Status of production at LNF

1
Status of production at LNF
Ch. 43
3 ch/week
Christmas
E.Dane and C. Forti Meeting with LHCb
referees Firenze 14-mar-05
2
Chamber closing rate (averaged in groups of 3
chambers)
Christmas
In last 3 weeks, we closed one chamber every
Monday-Wednesday-Friday
3
LNF production schedule (updated 8-Mar-05)
56 M3R3 (525) M5R3 52 M5R4 52 M1R3 42
M1R4 259
2 weeks (Christmas) 1w Easter 4w Summer
Switch to M1 1 month End M5R3begin-May-05 End
M5R4end-Nov-05 End ALLmid-sep-06 Assuming a
rate of 3 ch./week also for M5 expected end is
mid July 2006
4
LNF-M5R3 gain uniformity (updated 4-march)
All 38 tested chambers are GOOD
All gaps _at_ 2.75 kV. No equalization is applied
50 V
80 V
5
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.
6
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.
7
Ferrara production updated at March 4-th
8
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 (48spare) chambers
• The production status can be checked at the web
  address
• http//www.lnf.infn.it/esperimenti/lhcb/pri
  vate/mwpc/construction/php/BuildChamber.php
• we are trying to keep it updated on a
  weekly basis

9
Ferrara production rate
We expect to finish the M2R3 production at the
beginning of april
10
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 I _at_ 2.75kV
• Chamber 21 tested in Rome II _at_ 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

11
Gas leak and HV test in Ferrara
Dark current
Gas leak
Dark current is measured about 2 hours after
reaching 2.85 kV Gas leak is measured _at_ 5 mbar
of overpressure
12
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
13
Chamber production rate _at_ CERN

• 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

Pannelli M2R2 filati
Camere M2R2 prodotte
14
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.

15
Trasparenze di riserva
16
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

17
Requirements on MWPC
Panel planarity ? gas gap uniformity 95 panel
area in 90 mm (5 in 180 mm)
PANELS REJECTED 7
Distance wire plane - cathode plane PANELS
REJECTED negligible 2.5 mm 100 mm
Wire pitch 95 in 2 mm 50 mm (5 in 2 mm 100
mm) Wire tension 50 90 g
WIRES CHANGED lt 1
Tests on assembled chambers (results shown later
for each site)
Gas tightness DP lt 2 mbar/hr _at_ 5 mbar
overpressure
Partially-tested
Small dark current (lt 50 nA/chamber) _at_ 2.85-2.95
kV
Fully-tested
Gain uniformity G0/1.7 lt G lt G01.7 (in 100 of
each double-gap area) with respect to the
average gain G0.
The measure of the gas leakage, is obtained by
correcting the DP(t) behavior by using the data
of the reference chamber.
18
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 DP
of 5 mbar. Then, we record DP 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 DP(t) behavior by using the data
of the reference chamber.
19
Gas leakage test (II)
The measure of the gas leakage, is obtained by
correcting the DP(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.
The measure of the gas leakage, is obtained by
correcting the DP(t) behavior by using the data
of the reference chamber.
20
Wire pitch measurement (I)
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 requirement on the wire pitch (WP) is WP 2
mm 50 µm (95 of pitches) 100 µm (5 of
pitches)
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.
Sample image from scanning device
The measure of the gas leakage, is obtained by
correcting the DP(t) behavior by using the data
of the reference chamber.
21
Wire pitch measurement (II)
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.
The measure of the gas leakage, is obtained by
correcting the DP(t) behavior by using the data
of the reference chamber.
22
Wire Tension Measurement in FE
This method has been developed together with
Firenze and Roma II
The signal is sent to a PCs soundcard, a FFT is
applied and the fundamental frequency is
searched between 310 and 600 Hz (for M2R3 panels)
23
Wire Tension Measurement in FE
The measurement takes about 2 sec/wire (2 panels
1200 wires in 40 min)
24
Measurement of the gain uniformity
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.
The method used is similar in INFN and PNPI
sites. At CERN, where chambers are smaller, a
different method is used (see later).
Example of a result of the scan of a gap with
radioactive source
Y position in the gap
Current (nA)
The measure of the gas leakage, is obtained by
correcting the DP(t) behavior by using the data
of the reference chamber.
25
Test of CERN chambers with radioactive source
method

• All anodes connected together ? ADC ?Amplitude
  spectrum
• Cathode connected to the delay line ? TDC ? Pad
  location

ADC spectrum
Delay line output
Peak position of the signal induced by the gammas
of the 241Am
Time (ns)
26
Classification criteria on gain average and
uniformity
Testbeam oct. 03 2-GAP
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? DV 85 V
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
(? DV 50 V) B within a factor 1.7 (? DV
80 V) C not satisfying criteria A and B
Chamber class AA,AB,BA ? GOOD BB ?
RESERVE BC,CB,CC ?REJECTED