1. Run13 MUID Hit Efficiency RIKEN/RBRC Itaru Nakagawa 1

2. MUID Hit Efficiency 1.data driven method 2.HV Method Analysis note 1137Analysis note 501 2  V=  I R

3. HV method basics MUID has voltage sagging circuit in order to protect wires in tube in case of over current draw. The more the current, the more voltage to be dropped. So effective HV at tube will be lower than supplied voltage from power supply. 3 Empirical Formula: 5uA extra current causes typically - 100V voltage sagging.

4. Procedure Currents for Physics Runs Extract currents per HV chain (typically 20 tubes per HV chain) Subtract baseline currents Baseline currents are taken from cosmic runs (293 runs in Run13) Subtract number of broken wires Evaluate total number of active tubes to calculate average tube current 4 Average Tube Currents for Efficiency

5. 5 Drawing Currents / HV Chain [uA] Run Number Currents per HV Chain Stable baseline Unstable baseline

6. Baseline Subtracted Current 6 Stable after baseline subtraction

7. 7 Drawing Currents per HV Group Horizontal axis : Luminosity Average Current per Tube [uA] I0I0 I1I1 I2I2

8. Observered Currents Cross Checks Clear correlation of the drawing current vs. luminosity. Currents are proportional to the geometric distance from the beam pipe. 8 HV Group (Vertical)HV Group (Horizontal) I0I0 I1I1 I2I2 From geometry of HV group, one expect following relations Confirmed most of cases in both Vertical and Horizontal Planes

9. Current -> Efficiency 9

10. 10 Efficiency

11. Conclusion MUID hit efficiencies were calculated using HV method to cross check data driven results. Resulting efficiencies calculated by HV method are generally overestimating these of data driven method According to MUID experts, the formula correlates between current and efficiency used in present analysis may not be up-to-date. Updating formula by redoing HV scan using cosmic data may resolve the discrepancy. 11

12. Problems However intrinsic difference between HV method and data driven is not trivial to make correction. The HV method evaluates average while data driven evaluates instantaneous efficiency. No good way to address this hasn’t been invented/established so far. 12

13. BACKUP 13

14. Drawing Currents 14

15. Baseline Linear Interpolation 15

16. 16 Baseline Subtraction Raw current baseline After baseline subtraction

17. Broken Wire Estimation Number of Broken Wires are not in any database/records. Typical cases, the broken wires can be estimated by the drawing current during cosmic runs. Expected drawing currents are V*(1+2.5N) where N is number of broken wires and V=4.4kV. I=4.4uA (N=0), I=14uA (N=1), I=25uA (N=2)… 17

18. Broken Wire Estimation (Good Samples) Broken Wire = 0 Broken Wire = 1 Broken Wire = 2 Drawing Current Run Number

19. Broken Wire Estimation (Not Clear Samples) Broken Wire = 1 or 2 ?