EP-DT
Detector Technologies
Strategies for reducing the
environmental impact of gaseous detector operation
at the CERN LHC experiments
Mar Capeans, Roberto Guida, Beatrice Mandelli
CERN
The 14th Vienna Conference on Instrumentations
16 February 2016
1
Outline
Green House Gas (GHG) Emission from particle detection at LHC
Reduction of GHG emission at LHC
- Gas Recirculation system
- Gas Recuperation system
- Achievements during LS1 and future expectations
Search for new environmentally friendly gases for particle detectors
- RPC operation with eco-friendly gases
Beatrice Mandelli
2
16 Feb 2016
GHG for particle detection at LHC
A greenhouse gas is any gaseous compound that is capable of absorbing
infrared radiation, thereby trapping and holding heat in the atmosphere
GWP 1430
GWP 5700
GWP 22200
GWP is a relative measure of
how much heat a greenhouse
gas traps in the atmosphere
SF6
9%
CF4
20%
C2H2F4
71%
Total GHG contribution
Beatrice Mandelli
3
16 Feb 2016
GHG for particle detection at LHC
A greenhouse gas is any gaseous compound that is capable of absorbing
infrared radiation, thereby trapping and holding heat in the atmosphere
GWP 1430
GWP 5700
GWP 22200
GWP is a relative measure of
how much heat a greenhouse
gas traps in the atmosphere
SF6
9%
CF4
20%
C2H2F4
71%
Total GHG contribution
Beatrice Mandelli
European Union “F-gas regulation”:
- Limiting the total amount of the most important F-gases that
can be sold in the EU from 2015 onwards and phasing them
down in steps to one-fifth of 2014 sales in 2030.
- Banning the use of F-gases in many new types of equipment
where less harmful alternatives are widely available.
- Preventing emissions of F-gases from existing equipment by
requiring checks, proper servicing and recovery of the gases
at the end of the equipment's life.
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16 Feb 2016
Where does the GHG emission come from?
C2H2F4
SF6
CF4
GHG emission in Run1 [%]
50
37.5
25
12.5
0
ATLAS
CMS
ALICE
LHCb
Very large
Detector volumes!
10-100 m3
Small
Detector volumes!
0.01 - 0.3 m3
Beatrice Mandelli
4
16 Feb 2016
Where does the GHG emission come from?
C2H2F4
SF6
Most of
the syste
ms
already r
ecirculat
e gas!
80
GHG emission in Run1 [%]
GHG emission in Run1 [%]
50
CF4
37.5
25
12.5
0
ATLAS
CMS
ALICE
60
40
20
0
LHCb
RPC
RICH 2
CSC
MWPC
GEM
Leaks in detectors
(ATLAS and CMS)
Very large
Detector volumes!
No recirculation
(ALICE MTR)
10-100 m3
Small
Detector volumes!
0.01 - 0.3 m3
Permeation to Air
(CMS)
No recirculation
(LHCb)
Beatrice Mandelli
4
16 Feb 2016
Gas Systems at the LHC experiments
Open mode operation
GAS MIXER
DETECTOR
12 LHC gas systems in open mode
Advantages:
- simple operation, flexibility
Disadvantages:
- potential source of high gas consumption
EXHAUST
Gas recirculation system
GAS MIXER
DETECTOR
13 LHC gas systems in closed mode
Advantages:
- reduction of gas consumption Disadvantages:
- complex systems
- constant monitoring (hardware and gas)
- sophisticated gas purifying techniques
EXHAUST
Gas recuperation plant
GAS MIXER
DETECTOR
5 LHC gas systems with gas recuperation
Advantages: - further reduction of gas consumption
Disadvantages:
- higher level of complexity
- dedicated R&D
EXHAUST
GAS
SEPARATION
Beatrice Mandelli
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16 Feb 2016
Gas recirculation systems
Thanks to gas recirculation GHG emission already reduced by > 90%!!!
Nevertheless…
-
85% of remaining emission still from gas recirculation systems… why?
- Large detector volumes and presence of detector leaks
-
15% of remaining emission from open mode gas systems
- Upgrade to gas recirculation!
Beatrice Mandelli
6
16 Feb 2016
Gas recirculation systems
GHG Emission [%]
Thanks to gas recirculation GHG emission already reduced by > 90%!!!
100
75
50
25
0
85-90% 90-95% 95-99% >99%
Gas recirculation efficiency
Nevertheless…
-
85% of remaining emission still from gas recirculation systems… why?
- Large detector volumes and presence of detector leaks
-
15% of remaining emission from open mode gas systems
- Upgrade to gas recirculation!
Beatrice Mandelli
6
16 Feb 2016
Gas recirculation systems: improvements
Improvements during LS1:
- ALICE MTR in gas recirculation
- C2H2F4-iC4H10-SF6 (89.7-10-0.3)
- 30% GHG reduction (4% wrt total emission)
- At maximum exploitation: 90% GHG reduction
-
Tuning of gas recirculation systems
- LHCb RICH1, RICH2, ALICE TOF, …
- 40% GHG reduction per system (2% wrt total emission)
-
Leak searches
Implementation of flexible gas recirculation unit
- Suitable for lab, test-beam, upgrades and R&D
applications
- 10% of GHG emission during LS1 came from
detector R&D and upgrades
Upgrades during YETS:
- LHCb GEM in gas recirculation
- Intense R&D needed
- It will pave the way for CMS GEM
- When fully operational: 90% GHG reduction
(6% wrt total emission)
Beatrice Mandelli
7
16 Feb 2016
Gas recirculation systems: improvements
Improvements during LS1:
- ALICE MTR in gas recirculation
- C2H2F4-iC4H10-SF6 (89.7-10-0.3)
- 30% GHG reduction (4% wrt total emission)
- At maximum exploitation: 90% GHG reduction
-
Tuning of gas recirculation systems
- LHCb RICH1, RICH2, ALICE TOF, …
- 40% GHG reduction per system (2% wrt total emission)
-
Leak searches
Implementation of flexible gas recirculation unit
- Suitable for lab, test-beam, upgrades and R&D
applications
- 10% of GHG emission during LS1 came from
detector R&D and upgrades
Upgrades during YETS:
- LHCb GEM in gas recirculation
- Intense R&D needed
- It will pave the way for CMS GEM
- When fully operational: 90% GHG reduction
(6% wrt total emission)
Beatrice Mandelli
7
16 Feb 2016
Gas recirculation systems: improvements
Improvements during LS1:
- ALICE MTR in gas recirculation
- C2H2F4-iC4H10-SF6 (89.7-10-0.3)
- 30% GHG reduction (4% wrt total emission)
- At maximum exploitation: 90% GHG reduction
-
Tuning of gas recirculation systems
- LHCb RICH1, RICH2, ALICE TOF, …
- 40% GHG reduction per system (2% wrt total emission)
- Suitable for lab, test-beam, upgrades and R&D
applications
- 10% of GHG emission during LS1 came from
detector R&D and upgrades
Upgrades during YETS:
- LHCb GEM in gas recirculation
- Intense R&D needed
- It will pave the way for CMS GEM
- When fully operational: 90% GHG reduction
(6% wrt total emission)
1.3
1.2
1.1
1
0.9
Normalized Gain
-
Leak searches
Implementation of flexible gas recirculation unit
Normalized Gain
-
1.3
recirculation
1.1 no purifiers
1.2
open mode
1
0.9
0.8
0.8
0.7
Open Mode0.7
Recirc 65%
Recirc 80%0.6
Recirc 90%0.5
Recirc 95%
Recirc 50%0.4
0.6
0.5
0.4
0.3
0
0.9
recirc
with purif
0.3 1.8
0
Open Mode
Recirc 65%
Recirc 80%
Recirc 90%
Recirc 95%
Recirc 50%
0.92.7
1.83.6
2.74.5
Integrated ChargeIntegrated
[mC/cm2] Ch
Beatrice Mandelli
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16 Feb 2016
Gas recirculation systems: complexity
Concentration in the Mixture [% Vol]
Destabilisation of the gas mixture
100
90
Ar
CF4
CO2
80
70
60
50
40
30
20
10
0
-200 -150 -100 -50
0
50
100 150 200
Time [min]
Creation and accumulation of impurities
Test at GIF
Gas recirculation systems are complex and
they need particular attention
Gas detector performance and operation
can be affected!
Beatrice Mandelli
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16 Feb 2016
Gas Recuperation system: CMS CSC example
If detectors permeable to Air
not possible to go high in recirculation!
Detector volume
Nominal Flow
90 m3
6 m3/h
Operating gas mixture CO2-Ar-CF4 50-40-10
Gas mixture
impurity limits
O2: 100 ppm
N2: 3000 ppm
Average O2 intake in
one gas replacement
300 ppm
Average N2 intake in
one gas replacement
1200 ppm
Fresh gas
replenishing rate
630 l/h
Beatrice Mandelli
9
16 Feb 2016
Gas Recuperation system: CMS CSC example
If detectors permeable to Air
not possible to go high in recirculation!
Detector volume
Nominal Flow
CF4 RECUPERATION
90 m3
6 m3/h
Operating gas mixture CO2-Ar-CF4 50-40-10
Gas mixture
impurity limits
O2: 100 ppm
N2: 3000 ppm
Average O2 intake in
one gas replacement
300 ppm
Average N2 intake in
one gas replacement
1200 ppm
Fresh gas
replenishing rate
630 l/h
Recuperation of CF4 with warm separation!
-
Innovative CF4 recuperation plant
- Complex, long R&D development (first attempt of warm separation)
- Impact today: 37% GHG reduction (4.6% wrt total emission)
-
Still needs optimisation of the CF4 separation process
- Future expectation: 50-60% GHG reduction (12% wrt total emission)
Beatrice Mandelli
9
16 Feb 2016
Gas Recuperation system: CMS CSC example
Phase 0:
CSC gas mixture
from the exhaust
Ar 63% Phase 1:
CO2 <1%
Absorption of CO2
CF4 37% CF4 bulk separation
Ar 40% CO2 50%
CF4 10%
Ar 65% CO2 ~ppm
CF4 35%
Phase 2:
Absorption of
remaining CO2
Phase 3a:
CF4 absorption
Currently recuperation efficiency ~ 50%
-
About 100 m3 of CF4 recuperated during Run 1
CF4 quality satisfactory
CSC detector operated with recuperated CF4 during LS1
- No change in the CSC performance observed
Beatrice Mandelli
10
Phase 3b:
CF4 extraction
Ar 10% CO2 ~ppm
CF4 90%
16 Feb 2016
GHG emission: achievements from Run1 to Run2
Best expectation after upgrade or
tuning of the system
GHG reduction:
achievements and expectation [%]
100
Two large systems
(RPC, CSC)
- Leak search
- CF4 recuperation
One large
system (RPC)
- Leak search
25
0
Beatrice Mandelli
Small systems
(RPC: TOF, MTR)
- Leak search
- MTR-RPC gas recirc
75
50
Small systems
(RICH, MWPC, GEM)
- GEM gas recirculation
from 2016
ATLAS
ALICE
CMS
11
LHCb
16 Feb 2016
Status of RPC systems for Run 2 and beyond
ATLAS and CMS RPC systems are the main contributors to GHG emission
-
Gas systems already in recirculation mode at the maximum possible rate allowed by
the present detector leaks
- Under study the possibility to tune the gas flow according to run periods
-
Detector leaks localised in few chambers but difficult to repair
After leak search campaign during LS1: 11% (ATLAS) and 6% (CMS) GHG reduction
(3% and 2.3% wrt total emission)
2%
1%
9%
9%
Even if leaks will be fixed,
what is the maximum recirculation rate
for safe RPC operation?
80%
RPC
CSC
GEM
MWPC
RICH
Is it possible to change
the gas mixture?
Beatrice Mandelli
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16 Feb 2016
New environmentally friendly gases
HFC phase down schedule
by Linde Group
HFC phase down
-
C2H2F4 is being
phased out by EU
- C2H2F4 and SF6 will
remain available for
research applications
- But price could raise…
Run 2
Run 4
Run 3
Hydro-Fluoro-Olefin (HFO)
C=C double bond
fluorine-containing
hydrogen-containing
HFO-1234yf (flam)
HFO-1234ze
(C3H2F4)
(C3H2F4)
GWP 4
GWP 6
Refrigerant properties of both HFOs are well known while
studies of ionisation processes in particle detectors just started…
Beatrice Mandelli
13
16 Feb 2016
Other possible environmentally friendly gases
Alternatives to C2H2F4 (GWP 1430):
Hydro-Fluoro-Carbon (HFC)
C-C bond
fluorine-containing
hydrogen-containing
HFC-245fa
HFC-32 (flam)
HFC-152a (flam)
(C3H3F5)
(CH2F2)
(C2H4F2)
GWP 1030
GWP 675
GWP 120
Alternatives to CF4 (GWP 5700) and SF6 (GWP 22200):
Beatrice Mandelli
Trifluoroiodomethane
HFB
(toxyc!)
(CF3I)
(C4F6)
(C3F6)
GWP <5
GWP 260
GWP <5
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16 Feb 2016
RPC performance with new freons
Direct replacement of C2H2F4 (or SF6) with HFOs:
Both HFOs substituted to C2H2F4, iC4H10 or
SF6 to study the properties of the new gas
mixture:
-
Mixer
R134a
iC4H10
GC/MS
MS
SF6
similar behaviour of the two HFOs
HFOs are much less electronegative than SF6
HFOs has less quencing effects than iC4H10
HFOs cannot directly replace C2H2F4
OV1
PPU
MS5A
R1234yf
RPC 1
HFOs and Argon mixtures:
scintillator
RPC 2
scintillator
Coincidence
Efficiency and Streamer Probability
IN
IN
1
x7
x7
OUT
0.9
0.8
TRG TRG
ATLAS-CMS gas mixture
0.7
R1234ze-Ar-iC4H10 74-21-5
R1234ze-Ar-iC4H10 52.2-42.5-5
0.6
0.5
0.4
RPC operation in avalanche mode
for ATLAS and CMS
- With Ar RPCs work in streamer
- Not suitable for LHC
0.3
-
0.2
0.1
0
8000
V1720
RPC 1 RPC 2
8600
9200
9800
10400
11000
RPC operation needs to consider
ATLAS-CMS requirements and
conditions
High Voltage [V]
Beatrice Mandelli
15
16 Feb 2016
Efficiency and Streamer Probability
RPC performance with new freons
More complex gas mixtures:
Addition of He:
- help in reduced the HV working point
- Not enough for streamer suppression
Addition of He and C2H2F4:
- 70% GWP reduced with respect to
standard gas mixture
- Good operation in avalanche mode
(suitable for LHC operation)
- Still a long R&D in front of us
1
0.9
0.8
0.7
ATLAS-CMS gas mixture
0.6
R1234ze-iC4H10-SF6 95.2-4.5-0.3
0.5
R1234ze-He-iC4H10-SF6 45.2-50-4.5-0.3
0.4
0.3
0.2
0.1
0
8000
8600
9200
9800
Further tests needed for
10400
11000
High Voltage [V]
Efficiency and Streamer Probability
- radiation hardness
- reactivity to detector and gas
components
- aging effects
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
8000
8600
9200
9800
10400
11000
High Voltage [V]
Beatrice Mandelli
16
16 Feb 2016
Conclusions
-
The current GHG emission is produced by few detector systems
- Constrains on operation conditions
- Leaks on detectors -
Gas systems well mastered
- All detectors using GHG are operated with gas recirculation systems
- Technologies to recuperate gas well established
-
R&D on gas and detector starting
- Intense R&D activities in the communities
- Summarise requirements for future detectors -
New environmentally friendly gases
- Different alternative for C2H2F4 have been identified and under test
- Investigate SF6 and CF4 replacements
- Preliminary results are encouraging for RPC but still a long way in front of us
Beatrice Mandelli
17
16 Feb 2016