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Progress report on

Calorimeter design comparison simulations

MICE detector phone conference2006-02-22

Rikard Sandström

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The sandwich calorimeter

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Reminder of run plan

• Stage 1– Pi & Mu

• 100<pz<300 MeV/c

• Stage 6– Mu & mu-decay

• 140 MeV/c• 170 MeV/c• 200 MeV/c• 240 MeV/c• Tilley’s TURTLE beam, with diffuser

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Method, page #11. Write a document explaining what to do and why

• Not in the document = not on the table.2. Simulate beams of 10k events, wide distributions.3. Use those to find useful variables for PID.

• Find combinations of detectors, such that given A, expect B.

• When finished, there should be no covariance between variables.

4. Make fits for all expected values, and create “discrepancy variables” 1-expected/measured.• Zero means very muon like.

5. Run 120k events of muons per experimental scenario.• ~ 2Gb of data per file

6. For every such scenario, also run 120k muons with 40 ns lifetime to generate background.• Muons not decayed at TOF2 are filtered out of analysis.

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Method, page #2

7. Digitize every simulated beam.8. Convert to ROOT trees, and tag good/bad event.9. For every scenario, merge the muon sample with

the background sample. 10. Train a Neural Net on the half of the merged &

filtered sample (training sample).11. Using the weights acquired by Neural Net, assign a

weight all other events (the test sample).12. Make cut on the weight such that signal efficiency is

99.90%13. The same cut gives background rejection, and thus

purity after PID.

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Sandwich

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Stage 6 – general setup

• All is MICE default. Exceptions:– Empty absorbers.– RF cavities turned off.

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Stage 6 - smearing• Since no reconstruction

application in G4MICE yet, used gaussian smearing of t & p.– Added 70 ps resolution to

time of flight.– Added smearing to

trackers: px= py= 2.0 MeV/c,

pz=0.209 px pz/pt √2 x= y= 0.5 mm• Reproduces approximately

M. Ellis LBNL’05

• As with stage 1, simple cuts do no longer help when adding smearing to trackers & tof.– Fitting with a neural net.

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Stage 6 – networks used

• 140 MeV/c– 9:5:2:1 architecture– Using barycenterDiscrepancy.

• 170, 200 ,240 MeV/c & TURTLE– 8:7:1 architecture– barycenterDiscrepancy does more damage than

help, and is not included as input.

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Stage 6 - purity• In stage 6, objective is to

measure emittance to high precision.– Requires high purity from

background.• Requirement:

– Signal efficiency = 99.90%.– Purity = 99.80%.

• Safety margin: – 3 times expected

background.• At non flip magnetic field

mode, expect much more background since fewer background tracks lost at absorbers.

– Safety margin can be expressed as purity = 99.93%

Initial mom[MeV/c]

Input purity

Req. BG rej.(purity 99.80%)

Safety BG rej.(purity 99.93%)

140 99.54 >56.2 >85.4

170 99.62 >47.4 >82.5

200 99.65 >43.4 >81.2

240 99.75 >20.4 >73.5

Turtle 99.58 >52.7 >84.2

Not meeting req. Meeting basic req. Meeting safety req.

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Correctly ID 99.9% of signal,correctly ID 87.6% of background

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Results - Stage 6, 140 MeV/c

Req. purity

Safety purity

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Results - Stage 6, 170 MeV/c

Safety purity

Req. purity

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Results - Stage 6, 200 MeV/c

Safety purity

Req. purity

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Results - Stage 6, 240 MeV/c

Safety purity

Req. purity

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Stage 6 – TURTLE beam

• A TURTLE beam with the design presented at RAL Oct’05 is the most realistic beam available.– Requires a 7.6 mm diffuser after TOF1.

• Pz,TOF1= 236 ± 26 MeV/c , non-Gaussian.

• In order to make G4MICE place the diffuser, I had to place it at z=-6078 mm.– It should be at z=-6014.8 mm.– Chris Rogers says:

• Z=-6010mm -> -3.10 T• Z=-6080mm -> -2.51 T• “…should be okay for PID stuff, but may I still need to fix it

for beam optics stuff.”

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Stage 6 – energy loss in diffuser

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Results - Stage 6, TURTLE

• Not finished yet– Everything is simulated; simulation files are being

digitized right now.

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Results – Stage 6, summary BG rejection

Initial mom.

No cal.,with TOF

KL, no TOF

SW, no TOF

KL, with TOF

SW, with TOF

140±14 MeV/c

47.8% 56.2% 79.5% 58.2% 79.5%

170±17MeV/c

54.1% 48.8% 56.4% 59.0% 67.8%

200±20MeV/c

59.0% 57.3% 74.2% 79.4% 87.6%

240±24MeV/c

64.5% 65.0% 91.4% 80.0% 92.2%

TURTLENot meeting req. Meeting basic req. Meeting safety req.

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Requirements for CKOV2

• In order for an extra detector to be useful, it should have a background rejection capability (in order to meet safety requirement) as a function of input purity and previous background rejection. – While loosing no signal events.– Assuming BG rejection of CKOV2 not correlated to

previous BG rejection:

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pz,TOF1 pz,CKOV2Input purity

Rejected by SW

Min req. rej by CKOV

140 ± 14 MeV/c

113 ± 23 MeV/c

99.54% 79.5% >29%

170 ± 17 MeV/c

148 ± 22 MeV/c

99.62% 67.8% >46%

200 ± 20 MeV/c

178 ± 26 MeV/c

99.60% 87.6% 0% Not needed

240 ± 24 MeV/c

212 ± 38 MeV/c

99.75% 92.2% 0% Not needed

TURTLE 200 ± 30 MeV/c

99.58%

Requirements for CKOV2, table

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Summary

• Hardest momentum for PID is pz,TOF1 170 MeV/c.

• Sandwich design has better performance than KLOE Light.– Best is trackers + TOFs + Sandwich calorimeter.– It is fairly easy to meet basic purity requirement. – At medium and high momenta it is possible to meet

safety requirements.

• CKOV2– Not needed at high momentum. (pz,CKOV2≥180 MeV/c)

– Must be able to reject 30-50% of background at 100% signal efficiency for lower momentum.

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Appendix

• Here are slides of variables used for PID, but where not presented.

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