title: Development and Characterization of a High Sensitivity Segmented Fast Neutron Spectrometer (FaNS-2).
abstract: We present the development of a segmented fast neutron spectrometer (FaNS-2) based upon plastic scintillator and3He proportional counters. It was designed to measure both the flux and spectrum of fast neutrons in the energy range of few MeV to 1 GeV. FaNS-2 utilizes capture-gated spectroscopy to identify neutron events and reject backgrounds. Neutrons deposit energy in the plastic scintillator before capturing on a3He nucleus in the proportional counters. Segmentation improves neutron energy reconstruction while the large volume of scintillator increases sensitivity to low neutron fluxes. A main goal of its design is to study comparatively low neutron fluxes, such as cosmogenic neutrons at the Earth's surface, in an underground environment, or from low-activity neutron sources. In this paper, we present details of its design and construction as well as its characterization with a calibrated252Cf source and monoenergetic neutron fields of 2.5 MeV and 14 MeV. Detected monoenergetic neutron spectra are unfolded using a Singular Value Decomposition method, demonstrating a 5% energy resolution at 14 MeV. Finally, we discuss plans for measuring the surface and underground cosmogenic neutron spectra with FaNS-2.
authors.affiliation: Wright Laboratory, Yale University, New Haven, CT 06511 USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Langford
authors.affiliation: Department of Physics, University of Maryland, College Park, MD 20742 USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Beise
authors.affiliation: Department of Physics, University of Maryland, College Park, MD 20742 USA.
authors.forename: H
authors.initials: H
authors.lastname: Breuer
authors.affiliation: Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Heimbach
authors.affiliation: Department of Physics, University of Maryland, College Park, MD 20742 USA.
authors.forename: G
authors.initials: G
authors.lastname: Ji
authors.affiliation: Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Nico
keywords: Hybrid detectors; Neutron detectors; Particle identification methods; Spectrometers