Effect of ultrastrong magnetic fields on laser-produced gamma-ray flashes

Laser produced gamma-photons can make an important impact on applied and fundamental physics that require high gamma-photon yield and strong collimation. We propose the addition of a constant magnetic field to the laser-solid interaction to obtain the aforementioned desired gamma-photon properties. The gamma-ray flash spatial and spectral characteristics are obtained via quantum electrodynamic particle-in-cell simulations. When the constant magnetic field aligns with the laser magnetic field, then the gamma-ray emission is significantly enhanced. Moreover, the gamma-photon spatial distribution becomes collimated, approximately in the form of a disk.