PPINT

  Incoherent particle-particle interaction such as incoherent pair creation   and bremsstrahlung. The following processes are included:

Breit-Wheeler

Bethe-Heitler

Landau-Lifshitz

All the processes except for Breit-Wheeler are cvalculated using the virtual photon approximation. The circular polarization effect of the initial photons is included in the Breit-Wheeler process but all other polarization effects are ignored.

[Specify virtual photon options] PPINT VIRTUALPHOTON[,] [LOCAL,] [FIELDSUPPRESSION,] [EMIN,] ;

LOCAL

Flag to adopt local virtual photon, i.e., to ignore the effects due to the finite transverse extent of virtual photons. Default is non-local.

FIELDSUPPRESSION

Flag to include the virtual-photon suppression effect due to strong external fields (normally, the beam-field by the on-coming beam). This can be effective when LOCAL is not specified. See section 3.4 of [6]. Default: does not include this effect.

EMIN

Minimum energy of final electron/positron energies in eV. Default is twice the rest mass of electron. = 1.022E6. This parameter is not directly related to virtual photons but included here because it is common to all the processes. The purpose of this parameter is to save computing time. The creation of pairs does not take too much computing time but to track extremely low-energy pairs in a strong beam field is very expensive. The worst ones are the pair particles having the sign of charge opposite to that of the on-coming beam because they are trapped in the strong field region. If you are not interested in them, you can eliminate them during the PUSH loop as
CLEAR BEAM, INCP, RIGHT, KIND=2;
CLEAR BEAM, INCP, LEFT, KIND=3;
if the right(left)-going beam is electron(positron).

[Specify individual processes] PPINT BWBHLLBREMSSTRAHLUNG[,] [RIGHT,] [LEFT,] [ENHANCE=,] ;

BW,BH,LL,BREMSSTRAHLUNG

Specify one of Breit-Wheeer, Bethe-Heitler, Landau-Lifshitz, and Bremsstrahlung interactions. If more than one of these are needed, apply PPINT command repeatedly. No default.

RIGHT,LEFT

Applies to Bethe-Heitler and Bremsstrahlung. The Bethe-Heitler process has two possible combinations, namely, (,e) and (e,). RIGHT/LEFT option specifies the photon is right-going or left-going or both. Default is both.
The Bremsstrahlung is treated as the interaction between real e and a virtual photon. Therefore, it also has two possible combinations. This operand specifies which beam is the real particle.

Event rate enhancement factor.   It is unity when the number of created macro-pairs is the same as the expected number of real pairs, i.e., the weight of the pair particle is . Default =0.1.

In using ABEL one had to define the minimum scattering angle and minimum transverse momentum. This was due to the ultra-relativistic approximation employed there. CAIN does not need these parameters.