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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.
Next: PUSHENDPUSH
Up: Commands
Previous: LUMINOSITY
Toshiaki Tauchi
Thu Dec 3 17:27:26 JST 1998