating crystal based neutrino detector at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory, for the detection of low-mass dark matter particles and non-standard neutrino interactions (NSIs), as part of the detector R&D effort of the COHERENT experiment. The main objectives are

to verify that the high light yield of undoped CsI crystals measured above 13 keV at 77 K still holds down to the desired energy threshold,
to measure nuclear quenching factor of undoped cryogenic CsI at the Triangle Universities Nuclear Laboratory, and
to switch light sensors from photomultiplier tubes (PMTs) to silicon photomultiplier (SiPM) arrays.

In 2017, the COHERENT collaboration detected neutrinos emitted from the SNS through a long-seeking physics process named coherent elastic neutrino-nucleus scatterings (CEvNS) using a 14 kg CsI(Na) detector. A PMT was used as the light sensor in that detector. A serious background limiting the detector sensitivity was the Cherenkov radiation emitted from the PMT quartz window by charged particles. The switch from PMTs to SiPM arrays is used to completely eliminate this background, since SiPM arrays do not have a quartz window. In order to reduce the high dark count rate of SiPMs at room temperature, they need to be cooled, by liquid nitrogen for convenience. The cryogenic operation calls for undoped CsI/NaI instead of doped ones, since the former at 77 Kelvin have about twice
higher light yields than the latter at 300 Kelvin. Compared to the original COHERENT CsI(Na) detector, the combination of the high photon-detection efficiency of SiPMs and the high light yield of undoped crystals at 77 Kelvin, leads to at least an order of magnitude increase of the detectable CEvNS events, given a similar exposure.

If successful, the proposed study will be followed by the design of a 10 kg prototype detector operating at the SNS. Its sensitivities to the proposed dark matter and NSI searches have been proven to be very competitive in two published scientific papers.