LASERQED

  LASERQED COMPTONBREITWHEELER[,] NPH=, [NY=,] [NXI=,] [NLAMBDA=,] [NQ=,] XIMAX=, LAMBDAMAX=, ETAMAX=, [PMAX=,] [ENHANCEFUNCTION=,] ;

COMPTONBREITWHEELER

   Specifies which parameters to define here.

Maximum number of laser photons to be absorbed in one process.
If <0, turn off Compton or Breit-Wheeler.
If =0, use linear Compton/Breit-Wheeler formula.
If , use nonlinear formula.
Note that and are different. The former is the limit of , which contains term only, where as the latter is a truncation of the exact series with respect to . When , none of the following variables are needed.
When , only longitudinal polarization is considered and the lasers must be circularly polarized by 100% (i.e., , ).

Number of abscissa for final energy. Default=20.

Number of abscissa for parameter. Default=20.

Number of abscissa for parameter. Applies to Compton case only. Default=20.

Number of abscissa for q parameter. Applies tp Breit-Wheeler case only. Default=50.

Maximum value of for the table.

Maximum value of for the table. Applies to Compton case only.

Maximum value of for the table. Applies to Breit-Wheeler case only.

Maximum probability of events per one time step. If the computed probability exceeds , CAIN of present version stops with a message.

Defines a function in order to enhance a part of spectrum.   It is defined as an expression containing Y as the final energy parameter (Y). Its value must be for Y. Generally speaking, Y close to 1 generates low energy charged particles. For example,
E NH=1+Step(Y-0.8)*(Y-0.8)*10
will enhance the events with Y>0.8 by a factor upto 3 (at Y=1).
In the program, the real spectrum function is multiplied by and, when an event is generated, the created particles are asigned a weight .
Note that slightly larger than 1 is useless (even harmful) because a small fraction of the parent particle will remain as a macro-particle, causing a waste of computing time. In the example above, exactly for Y<0.8.
This function is used only during the initialization by LASERQED command. Therefore, if the expression contains user-defined parameters, their values at the time of LASERQED command are used. Changing them afterwards will not affect the computation.

See Sec.5.7.3 and Appendix.A for more detail