FLUKA: SOURCE
Previous Index Next
SOURCE
invokes the use of a user-defined source routine SOURCE
See also BEAM, BEAMPOSit, POLARIZAti, SPECSOUR, USRICALL, USRGCALL
This option allows to input up to 18 double precision parameters
chosen by the user, to be passed to the user routine SOURCE. To
pass more than 6 parameters, two successive SOURCE cards are required.
First card:
WHAT(1..6)
: user parameters to be passed to the SOURCE routine as
a double precision subarray WHASOU(1)...WHASOU(6)
(via COMMON SOURCM, in the INCLUDE file of the same name)
SDUM
= any user dependent character string (not containing "&")
to be passed to the SOURCE routine as a character
variable SDUSOU (via COMMON CHSOCM, in INCLUDE file SOURCM)
Continuation card:
WHAT(1..6)
: user parameters to be passed to the SOURCE routine as
a double precision subarray WHASOU(7)...WHASOU(12)
SDUM
= "&" in any position in column 71 to 78 (or in the last
field if free format is used)
Default
(option SOURCE not given): subroutine SOURCE is not called
Notes:
1) In many simple cases, the primary particle properties can be defined
by just two input cards: BEAM and BEAMPOS. The two options define the
type of the particle, its energy/momentum (monoenergetic or simply
distributed) and its starting position and direction (also sampled
from a few simple distributions centred around the z-axis). A third
option, POLARIZAti, can be used to complete the description of the
primaries in case they are totally or partially polarised.
2) However, there are more complex situations where the type of primary
particles and their phase space coordinates must be sampled from
different types of distributions, read from files, or generated by a
rule decided by the user. To handle these cases, it is possible to
call a user routine SOURCE which can override totally or in part the
definitions given in input. The call is activated by option SOURCE.
A default version of the routine, which leaves any other input
definition unchanged, is present in the FLUKA library. Instructions on
how to write, compile and link SOURCE are given in 13}.
3) Even when overridden by SOURCE, the momentum or kinetic energy defined
by WHAT(1)
of option BEAM is meaningful, since it is taken as maximum
energy for several scoring facilities. Therefore, it is recommended to
input in any case a BEAM card with the maximum energy expected in the
current run.
4) The user has the possibility to write a flexible SOURCE routine which
can handle different cases without being recompiled and linked. The 12
WHASOU optional double precision parameters and the SDUSOU character
string can be combined to provide a multitude of possible options.
5) Initialisations (for instance reading data from files, or spectrum
normalisation needed for sampling) can be done in SOURCE itself, as
explained in 13}, or in two other user routines USRINI and USRGLO.
USRINI is called every time a card USRICALL is found in input (see 13}),
while USRGLO is called before any other initialisation made by FLUKA.
Note that more than one primary particle can be sampled in a same call
to SOURCE and loaded into stack for later transport. A further user
routine, USREIN (see 13}), which is called just after SOURCE and
before the sampled primary (or primaries) are transported, allows the
user to do an initialisation at the beginning of each event. An event
is defined as all the histories of primaries sampled in a single call
to SOURCE and of their descendants. Routine USREOU is called instead at
the end of each event.
6) In old versions of FLUKA, the call to SOURCE was requested by means of
a flag in card START. This feature has been discontinued.
Example 1:
SOURCE
Example 2:
SOURCE 12.58 1.0 -14. 0.987651 100. 365.FLAG18
SOURCE 999.2 &
Previous Index Next
