Unfolding neutron spectrum with Markov Chain Monte Carlo at MIT research Reactor with He-3 Neutral Current Detectors

A. Leder*, A. J. Anderson, J. Billard, E. Figueroa-Feliciano, J. A. Formaggio, C. Hasselkus, E. Newman, K. Palladino, M. Phuthi, L. Winslow, L. Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


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.

Original languageEnglish (US)
Article numberP02004
JournalJournal of Instrumentation
Issue number2
StatePublished - Feb 2 2018


  • Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc)
  • Gaseous detectors
  • Neutrino detectors
  • Neutron detectors (cold, thermal, fast neutrons)

ASJC Scopus subject areas

  • Mathematical Physics
  • Instrumentation


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