HLab meeting

1. HLab meeting 10/23/07 K. Shirotori

2. BD repair

3. BD

4. The modification of SKS Present SKS 2.2T 2.7T q~20° q~20° 1.05 GeV/c (p+, K+) reaction (K+ 0.72 GeV/c) • Scattered particles are not focused and present drift chambers (SDC3,4) are small for large reaction angle (half acceptance).

5. The modification of SKS • Keeping large acceptance and wide angular coverage by large drift chambers (2m×1m) (from BNL and Freiburg) • Incident beam angle and position of drift chambers are optimized by keeping acceptance for the 1.5 GeV/c beam condition. q~20°

6. The modification of SKS • Keeping large acceptance and wide angular coverage by large drift chambers (2m×1m) (from BNL and Freiburg) • Incident beam angle and position of drift chambers are optimized by keeping acceptance for the 1.5 GeV/c beam condition. ゆるげん 270cm 170cm

7. BD • Effective area • 214  114 cm2 • Max drift length • 1 cm • Configuration • XX’ UU’ VV’ • Read out channel • 736 ch / (XX’UU’VV’ ) • Resolution • =0.4mm

8. G10 plane BD size 2840 Effective area -30° 30° 2140 1840 U V 1140 X 250 250

9. Repair

10. Repair : Wire exchange • Exchange all anode wires 20 mm ⇒ 25 mm • It takes a lot of times to repair the BD during the beam time.

11. Repair plan • To check 20 mm plane as a reference • Exchange all wires of one plane • ~3 days for exchanging • To check 25 mm plane • Clean up, HV and current check…. • If 3 is OK, we will exchange other planes.

12. Check points of a reference plane • HV and current check • Anode : +1800 V, ~1 mA • Potential : -450 V/-350V, 0.5 mA/0.8 mA • Signal check • Noise level ~16 mV • Plateau measurement • Ar:CO2 = 80:20, 55:45 • 90Sr source ⇒ Ar:C2H6 = 1:1, cosmic ray • Gas displacement • 400 cc/min @ Volume of BD ~150000 cc ⇒ 6 hours for 1 gas displacement • 1-exp(-7cycle)~0.999 ⇒42 hours

13. Signals • Ar:CO2 = 80:20 • +1800 V @ anode • 90Sr source • Preamp property • Rise time : ~20 ns • Decay constant : ~20 ns

14. Plateau measurement 1 Ar:CO2 = 55:45 Ar:CO2 = 80:20 Source (Wire∩Scinti)/Sincti BD ~60 mm Scinti : 100 mm×100 mm×2 mm

15. Plateau measurement 2 Ar:CO2 = 80:20 (Scinti∩Scint)∩Wire /(Scinti∩Scint) Source 90Sr: 1~3 MeV electron dE/dX estimation 2 mm Scinti: 200~400 keV 60 mm Ar gas: 10~20 keV Scinti: 20 mm×30 mm×2 mm BD ~60 mm Scinti: 20 mm×50 mm×3 mm

16. Present status • All 20 mm wires of one U-plane was exchanged to 25 mm wires. ⇒Clean up solder flux around the solder points • The check of 20 mm reference U-plane ⇒To measure plateau curve by Ar:C2H6 = 1:1 gas by cosmic ray • One repair cycle will be finished soon. • Totally finished by March 2008.

17. Schedule • 9/3~7: Building clean room • 9/10~14 : Open the chamber • 9/18~28 : Wire repair • 10/2~6 : Signal check for 25 mm plane • 10/9~11 : Signal check for 20 mm plane • 10/22~ : Clean up 25 mm plane, signal check for 20 mm plane other mixed gas

18. Pictures

19. Open the chamber

20. 25 mm plane repair Broken wires

21. 25 mm plane repair Anode Potential -350 V Potential -450 V

22. 25 mm plane repair

23. 25 mm plane repair

24. Spark points +2000 V -450 V +2000 V 1 mm -450 V