Status of GEM T2 assembly Outline Status of the GEM components Summary Tests TOTEM Collaboration meeting CERN / Risto Orava for Kari Kurvinen

GEM FOILS Visual & optical scanning 48 foils scanned selection criteria not decided → all foils accepted so far Leakage current measurements >30 foils measured 2 discarded due to high currents Framing 28 foils glued to the frames 2 foils with frames lost due to a failure of glueing (part of the foil detaches from the frame during the curing phase) GEM frames for 6 GEMs (18 pcs) ordered from CNCenter Ltd in Helsinki (more will be ordered if the quality is confirmed).

Readout boards 10 delivered to Helsinki including 3 bad ones (problems in glueing & cutting (CERN-EST-DEM)) readout connectors only for 3 GEMs, –more ordered >2 months ago, not yet delivered –needed for capacitance measurements –must be soldered before the glueing of the GEM pile onto the r.o.b. semi-automatic capacitance measurements done for the three finished r.o.b. and manually partly for the four ones (3 sectors only per r.o.b.). → acceptable quality

DRIFT FOILS 7 drift foils glued to the sandwich 6 drift foils of the latest delivery batch turned out to be mirror images → new foils ordered from a Finnish company, delivery within two weeks.

Small items GEM support 12 manufactured from brass for the beam test HV connectors (LEMO) 25 male and female ones ordered and delivered Gas connectors received from CERN-EST-DEM with plastic adapters some cracks observed in the adapters → gas leakages several aluminium ones manufactured in Helsinki

Summary of the status of GEM assembly Finished HG1, HG2, HG3 4 GEM piles finished: HG4, HG5, HG6, HG7 and waiting for r.o.b.s rest of the foils have been scanned and the leakage current measurements done rest of the r.o.b.s checked manually (only a few sectors), will be re-checked after assembling the connectors COMPONENTS LEFT readout board connectors 0 pcs drift foils: for 0 GEMs ( 6 ordered from Helsinki) drift frames: for 4 GEMs GEM foils: for 3 GEMs GEM frames: for 1 GEM ( 6 more from CNCenter Ltd next week?) r.o.b. 4 pcs voltage divider PCB: 6-8 pcs gas connectors: a plenty of HV connectors for cables: 25 pcs we cannot continue any further due to the lack of components (r.o.b. connectors!) → working at the moment with the testing procedures (ARC system)

TESTS DEFECT HUNTING IMPROVED → Good resolution for spotting etching defects: Practically all the defects are found and only around 10% of the identified defects are false, such as dust particle shadows, dark spots in copper surface or hole distortion by scratches ALGORITHM OPTIMIZED → the hole size distribution much better OPTICAL SCANNING We now consider that the scanning method satisfies the quality checking needs of the GEM foils → parameters fixed, no more development work

Analysis of defects and hole sizes An example of a good foil

Large regions of small holes Example 2:

A foil with many defects 127 defects classified as significant by size 84 significant defects on the backside defects distributed evenly over the whole GEM area Example 3: manufacturing process not clean enough

Capacitance measurement of readout boards semi-automatic capacitance measurement systems works well ! operation based on a GPIB- controlled LCR meter, XYZ table and a special fan-out card with a 130 pin mating connector. measures a relative capacitance variation from pin to pin. measurement time 10 min/conn. strip/pad capacitances easily measured also for an assembled GEM. a short between a strip and a pad !

We will continue these measurements with ARC-system, which has already collected 90 Sr data (both from strips and pads), but not yet optimally tuned.. -independent of calibration – scale by -Fe55 peak  210 primary electrons - mean ch. – 28 el. (vs. 30&TDR) -(53 mv/fC) (run at M = 8000)