Acceleration of a trailing positron bunch in a plasma wakefield accelerator

作者：Doche, A.^*; Beekman, C.; Corde, S.^*; Allen, J. M.; Clarke, C. I.; Frederico, J.; Gessner, S. J.; Green, S. Z.; Hogan, M. J.; O'Shea, B.; Yakimenko, V.; An, W.; Clayton, C. E.; Joshi, C.; Marsh, K. A.; Mori, W. B.; Vafaei-Najafabadi, N.; Litos, M. D.; Adli, E.; Lindstrom, C. A.; Lu, W.

来源：Scientific Reports, 2017, 7(1): 14180.

DOI：10.1038/s41598-017-14524-4

• ELECTRON-BEAM

High gradients of energy gain and high energy efficiency are necessary parameters for compact, cost-efficient and high-energy particle colliders. Plasma Wakefield Accelerators (PWFA) offer both, making them attractive candidates for next-generation colliders. In these devices, a charge-density plasma wave is excited by an ultra-relativistic bunch of charged particles (the drive bunch). The energy in the wave can be extracted by a second bunch (the trailing bunch), as this bunch propagates in the wake of the drive bunch. While a trailing electron bunch was accelerated in a plasma with more than a gigaelectronvolt of energy gain, accelerating a trailing positron bunch in a plasma is much more challenging as the plasma response can be asymmetric for positrons and electrons. We report the demonstration of the energy gain by a distinct trailing positron bunch in a plasma wakefield accelerator, spanning nonlinear to quasi-linear regimes, and unveil the beam loading process underlying the accelerator energy efficiency. A positron bunch is used to drive the plasma wake in the experiment, though the quasi-linear wake structure could as easily be formed by an electron bunch or a laser driver. The results thus mark the first acceleration of a distinct positron bunch in plasma-based particle accelerators.

• 出版日期2017-10-27
• 单位清华大学