1.
Phys Rev Lett
; 105(1): 015003, 2010 Jul 02.
Artigo
em Inglês
| MEDLINE
| ID: mdl-20867455
RESUMO
Detailed angle and energy resolved measurements of positrons ejected from the back of a gold target that was irradiated with an intense picosecond duration laser pulse reveal that the positrons are ejected in a collimated relativistic jet. The laser-positron energy conversion efficiency is â¼2×10{-4}. The jets have â¼20 degree angular divergence and the energy distributions are quasimonoenergetic with energy of 4 to 20 MeV and a beam temperature of â¼1 MeV. The sheath electric field on the surface of the target is shown to determine the positron energy. The positron angular and energy distribution is controlled by varying the sheath field, through the laser conditions and target geometry.