Ultra-intense gamma-rays created using the Texas Petawatt Laser

High e+/e− Ratio Dense Pair Creation with 1021W.cm−2 Laser Irradiating Solid Targets

“…For these targets the observed positron yields were ~3 × 10 10 /str. Integrating over an emission cone of 25 o (~laser incident angle, see also 3 25 29 ), we conservatively estimate a total positron yield of N + ~1.8 × 10 10 for 100 J of laser energy. Detailed GEANT4 simulations 25 show that in this case the emerging positrons are concentrated in a pill box of diameter D ~ 0.4 mm and thickness cΔt ~ 90 μm, where Δt =3 00 fs is the pulse duration of the emerging positrons.…”

Pair creation in collision ofγ-ray beams produced with high-intensity lasers

“…However, the proposed scheme cannot be operated with multiple laser shots, and it is prone to a high noise level due to the presence of a significant mass of heavy material. Moreover, the authors of a recent study of the Bremsstrahlung process on a petawatt laser facility with the intensity close to 10 21 W/cm 2 [23] reported a photon spectrum with a relatively low effective temperature of less than 10 MeV and a cut-off energy below 100 MeV. The softening of the photon spectrum is explained by an efficient creation of secondary electrons in the gold target.…”

Explosive Nucleosynthesis Study Using Laser Driven γ-ray Pulses

“…Because the neutrino-nucleus interaction is extremely weak, the neutrino process alone can play a significant role in the syntheses of isotopes which are bypassed by other major processes such as r, s, and γ processes. The neutrino process in supernova explosions was proposed as the astrophysical origin of rare isotopes such as 7 Li, 11 B, 19 F, 138 La, and 180 Ta [16,17]. Among elements heavier than iron, only two isotopes of 138 La and 180 Ta were known as the ν isotopes.…”

“…A method to directly measure the stellar reaction rate has been used for the study of the s process, in which neutron beams of stellar continuous energies at kT = 25-30 keV were generated by the 7 Li(p, n) reaction with proton beams provided from accelerators [22,23]. The thickness of 7 Li targets and the scattered angles of neutrons have been tuned to obtain the neutron beam with the quasi-stellar energy spectrum. The 3 H(p, n) and 18 O(p, n) reactions are also used for kT = 52 keV [24] and 5 keV [25], respectively.…”

“…Photons in the MeV energy region play an important role in explosive nucleosyntheses in novae and supernovae such as γ process and neutrino-induced reactions in supernova explosions (ν process). Continuous energy γ-rays have been generated using high peak power lasers, although their measurements have been a technical challenge (for example, see [7][8][9]). In this paper, we propose nuclear experiments using laser-driven γ-ray pulses to simulate stellar nuclear photoreactions.…”