Ultrashort megaelectronvolt positron beam generation based on laser-accelerated electrons

Abstract

Experimental generation of ultrashort MeV positron beams with high intensity and high density using a compact laser-driven setup is reported. A high-density gas jet is employed experimentally to generate MeV electrons with high charge; thus, a charge-neutralized MeV positron beam with high density is obtained during laser-accelerated electrons irradiating high-Z solid targets. It is a novel electron–positron source for the study of laboratory astrophysics. Meanwhile, the MeV positron beam is pulsed with an ultrashort duration of tens of femtoseconds and has a high peak intensity of 7.8 × 1021 s−1, thus allows specific studies of fast kinetics in millimeter-thick materials with a high time resolution and exhibits potential for applications in positron annihilation spectroscopy.

Dense GeV electron–positron pairs generated by lasers in near-critical-density plasmas

“…3c). This peak density is much higher than that reported in the both BW and BH experiments as well as relevant simulations8910111213141516192728293031. The total positron yield is as high as 1.05 × 10 11 , which is more than an order of magnitude larger than that in laser foil interactions27, although our laser intensity is lower by more than an order of magnitude.…”

“…Assuming equal beams and Gaussian profiles in all dimensions with a beam size, conservatively, for example, , it is estimated that the peak geometric luminosity of such a 4−5 GeV centre-of-mass (CM) e − e + collider is as high as 10 33  cm −2  s −1 , which is comparable to the state-of-art colliders worldwide3. One may even scale the proposed scheme to TeV CM e − e + collision, which is a unique feature of our scheme as compared with the others8910111213141516262728293031.…”

“…Later, they collide with the focused counter-propagating laser waves from the opposite directions, initiating the multi-photon BW process. Here, the BH process is intrinsically inefficient because of the low-Z NCD plasmas and the thin Al cone thickness891011121314. Therefore, this process can be reasonably ignored in our simulations.…”

“…So far, the major way of producing positrons with lasers in experiments relies upon the BH process, which is based on the decay of bremsstrahlung γ-rays from electrons in high-Z targets. It is shown that energetic positrons could be obtained by direct laser–solid interactions8910 or by laser-driven electrons colliding with solid targets11121314. However, the positrons obtained have a low density of ∼10 16−17  cm −3 with a laser energy conversion efficiency to positrons around ∼0.02% only1516.…”

An Analysis on the Sign of Gravity of Antimatter

“…In early of 2016, Xu et al [17] presented a method of experimental generation of ultrashort MeV electron and positron beams with high intensity and high density using a setup in which a compact laser beam above an argon gas jet emitted from a supersonic conical nozzle to produce electrons which are directed onto a high-Z solid target behind the gas jet to generate electron-positron pairs. This means high energy γ ray photon can transfer into some kind of matter and antimatter, so the follow formula can be gained.…”