Response characterization for an EJ315 deuterated organic-liquid scintillation detector for neutron spectroscopy

• A time-of-flight measurement of neutron response for scintillation detectors is described.
• Light-output relations presented for deuterated EJ315 and hydrogen-based EJ309 scintillators.
• Measured neutron response matrices are presented for EJ315 and EJ309.
• The backscatter preference of n–d scattering is prominent in the response of the deuterated EJ315.

Organic liquid scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control applications. Deuterated liquids, such as EJ315, are attractive for spectroscopy applications because the backward-peaked n–d scattering results in enhanced coupling between incident neutron energy and resulting pulse height. This will likely allow better spectrum unfolding. In this work, we present a measured neutron response matrix for a three-by-two-in. cylindrical EJ315 detector, and compare to the hydrogen-based liquid EJ309 in an otherwise identical assembly. We also present measured light-output relations for both detectors. A continuous-spectrum neutron source, obtained with the bombardment of 11B with 5.5-MeV deuterons at the tandem Van de Graaff accelerator at the University of Notre Dame, was used for the measurement. Detected neutrons were sorted via time of flight into 100-keV energy groups, over the energy range from 0.5 to 15 MeV. The resulting response matrix represents a detailed characterization of pulse-height response to neutrons over that energy range. To the authors' knowledge, a measured response matrix and light-output relation for EJ315 have not been reported, and published characterizations of the similar NE230 are of less detail over this energy range. Matrix-condition analysis indicates an advantage for EJ315 over EJ309 in the number of independent parameters available in inversion procedures.