Supercrystal positions

The current endcap geometry is based on the following set of parameters;

Notes:

1. Supercrystal size supplied by Brian Smith, 8 August 2000, based on measurements of a real alveolar, as recorded in drawing 1-TB-0054-118-00-C.   The supercrystal dimensions quoted are those of the "envelope" rather than the physical alveolar box.
2. The rear size is calculated rather than measured.  The actual supercrystal has a parallel-sided housing forming the rear 60.2mm of the overall length.  The calculations are based on a uniformly-tapered volume with the same length, front size and taper angle.
3. "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.
4. 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.
5. The "Extra clearance" at the X and Y axes is the additional spacing allowed for installation within (X) and between (Y) endcap dees.
6. The coordinates given here have been confirmed by an independent calculation by Victor Goussev based on a specification by Justin Greenhalgh.

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.

Previous versions of the geometry are still stored.  Click on the relevant dates to get the information.