CERN Program Library Long Writeup W5013 - CERNLIB ...

Geant 3.16 GEANT User’s Guide CONS310
Origin : R.Brun, G.N.Patrick Submitted: 23.01.84
Revision : Revised: 19.10.94
Documentation :
Branching Ratios and Particle Decay Modes
CALL GSDK
(IPART,BRATIO,MODE)
IPART (INTEGER) GEANT particle number;
BRATIO (REAL) array of branching ratios in %, maximum 6;
MODE (INTEGER) array of partial decay modes.
GSDK stores the branching ratios and partial decay modes for two and three body particle decays into the
data structure JPART. The decay modes should be coded into the array MODE such that:
where:
MODE(I) = 10 4 N3 + 10 2 N2 + N1 for I=1,···,6
N1 particle number for decay product 1;
N2 particle number for decay product 2;
N3 particle number for decay product 3 (if any).
It is important to note the following:
• prior to calling GSDK, all parent and secondary particles should have been defined by GSPART;
• if less than six decay modes are defined the remaining elements of BRATIO and MODE must be set to
zero.
For a given particle, IPART, the decay parameters are stored into the JPART data structure as follows:
JPA
JDK1
JDK2
BR(I)
MODE(I)
= LQ(JPART-IPART) pointer to the bank containing the information on the particle IPART;
= LQ(JPA-1) pointer to branching ratios bank;
= LQ(JPA-2) pointer to decay modes bank;
= Q(JDK1+I) I th branching ratio;
= IQ(JDK2+I) I th decay mode, where I=1,···,6.
When a particle decays during tracking, the routine GDECAY is called. If branching ratios and modes have
been stored by GSDK, then GDECAY generates the decay products in the 2- or 3-body phase space. If no
branching ratios have been defined by GSDK, the user routine GUDCAY is called, where the user can code
special decay modes and branching ratios. All data taken from Aguilar Benitez [4].
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