Compact Spectral Characterization of 5-500 MeV X-rays from the Texas Petawatt Laser-Driven Plasma Accelerator

TL;DR

This paper presents a compact, modular calorimeter system capable of single-shot spectral characterization of high-energy x-rays from laser plasma accelerators, enabling rapid and detailed spectral analysis.

Contribution

It introduces a novel, compact calorimeter and a fast reconstruction algorithm for spectral measurement of 5-500 MeV x-rays from laser-driven plasma accelerators.

Findings

Successfully reconstructs x-ray spectra in about 10 seconds.

Capable of measuring x-rays from a few MeV to over 100 MeV.

Demonstrates detailed spectral characterization of laser plasma generated x-rays.

Abstract

We reconstruct spectra of secondary x-rays generated from a 500 MeV - 2 GeV laser plasma electron accelerator. A compact (7.5 $\times$ 7.5 $\times$ 15 cm), modular x-ray calorimeter made of alternating layers of absorbing materials and imaging plates records the single-shot x-ray depth-energy distribution. X-rays range from few-MeV inverse Compton scattered x-rays to $\sim$100 MeV average bremsstrahlung energies and are characterized individually by the same calorimeter detector. Geant4 simulations of energy deposition from mono-energetic x-rays in the stack generate an energy-vs-depth response matrix for the given stack configuration. A fast, iterative reconstruction algorithm based on analytic models of inverse Compton scattering and bremsstrahlung photon energy distributions then unfolds x-ray spectra in $\sim10$ seconds.