Neutrino-Argon Cross Section Measurements at Spallation Neutron Source
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### Physics: 2020.11.10

- Materials:
- Jason Newby's [talk at Neutrino 2020](https://indico.fnal.gov/event/43209/contributions/187864/attachments/129156/158575/2020Neutrino_COHERENT_Newby_final.pdf)
- Rebecca Rapp's [talk 2019](https://conference.sns.gov/event/171/attachments/258/1358/fpsts2019_rapp.pdf)
- Second target station of SNS [Snowmass 2021 LOI](http://www.snowmass21.org/docs/files/summaries/NF/SNOWMASS21-NF6_NF9-CF1_CF0-TF11_TF0-IF2_IF8_Kate_Scholberg-161.pdf)
- Opportunities for Neutrino Physics at the Spallation Neutron Source: A White Paper (last update in 2018): [arXiv: 1211.5199](https://arxiv.org/abs/1211.5199)
- Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) physics and impacts
- Non-Standard Interation (NSI): related ambiguity in DUNE mass ordering determination
- Beam-induced dark matter particles
- CEvNS has keV-scale visible energy (< 30 keV), and requires low-threshold detector
- Synergies on light detector R&D?

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### Conversation with Marcel Demarteau and Jason Newby@ORNL: 2020.11.10

- The largest systematic uncertainty of the COHERENT measurement is from neutrino fluxes.
- Neutrino flux monitor: heavy water, aiming to 2-3% precision, top priority and endorsed by HEP@DOE. $O(100k)
- Possible to have 1 ton LAr detector in Neutrino Alley
- Short term goal: use SNS as a neutrino test beam
- Long term goal: Second Target Station, larger detectors for neutrino physics
- ORNL has a reactor, which provides a continuous source of electron antineutrinos.
- ORNL works on LEGEND 1000, a 0vbb experiment.
- ORNL also has theorists calculating/simulating supernova neutrino fluxes and neutron star mergers.
- Challenges for neutrino cross section measurements: statistics
- COHERENT is planning a 1-ton LAr detector in Neutrino Alley.
- Focusing on CEvNS measurements
- Therefore the detector uses LAr scintillation light only; has light detectors, PMTs, only.
- Charge readout is not included in the baseline design.
- To possibly cope with the CC neutrino-Ar interactions, they may use dynamic ranges: high gain for CEvNS (keV) and low gain for CC neutrino-Ar (MeV).
- Want to switch to SiPMs for larger active volume.
- No fund for this detector now. (Oak Ridge funding by IF@HEP)
- Currently supported by a LAr LDRD and Indiana University by NSF.
- No R&D needed for the PMT design
- Inclusive CC neutrino-Ar cross section measurements are acheivable with the baseline design (light detectors only, 1t of LAr)
- Rex Taylor at Indiana University is leading CEvNS in Ar
- The physics with the Ar detector will be finished in half a year
- Nobody is leading the CC nu-Ar cross section effort
- There is room for 2 of identical 1-ton LAr detectors in Neutrino Alley
- A demonstrator of LArTPC in Neutrino Alley is welcome
- For CC neutrino-Ar cross section measurements, Jason suggests to approach to the COHERENT collaboration, expressing my interest, and see if it will be included in the collaboration (confirmed by the spoke, Kate), or we should create another one. In either case we will work closely with the COHERENT collaborators.
- For my proposal, in particular ECA, letters from ORNL (Marcel) and COHERENT are needed. In the letter it can be addressed that this proposal aims to have inclusive CC nu-Ar cross sections serving as a project shifting to the one using Second Target Station.
- Ask Kate again about when it is a good timing to apply for ECA on this topic: this year or next.

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