Bound-freee+e−pair creation with a linearly polarized laser field and a nuclear field

Abstract

The process of bound-free pair production of electrons and positrons in combined laser and Coulomb fields is investigated. It is assumed that an ion collides at relativistic speed with an intense x-ray laser beam of linear polarization. The process proceeds nonlinearly due to simultaneous absorption of a few laser photons. The capture of the electron into the ground state and the L-shell is considered. The scaling of the total rate, the angular distributions of the emitted positrons and a comparison to the competing free-free channel are surveyed. Numerical results of pair production rates for parameters for the planned x-ray free electron lasers at DESY and SLAC are presented. We find that pair production with these laser facilities can become observable in the near future.

Suppression of pair creation due to a steady magnetic field

“…Theoretical calculations were based on a laser-dressed quantum electrodynamics [17]. Theoretical predictions were also made for the pair creation that involves the nucleus in the laser fields [18][19][20][21][22][23][24]. The creation process triggered solely by a laser has the virtue of being free of any nuclear processes and can be studied more unambiguously on the theoretical level.…”

Polarization effects in bound-free pair production

“…Therefore, only the combination µ f = +1/2 and m s = +1/2 can compensate the helicity λ = +1, see Eq. (15). However as we already mentioned above, m s is the projection of the positron spin on the direction of the incident light which is related to the helicity as m s = m s = +1/2 for θ + = 0 • and m s = − m s = −1/2 for θ + = 180 • .…”

“…In contrast, for larger angles θ + the degree of polarization decreases and reaches the value P pos (θ + ) = −1 for θ + = 180 • ; the effect which can be expected from Eq. (15). The behaviour of P pos (θ + ) between the two ultimate angles θ + = 0 • and θ + = 180 • strongly depends on the positron energy and charge of the target ion.…”

“…A large number of theoretical studies of photo-induced bound-free pair production has been performed during the last couple of decades [11][12][13][14][15][16]. Most of these studies have been focused on the total and angle-differential cross sections while much less attention has been paid to the polarization of the positrons and residual hydrogenlike ions.…”

Phase effects in laser-induced electron-positron pair creation

“…. , 16. Each of the calculated values was obtained as the average of more than 10 9 sample points in each Monte Carlo run.…”