C$^{7}$LYC: A New Scintillator for Fast Neutron Spectroscopy

Abstract

The scintillator Cs 2 LiYCl 6 (CLYC) has emerged as a versatile detector for both gammas and neutrons, with excellent pulse shape discrimination. Originally developed as a thermal neutron counter, the discovery of its unexpected and unprecedented ∼ 10% pulse height resolution for fast neutrons in the few MeV range has prompted studies to benchmark its use in low-energy nuclear science and applications. Since the typical long time-of-flight arms are not needed for achieving good energy resolution, geometrical efficiency can be enhanced by positioning the detectors much closer to the target. We have constructed a 16-element array of 1" × 1" 7 Li-enriched C 7 LYC, to eliminate the dominant peak in the spectrum from thermal neutron capture on 6 Li, leaving the energy region above 3 MeV with a clean baseline for fast neutron spectroscopy. We have also procured the first ever 3" × 3" C 7 LYC crystal. Test experiments under way with C 7 LYC include elastic and inelastic neutron scattering cross sections at Los Alamos with a pulsed white neutron source, efficiency measurements using mono-energetic neutron beams up to a few MeV at UMass Lowell, and fission neutron measurements with GRETINA and CHICO detector arrays at Argonne. Beta-delayed neutron spectroscopy experiments have also been initiated at the CARIBU and NSCL facilities, to evaluate C 7 LYC as a possible candidate for auxiliary scintillator arrays for stopped beam physics at the next generation rare isotope accelerators.

Gravitational waves from isolated neutron stars: Mass dependence of r -mode instability

“…The theoretical estimate for value of the NSE at saturation density E sym (ρ 0 )=30.71±0. 26 MeV obtained from the present calculations (DDM3Y) is reasonably close to the value of S v =30.048 ±0.004 MeV extracted [43] from the measured atomic mass excesses of 2228 nuclei. The value of NSE at ρ 0 remains mostly the same which is 30.03±0.…”

“…Our present result (DDM3Y) of 30.71±0. 26 MeV is reasonably close to that obtained using Skyrme interaction SkMP (29.9 MeV) [47], Av18+δv+UIX * variational calculation (30.1 MeV) [41].…”

“…The value of NSE at ρ 0 remains mostly the same which is 30.03±0. 26 MeV if one uses the mathemat- [44][45][46] appears well established empirically. The different parameterizations of RMF models, which fit observables of isospin symmetric nuclei nicely, steers to a comparatively wide range of predictions of 24-40 MeV for E sym (ρ 0 ) theoretically.…”

“…Obviously, the constants C and β determined by this methodology depend upon ǫ 0 , ρ 0 , the index n of the density dependent part and through the volume integral J 0 v00 , on the strengths of the M3Y interaction . The calculations have been carried out by using the values of saturation density ρ 0 = 0.1533 fm −3 [25] and saturation energy per nucleon ǫ 0 = −15.26 MeV [26] for the SNM. ǫ 0 is the co-efficient a v of the volume term of Bethe-Weizsäcker mass formula, calculated by fitting the recent experimental and estimated Audi-Wapstra-Thibault atomic mass excesses [27].…”