# Photon 2015

15-19 June 2015
Asia/Novosibirsk timezone

## Photon spectrum and polarization for high conversion efficiency in Compton backscattering process

19 Jun 2015, 11:05
15m
Photon collider prospects, new acceleration techniques and future accelerators

### Speaker

Prof. Alexander Potylitsyn (National Research Tomsk Polytechnic University, National Research Nuclear University “MEPhI”)

### Description

The paper [1] reviewed the principles of creation of high-energy $\gamma\gamma$ collider. However, after the discovery of Higgs boson, the authors of paper [2] proposed the concept of the so-called low-energy $\gamma\gamma$ collider (for which the required energy of the electrons does not exceed 80 $MeV$, if the energy of the laser photons is equal to 3.5 $eV$) . In both cases it is necessary to use high power lasers ($10^{18}$ $W/cm^2$) to obtain a desired luminosity. The density of photons in a laser flash is so great that the nonlinear interactions and the possibility of multiple scattering of electrons passing through such “light target” should be taken into account when calculating electron-photon collisions. For such powerful lasers, the conversion coefficient - the ratio of the number of scattered photons to the number of initial electrons [1] - in this case may exceed unity. Since the scattering of laser photons on electrons of the incident beam is a stochastic process, the conversion coefficient is nothing more than the average number of emitted photons $\bar{k}$ [3]. Multiple scattering and substantial change in the energy (and in the cross section) of the electrons along the trajectory in the laser pulse will lead to a deviation of collision statistics from the Poisson law. To simulate multiple scattering of electrons in the light target, we developed Monte-Carlo code which takes into account the nonlinearity of the Compton scattering including spin-flip processes which affect the polarization characteristics of the final particles. The results of calculation of the spectra and polarization characteristics of electrons and photons are presented. Contribution of the electron trajectories with the number of collisions $k \ge 2$ results in substantial enrichment of the resulting spectrum by "soft" photons, which leads to some difference in calculated spectrum from the one obtained by CAIN [4]. [1] V. Telnov, NIMA 355 (1995) 3-18 [2] S.A. Bogasz, J. Ellis, L. Lusito et al., arXiv:1208.2827 [3] A.P. Potylitsyn, A.M. Kolchuzhkin, EPL, 100(2012) 24006 [4] P. Chen, G. Horton-Smith, T. Ohgaki, A. W. Weidemann and K. Yokoya, Nucl. Instrum.Meth. A355, 107 (1995)

### Primary author

Prof. Alexander Potylitsyn (National Research Tomsk Polytechnic University, National Research Nuclear University “MEPhI”)

### Co-authors

Prof. Anatoly Kolchuzhkin (Moscow state Technological Universityv) Prof. Michael Strikhanov (National Research Nuclear University “MEPhI”) Sergey Strokov (Tomsk Polytechnic University)

 Slides