Unfolding neutron spectrum with Markov Chain Monte Carlo at MIT research Reactor with He-3 Neutral Current Detectors [Measuring neutron spectrum at MIT research reactor utilizing He-3 Bonner Cylinder Approach with an unfolding analysis]

Journal Article · 01 February 2018 · Journal of Instrumentation

DOI: https://doi.org/10.1088/1748-0221/13/02/P02004 · OSTI ID:1407124

Leder, A.  ^[1]; Anderson, A. J.  ^[2]; Billard, J. ^[3]; Figueroa-Feliciano, E. ^[4]; Formaggio, J. A. ^[1]; Hasselkus, C. ^[5]; Newman, E. ^[1]; Palladino, K. ^[5]; Phuthi, M. ^[1]; Winslow, L. ^[1]; Zhang, L. ^[1]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2. Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Univ. of Chicago, Chicago, IL (United States)
3. Univ. Lyon (France)
4. Northwestern Univ., Evanston, IL (United States)
5. Univ. of Wisconsin, Madison, WI (United States)

Here, the Ricochet experiment seeks to measure Coherent (neutral-current) Elastic Neutrino-Nucleus Scattering (CEνNS) using dark-matter-style detectors with sub-keV thresholds placed near a neutrino source, such as the MIT (research) Reactor (MITR), which operates at 5.5 MW generating approximately 2.2 × 10¹⁸ ν/second in its core. Currently, Ricochet is characterizing the backgrounds at MITR, the main component of which comes in the form of neutrons emitted from the core simultaneous with the neutrino signal. To characterize this background, we wrapped Bonner cylinders around a ³₂He thermal neutron detector, whose data was then unfolded via a Markov Chain Monte Carlo (MCMC) to produce a neutron energy spectrum across several orders of magnitude. We discuss the resulting spectrum and its implications for deploying Ricochet at the MITR site as well as the feasibility of reducing this background level via the addition of polyethylene shielding around the detector setup.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1407124
• Alternate ID(s): OSTI ID: 22899939
• Report Number(s): FERMILAB-PUB--17-441-AE; arXiv:1710.00802; 1628106
• Journal Information: Journal of Instrumentation, Journal Name: Journal of Instrumentation Journal Issue: 02 Vol. 13; ISSN 1748-0221
• Publisher: Institute of Physics (IOP)Copyright Statement
• Country of Publication: United States
• Language: English