Gas Gain Monitoring e attivita’ all’ISR Status, problemi, organizzazione

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb 2008

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Gas Gain Monitoring e attivita’ Gas Gain Monitoring e attivita’ all’ISRall’ISR

Status, problemi, organizzazioneStatus, problemi, organizzazione

Stefano BiancoLaboratori Nazionali di Frascati dell’INFN

1. Status of ISR Closed Loop recirculation gas system

2. Gas Analyses3. Gas Gain Monitoring System

Tests and Integration4. Master Planning

https://twiki.cern.ch/twiki/bin/view/CMS/RpcGasGain


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1.STATUS OF ISR CLOSED LOOP1.STATUS OF ISR CLOSED LOOP(see Roberto Guida’s Talks in Twiki Page)(see Roberto Guida’s Talks in Twiki Page)

• Stable operation with 10% fresh mix during 2007Stable operation with 10% fresh mix during 2007– Up to 2 months filters lifetime with no currents increaseUp to 2 months filters lifetime with no currents increase

• August 2007 Freon supplier changed, air August 2007 Freon supplier changed, air contamination discovered and studied by Robertocontamination discovered and studied by Roberto– Manpower burden for purging new bottlesManpower burden for purging new bottles

• September 2007 new double gaps installed at ISRSeptember 2007 new double gaps installed at ISR• November-December 2007 new GC-MS arrived, November-December 2007 new GC-MS arrived,

commissioned, operated. commissioned, operated. • January 2008 one-year Technical Student for ISR January 2008 one-year Technical Student for ISR

Closed Loop (S.Colafranceschi, Frascati)Closed Loop (S.Colafranceschi, Frascati)• January - February 2008 problem of air intake in January - February 2008 problem of air intake in

Closed Loop, fixedClosed Loop, fixed• Now Closed Loop operational, restarted, currents Now Closed Loop operational, restarted, currents

are slowly increasingare slowly increasing


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1.STATUS OF ISR CLOSED LOOP1.STATUS OF ISR CLOSED LOOP(see Roberto Guida’s Talks in Twiki Page)(see Roberto Guida’s Talks in Twiki Page)

• Run with saturated filters till currents increase, then Run with saturated filters till currents increase, then regenerateregenerate

• Perform Gas analysis samplings between filters Perform Gas analysis samplings between filters regenerationsregenerations

• System operates correctly between System operates correctly between filters regenerationsfilters regenerations

• Currents increase was always Currents increase was always recovered by regenerating filters recovered by regenerating filters and/or switching to Open Modeand/or switching to Open Mode

• No permanent damage was ever No permanent damage was ever foundfound

• We use ISR as a unique tool to understand and optimize We use ISR as a unique tool to understand and optimize the chemistry of filtersthe chemistry of filters


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2.Gas analysis2.Gas analysisCONCLUSIONS AND OUTLOOK on analyses CONCLUSIONS AND OUTLOOK on analyses

• Presence of HF in system, and trace elements (metals, Presence of HF in system, and trace elements (metals, etc)etc)

• The system is very complex. Many different chemical The system is very complex. Many different chemical compositions in the system components. The presence compositions in the system components. The presence of F compounds in gas-mix damages some af them.of F compounds in gas-mix damages some af them.

• These results are preliminary. We need different These results are preliminary. We need different operating procedures for studying the filters kinetic and operating procedures for studying the filters kinetic and customize best desorbtion process.customize best desorbtion process.

• Although filters need to be chemically characterized, the Although filters need to be chemically characterized, the set-up currently used is able to operate correctly the set-up currently used is able to operate correctly the CMS-RPC detector. CMS-RPC detector.

• SEM-EDS analyses are currently in progress on bakelite SEM-EDS analyses are currently in progress on bakelite • We are setting up a new procedure for analyses on gas We are setting up a new procedure for analyses on gas

at ISRat ISR

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o Gas sampling and analysis at the ISR Gas sampling and analysis at the ISR Closed Loop performed by Roberto in the Closed Loop performed by Roberto in the past (see RPC07 Mumbai, January 2008)past (see RPC07 Mumbai, January 2008)

Observed production of HF and metallic trace Observed production of HF and metallic trace elements elements

o Ad-hoc sampling points setup by Roberto Ad-hoc sampling points setup by Roberto (before and after filters) (before and after filters)

o New sampling scheme (Saviano, Piga, New sampling scheme (Saviano, Piga, Ferrini)Ferrini)

Gas is bubbled in LiOH solution for a better Gas is bubbled in LiOH solution for a better absorption of pollutantsabsorption of pollutants

2. GAS SAMPLING AND ANALYSIS2. GAS SAMPLING AND ANALYSIS


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2. GAS SAMPLING AND ANALYSIS2. GAS SAMPLING AND ANALYSIS• Using LiOH solution reaction formula Using LiOH solution reaction formula

2LiOH2LiOH + Me + Me 2+2+ --> Me(OH) --> Me(OH)2 2 + 2Li+ 2Li++

• After sampling amount of LiOH solution will be analyzed by IC After sampling amount of LiOH solution will be analyzed by IC (Ionic Chromatograph) for F(Ionic Chromatograph) for F-- and other anions and the remnant and other anions and the remnant will be acidified with HNOwill be acidified with HNO33 and analyzed by ICP-AES (Inductive and analyzed by ICP-AES (Inductive Coupled Plasma- Atomic Emission Spectrometry) for metallic Coupled Plasma- Atomic Emission Spectrometry) for metallic cations cations – Ppm-sensitivity analyses (Univ. Roma) using IC and ICP-AESPpm-sensitivity analyses (Univ. Roma) using IC and ICP-AES

• Anions F-, S--, solfati, cloruri using IC at Univ. RomeAnions F-, S--, solfati, cloruri using IC at Univ. Rome• Metals at Ministry of industryMetals at Ministry of industry

• F- specific electrodes for HF accumulation measurements (INFN F- specific electrodes for HF accumulation measurements (INFN funded)funded)

• Tested in Frascati sampling procedure to avoid backdiffusion of Tested in Frascati sampling procedure to avoid backdiffusion of LiOH into Closed Loop, no big change in pH of HLiOH into Closed Loop, no big change in pH of H22O control flask, O control flask, analysis of Hanalysis of H22O in progress (ICP-AES)O in progress (ICP-AES)

• Now procuring sampling material (plastic flasks, tubing, etc) Now procuring sampling material (plastic flasks, tubing, etc)

LiOH

One-way valve

tubing foradditional filtering

Gas mix


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2. TEST IN FRASCATI2. TEST IN FRASCATI

• Tested in Frascati sampling procedure to avoid backdiffusion of Tested in Frascati sampling procedure to avoid backdiffusion of LiOH into Closed Loop.LiOH into Closed Loop.

• Li concentration, mg/l:Li concentration, mg/l:– flask 2 = 0.28 +- 0.06 mg/lflask 2 = 0.28 +- 0.06 mg/l– flask 4 = 0.22 +- 0.06 mg/lflask 4 = 0.22 +- 0.06 mg/l

• NO BACKWARDS DIFFUSION OF Li OBSERVEDNO BACKWARDS DIFFUSION OF Li OBSERVED

One-way valve

H2OLiOH

Gas mix

empty

H2O

31

2

4


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3.3.Gas Gain Monitoring System Gas Gain Monitoring System teststests

• System operational at ISR, working on System operational at ISR, working on integration with DCSintegration with DCS

• Tests on sensitivity of charge and Tests on sensitivity of charge and avalanche/streamer ratios for working avalanche/streamer ratios for working point changespoint changes

• Good sensitivity in avalanche-to-Good sensitivity in avalanche-to-streamer transition regionsstreamer transition regions

• Run with (0% SF6) --> (0.3% SF6) taken Run with (0% SF6) --> (0.3% SF6) taken at ISR last week, analysing resultsat ISR last week, analysing results

4 marzo 08Stefano Bianco (Frascati) - CMS RPC Italia Feb 2008 9

Preliminary studiesPreliminary studiesCosmic Rays charge distributionCosmic Rays charge distribution

PedestalAvalanche + Streamer

HV= 10.2 kV; HVeff=10.7 kV; Gate=100ns; T=22°C; RH=50%; 26 Oct2007

Streamer

cou

nts

ADC chpC

PedestalAvalanche

HV=9.4kV; HVeff=9.9kV; Gate=100ns; T=22°C ; RH=50%; 26 Oct2007

cou

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CMS RPC preliminary

CMS RPC preliminaryAvalanche threshold

pC

Avalanche threshold

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Preliminary studiesPreliminary studiesSensitivity of charge distribution to HV Sensitivity of charge distribution to HV (2/3)(2/3)

Inefficiency regionInefficiency regionavalanche

avalanche

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A very rough estimate of sensitivity A very rough estimate of sensitivity to working point changes in to working point changes in avalanche – streamer transitionavalanche – streamer transition

Working in the avalanche + Working in the avalanche + streamer region provides a streamer region provides a sensitivity of 1.25 pC/10 V sensitivity of 1.25 pC/10 V

CMS RPC preliminary

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100 pC

€

ΔQΔV

=1.25pC

10V=25channels

10V


Preliminary studiesPreliminary studiesSensitivity of charge distribution to HV Sensitivity of charge distribution to HV (3/3)(3/3)

Transition region pedestal toTransition region pedestal to

avalanche and avalanche toavalanche and avalanche to

streamer are sensitive to workingstreamer are sensitive to working

point changespoint changes

Blue curve avalanche yieldBlue curve avalanche yieldblack curve streamer yieldblack curve streamer yield

avala

nch

eavala

nch

e

Avalanche + streamerAvalanche + streamer

Inefficiency regionInefficiency region

CMS RPC preliminary

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ΔεΔV

=1.3%

10V


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Integration with DCSIntegration with DCS

• Yesterday CAEN SY1527 at ISR was Yesterday CAEN SY1527 at ISR was read by PVSS/DCS read by PVSS/DCS (S.Colafranceschi, thanks to (S.Colafranceschi, thanks to G.Polese helpdesk)G.Polese helpdesk)

CURRENTS MONITORPLOT HERE


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Master Planning V1Master Planning V1• 25/2 Closed Loop running with saturated filters25/2 Closed Loop running with saturated filters• 3/3 Currents start increasing3/3 Currents start increasing

– stop CLstop CL– regenerate filters, take samples of used filtersregenerate filters, take samples of used filters– restart CLrestart CL– Switch gaps to individual CAEN HV SY1527Switch gaps to individual CAEN HV SY1527

• 10/3 Giardoni, Pierluigi @ ISR10/3 Giardoni, Pierluigi @ ISR– Transport material (PC, gas sensor box, RAID backup, opt fiber)Transport material (PC, gas sensor box, RAID backup, opt fiber)– check air-tightness of 3 gas gain monitoring gaps, connect 3 gas gain monitoring gaps to check air-tightness of 3 gas gain monitoring gaps, connect 3 gas gain monitoring gaps to

closed loopclosed loop– Connect 5 large DG to HVConnect 5 large DG to HV

• 24/3 Currents start increasing Giardoni, Ponzio, Ferrini @ISR24/3 Currents start increasing Giardoni, Ponzio, Ferrini @ISR– stop CLstop CL– take samples of exausted filters, install new filters,take samples of exausted filters, install new filters,– install sampling flasks, install F- specific electrodesinstall sampling flasks, install F- specific electrodes– restart CL, start gas samplingrestart CL, start gas sampling

• 30/3 Benussi, Pierluigi @ ISR30/3 Benussi, Pierluigi @ ISR• 6/4 Benussi, Passamonti @ISR6/4 Benussi, Passamonti @ISR• 13/4 Benussi, Russo @ ISR13/4 Benussi, Russo @ ISR• 15/4 Currents start increasing15/4 Currents start increasing

– Stop CLStop CL– Take samples of used filters, regenerate filters, resume sampling 20/4 Benussi, Ponzio @ Take samples of used filters, regenerate filters, resume sampling 20/4 Benussi, Ponzio @

ISRISR

• 27/4 Bianco, Russo @ISR27/4 Bianco, Russo @ISR• May May

– Start Gas and filters sampling with individual purifiersStart Gas and filters sampling with individual purifiers

• May-June May-June – Install gaps at SGX5Install gaps at SGX5


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IssuesIssues• Installation of gas gain monitoring at SGX5Installation of gas gain monitoring at SGX5

– Gas Gain monitoring very useful at ISR now. Two-stage installation proposed:Gas Gain monitoring very useful at ISR now. Two-stage installation proposed:• Stage 0Stage 0

– Installing gaps with no integration racks, minimal operationInstalling gaps with no integration racks, minimal operation» Need basements, power, networkNeed basements, power, network» MAY - JUNEMAY - JUNE

• Stage 1Stage 1– Gas integration rackGas integration rack

» Negotiate cost with F.HahnNegotiate cost with F.Hahn» Time schedule ?Time schedule ?

• Integration with DCSIntegration with DCS– HV and current monitoring OKHV and current monitoring OK– Gain monitoring parameters to DCSGain monitoring parameters to DCS

• Event Header 5wordsEvent Header 5words• 8gaps * 10words/gap8gaps * 10words/gap• 1run=10k events = 1000s = 20min 1run=10k events = 1000s = 20min

– TOT ~ 100words/runTOT ~ 100words/run• PROPOSAL: RUN LOCALLY DAQ, write DST to file, access file via PVSS/DCS, load DCS PROPOSAL: RUN LOCALLY DAQ, write DST to file, access file via PVSS/DCS, load DCS

Database.Database. ADDITIONAL REQUESTSADDITIONAL REQUESTS

– Missioni estere, consumiMissioni estere, consumi


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CONCLUSIONSCONCLUSIONS• Closed Loop @ ISR showed how 10% fresh mix Closed Loop @ ISR showed how 10% fresh mix

operation is possible for several weeks between operation is possible for several weeks between filters regenerationsfilters regenerations

• Results on filters bakelite and gas show presence Results on filters bakelite and gas show presence of HF and trace elements (metals mainly) of HF and trace elements (metals mainly)

• System is complex (bakelite, gas, filters) and it is System is complex (bakelite, gas, filters) and it is being characterized by new gas analysesbeing characterized by new gas analyses

• Closed Loop for CMS RPC can be used at SX5Closed Loop for CMS RPC can be used at SX5• Full understanding of filter, gas, materials Full understanding of filter, gas, materials

chemistry in progress at ISR (six months-one chemistry in progress at ISR (six months-one year)year)

• DRAFTSDRAFTS– Gas filters bakelite analysis (90%)Gas filters bakelite analysis (90%)– CFD simulation of flux in small gaps (80%)CFD simulation of flux in small gaps (80%)– Gas Gain Monitoring gaps (10%)Gas Gain Monitoring gaps (10%)– High-statistics bakelite analysisHigh-statistics bakelite analysis


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CMS-ATLAS-OPERA CMS-ATLAS-OPERA collaborationcollaboration


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SPARESPARE


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Slow CtrlGC, p/T/RH/Ph

CMS

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SGX Bldg

RPC TRIG2RPC TRIG1

RPC TRIG4RPC TRIG3

RPC PAD REF2RPC PAD REF1

RPC PAD MON6RPC PAD MON5

REFERENCE half wheel lines

VENT

VENT

RPC PAD MON4

RPC PAD MON3RPC PAD MON2RPC PAD MON1MONITOR

VENT

Gas Gain Monitor (conceptual designGas Gain Monitor (conceptual design))

VENT

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Gas Gain Monitoring e attivita’ all’ISR Status, problemi, organizzazione

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