Run13 MUID Hit Efficiency

RIKEN/RBRCItaru Nakagawa

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MUID Hit Efficiency1. data driven method 2. HV Method

Analysis note 1137 Analysis note 501 2

DV=DI R

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.

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Empirical Formula:

5uA extra current causes typically -100V voltage sagging.

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

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Average Tube Currents for Efficiency

5

Dra

win

g Cu

rren

ts /

HV

Chai

n [u

A]

Run Number

Currents per HV Chain

Stable baseline

Unstable baseline

Baseline Subtracted Current

6

Stable after baseline subtraction

7

Drawing Currents per HV Group

Horizontal axis : Luminosity

Aver

age

Curr

ent p

er T

ube

[uA]

I0

I1

I2

Observered Currents Cross Checks• Clear correlation of the drawing current vs.

luminosity.• Currents are proportional to the geometric

distance from the beam pipe.

8HV Group (Vertical) HV Group (Horizontal)

I0

I1

I2

From geometry of HV group, one expect following relations

Confirmed most of cases in both Vertical and Horizontal Planes

Current -> Efficiency

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10

Efficiency

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.

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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.

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BACKUP

13

Drawing Currents

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Baseline Linear Interpolation

15

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Baseline SubtractionRaw current

baselineAfter baseline subtraction

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)…

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Broken Wire Estimation (Good Samples)

Broken Wire = 0

Broken Wire = 1

Broken Wire = 2

Dra

win

g Cu

rren

t Run Number

Broken Wire Estimation (Not Clear Samples)

Broken Wire = 1 or 2 ?