Status of production at LNF E.Dane’ and C. Forti – Meeting with LHCb referees Firenze 14-mar-05 Christmas 3 ch/week Ch. 43

Chamber closing rate (averaged in groups of 3 chambers) Christmas In last 3 weeks, we closed one chamber every Monday-Wednesday-Friday

Switch to M1 and Christmas today Start M5R4 Summer Easter Summer Start M1R4 LNF production schedule (updated 8-Mar-05) 56 M3R3 + (52+5) M5R M5R M1R M1R4 = weeks (Christmas) + 1w Easter + 4w Summer Switch to M1 ~ 1 month End M5R3=begin-May-05 End M5R4=end-Nov-05 End ALL=mid-sep-06 Assuming a rate of 3 ch./week also for M5: expected end is ~ mid July 2006

LNF-M5R3 gain uniformity (updated 4-march) All 38 tested chambers are GOOD All 2.75 kV. No equalization is applied ±50 V±80 V

Table for the assembly of two M1 chambers simultaneously GEM group moved to a new clean room and left free space in our clean room. We have equipped this space with a new long table, which will allow to assemble two M1 chambers simultaneously.  we firmly believe that we can produce at least 4 M1 chambers per week.

Container for chamber storage and transportation Last Friday we switched on a group of 18 M3R3 chambers (one trolley) using a single HV channel. These chambers have been OFF and flushed with Argon for several months. ~10 days ago we began to flush them with gas mixture 40/40/20. We reached 2.75 kV (in 2 days) without any problem.

Ferrara production updated at March 4-th

Summary of chambers built in Ferrara Assembled: 49 Tested 46 Good (passed the gas leak + HV + source test): 36 Bad (unrecoverable): 6 (CH0,1,3,4,18,27) To be recovered: 4 (ch 39 for gas leak, ch 2,5,10 for HV) Chamber #46 has 3 panels recovered from bumps, it passed the HV test but still needs to be tested with source At present we have panels ready to assemble 4 more chambers We have to build 52 (48+spare) chambers The production status can be checked at the web address: we are trying to keep it updated on a weekly basis

Ferrara production rate We expect to finish the M2R3 production at the beginning of april

Chambers tests in Ferrara No big issues with HV training About 20% have to be recovered (it takes about half a day) for gas leak From our preliminary tests all chambers have a very uniform gain: 95% of each gap area is within 25% wrt the average 2.75kV Chamber #21 tested in Rome 2850V showed some problems, it will be tested again The Rome II source test table is now in Ferrara Several chambers have been tested in both Ferrara and Rome II to get normalization constants In the next weeks the source tests in Ferrara will be normalized to the standard one

Gas leak and HV test in Ferrara Dark current is measured about 2 hours after reaching 2.85 kV Gas leak is 5 mbar of overpressure Dark current Gas leak

Status of production at CERN The change from M3R2 to M2R2 has been carried out without any major problems. We are at nominal production speed of 2 chambers per week. Material supply for M2R1 is already well advanced. Concerning the panel equipment with electrical components and the HV-test of panels we are 1 week late. This is due to increased number of wires to be replacement (problems with tension). The bad winding at the wire spool end causes quite some problem to the wire tension  B. Schmidt got in contact with Luma

Chamber production CERN Pannelli M2R2 filati Camere M2R2 prodotte We are one week late in regard to our planning. The delay of the assembly can be recovered more easily. Strange behavior of leak test for first 2 chambers under investigation

Uniformity of CERN M3R2 chambers Erica has set up the hardware for the M3R2 uniformity tests. 8 chambers of this regions have been checked. We will continue with the tests of this region with the manpower available. New help from CBPF is foreseen before the next change to M2R1.

Trasparenze di riserva

Conclusioni di Ferrara Since beginnning of December we are keeping a constant production rate of 2 ch/week The problem of the bumps on the panels (which appeared in January) now seems to be solved (by drilling holes in the existing panels and improving the injection technique for the new ones) The material procurement is OK, apart from minor issues: – In the last batch, 5 panels have problems with the grove for the glue on HV bars – From time to time the wire seems to have some defects – Spool of guard wire twisted – Some difficulties in the HV cables procurement We still have some difficulties in recovering hospital panels/chambers (lack of manpower) We expect to finish the production of M2R3 in about 1 month, for the beginning of april we need panel of new type (M5R2) From the next chamber type (M5R2) we plan to implement some small changes in the tooling to further improve the production

Requirements on MWPC The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. Panel planarity  gas gap uniformity: 95% panel area in ± 90  m (5% in ± 180  m) PANELS REJECTED ~7% Wire pitch: 95% in 2 mm ± 50  m (5% in 2 mm ± 100  m) Wire tension: 50 ÷ 90 g WIRES CHANGED < 1‰ Gas tightness:  P < 2 5 mbar overpressure Gain uniformity: G 0 /1.7 < G < G 0 *1.7 (in 100% of each double-gap area) with respect to the average gain G 0. Distance wire plane - cathode plane: PANELS REJECTED: negligible 2.5 mm ± 100  m Small dark current (< kV Tests on assembled chambers (results shown later for each site) Partially-tested Fully-tested

Gas leakage test (I) In order to minimize the gas refill rate, the maximum leakage allowed for each chamber is 2 mbar/h. To verify the gas tightness of a chamber, we inflate it with nitrogen up to an overpressure P of 5 mbar. Then, we record P as a function of time, during about one hour. The measurement is sensitive to variations of the external temperature. In order to correct this effect, a second chamber is used as a reference. The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber.

Gas leakage test (II) The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. If a chamber leaks, usually we can recover it by putting glue all around the chamber, between each pair of panels. For ex. In LNF, over 73 chambers produced, only one was not recovered.

Wire pitch measurement (I) The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. The wire position is precisely determined by the pitch of the wiring machine combs, however it is important to check that no wire is out of the acceptance. The WP measurement is performed with an automatic device, based on two cameras scanning the panel and a software for image acquisition and analysis. An accuracy of about 20 µm is obtained. The requirement on the wire pitch (WP) is: WP = 2 mm ± 50 µm (95% of pitches) ± 100 µm (5% of pitches) Sample image from scanning device

Wire pitch measurement (II) The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. The range 2 mm ± 50 µm corresponds to the red lines drawn at 211 ± 5 pixels. For example in LNF, over all chambers produced (~180,000 wires), we changed only few wires with wrong pitch. The fraction is somewhat higher at CERN, where the wires touch the HV bars, but this is not a cause of worry.

Laser Photodiode wire Mechanical excitation Panel This method has been developed together with Firenze and Roma II The signal is sent to a PC’s soundcard, a FFT is applied and the fundamental frequency is searched between 310 and 600 Hz (for M2R3 panels) Wire Tension Measurement in FE

Laser Mechanical Excitation Photodiode The measurement takes about 2 sec/wire (2 panels ~1200 wires in 40 min) Wire Tension Measurement in FE

X position in the gap (Wire-pad #) Measurement of the gain uniformity The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. Uniformity of the gap gain is measured with a radioactive source. The current drawn by each gap is monitored while the lead case containing the source is moved by means of a mechanical arm. These measurements allow to check the gain uniformity within each gap and to compare different chambers among them. Y position in the gap Current (nA) Example of a result of the scan of a gap with radioactive source The method used is similar in INFN and PNPI sites. At CERN, where chambers are smaller, a different method is used (see later).

Test of CERN chambers with radioactive source: method 241 Am source All anodes connected together  ADC  Amplitude spectrum Cathode connected to the delay line  TDC  Pad location ADC spectrum Delay line output Time (ns) Peak position of the signal induced by the gammas of the 241Am

Classification criteria on gain average and uniformity Chamber class: AA,AB,BA  GOOD BB  RESERVE BC,CB,CC  REJECTED The HV plateau width is determined by the minimum efficiency and by the maximum average number of pad-hit. From test-beams, these requirements define a ~170 V wide region   V = ±85 V Testbeam oct. ’03: 2-GAP For each double-gap, we provide the class: A = all currents measured with source are within a factor 1.4 from the average current of all 2-gaps (   V = ±50 V) B = … within a factor 1.7 (   V = ±80 V) C = not satisfying criteria A and B