The System Shapes

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| Geant 3.10  |               GEANT User's Guide              | GEOM050  ##
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Author(s) : R.Brun,A.McPherson                         Submitted: 15.08.83
Origin    : Same                                         Revised: 22.04.86
                                  

The system shapes supported at present are as follows:

(For each shape the local reference system is shown in the corresponding Figure)

1 'BOX

'is a box. It has 3 parameters, the half lengths in x, y and z.

2 'TRD1'

is a trapezoid with only the x length varying with z. It has 4 parameters, the half length in x at the low z surface, that at the high z surface, the half length in y and in z.

3 'TRD2'

is a trapezoid with both x and y lengths varying with z. It has 5 parameters, the half length in x at the low z surface, that at the high z surface, the half length in y at the low z surface, that at the high z surface, the half length in z.

4 'TRAP'

is a general trapezoid, i.e. one for which the faces perpendicular to z are trapezia and their centres are not at the same x, y. It has 11 parameters: Dz the half length in z, Th Phi the polar angles from the centre of the face at z=-Dz to that at z=+Dz, H1 the half length in y at z=-Dz, LB1 the half length in x at z=-Dz and y=low edge, LH1 the half length in x at z=-Dz and y= high edge, Th1 the angle w.r.t. the y axis from the centre of the low y edge to the centre of the high y edge, and H2, LB2, LH2, Th2 the corresponding quantities at z=+Dz.

5 'TUBE'

is a tube. It has 3 parameters, the inside radius, the outside radius and the half length in z.

6 'TUBS'

is a phi segment of a tube. It has 5 parameters, the same 3 as 'TUBE' plus the phi limits. The segment starts at the first limit and includes increasing phi value up to the second limit or that plus 360 degrees.

7 'CONE'

is a conical tube. It has 5 parameters, the half length in z, the inside and outside radii at the low z limit and those at the high z limit.

8 'CONS'

is a phi segment of a conical tube. It has 7 parameters, the same 5 as 'CONE' plus the phi limits.

9 'SPHE'

is a segment of a spherical shell. It has 6 parameters, the inside radius, the outside radius, the theta limits and the phi limits. At present, for the drawing package only first two parameters are significant (inside radius and outside radius) and such a shape is always drawn as a full sphere.

10 'PARA'

is a parallelepiped. It has 6 parameters, the half length in x, the half length in y, the half length in z, the angle w.r.t. the y axis from the centre of the low y edge to the centre of the high y edge, and the theta phi polar angles from the centre of the low z face to the centre of the high z face.

11 'PGON'

is a polygon. It has at least 10 parameters, the lower phi limit, the range in phi, the number of straight sides (of equal length) between those phi limits, the number of z planes (at least two) where the distances to the z axis are changing, z coordinate of first plane, the shortest distances RMIN RMAX from the z axis to the inside straight edge and the outside straight edge for the first plane, Z, RMIN, RMAX for the second plane, and so on.

12 'PCON'

is a polycone. It has at least 9 parameters, the lower phi limit, the range in phi, the number (at least two) of z planes where the radius is changing for each z boundary and the z coordinate, the minimum radius and the maximum radius.

28 'GTRA'

general twisted trapezoid. (Not guaranted to be supported in the future)

Essentially it is a TRAP shape, except that it is twisted in the x,y plane as a function of z. At z=+/-DZ the parallel sides are inclined to the x axis by +/- an angle TWIST, which is one of the parameters. The shape is defined by the eight corners and is assumed to be constructed of straight lines joining points on the boundary of the trapezium at z=-DZ to the corresponding points on the boundary at z=DZ. So far, it is not allowed to divide volumes with shape GTRA.

GTRA Parameters

User Supplied:

DZ =

Half length perpendicular to the parallel faces (Z axis).

TH =

Theta (polar angle) of line joining centres of parallel faces.

PH =

Phi (azimuth) of line joining centres of parallel faces.

TWIST =

Twist angle of parallel sides at z=+/-DZ.

Y1 =

Half distance between parallel sides at z=-DZ.

XL1 =

Half length of low y parallel side at z=-DZ.

XH1 =

Half length of high y parallel side at z=-DZ.

TH1 =

Angle to perpendicular to parallel sides of line joining their centres at z=-DZ.

Y2 =

Half distance between parallel sides at z=DZ.

XL2 =

Half length of low y parallel side at z=DZ.

XH2 =

Half length of high y parallel side at z=DZ.

TH2 =

Angle to perpendicular to parallel sides of line joining their centres at z=DZ.

Internal:

First 12 are the user supplied parameters. Then there are an extra 18 which are as follows:

DX0DZ =

DX/DZ for the line joining the centres of the faces at Z=+/-DZ.

DY0DZ =

DY/DZ for the line joining the centres of the faces at Z=+/-DZ.

X01 =

X at Z=0 for line joining the + on parallel side, perpendicular corners at Z=+/-DZ.

Y01 =

Y at Z=0 for line joining the + on parallel side, + on perpendicular corners at Z=+/-DZ.

DXDZ1 =

DX/DZ for line joining the + on parallel side, + on perpendicular corners at Z=+/-DZ.

DYDZ1 =

DY/DZ for line joining the + on parallel side, + on perpendicular corners at Z=+/-DZ.

X02 =

X at Z=0 for line joining the - on parallel side, + on perpendicular corners at Z=+/-DZ.

Y02 =

Y at Z=0 for line joining the - on parallel side, + on perpendicular corners at Z=+/-DZ.

DXDZ2 =

DX/DZ for line joining the - on parallel side, + on perpendicular corners at Z=+/-DZ.

DYDZ2 =

DY/DZ for line joining the - on parallel side, + on perpendicular corners at Z=+/-DZ.

X03 =

X at Z=0 for line joining the - on parallel side, - on perpendicular corners at Z=+/-DZ.

Y03 =

Y at Z=0 for line joining the - on parallel side, - on perpendicular corners at Z=+/-DZ.

DXDZ3 =

DX/DZ for line joining the - on parallel side, - on perpendicular corners at Z=+/-DZ.

DYDZ3 =

DY/DZ for line joining the - on parallel side, - on perpendicular corners at Z=+/-DZ.

X04 =

X at Z=0 for line joining the + on parallel side, - on perpendicular corners at Z=+/-DZ.

Y04 =

Y at Z=0 for line joining the + on parallel side, - on perpendicular corners at Z=+/-DZ.

DXDZ4 =

DX/DZ for line joining the + on parallel side, - on perpendicular corners at Z=+/-DZ.

DYDZ4 =

DY/DZ for line joining the + on parallel side, - on perpendicular corners at Z=+/-DZ.