Light response of poly(ethylene 2,6-naphthalate) to neutrons

There is an increasing necessity for low background active materials as ton-scale, rare-event and cryogenic detectors are developed. Poly(ethylene-2,6-naphthalate) (PEN) has been considered for these applications because of its robust structural characteristics, and its scintillation light in the blue wavelength region. Radioluminescent properties of PEN have been measured to aid in the evaluation of this material. In this article we present a measurement of PEN's quenching factor using three different neutron sources; neutrons emitted from spontaneous fission in ²⁵²Cf, neutrons generated from a DD generator, and neutrons emitted from the ¹³C(α,n)¹⁶O and the ⁷Li(p,n)⁷Be nuclear reactions. The fission source used time-of-flight to determine the neutron energy, and the neutron energy from the nuclear reactions was defined using thin targets and reaction kinematics. The Birks’ factor and scintillation efficiency were found to be kB = 0.12 ± 0.01 mm MeV⁻¹ and S = 1.31 ± 0.09 MeV_eeMeV⁻¹ from a simultaneous analysis of the data obtained from the three different sources. With these parameters, it is possible to evaluate PEN as a viable material for large-scale, low background physics experiments.