The coincidence counting technique for orders of magnitude background reduction in data obtained with the magnetic recoil spectrometer at OMEGA and the NIF

D T Casey; J A Frenje; F H Séguin; C K Li; M J Rosenberg; H Rinderknecht; M J-E Manuel; M Gatu Johnson; J C Schaeffer; R Frankel; N Sinenian; R A Childs; R D Petrasso; V Yu Glebov; T C Sangster; M Burke; S Roberts

doi:10.1063/1.3605483

The coincidence counting technique for orders of magnitude background reduction in data obtained with the magnetic recoil spectrometer at OMEGA and the NIF

Rev Sci Instrum. 2011 Jul;82(7):073502. doi: 10.1063/1.3605483.

Authors

D T Casey¹, J A Frenje, F H Séguin, C K Li, M J Rosenberg, H Rinderknecht, M J-E Manuel, M Gatu Johnson, J C Schaeffer, R Frankel, N Sinenian, R A Childs, R D Petrasso, V Yu Glebov, T C Sangster, M Burke, S Roberts

Affiliation

¹ Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139, USA.

PMID: 21806180
DOI: 10.1063/1.3605483

Abstract

A magnetic recoil spectrometer (MRS) has been built and successfully used at OMEGA for measurements of down-scattered neutrons (DS-n), from which an areal density in both warm-capsule and cryogenic-DT implosions have been inferred. Another MRS is currently being commissioned on the National Ignition Facility (NIF) for diagnosing low-yield tritium-hydrogen-deuterium implosions and high-yield DT implosions. As CR-39 detectors are used in the MRS, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). The coincidence counting technique was developed to reduce these types of background tracks to the required level for the DS-n measurements at OMEGA and the NIF. Using this technique, it has been demonstrated that the number of background tracks is reduced by a couple of orders of magnitude, which exceeds the requirement for the DS-n measurements at both facilities.