CERN Program Library Long Writeup W5013 - CERNLIB ...

1.DZ half-length along the z axis;
2.THET polar angle of the line joining the centre of the face at -DZ to the centre of the one
at +DZ;
3.PHI azimuthal angle of the line joining the centre of the face at -DZ to the centre of the
one at +DZ;
4.TWIST twist angle of the faces parallel to the x-y plane at z = ±DZ around an axis parallel
to z passing through their centre;
5.H1 half-length along y of the face at -DZ;
6.BL1 half-length along x of the side at -H1 in y of the face at -DZ in z;
7.TL1 half-length along x of the side at +H1 in y of the face at -DZ in z;
8.ALP1 angle with respect to the y axis from the centre of the side at -H1 in y to the centre
of the side at +H1 in y of the face at -DZ in z;
9.H2 half-length along y of the face at +DZ;
10.BL2 half-length along x of the side at -H2 in y of the face at +DZ in z;
11.TL2 half-length along x of the side at +H2 in y of the face at +DZ in z;
12.ALP2 angle with respect to the y axis from the centre of the side at -H2 in y to the centre
of the side at +H2 in y of the face at +DZ in z;
Note: this shape suffers from the same limitations than the TRAP: the tracking routines assume
that the faces are planar, but this constraint is not easily expressed in terms of the 12 parameters.
Additionally, no check on the faces is performed in this case. Users should avoid to use this
shape as much as possible, and if they have to do so, they should make sure that the faces are
really planes. If this is not the case, the result of the transport is unpredictable.
To accelerate the computations necessary for transport, 18 additional parameters are calculated
for this shape:
1.DX0DZ dx/dz of the line joining the centres of the faces at z=±DZ;
2.DY0DZ dy/dz of the line joining the centres of the faces at z=±DZ;
3.X01 x at z=0 for line joining the + on parallel side, perpendicular corners at z=±DZ;
4.Y01 y at z=0 for line joining the + on parallel side, + on perpendicular corners at z=±DZ;
5.DXDZ1 dx/dz for line joining the + on parallel side, + on perpendicular corners at z=±DZ;
6.DYDZ1 dy/dz for line joining the + on parallel side, + on perpendicular corners at z=±DZ;
7.X02 x at z=0 for line joining the - on parallel side, + on perpendicular corners at z=±DZ;
8.Y02 y at z=0 for line joining the - on parallel side, + on perpendicular corners at z=±DZ;
9.DXDZ2 dx/dz for line joining the - on parallel side, + on perpendicular corners at z=±DZ;
10.DYDZ2 dy/dz for line joining the - on parallel side, + on perpendicular corners at z=±DZ;
11.X03 x at z=0 for line joining the - on parallel side, - on perpendicular corners at z=±DZ;
12.Y03 y at z=0 for line joining the - on parallel side, - on perpendicular corners at z=±DZ;
13.DXDZ3 dx/dz for line joining the - on parallel side, - on perpendicular corners at z=±DZ;
14.DYDZ3 dy/dz for line joining the - on parallel side, - on perpendicular corners at z=±DZ;
15.X04 x at z=0 for line joining the + on parallel side, - on perpendicular corners at z=±DZ;
16.Y04 y at z=0 for line joining the + on parallel side, - on perpendicular corners at z=±DZ;
17.DXDZ4 dx/dz for line joining the + on parallel side, - on perpendicular corners at z=±DZ;
18.DYDZ4 dy/dz for line joining the + on parallel side, - on perpendicular corners at z=±DZ;
29 CTUB cut tube, a tube cut at the extremities with planes not necessarily perpendicular to the z axis. It
has 11 parameters:
GEOM050 – 4 113