Spectral and spatial characterisation of laser-driven positron beams

G Sarri,D Symes,J Warwick,G M Samarin,K Krushelnick,K Poder,T Dzelzainis,W Schumaker,M Zepf,Z Najmudin,A G R Thomas,L Romagnani,D Doria,S Kuschel,S P D Mangles,J Cole,M Yeung

doi:10.1088/0741-3335/59/1/014015

Abstract

The generation of high-quality relativistic positron beams is a central area of research in experimental physics, due to their potential relevance in a wide range of scientific and engineering areas, ranging from fundamental science to practical applications. There is now growing interest in developing hybrid machines that will combine plasma-based acceleration techniques with more conventional radio-frequency accelerators, in order to minimise the size and cost of these machines. Here we report on recent experiments on laser-driven generation of high-quality positron beams using a relatively low energy and potentially table-top laser system. The results obtained indicate that current technology allows to create, in a compact setup, positron beams suitable for injection in radio-frequency accelerators.

Highlights

The generation of high-quality positron beams is a central area of research in experimental physics, due to their direct application in a wide range of physical subjects, including nuclear physics, particle physics, astrophysics, and material science
The geometrical emittance at 500 MeV of the positron beam generated in the present experiment can be estimated to be ≈ 0.3 π mm mrad
We report on experimental results focussed on spatially and spectrally characterising ultra-relativistic positron beams generated in a fully laser-driven setup

Summary

Introduction

The generation of high-quality positron beams is a central area of research in experimental physics, due to their direct application in a wide range of physical subjects, including nuclear physics, particle physics, astrophysics, and material science. The simplest way of generating positrons relies on the electromagnetic cascade initiated by an ultrarelativistic beam (mainly of electrons or photons) as it prop agates through a high-Z solid target. Generation of a high-energy photon following bremsstrahlung of the electron (positron) in the field of a nucleus [1], and 2. As a rule of thumb, one can approximate each step of the cascade to occur within one radiation length of the material that, in the ultra-relativistic approximation, can be expressed as [4]: LRAD ≈ 4α(Zα)12nλCL0 (1)

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Results

Discussion

Conclusion