Difference: TRTHTmiddleBitTuing (4 vs. 5)

Revision 52015-06-19 - KyungeonChoi

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META TOPICPARENT name="KyungeonChoi"

TRT HT middle bit tuning

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  The ASBDLR has a separate discriminators for tracking (low threshold) and TR photon (high threshold). High threshold discriminator has an additional shaping circuitry with a peaking time of 11ns to preserve signal uniformity. The HT signal has to be stretched to increase HT middle bit fraction as shown below. New HT shape (HT shape 3) has slower falling time than origianl HT shape and peaking time also delayed about 1.5 ns.
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HTshape.pdf
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HTshape.png
  The Figure below shows the agreement of HT middle bit fraction between data and MC as a function of HT ΔT0 shift for different TRT partitions. HT middle bit fraction is always underestimated with original HT shape for all HT ΔT0 shifts. HT shape 3 is sufficiently large to have a perfect data/MC agreement.
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tuningHTshape.pdf
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tuningHTshape.png
 

Tuning of high threshold value

High threshold has to be tuned to restore an increased HT probability due to the new HT shape. HT probability increased 8.9% for Barrel short straws, 9.8% for Barrel long straws, 8.0% for Endcap A-wheels and 6.9% for Endcap B-wheels as shown in below figure. High threshold values are raised accordingly to restore original HT probability for each TRT partitions. Below table shows original high threshold values and new high threshold values to cope with new HT shape.

Original high threshold New high threshold
Barrel short 0.006047 0.006576
Barrel long 0.005477 0.006016
Endcap A-wheel 0.005916 0.006390
Endcap B-wheel 0.005680 0.006074
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tuningHLthreshold_HTprob.pdf
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tuningHLthreshold_HTprob.png
 

Tuning of high threshold ΔT0 shift

Since there is an additional shaping circuitry for high threshold, high threshold T0 setting can be differ from overall (or low threshold) T0 setting. Tuning of high threshold T0 setting is done by an additional T0 shift on top of overall T0 setting. The shift is applied after discrimination so that it has a discrete step of 0.78125 ns (See Andrew's slides for the detail). The implementation can be applied for each TRT partitions: Barrel short, Barrel long, Endcap A-wheel and Endcap B-wheel.

Following figure shows data and MC agreement of HT middle bit fraction as a function of HT ΔT0 shift. Different colors represent each TRT partitions, and empty squares have intersection point(s) with a red dashed line which means perfect data and MC agreement. Red arrows indicate possible HT ΔT0 shifts from original digitization setting. Barrel short is straightforward since it has only one point of intersection, but other three TRT partitions have two points of intersections. HT bit pattern distribution can be used to determine better HT ΔT0 shifts as shown below.

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tuningHTdeltaT0.pdf
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tuningHTdeltaT0.png
  The criterion for better HT ΔT0 shift from HT bit pattern distribution is the data and MC agreement of HT bit high patterns, especially one HT bit high patterns since they mainly affect HT middle bit fraction. It is clear that Endcaps show better agreement with HT ΔT0 shift of -4.6875 ns (Blue line) for all HT bit patterns. The optimal HT ΔT0 shift for Barrl long is chosen to have a better one HT bit high pattern agreements.
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tuningHTdeltaT0_HTbitpattern.pdf
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tuningHTdeltaT0_HTbitpattern.png
 

Final results

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Barrel long 0.9952 0.0006
Endcap A-wheel 0.9997 0.0006
Endcap B-wheel 1.0013 0.0006
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final_HTmiddleBitfraction.pdf
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final_HTmiddleBitfraction.png
  There are also noticeable improvements in the HT bit pattern distributions with tuning as shown below.
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final_HTbitpattern.pdf
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final_HTbitpattern.png
 

References

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META FILEATTACHMENT attachment="HTshape.pdf" attr="" comment="HT shape all" date="1434526476" name="HTshape.pdf" path="HTshape.pdf" size="16188" user="kchoi" version="1"
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META FILEATTACHMENT attachment="tuningHLthreshold_HTprob.pdf" attr="" comment="" date="1434528247" name="tuningHLthreshold_HTprob.pdf" path="tuningHLthreshold_HTprob.pdf" size="194184" user="kchoi" version="1"
META FILEATTACHMENT attachment="tuningHTdeltaT0.pdf" attr="" comment="" date="1434530215" name="tuningHTdeltaT0.pdf" path="tuningHTdeltaT0.pdf" size="425070" user="kchoi" version="1"
META FILEATTACHMENT attachment="tuningHTdeltaT0_HTbitpattern.pdf" attr="" comment="" date="1434530227" name="tuningHTdeltaT0_HTbitpattern.pdf" path="tuningHTdeltaT0_HTbitpattern.pdf" size="391163" user="kchoi" version="1"
META FILEATTACHMENT attachment="final_HTmiddleBitfraction.pdf" attr="" comment="" date="1434530530" name="final_HTmiddleBitfraction.pdf" path="final_HTmiddleBitfraction.pdf" size="171130" user="kchoi" version="1"
META FILEATTACHMENT attachment="final_HTbitpattern.pdf" attr="" comment="" date="1434530771" name="final_HTbitpattern.pdf" path="final_HTbitpattern.pdf" size="127161" user="kchoi" version="1"
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META FILEATTACHMENT attachment="HTshape.png" attr="" comment="" date="1434687881" name="HTshape.png" path="HTshape.png" size="306658" user="kchoi" version="1"
META FILEATTACHMENT attachment="final_HTbitpattern.png" attr="" comment="" date="1434687895" name="final_HTbitpattern.png" path="final_HTbitpattern.png" size="315597" user="kchoi" version="1"
META FILEATTACHMENT attachment="final_HTmiddleBitfraction.png" attr="" comment="" date="1434687909" name="final_HTmiddleBitfraction.png" path="final_HTmiddleBitfraction.png" size="714927" user="kchoi" version="1"
META FILEATTACHMENT attachment="tuningHLthreshold_HTprob.png" attr="" comment="" date="1434687920" name="tuningHLthreshold_HTprob.png" path="tuningHLthreshold_HTprob.png" size="700817" user="kchoi" version="1"
META FILEATTACHMENT attachment="tuningHTdeltaT0_HTbitpattern.png" attr="" comment="" date="1434687933" name="tuningHTdeltaT0_HTbitpattern.png" path="tuningHTdeltaT0_HTbitpattern.png" size="571191" user="kchoi" version="1"
META FILEATTACHMENT attachment="tuningHTdeltaT0.png" attr="" comment="" date="1434687950" name="tuningHTdeltaT0.png" path="tuningHTdeltaT0.png" size="1048821" user="kchoi" version="1"
META FILEATTACHMENT attachment="tuningHTshape.png" attr="" comment="" date="1434687962" name="tuningHTshape.png" path="tuningHTshape.png" size="532238" user="kchoi" version="1"
 
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