COHERENT at the Spallation Neutron Source Barbeau, P.S; Efremenko, Yu; Scholberg, K
Annual review of nuclear and particle science,
09/2023, Letnik:
73, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory provides an intense, high-quality source of neutrinos from pion decay at rest. This source was recently used for the first ...measurements of coherent elastic neutrino-nucleus scattering (CEvNS) by the COHERENT Collaboration, which resulted in new constraints of physics beyond the Standard Model. The SNS neutrino source will enable further CEvNS measurements, exploration of inelastic neutrino-nucleus interactions of particular relevance for understanding supernova neutrinos, and searches for accelerator-produced sub-GeV dark matter. Taking advantage of this unique facility, COHERENT's suite of detectors in Neutrino Alley at the SNS is accumulating more data to address a broad physics program at the intersection of particle physics, nuclear physics, and astrophysics. This review describes COHERENT's first two CEvNS measurements, their interpretation, and the potential of a future physics program at the SNS.
There is a global trend to increase the light yield of CsI scintillators used in neutrino and dark matter detection by operating undoped crystals at cryogenic temperatures. However, high light yield ...alone is not sufficient to guarantee a low-energy threshold. The response of undoped crystals to nuclear recoils at cryogenic temperatures is equally important. A liquid nitrogen-based cryostat was developed to measure the nuclear quenching factor of a small undoped CsI crystal using monoenergetic neutron beams at the Triangle Universities Nuclear Laboratory (TUNL). To minimize neutron scattering, high-Z materials were reduced around the crystal. The structure and performance of the cryostat are described in detail. Using this cryostat, a system light yield of 33.4±2.0 photoelectrons per keV electron-equivalent (PE/keVee) was observed at 5.9 keVee, enabling the measurement of nuclear quenching factors at very low energies. The results of the quenching factor measurement will be reported in a subsequent paper.
Non-negligible negative overshoot was observed in the tails of the observed light pulses. The origin of this issue and the correction procedure are described in detail. This information may be useful for others who encounter similar technical challenges.
A core-collapse supernova will emit a neutrino burst that can be detected on Earth. If the neutrinos travel through the Earth before reaching the detector they oscillate via interaction with Earth's ...matter, yielding oscillations in the neutrino energy spectrum. The frequency of these oscillations in energy is correlated with the pathlength traveled in the Earth and therefore contains information on the supernova location. For this technique to be useful for pointing, good energy resolution, well-known oscillation parameters and high statistics are required. This method is inferior to pointing with elastic scattering in a water Cherenkov detector but could be applied for scintillator-type detectors which have better energy resolution but weak intrinsic pointing capabilities. By the time a nearby supernova happens the requirements might well be fulfilled, and if no water Cherenkov detector is running at that time it may provide the only possibility to gain directional information. The pointing quality can be further improved by the combination of measurements from multiple detectors and also by taking relative timing into account.
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