Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1, Ckov2, Tof2 MICE Pid Tele-Meeting

Steve Kahn

31 March 2005

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Improvements to G4Mice Relevant to the Cherenkov Detectors

• Ckov1:– Implement the new Mississippi geometry.– Corrections to better handle the threshold effect for PE

generation.

• Ckov2:– Better model the materials used in Ckov2.

• Previous version had too much material in the beam windows.

• We now take into account the reduced material due to the honeycomb geometry.

– Updated Ckov2 dimensions.

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Materials for CKOV2 GG 2/22/2005

Shape and Nr Item Material Manufacturer Structure Type Thickness Tranverse dimensions Density or

(mm) (mm) Areal weight1 Particle entrance window Composite material Eurocomposites Aluminium skin 1 2700

EC-PI 60 AV Alu core Honeycomb ECM 6.4-82 8 82Aluminium skin 1 2700

Total thickness 10 about 6.60

2 Aerogel box Composite material Eurocomposites Epoxy fiber glass G10 0.3 2164EC-PI 13 NE Nomex core honeycomb ECA-I 3.2 64 9.4 64

Epoxy fiber glass G10 0.3 2164Total thickness 10 about 1.9

3 Mirrors Polycarbonate Clear transparent Clear transparent 5 1400(Lexan)

4 Pyramid support Composite material Eurocomposites Epoxy fiber glass G10 0.3 2164EC-PI 13 NE Nomex core honeycomb ECA-I 3.2 64 9.4 64

Epoxy fiber glass G10 0.3 2164Total thickness 10 about 1.9

5 Winston cones PMMA Polymethylmetacrylate Clear transparent 1200

6 Optical windows B270 Schott Glass Clear transparent 10 2300

7 Main vessel Soft steel Nickel plated iron 7870

8 Magnetic shielding Mumetal IMPHY-France 0.5 7870

9 Aerogel radiator Aerogel Matsushita Silicon dioxyde 100 Diameter 800 mm 111

10 O-rings Viton

11 Window for aerogel box Mylar Dupont C10H8O4 Clear transparent 0.1 1400

12 Atmosphere inside vessel Helium Atmospheric pressure 0.162

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Event Samples for Ckov1 Study

• Samples with 50% and 50% are generated.– Events are generated just before Tof0 (-15750 mm) with

x=y=50 mm

x’=y’=25 mr

– Samples were run with the following momenta.• 180, 200, 220, 240, 260 MeV/c.

– Current G4Mice problem generates contamination with constant KE, where it should be constant momentum since they survive the final dipole bend. Consequently muon and pion samples must be run separately.

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Cherenkov Systems

• Upstream Ckov

– C6F14 radiator with n=1.25

– 4 PMTs

• 2 on top, 2 on bottom.

– Threshold cherenkov:

• 0.7 MeV for electrons

• 140 MeV for muons

• 190 MeV for pions

• Downstream Ckov– Aerogel with n=1.03

– 12 PMTs on 12-sided polygon.

– Typically on electrons visible since pion threshold is > 500 MeV.

– Requires TOF coincidence.

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Cherenkov Threshold Effect

•The number of Č photons generated by the passage of a charged particle through the radiator is

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PEs generated: 181 MeV/c

• No Pion plot since pions are below threshold for 181 MeV/c• Units on the abscissa are arbitrary at this point.

– They are valid for comparison from plot to plot.

– I believe that they are high by a factor of 5.

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s generated: 200 MeV/c

• Although 200 MeV/c are above threshold none were generated in the run.

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s generated: 220 MeV/c

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s generated: 240 MeV/c

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s generated: 260 MeV/c

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Photon Generation in the Cherenkov Detectors

• For each track that crosses the radiator with a velocity above threshold a number of photons are generated proportional to the deposited energy.

• We currently do not use the Cherenkov photon facility in Geant4.

– There is some question as to how well it works with reflective surfaces.

• Imaginary photons are generated in a cone (at the č angle) around the particle direction.

• Since all mirrors are at 45º w.r.t. the beam direction, we can position the PMTs on an imaginary plane.

– The č photons that intercept the PMT circles are “seen”.

– Note that Ckov1 has an angle of 53°. The circles should be ellipses. This has not yet been taken into account

• Note that in Ckov 1 we are dealing with only 4 PMTS.

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s seen: 181 MeV/c

• No seen pions since they are below threshold.

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s seen 200 MeV/c

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s Seen 220 MeV/c

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s seen: 240 MeV/c

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 PE’s seen: 260 MeV/c

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov1 Efficiency as a Function of Energy

P=180 MeV/c P=240 MeV/c

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Data Sample for Downstream Detectors

• Generated samples of muons and electrons.– 20 K events of each kind– Tracks started at –4802 mm. Near the beginning of the

upstream SciFi.

– Muons have KE 120 MeV. E225 MeV.

– Electrons have KE centered at 70 MeV and have E/E=35%.

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Tof2 Muon Position Scatter Plot

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Tof2 Muon Position Projections

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Tof2 Muon Radial Distribution

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Tof2 Electron Position Scatter Plot

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Tof2 Electron Position Projections

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Tof2 Electron Radial Distribution

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov2 Muon Position Scatter Plot

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov2 Muon Position Projections

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov2 Muon Radial Distribution

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov2 Electron Position Scatter Plot

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov2 Electron Position Projections

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov2 Electron Radial Distribution

Mar 31, 2005 Steve Kahn -- Ckov and Tof Detector Simulation

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Ckov2 Efficiency