1. KEK Cosmic Tests Run Status + Summary Dan Burke 22/01/06

2. Outline jCF4 measurements and tracks Energy resolution comparisons Gain measurement Summary of jT2K gas data Results for jT2K gas [Ar jCF4Iso (95-03-02)] Conclusions and future plans

3. jCF4 – AfterPulses With the ArCF4 we found afterpulses similar to the October results (*picture from Oct.)

4. Adding isobutane improves stability, stops after-pulses, and improves resolution on 55 Fe Ar+jCF4 3% jT2K gas Comparison

5. Gain for the T2K gas RUN at 340 V Gain ~ 4000

6. Run Summary jT2k Gas @ 168.7 V/cm  ~13k events  60-70% good events jT2K Gas @ 80 V/cm  Currently 2200 events  ~400 events/h  Continuing run until tomorrow afternoon (~10k events)

7. Track Drift Distances

8. Phi Distribution Distribution Used

9. Sample Tracks – T2K Gas 186.7V/cm

13. Drift Velocity Gas V drift (cm/  s)Magboltz(cm/  s) ArCF4Iso 186.7 V/cm (preliminary – possible faster than expected -or- not full drift length 7.4 ± 0.57.035 ± 0.003

14. Conclusion Great results so far, isobutane has eliminated the afterpulses Lots of data for T2K gas at two drift fields Continue with readings until tomorrow afternoon Change HV power supply with a KEK supply  Take more data after we leave Analyze results