Status of MWPC production and quality control The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. C. Forti – LHCC Comprehensive Review – CERN - 1 February 2005 Status of MWPC production in each site production rate problems during production manpower situation Material procurement Quality control tests on panels and wires (pitch, tension) tests on closed chambers gas tightness dark current gas gain uniformity tests with beams (T11, GIF,…) Logistics

Status of production in LNF M3R3: needed=48 (+4 spare). We have built 58 chambers 2 not usable: 1 leaks gas; 1 has probably a broken wire; Test with source: 52 chambers very good (class A); 4 are good (class B) M5R3: needed=48 (+4 spare). We have closed chamber 28 on last Friday. 20 have been tested and satisfy the criteria: no gas leaks; no dark current; very good gain uniformity High production rate chambers/week LNF will complete: (52) M5R3 in April 2005 (52) M5R4 before the end of the year Still to build: (52) M1R3 (40) M1R4 ~ 9 months

Status of production in Firenze M5R4: needed=192 (+8 spare) = 148 (Firenze) + 52 (LNF) 21 chambers closed (26-Jan-05) Gas leakage: 18 chambers tested / 3 leaking HV training and test with source: 6 chambers tested / 2 rejected The 4 accepted chambers have : dark current < kV and are very good (Class A) Will complete:(148) M5R4 in June ~ 2 ch/week Then (70) M1R4 in ~ 7 months Production rate > 2 chambers/week In late with tests of chambers as we aimed to reach asap the maximum production speed. Now equipping a more powerful and efficient test facility (many HV channels, automatic source test, etc) and we are going to test quickly all chambers.

Status of production in Ferrara M2R3: needed=48 (+4 spare) 32 chambers closed (25-Jan-05) Gas leakage: 29 chambers tested: all OK HV training: 24 with dark current < kV / 3 with wire pads drawing current Test with 90 Sr source (by hand) : 27 chambers tested  all OK Test with 90 Sr source (in Rome-2) : Production rate increasing ch/week Will complete: 52 M2R3 at end of ~ 2 ch/week Comments:

Status of production in PNPI M3R4: needed=192 (+8 spare). Assembled 91 chambers (26-Jan) Gas leak test: 46 tested OK; 45 not tested HV test: 86 tested Test with source: 84 tested Still to build: (~100) M3R4 (150) M2R4 Production rate 3-4 chambers/week

Status of production at CERN M3R1: needed=12 (+2 spare). Total chambers built=16. All tested for gas leaks  OK All trained for HV: dark current < 10 HV=2.9 kV Gas gain uniformity: 14 chambers tested ? chambers very good (class AA,AB,BA); ? are good (class BB) M3R2: needed=24 (+2 spare). Closed chamber 21 on JAN tested for leaks (2 will be re-visited); 12 HV trained:no dark current; no chamber tested for gain uniformity Average rate increased after summer  2 chambers/week Main problems encountered ? Man-power situation ? CERN will complete: (26) M3R2 in end-jan 2005 Still to build: 40 M2R1/2 28 M4/5R1 26 M1R2

Construction material – All the material has been ordered with some spare (10%) Material Procurement (I) Faraday cage – Final FEE board dimensions – M3R3 ready – All the others need the preparation of drawings (M3R4-M2R3-M5R4+....) Honeycomb panels - We got samples of M1R3/R4 regions, cut at the right dimension and a quotation. Early 2005 we should go for the purchase and the production. Delivered material PNPI – M3R4 – Panels 70% - HV bars 100% - FR4 frames 100% PNPI – M2R4 – Panels 20% - HV bars 100% - FR4 frames 100% PNPI – M4R4 – Panels 0% - HV bars 90% - FR4 frames 0% CERN – Panels 60% INFN – M3R3 completed – M2R3 ~ completed – M5R4 Panels 20% HV bars ~ 40% FR4 frames 100% Other elements 100% M1 panels 0%

Panel production A strict monitoring of the panel quality and of the production rate is performed with regular visits (every two weeks) to the company and with checks at the production site. This is certainly the most critical item on the chamber and the production has to be followed closely. The required planarity is very demanding (± 90 micron) especially on the largest panels (400 x 1600 mm2). A rate of 250/month is mandatory to match the chamber production in the various sites (see next plots). To monitor the production yield a data base on each INFN site is operational. This tool helps also to have a more efficient chamber production. The yield appears quite good: approximately 90%. We are also developing a tool to recover non planar panels (especially the gold plated one, which are the most expensive). Material Procurement (II)

Panels needed at production sites according to official plan Panel production rate

Quality controls: MWPC specifications (From W. Riegler simulations, EDR – CERN – April 2003) The drift velocity is saturated I.e. it has a very weak dependence on the electric field. Therefore we mainly worry about gas gain variations that can move the working point within the plateau. If G 0 is the nominal gas gain, requiring : G 0 /1.25 < G < G 0 *1.25 (in 95% of the gap area) G 0 /1.50 < G < G 0 *1.50 (in 5% of the gap area) translates into specifications of  gap:95% in ±90  m5% in ±180  m  pitch: 95% in ±50  m5% in ±100  m  wire y-offset: 95% in ±100  m 5% in ±200  m  wire plane y-offset: 95% in ±100  m 5% in ±200  m

Quality controls The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. HV bars: <10 4 kV Panel visual inspection Panel planarity and thickness uniformity  gas gap uniformity  gas gain variations: G 0 /1.25 < G < G 0 * % of the panel area in ± 90  m 5% of the panel area in ± 180  m Wire pitch: 95% in 2 mm ± 50  m 5% in 2 mm ± 100  m Wire tension: 50 ÷ 90 g Test HV in air: < 20 2 kV in each wired panel Gas tightness:  P < 2 mbar/hr Gain uniformity: 100% of the area of each double-gap within ± 80 V with respect to the average gain. After bar gluing: height of HV bars with respect to the cathode plane: mm ± 100  m Before wire winding: After wire winding: Tests on closed chambers: No dark kV

Panel planarity  Gap uniformity  Gain uniformity The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. Panel planarity  Gap uniformity  Gain uniformity From simulations (W. Riegler): G 0 /1.25 < G < G 0 *1.25  Gap = 5 mm ± 90  m (95% of detector area) ± 180  m (5% of detector area) Since the gap is provided by the 5mm spacers placed between the panels, along their frames, the gap uniformity is related to the uniformity of the panel thickness and to its planarity. The maximum fluctuation of the spacer thickness is ± 10  m. Here also we checked a production sample. The absolute value of the panel thickness is crucial only when a panel is wired on both sides (CERN and PNPI), because the distances between the wire planes and the panel surfaces depend on thickness. The requirement is T=9.0 ± 0.2 mm Panel thickness is measured at the company over a production sample and fluctuates by ~ ± 20  m

Check of panel planarity and thickness 90  m PANEL PLANARITY is checked (by hand) in each production site on ALL panels, before gluing the HV bars. PANEL THICKNESS is measured at the company over a production sample planarity < 90  m (95% of panel area) < 180  m (5% of panel area) d1d2 D Laser Beam Panel Thi Automatic system by Roma2 nearly ready

Check of HV bars before gluing them on panels Since few months we check all the HV bars: - visual inspection (we found broken R,C); - cleaning; - HV test: we require < 10 4 kV. Since we found a consistent fraction of bars drawing current, we changed the procedure: now Sei System send us the bars without conformal coating. Another (much better) company performs: cleaning; drying (in oven); putting conformal coating.

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.The requirement on the wire pitch (WP) is: WP = 2 mm ± 50 µm (95% of pitches) ± 100 µm (5% of pitches) The WP is measured with an automatic device, based on two cameras scanning the panel. An accuracy of about 20 µm is obtained. Sample image from scanning device 2 mm ± 50 µm  211 ± 5 pixels. Fraction of wires with wrong pitch < 1 per mil

Wire tension measurement The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. The wire mechanical tension must be in the range 50÷90 g in order to provide a good electrostatic stability. The tension is found by measuring the wire resonance frequency. Different methods are used. LNF: oscillations of the wire to be tested are induced by applying a periodic HV (about 900 V) with a frequency of 300 ÷ 400 Hz, between the wire and a non-oscillating sense wire parallel and close (~1 mm) to it. As a consequence, the capacitance C between the two wires oscillates. The maximum variation of C occurs at the resonance of the wire. Resolution is ~1 g and a M3R3 panel (660 wires) is measured in < 1 hour.

Laser Photodiode wire Mechanical excitation Panel This method has been developed together with Firenze and Roma II The signal is sent to a PC soundcard, a FFT is applied. The resonance frequency is searched between 310 and 600 Hz (for M2R3 panels). Wire Tension Measurement (Ferrara method) Laser Mechanical Excitation Photodiode The measurement takes about 2 sec/wire ( 2 panels ~1200 wires in 40 min )

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 84 chambers produced (58 M3R3+26M5R3), only one was not recovered.

HV training and Dark current LNF : all chambers with dark current 2.85 kV Procedure for conditioning of the chambers: 1) Start with HV+ and go to HV at which the current reaches nA and does not show the tendency to fast decrease (Normally this kV) 2) Switch to HV- and start from HV=0 to increase first quite fast (200 V/min) up to 1.5 kV. 3) Increase HV slowly till the current jumps to some value which SHOULD NEVER EXCEED 3-4  A. 4) Stop and wait till current drops to nA. Normally this takes small time. Then make the next step (~100 V) and so on. The training stops at HV= 2.15 kV. The procedure with the inverse polarity takes not more than one hour. After that they go to the normal polarity. In most cases HV=2.95 kV can be reached after such training. If not, a second round with the inverse polarity can be performed. Anyhow, the whole procedure allows to reach 2.95 kV in one day. PNPI : all chambers 2.95kV [Ar(40)/CO2(50)/CF4(10)]

Classification criteria on gain average and uniformity Each double-gap is classified in A,B,C classes according to: A. /1.4 *1.4 (equivalent to ± 50 V range) B. /1.7 *1.7 (equivalent to ± 80 V range) C. Requirement B not satisfied   V > 80 V For each double-gap, we provide the class: A = 100% of double-gap area in  V<50 V B = 100% of double-gap area in  V<80 V C = not satisfying criteria A and B Chamber class: AA,AB,BA=GOOD BB=SPARE BC,CB,CC=RESERVE The HV plateau width is determined by the minimum efficiency and by the maximum average number of pad-hit. From testbeams, these requirements define a ~170 V wide region

Test with radioactive source (LNF) The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. 137 Cs source case Profile view of a MWPC on the source test table. Uniformity of the gap gain is tested with a 40 mCi 137 Cs 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. Current (nA) X position in the gap Y position in the gap Example of a result of the scan with radioactive source

LNF-M3R3 Production overview = 456 (nA) Class B : 14, 39, 44, 58 Class A : all the remaining (52) No equalization is applied

LNF-M5R3 Production overview = 456 (nA) All 21 tested chambers are Class A : within ±50 Volts from average No equalization is applied

Test with radioactive source (PNPI) The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. The measurements are performed using a 9mC source with a rectangular collimator. The size of the collimator slit is 10x1 cm 2. In regular measurements the slit is adjusted to be parallel to the wire direction. The source is moved along the center part of the chamber. The chambers are operated at HV=2.7 kV with the gas mixture Ar(40)/CO2(50)/CF4(10). The ionization current is measured with the gamma source positioned at each pad of the chamber. The dark current is subtracted. The table below presents the ratios of the minimal (maximal) to the average values of the currents measured for each gap. Also, for comparison of the gas gains in various gaps in various chambers, the ratios are presented of the average currents measured in a given gap to a reference value ( Avr*) - average current from 4 gaps in Chamber N31.

Test of Ferrara Roma-2 Source Sr90 8 mCi electrons of ~2.5 MeV Collimated ~2 mm diameter

Test of Ferrara Roma2 Red: source at the edge of the two pads Black and green: at the center of each pad A B C D

Test of CERN chambers with radioactive source 241 Am source

Delay line (TDC) and ADC output All anodes connected together  ADC  Amplitude spectrum Cathode connected to the delay line  TDC  Pad location Delay line output ADC spectrum Time (ns)

Gas Gain Map Example of a map of the ADC peak For each pad of each gap Test station is operational Six chambers tested Gas gain RMS is ~10 % for all chambers

Test with cosmic rays (LNF) The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. The use of a cosmic ray stand allows to measure: - efficiency - time resolution - average hit-multiplicity - electronics noise The system allows to house and test up to six chambers simultaneously (600 channels). The trigger is given by three large scintillators (one above and two below the chambers) read out on both sides.The trigger rate is of about 15 Hz and its time resolution is about 2.8 ns. time spectrum We tested only few chambers, because we do not have still the final FEE. We plan to test all (or part of the) chambers, after the final FEE and the Faraday cage will be mounted on them.This is still under discussion.

Tests at GIF of a LNF chamber GIF: 137 Cs and ~100 GeV muon beam One M3R3 chamber (LNF) tested in July’04 (Public Note LHCb-MUON ) Reults for the LNF chamber:  > 98% and time r.m.s. 2.6 kV The effect of dead-time due to electronics can be studied also for hottest region M1R2. This is not true for the space-charge effect.

Tests at GIF: 137 Cs and ~100 GeV muon beam One M3R3 chamber (LNF) tested in July’04 (Public Note LHCb-MUON ) Reults for the LNF four-gap chamber:  > 98% and time r.m.s. 2.6 kV The effect of dead-time due to electronics can be studied also for hottest region M1R2. This is not true for the space-charge effect.

Once the chamber have been tested with radioactive source, FEE electronics, LV and Faraday Cage must be assembled on chamber (and tested). Part of this work will be done at the production sites (at LNF, for whole INFN, at PNPI and at CERN). Probably, for PNPI chambers, electronics will be assembled at CERN. The first chambers will be equipped as soon as the CARDIAC boards will be available. Shipping of INFN chambers to CERN: in special trolleys with shock absorbers stocked in a container (see photo). Shipping of PNPI chambers: in wooden boxes (CSC-CMS like) Storage at CERN : about 200 m 2 available (not so much) Gas flux – last test with HV – Installation on the detector We have yet to deploy a detailed plan for this part of the installation: check the time and the personnel needed; logistics at CERN and the infrastructure needed (gas, HV, etc...) set up the procedures and the team for the installation on the detector (integration among various labs) Preliminary plans to equip and to install chambers

Trolleys and container for chamber storage and tranportation Container with 6 trolleys of 18 chambers each = 108 chambers.

Conclusions

Spare transparencies follow

MWPC cross-section In stations M2-M5 the detectors are four-gap MWPCs 2 chamber layers are connected into one front-end. 4 layers are combined into one station.

Master plan june 2004

Closing dates of M5R3 LNF chambers

Closing dates of M5R4 Firenze chambers

Closing dates of Ferrara chambers

Closing dates of M3R1 and M3R2 CERN chambers

Closing dates of PNPI-M3R4 chambers

Sensitivity of the performance on chamber imperfections The drift velocity is saturated I.e. it has a very weak dependence on the electric field. Therefore we mainly worry about gas gain variations that can move the working point within the plateau. If G 0 is the nominal gas gain, we want the gas gain in 95% of the area of a single gap to be within G 0 /1.25 and G 0 *1.25 I. e. between 0.8G 0 and 1.25G 0. The remaining 5% of the area should have a gain within a factor 1.5 I.e. between 0.67G 0 and 1.5G 0 A gain change of a factor 1.25(1.50) corresponds to Voltage change of  34(62)V on top of the 2750V corresponding to  1.25(2.25)%. ®The gas gain changes by a factor 1.25(1.5) if the wire surface field changes by  1.25(2.25)%.  What chamber imperfections are allowed in order to keep the wire surface field within  1.25(2.25)% ?

d1d2 D Laser Beam Panel Thi = D-d1-d2 Thi Measurement scheme Panel measurement table Status report (R. Messi/E.Santovetti) The system appear to be extremely solid and precise The measurement of each point is repeatable at the level of ~ 10  m RMS ~ 3  m Max-min ~ 12  m

d1D2=Kost Thi Thi = 9.13mm Laser beam 38 vertical scans on 16 fixed points (mesurements on two different days Test of guides precision

Plateau width (M2-M5) From testbeams: plateau width=170 V for bigaps; 150 V for 4-gaps Testbeam oct. ’03: BIGAP Lower plateau limits: 95% for bigap (2.53 kV) / 99% quadrigap (2.55 kV) Upper limit: cluster size in quadrigap < 1.2  HV <2.7 kV (calculated from oct’03 results on the bigaps) GIF july ’04: 4-GAP 2.62 ± kV 99%

Plateau width (M1) GIF july ’04: DOUBLE-MONOGAP FROM GIF: Lower plateau limit:  =99% in double-monogap  HV=2.65 kV FROM OCT’03 (BIGAP): Upper limit: cluster size =1.2; in bigap HV~2.82 kV Work point ~ 2.72 kV Plateau width ~ 170 V Testbeam oct. ’03 : BIGAP

Wire tension measurement (LNF) The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. To measure 0, mechanical oscillations of the wire to be tested are induced by applying a periodic high voltage (about 900 V) with a frequency of 300 ÷ 400 Hz, between this wire (Cw) and a non-oscillating sense (Sw) wire placed parallel and close to it at a distance d of about 1 mm. The capacitance C between the two wires is given by: where a and b are radii of wires and l is the SW length. The wire mechanical tension must be in the range 50÷90 g in order to provide a good electrostatic stability. The wire tension  can be found by measuring its mechanical resonance frequency 0 with the formula:  : mass per unit length of the wire l: length of the wire LNF method

Wire tension measurement (LNF) The measure of the gas leakage, is obtained by correcting the P(t) behavior by using the data of the reference chamber. The oscillations result in a variation of C. The maximum variation of C occurs at the mechanical resonance of the chamber wire. A resolution of about 1 g is obtained and a M3R3 panel (660 wires) can be checked in less than 1 hour. LNF method

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

Gain average and uniformity The goal: to have all detector area within the HV plateau defined by the minimum efficiency and by the maximum cluster size M2-M5: the chamber is a 4-gap; the efficiency of each double-gap must be  > 95%. The 4-gap average n. of hits must be < 1.2 From testbeam of LNF chambers, these requirements define the following 170 V wide regions: M1: 2720 ± 85 V M2-M5: 2620 ± 85 V M1: the chamber is a double-gap; the efficiency must be  > 99% The double-gap average n. of hits must be < 1.2

M5R3 Chamber 14 Chamber production Overview You're logged in as lhcb Shows chambers. Last update: December 17, 2004, 3:21 pm LNF results: 58 chambers M3R3: 1 leaks; 1 broken GIF (?); 39 AA; 13 AB/BA; 4 BB 21 chambers M5R3: all AA