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  1. Gamma Irradiation Facility (GIF) RPC Gas System 2009 Summer Updates- Summer Student Report Emine Altuntas Stephen Fee Supervisors: Mar Capeans, Ivan Glushkov, Roberto Guida

  2. GIF Humidity and Temperature Control System – The Tent Current Status Inside The GIF • Construction and operation of the tent • Purpose of tent: - Controlled environment for temperature and humidity for the chambers • Achieved by temperature and humidity control devices • Conditions monitored by measurement devices in the tent • Tent is now sealed and operational at the GIF! 2.5 m 2 m 2 m

  3. GIF Humidity and Temperature Control System – The Tent Current Status Inside The Tent

  4. GIF Irradiation positioning Safety zone ATLAS Tent Old position Safety zone RPC Tent ATLAS Tent Desired position

  5. GIF Humidity and Temperature Control System – The Tent • Air conditioner - • Control of Temperature and Dehumidification (but not to setpoint) • Dehumidifier - Dehumidification (not to setpoint) • Both are protected by lead shielding • Current conditions in tent are approximately 40 %RH to 50 %RH, temperature of 20 °C • Maintained at this state by the dehumidifier and air conditioning • Limitations: the devices cannot be controlled remotely, no set point for humidity

  6. GIF Humidity and Temperature Control System – The Tent Measurement Devices in Tent - Hygrometer gives measurement of temperature and humidity in the tent - No need to protect from radiation – mechanical device - Needs regular checks for ink and paper changing Hygrometer • Weather station records live data to a PC in the GIF • - This data can be accessed remotely at any time Conclusion: We now have a system to control and measure the temperature and humidity for the chambers WeatherStation

  7. Checklist for the GIF - RPC Gas System • The RPC gas system checklist is completed every day. • A hard copy of each day’s checklist as well as an excel file record is kept for future data analysis. • In addition to the points shown here the supply mixture peak areas and the MS vacuum quality concentration units are recorded. • The supply mixture peak area and concentration values can be found at https://twiki.cern.ch/twiki/bin/view/LHCgas/GCMS. • With the transition to the closed loop configuration new check points need to be added. • A log file is added to each day’s GC-MS analysis folder at the GIF. • Thus data collection process can be followed more accurately in the future. Open mode Closed loop

  8. Checklist for the GIF - RPC Gas System • Right now the gas mixture is analyzed with the MS-GC every day at 6 different points: • Supply gas mixture to the open loop • Return gas mixture from the open loop • After MS5A purifier in the closed loop • After NiAl purifier in the closed loop • After R11 in the closed loop • The return mixture after all the purifiers in the closed loop

  9. GIF Gas System - Leak Hunt • Originally in the gas system, flow in ≠ flow out. More than 50% of gas was missing • Does not represent closed loop conditions, and costs money • Leaks suspected in the system

  10. Leak detection GIF Gas System - Leak Hunt • Firstly general gas detector and a Freon gas detector were used on the whole system • These devices identified many leaks in the system • Connection points, Teflon tape • Solution: Tightening of connections, replace tape, assistance from technicians • Still many leaks remained…

  11. Helium Leak Detector GIF Gas System - Leak Hunt • Procedure: • Run the system with 5% Hydrogen in nitrogen • Hydrogen will be released at high rate through the smallest leaks (small molecular size) • The detector was found to be very specific and accurate in the leak detection • Leaks were then fixed, the system is now running with no major leaks Conclusion: The helium leak detector is much more specific and faster than other methods and should be used for future leak detection

  12. Purifiers and Regeneration • The Purifiers Tested At the GIF • The open loop purifiers Molecular Sieve 3A, 4A, 5A NiAl, NiSi, R11, R12, SiGel 2 l cartridges • The closed loop purifiers Cartridge 1 (big one): 90 % MS4A + 10% MS5A Cartridge 2 (small one): R11 Cartridge 3 (small one): NiAl • The concentration levels of H2O and O2 are analyzed in every data collection. • Over time the sieves of each purifier become clogged. And purifiers do not perform at the desired level. • The increase in the tendencies of H2O and O2 levels indicate the need for regeneration.

  13. Purifiers and Regeneration • Regeneration Process Gas System Rack Gas flow control rack The heat controller Regenerator

  14. Purifiers and Regeneration • Regeneration Process • Inside the toaster the purifiers have been heated to 230 C • Each purifier is flushed with a standardized mixture of argon and 5% hydrogen. • In the case of MS4A and MS5A, as the purifier is heated the opening of the sieves increase. • As the purifier is flushed with gas, the molecules stuck between the sieves are removed. • Each purifier is regenerated for fourteen hours. • After the heat is turned down each purifier is flushed with the standardized gas mixture for another four hours.

  15. Purifiers Table

  16. GIF - RPC Gas System Checklist Data Analysis • Purpose – To acquire comprehensive and comparative graphs of the recorded values over time for further analysis • Method: The ISR RPC gas system checklist code is taken as the start point. • With the updates the current code; • Reads data records from the checklist excel file • The output graph files are recorded in the analysis folder • Each data entry is assigned to representative holder • Min and max finding for constructing the graphs

  17. GIF - RPC Gas System Checklist Data Analysis • With the updates the current code; • A comparative graph of active zone & open loop mixture temperature and RH values • A graph displaying the change in the current over time in each channel • The percentage deviation from the average current in each channel • Fresh gas mixture composition

  18. Air Calibration Report • Air calibration required to assist on ongoing gas measurements at the GIF • Aim: To achieve calibration for main components of air, plus additional components detected • Procedure: Analyse a known concentration of component using the GC-MS device • Result: The peak area can then be equated to the known concentration

  19. Air Calibration ReportOxygen Calibration • Achieved by analysing atmospheric air (21 %v/v oxygen) and bottle of 50 ppm oxygen in argon • Oxygen presents in module C (molecular sieve) of the GC (cannot separate air in modules A or B) • Oxygen could not be isolated from the 50 ppm analysis: Argon and oxygen peaks present at the same time • The calibration is thus based on analysis of air only

  20. Air Calibration Report Nitrogen Calibration Carbon Dioxide Calibration • Achieved by analysing atmospheric air, 78 %v/v Nitrogen • Nitrogen presents in module C (molecular sieve) of the GC (cannot separate air in modules A or B) • Achieved by analysing atmospheric air • CO2 presents in module B (PPU) of the GC • The concentration of CO2 in atmospheric air is taken to be 0.0383 % v/v for the calibration calculations.

  21. Air Calibration ReportWater Calibration • The two results are not in agreement. • Reason : The air analysis is not guaranteed to be accurate due to the possibility of change in the absolute humidity of the sample. This is because of the discrepancy between atmospheric pressure and GC carrier gas pressure. • Thus the calibration is based on 110ppm water in argon analysis • Achieved by analysing atmospheric air and bottle of 110 ppm water in argon • Water presents in module B (PPU) of the GC Ratio of peak area to concentration for air analysis = 1.35 Ratio of peak area to concentration for 110 ppm analysis = 10.07 Water peak from air • Water peak from 110 ppm analysis

  22. Air Calibration ReportArgon Calibration • Achieved by analysing bottle of (almost 100%) argon • Argon presents in modules A & B of the GC

  23. Air Calibration Report Conclusions • Calibration now available for the components of air:

  24. Looking Ahead • The existing checklist needs to updated with the addition of closed loop parameter readings • Such as, the closed loop temperature and humidity values • It is necessary to complete and test the ROOT checklist analysis code • For purifiers, regeneration is essential to be conducted without stopping the system and interrupting the data collection • Thus a similar setup to the one existing at LHC may be considered – of course taking into account time scale of this update and costs • The F- production rate to be studied • Hanna double channel analysis station • MS-GC software problems • The temperature and humidity control to be established for a long time in the tent – • no short term fluctuations • recording of values

  25. Acknowledgements • Experience with C++ and ROOT • Introduction to the gas systems • The physics behind the RPC’s and RPC performance issues • Other elements on RPC selection • MS – GC analysis procedure • Experience with MS – GC software integration techniques • Lectures by leading physicists in the field • Trips to the LHC experiments • Thanks for all the support • And assistance • And discussions - explanations • And fun conversations

  26. Personal Thoughts… • The aims are challenging since: • Many impurities • Varying concentrations • Some concentrations very low = difficult to remove • Unknown effects on the chambers Good Luck!

  27. Acknowledgements and Thanks • New experiences: • CERN • RPC • Working with radiation • Analysis methods and data analysis • Outcomes: • Experience in international working environment • Further knowledge and experience in important areas • Looks great on my C.V.! Thanks and please continue!