Measurements of fuel and ablator ?R in Symmetry-Capsule implosions with the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility.

The Review of scientific instruments

PubMedID: 25430283

Gatu Johnson M, Frenje JA, Li CK, Séguin FH, Petrasso RD, Bionta RM, Casey DT, Caggiano JA, Hatarik R, Khater HY, Sayre DB, Knauer JP, Sangster TC, Herrmann HW, Kilkenny JD. Measurements of fuel and ablator ?R in Symmetry-Capsule implosions with the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility. Rev Sci Instrum. 2014;85(11):11E104.
The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility (NIF) measures the neutron spectrum in the energy range of 4-20 MeV. This paper describes MRS measurements of DT-fuel and CH-ablator ?R in DT gas-filled symmetry-capsule implosions at the NIF. DT-fuel ?R's of 80-140 mg/cm(2) and CH-ablator ?R's of 400-680 mg/cm(2) are inferred from MRS data. The measurements were facilitated by an improved correction of neutron-induced background in the low-energy part of the MRS spectrum. This work demonstrates the accurate utilization of the complete MRS-measured neutron spectrum for diagnosing NIF DT implosions.