Quality Control of the Light Mixers
for the ATLAS Hadronic Tile Calorimeter

The light-mixers for the PMT blocks of the Hadronic Tile Calorimeter are produced and tested in the Optical laboratory of the Faculty of Mathematics and Physics, Charles University in Prague.

The QC is performed in the following steps:

1. The material was ordered and delivered in one batch in forms of sheets with thickness 20 mm. The quality and properties are identified by the producer Fa. Roehm, GmbH, Kirschenallee, 64293 Darmstadt, Germany.
   Material: PLEXIGLAS® XT 20070 - an extruded acrylic by the chemical name of polymethyl methacrylate (PMMA). PLEXIGLAS® XT 20070 is clear-transparent (92%) and highly UV-absorbing material.
2. The shape and the dimensions are given in the enclosed drawing.
3. The dimensions of each light-mixer are checked by digital length gauge Mitutoyo (accuracy 0.01 mm) to be inside the tolerances. 5% of each batch is measured and recorded.
4. All the surfaces are polished. Quality of the polished surfaces
   • planarity 0.3 m m
   • cleanness 5/3 x 0.25 (5 means the cleanness of the surfaces, 3 means max. three impurities of max. dimension 0.25 mm on the polished surface, DIN standard).
5. The quality of the polished surfaces of each produced light-mixer are inspected by means of a magnifying lens (6x) in a dark filed.
6. Each batch will be delivered in packs of 500 pieces.

Engineer: Jindrich Walter
Physicists: Rupert Leitner, Michal Suk
QC: Petr Tas