Survivability issues
TGC
Extreme
Operation
conditions
Gas
Gas Gain
Voltage
Safety
margin at
working
conditions
Comments
MDT
Comments
RPC
Comments
MMGAS
Comments
Total 14 KHz, 10 years, 107 sec each year,
Charged particles 300 Hz cm^2 (from CSC measurement 10Hz/cm^2 at 3*10^33
Photons
Neurons -3.105 cm2/s ?
Temperature variation inside the cavern ~3o (equivalent to 1% of voltage variation)
nAr/CO2
C2H2F4/IsoControl is
Ar/CO2
C5H12/CO2
93/7
C4H10/SF6
critical but
93/7
45/55
94.7/5/0.3
OK for
some H2O
present
required.
system of the
concentration
s.
6
4
10
OK
2*10
8 pC/mip
3 pC/photon
Can be factor 5*103-2*104
Saturation
????
~2 pC MIP
of 3 less.
1 pc/MIP
Op. voltage OK
Op. voltage:
Op. voltage:
Op. voltage:
2900V
2730 V
6000V
520V.
Margin:
Margin:
Margin: >1000V
Margin:
>600 V?
+ 60 V
~40 V
Final?
Working
point not
chosen yet
Spark rate
changes by
factor of 20
in the gas
gain range
Max
1.4 C/cm2
(expect.)
collected
charge at
max gain
Test carried Up to 10
out
C/cm2
Expected
spark rate
0 (if
everything
is normal)
Neutron
response
Sensitivity
1*10-3
Charge:
~50 pC (30
times more
than MIP)?
Small
volumes.
Gas
exchange
rate critical
3.6 C/cm
14*103*30*1012*10*107 = 4.5
C/cm2
Test is going
on0.025C/cm/d
Up to 1.3
C/cm now
Tested up to
0.3 C/cm
More tests
required
particularly
with new
material
0 (if
everything is
OK)
Spark/Self
limited streamer
with charge
factor 7-8 higher
than nominal
signal
Streamer
probability
~1% for
+1000 V to
nominal
Sensitivity
10-3
Charge factor
7-8 higher than
nominal signal
Total charge
<25% of that
from photons
More
Sensitivity
information? ~ 5 * 10-4
Charge:
~ 10 * MIP
No problem
But cross
talk in
~ 0.25
C/cm2
X-ray
Tested up to
~0.36
C/cm2.
Test in
reactor with
1.2 x 10^14
n/cm2 (20
years sLHC)
~<1Hz/cm2
Sensitivity
~5*10-4
Spark
probability
10-8 per
neutron for
GG 104
Some other
chambers
operated up
to 2 C/cm2
Accumulated
charge per
cm2 might
be more
than from
normal
avalanche
What?
Tested
seems OK
Photon
response
Main
concern
Probability
~ 10-2 ?
Charge ~5
pC
1. Main ageing tests
done for small
chambers.
2. Conditions of the
ageing test can be
critical
3. Stagnation of the
gas or small volume
exchange rate in
some parts of the
chamber can lead to
damage
4. Irradiation
products
accumulated in the
chambers can be a
real problem. Large
scale long term
tests are critical for
the chamber design.
present
electronic in
8 channels
Probability:
~ 8 * 10-3
Charge:
~ 2 * MIP
1. Control of the
production process
and validation of
the production
batches
2. Gas system must be
validated and new
coming parts have
to be validated
before installation.
Both issues are well
recognized and
understood. Extensive
experience from MDT
chamber construction.
Probability:
~ 10-2
Charge: 1.5 MIP
~ 2 * MIP
Ageing tests done for doses
almost 10 times less than
expected:
Major problems:
1. General behavior of the
resistive coating (both
after normal operation
and after a total number
of streamers with
significant safety
margin)? Resistivity
evolution?
2. Full scale prototype tests
at different operation
conditions.
3. If rate*charge is
significantly larger than
for the LHC chambers
dedicated studies for
Fluorine radical (HF)
effects must be done
4. Noise increase due to
??
1. If gas gain not chosen
one shell carry out the
tests at maximum
expected one.
2. Although ageing is
not expected still the
tests should be
carried out with a
large chamber size.
Any gas stagnations
effects?
3. The main concern is a
behavior of the
resistive coating.
4. An exact deposition
process and material
composition have to
be finalized and The
test with total number
of accumulated sparks
with significant safety
high rate (old chamber 1
kHz/cm2)?
5. Flow rate VS particle rate
-> stability is sensitive to
this
6. Surface defects & small
gap in mass production?
7. Gas flow uniformity &
small gap.
margin has be done
with large scale
prototype.
5. Some constrains on
the temperature
gradients over the
chambers
6. Production of large
chambers and
industrialization
For all technologies irradiation test facility for large scale detectors with rate
up to 30-40 KHz/cm2 is urgently required.