Calibrating the Response of Radiochromic Film to MeV Electrons for High-Energy-Density Plasma Diagnostics*

Radiochromic film (RCF) is a common diagnostic tool for short-pulse laser–plasma experiments due to its robustness and ease of use. At the Laboratory for Laser Energetics, RCF is typically used to diagnose proton images and spectra. Published literature indicates that the response of RCF has been thoroughly tested with high-energy protons, but few calibrations have been done with relativistic electrons in the MeV range. We present calibrations of three types of RCF based on known doses of ~23-MeV electrons supplied by the Idaho Accelerator Center and compare experimental data to particle–matter interaction simulations using Geant4. This calibration supports the development of new high-dose diagnostics to record relativistic electron flux using RCF, such as a large solid-angle electron spectral imager. We present results from recent OMEGA EP experiments and show that calibrated RCF-based diagnostics offer an improved measurement of relativistic electron fluences greater than 109 e-/cm2.