4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Gas Gain Monitoring e attivita’ all’ISR Status, problemi, organizzazione Stefano Bianco Laboratori Nazionali di Frascati dell ’ INFN 1.Status of ISR Closed Loop recirculation gas system 2.Gas Analyses 3.Gas Gain Monitoring System Tests and Integration 4.Master Planning

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb STATUS OF ISR CLOSED LOOP (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 increase August 2007 Freon supplier changed, air contamination discovered and studied by RobertoAugust 2007 Freon supplier changed, air contamination discovered and studied by Roberto –Manpower 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, commissioned, operated.November-December 2007 new GC-MS arrived, commissioned, operated. January 2008 one-year Technical Student for ISR Closed Loop (S.Colafranceschi, Frascati)January 2008 one-year Technical Student for ISR Closed Loop (S.Colafranceschi, Frascati) January - February 2008 problem of air intake in Closed Loop, fixedJanuary - February 2008 problem of air intake in Closed Loop, fixed Now Closed Loop operational, restarted, currents are slowly increasingNow Closed Loop operational, restarted, currents are slowly increasing

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb STATUS OF ISR CLOSED LOOP (see Roberto Guida’s Talks in Twiki Page) Run with saturated filters till currents increase, then regenerateRun with saturated filters till currents increase, then regenerate Perform Gas analysis samplings between filters regenerationsPerform Gas analysis samplings between filters regenerations System operates correctly between filters regenerationsSystem operates correctly between filters regenerations Currents increase was always recovered by regenerating filters and/or switching to Open ModeCurrents increase was always recovered by regenerating filters and/or switching to Open Mode No permanent damage was ever foundNo permanent damage was ever found We use ISR as a unique tool to understand and optimize the chemistry of filtersWe use ISR as a unique tool to understand and optimize the chemistry of filters

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Gas analysis CONCLUSIONS AND OUTLOOK on analyses Presence of HF in system, and trace elements (metals, etc)Presence of HF in system, and trace elements (metals, etc) The system is very complex. Many different chemical compositions in the system components. The presence of F compounds in gas-mix damages some af them.The system is very complex. Many different chemical compositions in the system components. The presence of F compounds in gas-mix damages some af them. These results are preliminary. We need different operating procedures for studying the filters kinetic and customize best desorbtion process.These results are preliminary. We need different operating procedures for studying the filters kinetic and customize best desorbtion process. Although filters need to be chemically characterized, the set-up currently used is able to operate correctly the CMS-RPC detector.Although filters need to be chemically characterized, the set-up currently used is able to operate correctly the CMS-RPC detector. SEM-EDS analyses are currently in progress on bakeliteSEM-EDS analyses are currently in progress on bakelite We are setting up a new procedure for analyses on gas at ISRWe are setting up a new procedure for analyses on gas at ISR G.SAVIANO RPC07 MUMBAI

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb oGas sampling and analysis at the ISR Closed Loop performed by Roberto in the past (see RPC07 Mumbai, January 2008)  Observed production of HF and metallic trace elements oAd-hoc sampling points setup by Roberto (before and after filters) oNew sampling scheme (Saviano, Piga, Ferrini)  Gas is bubbled in LiOH solution for a better absorption of pollutants 2. GAS SAMPLING AND ANALYSIS

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb GAS SAMPLING AND ANALYSIS Using LiOH solution reaction formulaUsing LiOH solution reaction formula 2LiOH + Me 2+ --> Me(OH) 2 + 2Li + After sampling amount of LiOH solution will be analyzed by IC (Ionic Chromatograph) for F - and other anions and the remnant will be acidified with HNO 3 and analyzed by ICP-AES (Inductive Coupled Plasma- Atomic Emission Spectrometry) for metallic cationsAfter sampling amount of LiOH solution will be analyzed by IC (Ionic Chromatograph) for F - and other anions and the remnant will be acidified with HNO 3 and analyzed by ICP-AES (Inductive Coupled Plasma- Atomic Emission Spectrometry) for metallic cations –Ppm-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 funded)F- specific electrodes for HF accumulation measurements (INFN funded) Tested in Frascati sampling procedure to avoid backdiffusion of LiOH into Closed Loop, no big change in pH of H 2 O control flask, analysis of H 2 O in progress (ICP-AES)Tested in Frascati sampling procedure to avoid backdiffusion of LiOH into Closed Loop, no big change in pH of H 2 O control flask, analysis of H 2 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 for additional filtering Gas mix

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb TEST IN FRASCATI Tested in Frascati sampling procedure to avoid backdiffusion of LiOH into Closed Loop.Tested in Frascati sampling procedure to avoid backdiffusion of LiOH into Closed Loop. Li concentration, mg/l:Li concentration, mg/l: –flask 2 = mg/l –flask 4 = mg/l NO BACKWARDS DIFFUSION OF Li OBSERVEDNO BACKWARDS DIFFUSION OF Li OBSERVED One-way valve H2OH2OLiOH Gas mix empty H2OH2O

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Gas Gain Monitoring System tests System operational at ISR, working on integration with DCSSystem operational at ISR, working on integration with DCS Tests on sensitivity of charge and avalanche/streamer ratios for working point changesTests on sensitivity of charge and avalanche/streamer ratios for working point changes Good sensitivity in avalanche-to-streamer transition regionsGood sensitivity in avalanche-to-streamer transition regions Run with (0% SF6) --> (0.3% SF6) taken at ISR last week, analysing resultsRun with (0% SF6) --> (0.3% SF6) taken at ISR last week, analysing results

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Preliminary studies Cosmic Rays charge distribution Pedestal Avalanche + Streamer HV= 10.2 kV; HV eff =10.7 kV; Gate=100ns; T=22°C; RH=50%; 26 Oct2007 Streamer counts ADC ch pC Pedestal Avalanche HV=9.4kV; HV eff =9.9kV; Gate=100ns; T=22°C ; RH=50%; 26 Oct2007 counts ADC ch CMS RPC preliminary Avalanche threshold pC Avalanche threshold L.BENUSSI RPC07 MUMBAI

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Preliminary studies Sensitivity of charge distribution to HV (2/3)‏ Inefficiency region avalanche Avalanche + streamer A very rough estimate of sensitivity to working point changes in avalanche – streamer transition Working in the avalanche + streamer region provides a sensitivity of 1.25 pC/10 V CMS RPC preliminary L.BENUSSI RPC07 MUMBAI 100 pC

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Preliminary studies Sensitivity of charge distribution to HV (3/3)‏ Transition region pedestal to avalanche and avalanche to streamer are sensitive to working point changes Blue curve avalanche yield black curve streamer yield avalanche Avalanche + streamer Inefficiency region CMS RPC preliminary L.BENUSSI RPC07 MUMBAI

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Integration with DCS Yesterday CAEN SY1527 at ISR was read by PVSS/DCS (S.Colafranceschi, thanks to G.Polese helpdesk)Yesterday CAEN SY1527 at ISR was read by PVSS/DCS (S.Colafranceschi, thanks to G.Polese helpdesk) CURRENTS MONITOR PLOT HERE

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Master 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 CL – regenerate filters, take samples of used filters –restart CL –Switch gaps to individual CAEN HV SY /3 Giardoni, ISR10/3 Giardoni, ISR –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 closed loop –Connect 5 large DG to HV 24/3 Currents start increasing Giardoni, Ponzio, Currents start increasing Giardoni, Ponzio, –stop CL –take samples of exausted filters, install new filters, –install sampling flasks, install F- specific electrodes –restart CL, start gas sampling 30/3 Benussi, ISR30/3 Benussi, ISR 6/4 Benussi, Benussi, 13/4 Benussi, ISR13/4 Benussi, ISR 15/4 Currents start increasing15/4 Currents start increasing –Stop CL –Take samples of used filters, regenerate filters, resume sampling 20/4 Benussi, ISR 27/4 Bianco, Bianco, MayMay –Start Gas and filters sampling with individual purifiers May-JuneMay-June –Install gaps at SGX5

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb Issues 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: Stage 0Stage 0 –Installing gaps with no integration racks, minimal operation »Need basements, power, network »MAY - JUNE Stage 1Stage 1 –Gas integration rack »Negotiate cost with F.Hahn »Time schedule ? Integration with DCSIntegration with DCS –HV and current monitoring OK –Gain monitoring parameters to DCS Event Header 5wordsEvent Header 5words 8gaps * 10words/gap8gaps * 10words/gap 1run=10k events = 1000s = 20min1run=10k events = 1000s = 20min –TOT ~ 100words/run PROPOSAL: RUN LOCALLY DAQ, write DST to file, access file via PVSS/DCS, load DCS Database.PROPOSAL: RUN LOCALLY DAQ, write DST to file, access file via PVSS/DCS, load DCS Database.  ADDITIONAL REQUESTS  ADDITIONAL REQUESTS –Missioni estere, consumi

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb CONCLUSIONS Closed ISR showed how 10% fresh mix operation is possible for several weeks between filters regenerationsClosed ISR showed how 10% fresh mix operation is possible for several weeks between filters regenerations Results on filters bakelite and gas show presence of HF and trace elements (metals mainly)Results on filters bakelite and gas show presence of HF and trace elements (metals mainly) System is complex (bakelite, gas, filters) and it is being characterized by new gas analyses System is complex (bakelite, gas, filters) and it is being 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 chemistry in progress at ISR (six months-one year)Full understanding of filter, gas, materials chemistry in progress at ISR (six months-one year) DRAFTSDRAFTS –Gas filters bakelite analysis (90%) –CFD simulation of flux in small gaps (80%) –Gas Gain Monitoring gaps (10%) –High-statistics bakelite analysis

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb CMS-ATLAS-OPERA collaboration

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

4 marzo 08 Stefano Bianco (Frascati) - CMS RPC Italia Feb USC5UXC5 C 2 H 2 F 4 /SF 6 /i-C 4 H 10 /H 2 O Slow Ctrl GC, p/T/RH/Ph CMS VENT PURIFIERS SGX Bldg RPC TRIG2 RPC TRIG1 RPC TRIG4 RPC TRIG3 RPC PAD REF2 RPC PAD REF1 RPC PAD MON6 RPC PAD MON5 REFERENCE half wheel lines VENT RPC PAD MON4 RPC PAD MON3 RPC PAD MON2 RPC PAD MON1 MONITOR VENT Gas Gain Monitor (conceptual design ) VENT