Sarri, G. and Schumaker, W. and Di Piazza, A. and Poder, K. and Cole, J. M. and Vargas, M. and Doria, D. and Kushel, S. and Dromey, B. and Grittani, G. and Gizzi, L. and Dieckmann, M. E. and Green, A. and Chvykov, V. and Maksimchuk, A. and Yanovsky, V. and He, Z. H. and Hou, B. X. and Nees, J. A. and Kar, S. and Najmudin, Z. and Thomas, A. G. R. and Keitel, C. H. and Krushelnick, K. and Zepf, M. (2013) Laser-driven generation of collimated ultra-relativistic positron beams. Plasma Physics and Controlled Fusion, 55 (12). ISSN 0741-3335
Full text not available from this repository.Abstract
We report on recent experimental results concerning the generation of collimated (divergence of the order of a few mrad) ultra-relativistic positron beams using a fully optical system. The positron beams are generated exploiting a quantum-electrodynamic cascade initiated by the propagation of a laser-accelerated, ultra-relativistic electron beam through high-Z solid targets. As long as the target thickness is comparable to or smaller than the radiation length of the material, the divergence of the escaping positron beam is of the order of the inverse of its Lorentz factor. For thicker solid targets the divergence is seen to gradually increase, due to the increased number of fundamental steps in the cascade, but it is still kept of the order of few tens of mrad, depending on the spectral components in the beam. This high degree of collimation will be fundamental for further injection into plasma-wakefield afterburners.