Generation of bright collimated vortex \(\gamma\)-ray via laser driven cone-fan target

• Published in: arXiv.org 2022-08
• Main Authors: Cui-Wen, Zhang, Mamat-Ali Bake, Xiao, Hong, Hai-Bo Sang, Bai-Song, Xie
• Format: Article
• Language: English
• Subjects: Angular momentum; Circular polarization; Electron beams; Electrons; Energy conversion efficiency; Gamma rays; Laser modes; Lasers; Photons; Simulation; Vortices
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2208.11918

We use numerical simulations to demonstrate that a source of bright collimated vortex \(\gamma\)-ray with large orbital angular momentum can be achieved by irradiating a circularly polarized laser with an intensity about \(10^{22}\rm{W/{cm^2}}\) on a cone-fan target. In the studied setup, electron beam of energy of hundreds of MeV and vortex laser pulse are formed. And furthermore a high quality vortex \(\gamma\)-ray is yielded with small divergence of \(5^{\circ}\) and high peak brilliance \(\sim5\times10^{22}\) photons \({\rm\cdot s^{-1} \cdot mm^{-2} \cdot mrad^{-2}}\) \(0.1\%\mathrm{BW}\) at \(10\mathrm{MeV}\). A considerable fraction of angular momentum of laser is converted to electron beam and vortex \(\gamma\)-ray, which are roughly \(27.8\%\) and \(3\%\), respectively. And the conversion efficiency of energy from laser to electron beam and vortex \(\gamma\)-ray are around \(41\%\) and \(3.8\%\). Moreover, comparative simulations for different right radius of cone reveal that there exists an optimal size that makes the highest angular momentum of \(\gamma\)-ray photons to be around \(2.8\times10^6\hbar\). The comparative simulations for different laser modes exhibit that it is more appropriate to choose the circularly polarized laser to generate vortex \(\gamma\)-ray than the Laguerre-Gaussian one.