Plastic Scintillator Option for DB

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Plastic Scintillator Option for DB
a simulation study by Maxim Gonchar, Yury
Gornushkin and Dmitry Naumov JINR, Dubna,
Russia
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Why Plastic Scintillator?
• A word of worry about it?
• Our analysis and suggestions to

Collaboration Meeting January 12-15 2007
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Why Plastic Scintillator?

• Muon veto system based on plastic scintillators
  is a robust, cost-effective and efficient
  approach.
• There is an extensive experience using of this
  technology (MINOS, OPERA) (Yuris talk later on
  this).

Target Tracker
Spectrometers
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Plastic Scintillator Option for muon veto _at_ DB

• A word of worry
• a gamma can kick out an electron from the medium
  due to the Compton scattering.
• If the flux of gammas is high enough they can
  produce fake triggers what is a bad thing.

• Are there reliable solutions?
• look for coincidences in different layers
  double, tripple, quatrupole, etc
• put the scintillator in water to shield against
  gammas

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Requirements for the muon veto
• Simulation Framework
• Trigger rate of muons vs Fake rate of gammas
• CDR numbers
• An attempt to understand Aberdeen tunnel data
• Study of various options for the plastic
  scintillator
• 3 layers by 1 cm thickness
• 4 layers by 1 cm thickness
• 3 layers by 1.5 cm thickness
• Conclusions and further work

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Requirements for the muon veto
• 99.5 efficiency to detect muons
• reduce fake trigger rate due to natural
  radioactivity

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Simulation Framework
• While DayaBay software is under development and
  revision (geometry via VGM, etc) build own light
  weight package as follows
• Generators
• Simple muon Generator following CDR for the
  modified Gaisser formula, ignore shape of
  mountains around
• Gamma spectrum as measured in Aberdeen tunnel
• Transport Geant4 to transport particles

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Simulation Framework
• While DayaBay software is under development and
  revision (geometry via VGM, etc) build own light
  weight package as follows
• Data Containers
• ROOT objects with hits, event header, detector
  responses
• Geometry Geometry Factor to test about 10
  (implemented) geometries

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Simulation Framework
• Visualization
• Use VGM to export Geant4 geometry to ROOT TGeo
  objects and visualize using ROOT (basically much
  more convinient than Geant4 shipped viewers)
• Analysis ROOT macros and C classes to analyse
  data

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas
• Main questions are
• how much gammas are more abundant than muons?
• how to reduce gamma's fake rate to a modest level?

• CDR numbers
• An attempt to understand Aberdeen tunnel data

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas
• We simulated gammas and muons passing through
  plastic scintillators as were measured in the
  Aberdeen tunnel

Collaboration Meeting January 12-15 2007
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A
Coin/min 916.9 /- 17.5
(47927 / 30217)
Coin/min 517.3 /- 13.2
B
(48546 / 29543)
C
397.3 /- 11.5
(38436 / 21581)
(38436 / 21581)
D
67.35 /- 1.3
(35892/21937)
I
64.8 /- 4.7
(13602 / 9663)
adopted from Ming-chung Chu ???
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas

used measured in Aberdeen spectrum
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas
• mode A

detector geometry from event viewer
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas
• mode A

energy released by gammas and muons in one plate
due to inclined muons
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas
• mode A

Probability to release energy by gammas and
muons in one plate
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas
• mode A

Coincidence by gammas and muons
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas

number of counts gamma flux x probability
(Egt532 keV) noise
muons are marginal

• comparing different configurations in Aberdeen
  experiment I
• estimate
• noise 3600 counts per minute
• gamma flux 38000 counts per minute 0.64
  Hz/cm2

this is known from MC for every configuration
combining this with Daniel Ngai et al
calculations it follows that muons are about 100
000 more suppressed than gammas
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas

there is a reasonable agreement for bottom
counter (2) and coincidences, while upper counter
counts systematically more than expected...may be
different threshold or so
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Study of various options for the plastic
  scintillator
• Keep in mind that the muon veto must be able to
  suppress gamma background by a factor 100000 or
  better 1000000
• We built 3 options
• detector 1 3 layers by 1 cm thick of
  scintillator
• detector 2 4 layers by 1 cm thick of
  scintillator
• detector 3 3 layers by 1.5 cm thick of
  scintillator

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Study of various options for the plastic
  scintillator
• Keep in mind that the muon veto must be able to
  suppress gamma background by a factor 100000 or
  better 1000000
• We built 3 options
• detector 1 3 layers by 1 cm thick of
  scintillator
• detector 2 4 layers by 1 cm thick of
  scintillator
• detector 3 3 layers by 1.5 cm thick of
  scintillator

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB
2 of 3 coincidence as a function of energy deposit
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Plastic Scintillator Option for muon veto _at_ DB
3 of 3 coincidence as a function of energy deposit
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Plastic Scintillator Option for muon veto _at_ DB

• Study of various options for the plastic
  scintillator
• Keep in mind that the muon veto must be able to
  suppress gamma background by a factor 100000 or
  better 1000000
• We built 3 options
• detector 1 3 layers by 1 cm thick of
  scintillator
• detector 2 4 layers by 1 cm thick of
  scintillator
• detector 3 3 layers by 1.5 cm thick of
  scintillator

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB
2 of 4 coincidence as a function of energy deposit
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Plastic Scintillator Option for muon veto _at_ DB
3 of 4 coincidence as a function of energy deposit
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Plastic Scintillator Option for muon veto _at_ DB
4 of 4 coincidence as a function of energy deposit
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Plastic Scintillator Option for muon veto _at_ DB

• Study of various options for the plastic
  scintillator
• Keep in mind that the muon veto must be able to
  suppress gamma background by a factor 100000 or
  better 1000000
• We built 3 options
• detector 1 3 layers by 1 cm thick of
  scintillator
• detector 2 4 layers by 1 cm thick of
  scintillator
• detector 3 3 layers by 1.5 cm thick of
  scintillator

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB
2 of 3 coincidence as a function of energy deposit
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Plastic Scintillator Option for muon veto _at_ DB
3 of 3 coincidence as a function of energy deposit
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Plastic Scintillator Option for muon veto _at_ DB

• Water shielding (studied 3 options with 3
  layers)
• 50 cm of water
• 100 cm of water
• 150 cm of water

put in water
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB
muon
2 of 3 coincidence as a function of energy deposit
no water
50 cm of water
100 cm of water
150 cm of water
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Plastic Scintillator Option for muon veto _at_ DB

• Conclusions
• Use of coincidence allows to suppress gamma
  background while keeping high efficiency of muon
  detection

from the data gamma flux 0.64 Hz/cm2 6.4 e3
Hz/m2
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Conclusions
• Water shielding greatly impoves the result and
  may provide an economic solution

from the data gamma flux 0.64 Hz/cm2 6.4 e3
Hz/m2
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Further work
• Implement this work into official Daya Bay code
  gt quite straightforward
• work more on optimization of thickness taking
  into account optics properties of plastic
  scintillator, p.e. and all that

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB

• Trigger rate of muons vs Fake rate of gammas
• Backup slides

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode B

detector geometry from event viewer
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode B

energy released by gammas and muons in one plate
due to inclined muons
Collaboration Meeting January 12-15 2007
39
Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode B

Probability to release energy by gammas and
muons in one plate
Collaboration Meeting January 12-15 2007
40
Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode B

Coincidence by gammas and muons
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode C

detector geometry from event viewer
Collaboration Meeting January 12-15 2007
42
Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode C

energy released by gammas and muons in one plate
due to inclined muons
Collaboration Meeting January 12-15 2007
43
Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode C

Probability to release energy by gammas and
muons in one plate
Collaboration Meeting January 12-15 2007
44
Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode C

Coincidence by gammas and muons
Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode D

detector geometry from event viewer
Collaboration Meeting January 12-15 2007
46
Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode D

energy released by gammas and muons in one plate
due to inclined muons
Collaboration Meeting January 12-15 2007
47
Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode D

Probability to release energy by gammas and
muons in one plate
Collaboration Meeting January 12-15 2007
48
Plastic Scintillator Option for DB

• Trigger rate of muons vs Fake rate of gammas
• mode D

Coincidence by gammas and muons
Collaboration Meeting January 12-15 2007
49
Plastic Scintillator Option for muon veto _at_ DB

• Study of various options for the plastic
  scintillator
• Keep in mind that the muon veto must be able to
  suppress gamma background by a factor 100000 or
  better 1000000
• We built 3 options
• detector 1 3 layers by 1 cm thick of
  scintillator
• detector 2 4 layers by 1 cm thick of
  scintillator
• detector 3 3 layers by 1.5 cm thick of
  scintillator
• detector 4 2 layers 1cm and 3 cm thick of
  scintillator

Collaboration Meeting January 12-15 2007
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Plastic Scintillator Option for muon veto _at_ DB
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Plastic Scintillator Option for muon veto _at_ DB
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Plastic Scintillator Option for muon veto _at_ DB
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Plastic Scintillator Option for muon veto _at_ DB
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Plastic Scintillator Option for muon veto _at_ DB
2 of 3 coincidence as a function of energy deposit