Supercrystal positions

The pre-August 2000 endcap geometry is based on the following set of parameters;

Notes:

1. Supercrystal size supplied by Brian Smith, 15 June 1999.
2. "Gap between Scs" refers to the parallel gap separating adjacent SC faces in a column, and includes 0.5mm each for clearance and size tolerance.
3. The "Gap between SC columns" is the allowed spacing between the logical envelopes which enclose the actual columns of SCs.  The physical spacing between SCs in adjacent columns is always at least this much, and generally rather greater.
4. The "Extra clearance" at the X and Y axes is the additional spacing allowed for installation within (X) and between (Y) endcap dees.

The coordinates of the SC corners in quadrant 1 are stored as a plain text file.  The file format is self-explanatory except for the numbering of supercrystal corners, which goes like this...

Seen from the CMS interaction point: front corners are numbered 1-4 with 1 at the top right, proceeding clockwise to 4 at the top left; rear corners similarly go 5-8 from top right to top left.  The "datum edge" connects corners 3 and 7.  The SCs are aligned such that every corner 1 lies at the same Z position - currently 3175mm from the centre of CMS.

In the TDR geometry some supercrystals at the inner and outer edges of the endcap are cut away to approximate a circular profile.   The coordinates of the corners of the border crystals are stored a a text file giving the position in (x,y,z) of each corner of the top and bottom crystals in each crystal column.  The corner numbering scheme for the crystals is the same as the SC version.