1. Brussels Gantry Ê Problem with vacuum chambers in plate 4 leaks in plates with gives communication between positions Ë Problem with rotation motor (U-motor) 4 uncontrollable shifts in angle: change motor or not ? Ì Could not start production of R5S modules due to the above 4 we could produce some if needed urgently Í Precision of the position of the 2D labels on frame Î We installed the new Gantry-DB, successfully… J.D’Hondt (for Brussels Group) CMS week – October 2004 J.D’Hondt

2. Vacuum problems in Aachen plates ~ 4 mm vacuum chambers in the plate plate : sandwich of two Al-layers glued together with Araldite (everywhere !!) leaks leaks : vacuum under 1 sensor  some force under other sensor Lots of plates affected → Aachen will cure the problem on all plates (open plate and re-glue them together)

3. Problem with rotation motor (U-motor) : dry assemblies R5S Very good !! dry assemblies in September Bram Meerschaut

4. Problem with rotation motor (U-motor) : dry assemblies R5S clear shifts from 1 assembly to another dry assemblies in September Bram Meerschaut

5. Bias in applied angle RMS ~ 1.7 mdeg applied angle : 100 mdeg These plots are made in July 2004 and where still valied in August. XY initial angle Due to some crash 2 years ago, the initial angle is lost. 

6. Bias in applied angle applied angle : 100 mdeg These plots are made now. RMS ~ 6.2 mdeg regular intervals ~15 mdeg shift Reason unknown. Aerotech contacted. Probably encoder ? Replace motor ? Re-tune encoder ?

7. Bias in applied angle  = 500 mdeg  RMS ~ 7.3 mdeg  = 50 mdeg  RMS ~ 5.5 mdeg  = 20 mdeg  RMS ~ 2.4 mdeg  = 100 mdeg  RMS ~ 6.2 mdeg applied angle : 20 mdeg applied angle : 50 mdeg applied angle : 500 mdeg Small angle to apply  small effect !!

8. How to solve the problem ? 1.Pre-align the sensors on the supply plate measure the angle to be applied between supply and assembly plate pick-up the sensor & move it slightly (in order not to touch the positioning pins) perform the necessary rotation put-down the sensor remeasure the angle which is supposed to be small now, hence small effect !! but this takes time… 4 plates a day with 2 sensor modules !! 2.Re-tune the rotation motor → try to perform the re-tune procedure ourselves Aerotech contacted (person who installed our Gantry isn’t there any more) monitor the precision: make the previous rotation plots every week but we have to understand why this effect occures 3.Replace the rotation motor we have a spare motor… but only one in the meanwhile we can replace out CCD camera (noise on one output line) this will take time and could evoke new unknown problems will hopefully solve the problem… this we will not have understood the problem can somebody give an estimate on the time and the issues we could encounter ?

9. Precision of 2D labels on frame 2D label has to be glued with a precision of 250 microns !?!? But…  Measured range of dimensions of 2D labels is ~70 microns (not ~4.500 but 5.350 mm !!)  Sometimes one has to polish the borders of the 2D labels > 100 microns  And to put it by hand by means of some jig (precision ~ 200 microns)  We don’t have that much spare graphite to waste !! (material for jig) This sound as the precision of 250 micron cannot be reached without serious thinking…

10. Summary Aachen plate issues () : Aachen plate issues ( not Lyon plate – only one sensor ) : Ê Vacuum chambers are connected in the plate Ë One plate already re-glued to be tested this week Rotation motor issues (): Rotation motor issues ( new problem ): Ê Uncontrolled shift in angle as the initial angle is lost (~15 mdeg) Ë Pre-alignment, re-tuning or replace the U-motor ? Ì All of them have ‘wanted’ and ‘less wanted’ features… (takes too much time, not understanding problem, unknown future problems ?) R5S module production ( ready but slow rate ): ¶ One plate with 1 position for the moment which is commissioned (teflon not flat enough in one position, one pin hole damaged on another position) (other R5S plate in Aachen for adaptations) J.D’Hondt