title: Gamma-to-electron magnetic spectrometer (GEMS): an energy-resolved γ-ray diagnostic for the National Ignition Facility.
abstract: The gamma-to-electron magnetic spectrometer, having better than 5% energy resolution, is proposed to resolve γ-rays in the range of E(o) ± 20% in single shot, where E(o) is the central energy and is tunable from 2 to 25 MeV. Gamma-rays from inertial confinement fusion implosions interact with a thin Compton converter (e.g., beryllium) located at approximately 300 cm from the target chamber center (TCC). Scattered electrons out of the Compton converter enter an electromagnet placed outside the NIF chamber (approximately 600 cm from TCC) where energy selection takes place. The electromagnet provides tunable E(o) over a broad range in a compact manner. Energy resolved electrons are measured by an array of quartz Cherenkov converters coupled to photomultipliers. Given 100 detectable electrons in the energy bins of interest, 3 × 10(14) minimum deuterium/tritium (DT) neutrons will be required to measure the 4.44 MeV (12)C γ-rays assuming 200 mg/cm(2) plastic ablator areal density and 3 × 10(15) minimum DT neutrons to measure the 16.75 MeV DT γ-ray line.
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. yhkim@lanl.gov
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.forename: H W
authors.initials: HW
authors.lastname: Herrmann
authors.forename: T J
authors.initials: TJ
authors.lastname: Hilsabeck
authors.forename: K
authors.initials: K
authors.lastname: Moy
authors.forename: W
authors.initials: W
authors.lastname: Stoeffl
authors.forename: J M
authors.initials: JM
authors.lastname: Mack
authors.forename: C S
authors.initials: CS
authors.lastname: Young
authors.forename: W
authors.initials: W
authors.lastname: Wu
authors.forename: D B
authors.initials: DB
authors.lastname: Barlow
authors.forename: J B
authors.initials: JB
authors.lastname: Schillig
authors.forename: J R
authors.initials: JR
authors.lastname: Sims
authors.forename: F E
authors.initials: FE
authors.lastname: Lopez
authors.forename: D
authors.initials: D
authors.lastname: Mares
authors.forename: J A
authors.initials: JA
authors.lastname: Oertel
authors.forename: A C
authors.initials: AC
authors.lastname: Hayes-Sterbenz