1. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS12 Drift Chamber Construction - Mac Mestayer Technical Details of Construction —buy endplates —build “box” —insert feedthroughs —string chambers Cost and Schedule

2. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS12 Drift Chambers Design: same concept as present chambers: NIM A449(2000)81 6 sectors, 3 regions 18 drift chambers 24192 sense wires drift chambers

3. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Endplates: many precise holes Number of Holes 4925 feedthrough holes 12 survey 3 datum & alignment 28 bolt & attachment 1.7 m First Order Placed -due back in March -large, modern milling machine

4. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Endplate Details 0.200 mm true position  “50  m”

5. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Endplates fit into Frames Receive endplates - inspect - measure hole positions - clean - shim - bolt and glue into frames

6. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Chamber Ready to String Box Assembled endplates attached attachment brackets affixed Next --- - mount on stringing fixture - insert feedthroughs - pre-tension - string wires - attach circuit boards - QA/QC

7. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS12 Stringing Fixture

8. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Parts: wire  circuit board conductive rubber circuit board crimp pin feedthrough endplate signal routing: wires  pre-amp wire

9. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Stringing wires between “slanted” endplates endplates “gravity” stringing wires: 9 cm - 4 m long wires strung individually wires attached by crimping wires positioned by “trumpet”

10. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Steps in Stringing

11. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Installing Pre-tensioning Wires Pre-tensioning - before we start stringing - use springs on guard wires - gradual release of tension

12. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Stringing the Chamber

13. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Bussing Field Wires - under the circuit board - gold-plated copper wire - one “miscellaneous part” - e.g. 16,000 ft. - $6000 - do this before mounting circuit boards

14. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Project Overview & Responsibilities Oversight: Jefferson Lab Design & Build Region 1: ODU Region 2: JLab Region 3: Idaho State Prototyping full-sized Reg. 1 prototype: Jlab, ODU plastic vs. metal-tipped feedthroughs: Jlab, ODU, ISU

15. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Drift Chamber Schedule PED

16. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS12 Drift Chamber PED test prototype this summer

17. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Drift Chamber Construction Schedule 3 YEARS

18. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Details: Stringing the Chambers ~2 yrs./ 6 chambers ~1/2 time for stringing

19. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Estimate the time; use labor cost tables “Bottoms-up” estimate - based on previous experience 2 people, 15 mins. per wire for stringing “stringing” per se takes 1/3 to 1/2 of the time 3 crews of 5 stringers for ~ 2 years 3 - 4 techs / scientists doing support, QA/QC “Top-down” - simple scaling of total elapsed time, accounting for fewer wires Costs: Stringing the Chambers

20. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS12 Drift Chamber Procurements/Expenses Task k$ stringing labor - estimate time - use labor rate

21. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS12 Drift Chamber: Construction Costs PED: 0.34 M$ Const: 4.50 M$ Total: 4.84 M$

22. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS12 Drift Chambers: Cost Same concept as present CLAS chambers Small extrapolations from current designs smaller cells, thicker wire, faster gas Cost estimates based on prior experience 180$ / sense wire : mechanical costs major cost is “wire-stringing” re-use most electronics Schedule and manpower allocation: prior experience Experts on staff and in CLAS collaboration

23. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Phenix DC’s (“jet-cell” type with 36 super-modules) Mechanical costs: $250/sense wire (but 7-8 other wires per sense wire) $50/total wire CLEO-c DC’s (“open-cell” with “square” cells) Mechanical costs: $40/total wire (labor not included) CLAS12 DC’s (“open-cell” with hexagonal cells) Mechanical costs: $180/sense wire $49/total wire (labor included) Cost Comparison: Other Drift Chambers

24. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer “Harder to do” Region 1: 7.5 mm cell; 1.8 m long wire Easier to do” smaller chambers 7 m endplate  4 m endplate chambers are flat stereo wires are all parallel sense wire: 20  m  30  m less breakage, easier to see ! Risks: Stringing the Chambers

25. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS Drift Chambers : History Operating successfully for ~10 years ….

26. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer CLAS Drift Chambers : History …. with good resolution mid-cell resolution is 200 - 250  m whole-cell average: 310, 315, 380  m; for R1, R2, R3 …. at the same voltage, with same efficiency  Ar/CO 2 shows no conventional aging

27. March 7, 2007 CLAS12 Drift Chamber Review Mac Mestayer Conclusions Large project: 18 chambers, 90K total wires Reliable design: should achieve resolution and efficiency goals Low risk cost and schedule: based on detailed knowledge from CLAS High probability of success: experienced people