Dispersion calibration for the National Ignition Facility electron–positron–proton spectrometers for intense laser matter interactions
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- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Max Planck Society, Garching (Germany). Max Planck Institute for Plasma Physics
- Univ. of California, San Francisco, CA (United States)
- Columbia Univ., New York, NY (United States)
- Univ. of Michigan, Ann Arbor, MI (United States). Center for Ultrafast Optical Science
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Univ. of Rochester, NY (United States). Lab. for Laser Energetics
Electron–positron pairs, produced in intense laser–solid interactions, are diagnosed using magnetic spectrometers with image plates, such as the National Ignition Facility Electron–Positron–Proton Spectrometers (EPPSs). Although modeling can help infer the quantitative value, the accuracy of the models needs to be verified to ensure measurement quality. The dispersion of low-energy electrons and positrons may be affected by fringe magnetic fields near the entrance of the EPPS. We have calibrated the EPPS with six electron beams from a Siemens Oncor linear accelerator (linac) ranging in energy from 2.7 MeV to 15.2 MeV as they enter the spectrometer. A Geant4 Tool for Particle Simulation Monte Carlo simulation was set up to match depth dose curves and lateral profiles measured in water at 100 cm source–surface distance. An accurate relationship was established between the bending magnet current setting and the energy of the electron beam at the exit window. The simulations and measurements were used to determine the energy distributions of the six electron beams at the EPPS slit. Furthermore, analysis of the scanned image plates together with the determined energy distribution arriving in the spectrometer provides improved dispersion curves for the EPPS.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program
- Grant/Contract Number:
- AC52-07NA27344; 20-LW-021
- OSTI ID:
- 1806410
- Alternate ID(s):
- OSTI ID: 1769447
- Report Number(s):
- LLNL-JRNL-817275; 1027215; TRN: US2213123
- Journal Information:
- Review of Scientific Instruments, Vol. 92, Issue 3; ISSN 0034-6748
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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