Transcript GEM Production in Helsinki

T2 GEM Production in
Helsinki
Kari Kurvinen 31.1.2006
TOTEM T2 EDR meeting
Radiation Detector Laboratory of Helsinki Institute of Physics (HIP) and
Department of Physical Sciences of University of Helsinki.
T2 GEM design
28 cm
• triple GEM foils
• Ar/CO2 70/30 gas mixture
• operating gas gain M = 8000
HV resistor divider board
• design by F.Sauli & L.Ropelewski
based on COMPASS GEM design
• GEM foils manufactured by CERN
• readout boards by CERN and a
commercial company
Test Cards
No bonding
anymore
READOUT
STRUCTURE
fully digital readout (no analog information used)
512 strips (pitch of 400 microns)
1560 pads (2x2 -> 7x7 mm2)
readout via connectors
XXX
support rails
radial strip
readout split
asymmetric
asymmetric spacers
HV
T2 GEM production in Helsinki
• construction of 40+ GEM detectors for TOTEM T2 is
on responsibility of the Helsinki group.
• a ”GEM production line” has been constructed in the
detector laboratory of HIP
• Compass GEM production as a guideline
(ref. M.Capean,
B.Ketzer, A.Placci,L.Ropelewski, F.Sauli, M.van Stenis; Construction of GEM
Detectors for the Compass Experiment, Technical Note TA1/00-03, CERNEP/TA1).
Facilities for
large GEM
production
oven for large foils
ultrasonic bath for large frames
dryboxes for leakage current
measurements and for storage
large area probe station
Production in clean rooms
• almost all the manufacturing phases in clean rooms.
• >120 m2 clean room (classes 100 & 1000) available.
• usage currently shared by TOTEM and ALICE groups.
service corridor
class 100
(20 m2)
component
testing TOTEM
manufacturing
TOTEM
used by ALICE
used by both
class 1000
(64 m2)
entrance
"coffee
room"
(15.5m2)
class 1000
(40.5m2)
Clean room monitoring
Particles
• temperature and humidity is continuously recorded as well
Main tasks in the production
I.
cleaning and varnishing of the frames.
II. glueing of the drift electrode.
III. streching and glueing of the GEM foils.
IV. testing the readout boards.
V. assembling all the parts together.
VI. assembling connectors (gas, HV).
VII. checking gas tightness.
VIII.electronic tests.
• Handling procedures of the separate detector
components are registered into a database.
• visual inspection
(coordinates of the major
defects recorded).
• optical scanning
• dried in a desiccator.
• 1. leakage current
measurements of all the
segments in the foils
(criteria <0.5 nA).
• streching and glueing on
the frames
• curing > 16 hours in oven
• cut out from the foil
• 2. leakage current
measurements
GEM FOILS
Leakage current measurements of GEM foils
• the four segments of the GEM foils are
measured separately by a picoamp meter.
•leakage currents measured three times during
assembly (as a bare foil, after framing and
after gluing into a stack).
36 measurement / detector
• a foil approved if current stays < 0.5 nA for 30+ min @500V
HV ramp up
in N2
> 5 min
in N2
C-segment
spark!
12 min
B-segment
Present status: 21 foils checked (incl. prototypes), 2 failed
12 min
READOUT BOARD
•
•
visual inspection
capacitance measurement
A.
B.
•
•
probe station & LCR meter
semiautomatic relay system
connectors soldered
short circuits burned
Assembling
components together
•
•
•
•
•
in clean room of class 100
all the three framed GEM
foils are glued one after
the other on the drift
frame (a special press
constructed).
consumption of the glue
measured.
3. leakage current of the
GEM foils checked after
gluing.
GEM stack glued on the
readout board.
Assembling connectors
gas tightness by
Araldite & Dow
Corning 1-2577
assembling:
i.
the voltage
divider PCB
ii. the adapters for
the gas connectors
and blocking the
holes on the
backside.
iii. HV cables
TESTS
•
•
GAS LEAKAGE TEST
ELECTRONIC TESTS
a. HV test in CO2 or N2
b. Basic measurement (gas amplification,
energy resolution)
c. Stability measurement
d. Gas gain scan over active area.
Gas tightness
TOOLS AVAILABLE
• comparison of inand outflow
• leak detector
• oxygen
measurement
from the outflow
Basic
measurements
of HG1
55Fe
Gas gain scan of
readout sectors
The gas gain of the whole readout sectors (128 strips or 120 pads) are measured.
Due to different capacitances of pad and strip sectors and a limitation of
preamplifier used the measurement may not be compared between pad and strip
sectors.
Gas gain scan with a
point source
•
•
Different areas of the second half
of the HG1 GEM were irradiated
by 55Fe source (50 points)
128 strips or 120 pads readout
Std.dev.:
on inner strips
on outer strips
on pads 8.1%
5.8%
10%
STATUS Jan. 2006
Prototypes
T2 GEMs
one for the beam test (Nov. 2004)
two built in Helsinki during 2005
•two built in Helsinki during 2005
• chambers for 3rd,4th and 5th
GEMs finished
Conclusions
• the radiation detector laboratory of
Helsinki has unique facilities to
assemble and test large area gaseous
detectors.
• a production of TOTEM T2 GEMs has
successfully started.