Assessment of Angular Spectral Distributions of Laser Accelerated Particles for Simulation of Radiation Dose Map in Target Normal Sheath Acceleration Regime of High Power Laser-Thin Solid Target Interaction—Comparison with Experiments

Andreea Groza,Elena Stancu,Dragana B Dreghici,Mihai Ganciu,Alecsandru Chirosca,Mihai Serbanescu,Bogdan Butoi

doi:10.3390/app10124390

Abstract

An adequate simulation model has been used for the calculation of angular and energy distributions of electrons, protons, and photons emitted during a high-power laser, 5-µm thick Ag target interaction. Their energy spectra and fluencies have been calculated between 0 and 360 degrees around the interaction point with a step angle of five degrees. Thus, the contribution of each ionizing species to the total fluency value has been established. Considering the geometry of the experimental set-up, a map of the radiation dose inside the target vacuum chamber has been simulated, using the Geant4 General Particle Source code, and further compared with the experimental one. Maximum values of the measured dose of the order of tens of mGy per laser shot have been obtained in the direction normal to the target at about 30 cm from the interaction point.

Highlights

We propose a simulation model to be used for the assessment of the radiation dose map in a target normal sheath acceleration (TNSA) regime for a high power laser-thin solid target interaction experiment
In the Groza’s et al paper [24], we reported a method for the assessment of the energy of the accelerated proton beams produced in high power laser-thin solid target experiments using a stack of CR-39 detectors
The results presented in this paper link the angular and energy distributions of electrons, protons, and photons calculated within 0–360◦, with an angular step of five degrees, to the radiation dose map

Summary

Introduction

High-intensity lasers have progressively been used in contemporary research for the study of matter under extreme conditions and to generate beams of accelerated particles [1,2,3,4,5,6].As result of the interaction of high-power laser pulses (I > 1019 W/cm , fs to ps pulse duration) with solid micrometer flat [1,2] or structured thin targets [2,6], by the target normal sheath acceleration (TNSA) mechanism, electron and proton beams with high directionality, small divergence, and energies up to tens of MeV [1,2,3,4,5,6] are generated.The TNSA regime involves complex physical phenomena and is usually considered to be the main rear surface ion acceleration mechanism. As result of the interaction of high-power laser pulses (I > 1019 W/cm , fs to ps pulse duration) with solid micrometer flat [1,2] or structured thin targets [2,6], by the target normal sheath acceleration (TNSA) mechanism, electron and proton beams with high directionality, small divergence, and energies up to tens of MeV [1,2,3,4,5,6] are generated. The subsequent arrival of the main laser pulse leads to the generation of hot electrons, as the pre-plasma electrons absorb a percentage of laser pulse energy. The further expansion of the electrons sheath into the vacuum determine a TV/m electric field, normal to the target surface. The impurities (water and organic molecules) adsorbed on the rear side of the target can be ionized in this strong electric field

Methods

Results

Conclusion