id_misc_types

               Monte Carlo Event Misc. Distribution Codes
               ==========================================
 
The miscellaneous distribution code and parameters (MISC1_PARAM and MISC2_PARAM)
have values that depend on the type of particle being generated.
 
 
Miscellaneous Distribution Code
===============================
 
Currently this is only used for optical photons.  The codes are:-
 
    ID      Mnemonic     Description
    --      --------     -----------
 
    -n       none        Give this particle the same polarization as particle n
                         (particle n must have already been generated).
                         Same warning as for direction types
    10       IDMFIX      Generate all events with the same polarization.
    20       IDMRAN      Generate events with random polarizations.
    30       IDMCER      Generate events with polarization for Cerenkov photons
                         (NOTE: This only works with direction dist IDACONE)
   100       IDMPL       Generate events with polarizations taken from a MCPL bank
                         (see MCPL bank).

 
Notes:  All implemented.
 
For the different distributions there are different input parameters to be
stored in the MISC1_PARAM array q.v.
 
 
MISC1_PARAM Array (5 reals)
===========================
 
Currently this is only used for optical photons:-
 
 
 MISC Type   Param. #   Description
 ---------   --------   -----------
 
    10       1,2,3     Selected polarization vectors.
    20       none
    30       none      (Takes direction from IDACONE parameters)
   100       none
 
 
MISC2_PARAM Array (10 integers)
===============================
 
MISC2_PARAM entry 7 is very important, it controls the region which the
generated particle is assumed to be in.  See id_pos_types.html.
 
For optical photon showers words 1 to 6 and 8 are defined as follows:-
 
   Param. #   Description
   --------   -----------
 
     1        Number of photons to generate (max # of photons if running flat dist)
     2        Position.
     3        Direction.
     4        Energy.
     5        Time.
     6        Polarization (parameters in misc1_param).
     8        Poisson flag (= 0 fixed, = 1 Poisson, =2 Flat)
 
Entries 2 to 6 of this table allows the user to choose between 2 situations
independently for each of the quantities:-
 
1)  All photons have the same value.  Do this by setting the word to 1. In this
    case the first photon uses the standard distribution codes and parameters
    and the value that results is copied to all other photons.  So, by setting
    MISC2_PARAM(4) to 1 all photons will have the same energy.
 
2)  All photons get different values drawn from the same distribution.  Do this
    by setting the word to anything but 1.  Traditionally the value choosen
    is the value of the corresponding distribution code for the particle
    entry. For example if POS_TYPE for the particle entry is set to IDDPNT, 
    then MISC2_PARAM(2) should be also set to IDDPNT.

Entry 8 is a flag that determines if the number of photons to generate is
fixed, a mean that is generated with poisson statistics, or a flat
distribution.  Note: the generator ALWAYS generates at least one photon
i.e. it picks again if the sampled number is zero.  As of version 4_0288 entry
8 also allows for a flat distribution in number of photons from 1 photon to
the number specified in entry 1.