The role of nanosecond duration pre-pulse pedestal (Amplified Spontaneous Emission (ASE) pre-pulse) in the propagation of 45 fs, 4 TW Ti:Sapphire laser pulse through a helium gas jet target has been investigated. We observed that the pre-pulse pedestal of about 1 ns duration and intensity 3 × 1012 W/cm2 creates pre-formed plasma with optical guiding channel like structure in the gas-jet at density around 3 × 1019 cm−3. Guiding of the 45 fs laser pulse (IL = 3 × 1018 W/cm2) in the pre-formed plasma channel, over a distance much longer than the Rayleigh length was also observed. The guiding of the laser pulse resulted in the generation of high energy electron beam by laser wake-field acceleration of self-injected electrons. The accelerated electron beam was quasi-monoenergetic with peak energy up to 50 MeV, low divergence in the range of 3–6 mrad, and bunch charge up to 100 pC.
# sunnyb@rrcat.gov.in / † htkim@gist.ac.krWe report here a systematic quantitative study on generation and characteristics of an active muon source driven by the interaction of an electron beam within the energy range of 1 -10 GeV from laser wakefield acceleration (LWFA) with a tungsten target, using Monte Carlo simulations. The 10-GeV electron beam, achievable in near future, from LWFA using femtosecond multi-PW lasers is employed to drive the bright source of muon pairs in a compact setup. We show that a highly directional and intense source of short-pulsed GeV muon pairs ( - + ) having peak brightness 5x10 17 pairs/s/cm 2 /sr and sub-100-ps duration could be produced using a quasi-monoenergetic 10-fs, 10-GeV electron bunch with 1-mrad divergence and 100-pC charge. The muon pairs are emitted from a point-like source with welldefined position and timing, and the source has size and geometric emittance about 1 mm and 40 m, respectively. Such muon sources can greatly benefit applications in muon radiography, studies on anomalous dipole moment and rare decays of muons, neutrino oscillations, and an injector of a future compact muon collider.
The inner-shell radiation (K-α) and the ionic line radiation (He-α) from magnesium plasma, generated by the interaction of a 3 TW, 45 fs laser, have been studied simultaneously using an x-ray crystal spectrograph. The effect of the variation of the laser intensity and its offset from the best focus position has been studied. He-α and K-α x-ray yields are found to scale with the laser intensity as IL1.5 and IL0.6 respectively. The K-α x-ray conversion shows a maximum at the best focus and reduces symmetrically on either side of the best focus position, whereas the He-α conversion peaks when the target is placed before the focused laser beam. The angular distribution for the He-α as well as the K-α emissions shows a maximum in the forward direction and the intensity reduces with the increase in angle θ with respect to the target normal as cosα θ. The value of α is 0.7 and 3 for He-α and K-α respectively. The experimentally observed variation of the He-α line conversion for different laser parameters has been explained by considering the change in preformed plasma conditions, and the variation in the K-α emission has been explained by considering hot electron generation and their propagation in the bulk solid target. The plasma conditions prevalent during the emission of the x-ray spectrum were identified by comparing the experimental spectra with the synthetic spectra generated using the spectroscopic analysis code PrismSPECT. The results will be useful in designing laser-produced plasma x-ray line radiation sources of photon energy in the range of 1–2 keV, for its potential use as a probe pulse in x-ray backlighting, or time-resolved x-ray diffraction studies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.