The user tools

The geometry through which the particles are transported is defined by the user via a set of calls to subroutines of the GEANT package.

The user can define a volume through a call to the subroutine:

GSVOLU

define ( instantiate) a volume by giving a NAME and the actual parameters to a shape; the position of the volume inside the bank JVOLUM is returned. If any of the parameters which express a length is negative, GEANT will assign to this parameter at tracking time the maximum value allowed, without protruding out of the mother which contains the particle transported.

A shape can be instantiated into a volume also without actual parameters. These will then be supplied when positioning each copy of the volume via the GSPOSP routine (see below). This allows to have many similar volumes with the same name and shape, but different actual parameters in each copy.

The user can position a volume through a call to either one of the following subroutines:

GSPOS

position a copy of a volume inside its mother with respect to the mother's reference system. A a point in space, a rotation matrix index, a copy number and the 'ONLY'/'MANY' flag are supplied;

GSPOSP

position a copy of a volume which has been instantiated without actual parameters inside its mother with respect to the mother reference system. The parameters of the copy being positioned are supplied as well. The volumes will be identified by name and copy number as for multiple copies of the same volume.

GSDVN

divide a volume in a given number of cells completely filling the mother. In this case the cell tracking medium is assumed to be the same as for the mother. See also GSDVN2.

GSDVT

divide a volume with slices of a given step. The cell tracking medium can be different from the one of the mother. See also GSDVT2.

GSDVX

divide a volume starting from a given offset. In addition to STEP and NDIV (with at least one of them positive to be effectively useful), the origin of the first cell, the cell tracking medium and eventually the computed (maximum) number of divisions must be specified.