1. The RPC Closed loop Gas System Slides from Bianco and Guida

2. Schedule for completion Status Supplier: ok Mixer: ok Humidifier: ok Purifiers: installed, but not commissioned Pre-distribution and pump: ok Final distribution:ok (minor detail to fix) Status Supplier: ok Mixer: ok Humidifier: ok Purifiers: installed, but not commissioned Pre-distribution and pump: ok Final distribution:ok (minor detail to fix) Pending issues IR mixture analyzer still under test Flammable gas detection system not ready Piping heating in the shaft Pending issues IR mixture analyzer still under test Flammable gas detection system not ready Piping heating in the shaft Commissioning strategy Phase 1: flush argon in the system for one week and monitoring the performance (expected in 1 month) Phase 2: injecting the RPC mixture and start final commissioning (expected end of the year) Phase 3: RPC operation with high percentage of fresh mixture (from 50% to 30%) Commissioning strategy Phase 1: flush argon in the system for one week and monitoring the performance (expected in 1 month) Phase 2: injecting the RPC mixture and start final commissioning (expected end of the year) Phase 3: RPC operation with high percentage of fresh mixture (from 50% to 30%)

3. Test in progress Open issues Purification cycle Effectiveness of the purification Fresh mixture percentage Stability of the system Open issues Purification cycle Effectiveness of the purification Fresh mixture percentage Stability of the system The RPC test site at ISR has been converted to a site for study the closed loop operation Few gaps equivalent to 5 RPCs under test with a closed loop prototype system. More gaps will arrive soon All the detectors are inside a hut with temperature and humidity kept at controlled values The mixture composition and quality are continuously monitored by means of a gas chromatograph The RPC test site at ISR has been converted to a site for study the closed loop operation Few gaps equivalent to 5 RPCs under test with a closed loop prototype system. More gaps will arrive soon All the detectors are inside a hut with temperature and humidity kept at controlled values The mixture composition and quality are continuously monitored by means of a gas chromatograph Gas recirculation Open mode

4. Recent results New cycle started on July 25 th Gas flow: 1 volume/2.5 h Fresh mixture injection: 30 % Gas quality checked every day with a GC System stable for about one month New cycle started on July 25 th Gas flow: 1 volume/2.5 h Fresh mixture injection: 30 % Gas quality checked every day with a GC System stable for about one month But aside problem: “air” (may be others) contaminant in the R134a cylinders Next step: start a new cycle decreasing the % of fresh mixture to 20

5. 10 R134a cylinders analyzed since July 15 th with the Gas Chromatograph: 5 cylinders < 500 ppm vol “air” 5 cylinders >> 10000 ppm vol “air” 10 R134a cylinders analyzed since July 15 th with the Gas Chromatograph: 5 cylinders < 500 ppm vol “air” 5 cylinders >> 10000 ppm vol “air” R134a cylinder impurities “air” concentration in one cylinder analyzed while purging Acceptable limit (500 ppm) Purged volume More impurities? Under investigation CERN gas supplier changed in March!! Need help of CERN

6. PURIFIERS Sampling taken on unused material, after use and after regeneration GAS Sampling taken in various conditions before and after purifiers PURIFIERS Sampling taken on unused material, after use and after regeneration GAS Sampling taken in various conditions before and after purifiers Chemical analysis Study the effectiveness of the regeneration: the procedure does not have effect on Fluride ions. Need to understand the lifetime of the filter Study the effectiveness of the regeneration: the procedure does not have effect on Fluride ions. Need to understand the lifetime of the filter Detailed CMS note in preparation. See also IEEE NSS, San Diego (USA), October 2006 Frascati preprint LNF-06/34 (P)

7. Gas quality monitoring by means of twelve 50cm x 50cm gaps with pad readout in a cosmic telescope. Under test at ISR knee +200 -200 @ GT Gas gain monitoring system

8. Possible scenario: Start with a70% re-circulation for the first month Go to 80 % re-circulation for the second month Go to 90 % re-circulation for third and fourth month Total cost: ~ 200 kCHF Include some contingency: 200 k < RPC gas < 300 k Possible scenario: Start with a70% re-circulation for the first month Go to 80 % re-circulation for the second month Go to 90 % re-circulation for third and fourth month Total cost: ~ 200 kCHF Include some contingency: 200 k < RPC gas < 300 k Gas cost estimation for a four months run (3 weeks per month) 1 vol/3h 18 m 3 Gas cost estimation for a four months run (3 weeks per month) 1 vol/3h 18 m 3 A start up scenario

9. There is no doubt that the RPC gas system is complex and it represents one of the key tools for the system operation At the start up some learning period will be necessary to bring the system to a stable state In 2008 low luminosity and “presumably” short running period (!!) We have one year work to setup the system and understand operation conditions Combined ATLAS CERN CMS effort Keep level of attention high, but no panic There is no doubt that the RPC gas system is complex and it represents one of the key tools for the system operation At the start up some learning period will be necessary to bring the system to a stable state In 2008 low luminosity and “presumably” short running period (!!) We have one year work to setup the system and understand operation conditions Combined ATLAS CERN CMS effort Keep level of attention high, but no panic Final remarks