1. Thomas Jefferson National Accelerator Facility Page 1 Hall B Drift Chambers Review, March 2007 George Jacobs Jefferson Lab Hall B 12 GeV Upgrade Drift Chamber Review Jefferson Lab March 6- 8, 2007 CLAS12 Drift Chambers Utilities and Support Systems

2. Thomas Jefferson National Accelerator Facility Page 2 Hall B Drift Chambers Review, March 2007 Drift Chamber Utilities and Support Systems The Drift Chamber Gas (DCGAS), Drift Chamber Low Voltage (DCLV), and Drift Chamber High Voltage (DCHV) systems are already in place with mature control, monitoring, and alarm subsystems. These systems will be USED in CLAS12 with minor modifications and upgrades.

3. Thomas Jefferson National Accelerator Facility Page 3 Hall B Drift Chambers Review, March 2007 CLAS DC Gas System Overview System consists of 2 separate mixing and storage systems System originally designed to mix 2 different gas mixtures Original design for Argon-Ethane and Helium-Ethane Current mix is 10% CO 2, 90% Argon in both Twin systems also provides redundancy System consists of 3 separate supply and pressure control systems System was originally designed to recirculate gas Current system exhausts to atmosphere Each region is separately monitored for contaminants System has active and passive safety controls Active controls isolate the detectors in case of high or low pressure Passive high capacity pressure relief bubblers attached to detector exhausts System designed to Fail Safe on loss of power

4. Thomas Jefferson National Accelerator Facility Page 4 Hall B Drift Chambers Review, March 2007 CLAS DC Gas – Mixing and Storage

5. Thomas Jefferson National Accelerator Facility Page 5 Hall B Drift Chambers Review, March 2007 MKS MFC based mixing system Panametrics TCU monitor the mix Calibration gases are used to match the mix Panametric moisture image monitors H 2 O Teledyne trace O 2 transmitters monitor O 2 MKS based pressure controls for DC Magnahelic based active safety system Bubbler based passive safety reliefs Fail Safe design on loss of power CLAS DC Gas Controls

6. Thomas Jefferson National Accelerator Facility Page 6 Hall B Drift Chambers Review, March 2007 Hall B Gas Shed

7. Thomas Jefferson National Accelerator Facility Page 7 Hall B Drift Chambers Review, March 2007 CLAS DC Gas Flow Paths

8. Thomas Jefferson National Accelerator Facility Page 8 Hall B Drift Chambers Review, March 2007 CLAS DC Gas Controls

9. Thomas Jefferson National Accelerator Facility Page 9 Hall B Drift Chambers Review, March 2007 CLAS DC Gas Hall Hardware

10. Thomas Jefferson National Accelerator Facility Page 10 Hall B Drift Chambers Review, March 2007 Current System Capacities R1 - 15 minutes at maximum flow rate (48 slm) R1 - 30 minutes standard flow (24 slm) R2 - 1.5 hours at maximum flow rate (90 slm) R2 – 2.25 hours at standard flow (60 slm) R3 – 3 hours at maximum flow rate (120 slm) R3 – 5 hours at standard flow (72 slm) CLAS DC Gas Volume Exchange Rate

11. Thomas Jefferson National Accelerator Facility Page 11 Hall B Drift Chambers Review, March 2007 EPICS DCGAS GUI CLAS DC Gas EPICS Interface

12. Thomas Jefferson National Accelerator Facility Page 12 Hall B Drift Chambers Review, March 2007 CLAS12 DC Gas Upgrade Complete System will be reused as is with minor plumbing mods required in the Hall 1) Relocate supply and exhaust manifolds in Hall 2) Run new piping to the manifolds from the hall gas panel 3) Run new piping from manifolds to the individual detectors in the Hall 4) Relocate the over and under pressure protection bubbler units New System Operating Parameters - CLAS12 gas volumes will be less than the current detectors for R2 and R3 - CLAS12 volume exchange rate for R2 and R3 will increase - CLAS12 volume exchange rate will decrease for R1 - CLAS12 R1 volume exchange time will increase to 1.25 hours - Gas flow capacity can be increased by adding pumps and/or adding parallel control valves Disconnect the gas lines from the old detectors and connect them to the new ones

13. Thomas Jefferson National Accelerator Facility Page 13 Hall B Drift Chambers Review, March 2007 CLAS DC Low Voltage DCLV supplies power to on chamber pre-amps HP6651 DC power supply rated at 8vdc 50amps LabView GUI based monitor and alarm system Very dependable Power supplies with only 1 crate failure in the 10+ years of operation

14. Thomas Jefferson National Accelerator Facility Page 14 Hall B Drift Chambers Review, March 2007 CLAS DC Low Voltage Monitoring System

15. Thomas Jefferson National Accelerator Facility Page 15 Hall B Drift Chambers Review, March 2007 The HP power supplies and GPIB monitoring equipment will be reused as is. No software changes are required for the LabView based monitor and alarm systems. Decrease channels per sector to 1344 reducing current to ~20 amps per sector Increase Segmentation to 1 fuse per 32 channels or 42 fuses per sector Reduce current per segment or fuse to <0.5 amps R3 DCLV is ready but R1 and R2 DCLV will require new distribution fuse boxes CLAS 12 conversion will require new DCLV cable runs from the fuse boxs to the patch panels on each sector. CLAS12 DC Low Voltage Upgrade

16. Thomas Jefferson National Accelerator Facility Page 16 Hall B Drift Chambers Review, March 2007 DCHV provides HV to the DC CLAS DCHV System consists of 3 CAEN System 527 HV Mainframes. System is controlled via a CAEN Network VME card using the DCHV GUI There are 10 HV modules per crate, 24 Channels per module, 40 micro-amps per channel 16 +HV and 16 -HV channels are available for each individual sector DCHV GUI allows for easy operations for ramping up and down the DCHV DCHV GUI permits operation of single sector, region, or channels DCHV GUI permits adjusting voltages, trip set points, ramp rates, etc CLAS DCHV – Drift Chamber High Voltage

17. Thomas Jefferson National Accelerator Facility Page 17 Hall B Drift Chambers Review, March 2007 CLAS DCHV Control GUI

18. Thomas Jefferson National Accelerator Facility Page 18 Hall B Drift Chambers Review, March 2007 CLAS DCHV Groups

19. Thomas Jefferson National Accelerator Facility Page 19 Hall B Drift Chambers Review, March 2007 R2 and R3 HV distribution panels can be used as is with new labels R1 requires new HV distribution panels to segment the HV channels Requires CAEN crate reprogramming for new group configurations CLAS12 DCHV – High Voltage Upgrade

20. Thomas Jefferson National Accelerator Facility Page 20 Hall B Drift Chambers Review, March 2007 CLAS12 Region I HV Patch Panel

21. Thomas Jefferson National Accelerator Facility Page 21 Hall B Drift Chambers Review, March 2007 CLAS12 Region I HV Patch Panel

22. Thomas Jefferson National Accelerator Facility Page 22 Hall B Drift Chambers Review, March 2007 CLAS R3 Repair

23. Thomas Jefferson National Accelerator Facility Page 23 Hall B Drift Chambers Review, March 2007 Summary  The required utilities, DCGAS, DCLV, and DCHV are already in place and require minimal modifications for the CLAS12 upgrade.  Systems have been refined and optimized over a decade of operation.  Controls and alarm systems are mature and have already been debugged.  The technical staff has many years of experience with these systems.  Trained system experts rotate for 24-7 on call support for these systems.