Ultra-bright γ -ray emission by using PW laser irradiating solid target obliquely

By using intense laser irradiating a micro plane target obliquely, an enhanced γ -ray source is generated. Due to the superposition of the incident and the reflected laser pulses, electron bunches with density of ∼300 n c are extracted and accelerated. When these electron bunches separate from the edge of the target that the laser is leaving, they co-propagate with the laser field and emit dense γ -rays simultaneously. Simulation results show that the emitted γ photons are 253 n c dense with an averaged energy of ∼12 MeV. The yield of γ photons is ∼7 × 10 12 , achieving a high brightness of ∼4 × 10 23 photons s − 1 mm − 2 mrad − 2 / 0.1 % BW . Influences of the laser intensity and the incident angle on the γ -rays emission are discussed. The γ -ray yield, the conversion efficiency from the laser to the γ -rays and the averaged γ -ray energy are increasing when irradiating a higher intensity laser. With the increasing of the incident angle, the peak photon density increases when the angle is smaller than 20° and then drops to a stable value, while the divergence decreases when the incident angle is smaller than ∼16° and then increases.