Well, It took a little while - but it was a simple error on your part Please see the instructions (kind of old I admit but anyhow) in http://www.sdcc.bnl.gov/brahms/private/computing/gbrahms/geant_setup.htm l Having done this the code works fine, otherwise the magnetic field and the structures used to evaluate are in fact undefined. So please review what has been done before. The case now worked for me by moving the field setting a question for you: Where is the macro initrandom() Is it in you local version of gbr2c.f ? If so please check into CVS. Flemming Setting the magnetic fields. The magnitude of the magnetic fields are set by the user command SET_FIELD. There are 5 fields that can be set. For the forward spectrometer they can be set as follows. At present only the effective edge is implemented. The field boundary is given by at half the gap before the core such that the total length is the length of the core plus the gap size. The field is constant over this entire range. The effective edge can also be set to be just inside the magnetic gap by means of the GAP representation of the field. * set D1 = -8 KG D2 = -8KG set_FIELD D1 -8 edge set_FIELD D2 -8 edge set_field M0 6 GAP ... * The command FIELD .. is now obsolete and should be avoided. Due to the internal representations of the magnetic properties these commands are only effective following the geodef command which defines the GEANT geometry and also calculated auxiliary parameters. ------------------------------------------------------ Flemming Videbaek Physics Department Brookhaven National Laboratory tlf: 631-344-4106 fax 631-344-1334 e-mail: videbaek@bnl.gov ----- Original Message ----- From: "Djamel Ouerdane" <ouerdane@nbi.dk> To: "devlist" <brahms-dev-l@bnl.gov> Sent: Wednesday, April 17, 2002 10:19 AM Subject: Re: brag and T2 > Hi Flemming et al, > > I made a simple tree with geant tables that you can find in > ~ouerdane/fv (geantTree.root) on rcas with the corresponding kumac, > I also made a picture of the simulation that you can see here: > > http://www.nbi.dk/~ouerdane/geant.gif which clearly shows that some tracks > go straight. > > The vertex dist is gaussain (+/- 20 cm with sigma = 18 cm), the momentum > range is from 1 to 6 GeV (flat dist) > > Peter reproduced the same behaviour. All physics was off except the eloss. > > Djam > > -- > Djamel Ouerdane ------------------------------------------o > | Niels Bohr Institute | Home: | > | Blegdamsvej 17, DK-2100 Ø | Jagtvej 141 2D, | > | Fax: +45 35 32 50 16 | DK-2200 Copenhagen N | > | Tel: +45 35 32 52 69 | +45 35 86 19 74 | > | http://www.nbi.dk/~ouerdane | > | ouerdane@nbi.dk | > o---------------------------------------------------------o >
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