CERN Program Library Long Writeup W5013 - CERNLIB ...

Geant 3.16 GEANT User’s Guide HITS510
Origin : W.Mitaroff Submitted: 21.02.85
Revision : Revised: 19.12.93
Documentation :
Digitisation for drift chambers
CALL GCDRIF
(RADD,ZMIN,ZMAX,DETREP,HITREP,IOUT*)
RADD
ZMIN
ZMAX
DETREP
HITREP
IOUT
(REAL) radius of cylindrical chamber in cm;
(REAL) z of lower end of cylindrical chamber;
(REAL) z of upper end of cylindrical chamber;
(REAL) array of 8 with detector description:
1 number of wires;
2 wire spacing in φ (radians);
3 cosine of wire angle with respect to the z axis;
4 sine of wire angle with respect to the z axis (signed like dφ/dz);
5 dφ/dz along wire;
6 φ of point with z =0on wire 1;
7 drift velocity (cm nsec −1 );
8 if > 0 user routine GUDTIM will be called to calculate drift time;
(REAL) array of 4 describing the track:
1 φ coordinate of intersection;
2 z coordinate of intersection;
3 dφ/dr;
4 dz/dr;
(INTEGER) array of 4 with digitisation information:
1 wire number (1...NWI with increasing phi), -1 if DETREP parameters are inconsistent;
2 drift time in nsec, > 0 if φ(hit) >φ(wire);
3 digitised current division information (relative position of charge along wire, per mille);
4 amount of charge deposited onto wire.
Digitisation routine for a cylindrical drift chamber.
Knowing the position Z of the deposit of charge we can calculate
ICD = L Z − Z l
Z u − Z l
where L = 1000 in the program. This is the information stored into IOUT(3).
CALL GCDERR
(ICD*,ERP,ERS)
ICD
ERP
(INTEGER) digitised current division information (≤ ICD ≤ 1000), overwritten on output with
the modified value taking into account the errors;
(REAL) variance of Gaussian pedestal errors on the measured pulse heights relative to the sum
of the pulse heights;
173 HITS510 – 1