nov. 07 2004beam catcher in kopio (h. morii) @ mikata kaon mini worksyop1 beam catcher in the kopio...
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Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 1
Beam Catcher in the KOPIO experiment
Hideki Morii (Kyoto Univ.)for the KOPIO collaborations
Contents1. What is Beam Catcher?2. Basic Design3. Expected Performance 4. Aerogel Quality Control System
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 2
Beam Catcher in the KOPIO experiment• KOPIO experiment measures KL 0mode• Identification : Detect and nothing veto
1. What is Beam Catcher?
Vetoing extra particle is predominant defense to BG
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 3
Beam Catcher
Catcher Module
Lead Converter
1. What is Beam Catcher?
• Photon veto which covers beam core region
• under high neutron rate– ~10GHz (>10MeV)
• Need to be…– efficient to rays : 99% @ 300MeV– inefficient to neutrons : 0.3% @ 0.8GeV
• Aerogel Cherenkov + distributed geometry
– suppress neutron efficiency
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 4
Beam Catcher – MC Event DisplayEvent Display for Event Display for neutron
Top View Top View
Side View Side View
Secondary particles are created isotropically
Can distinguish from neutron using geometry
Shower spreads forward
1. What is Beam Catcher?
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 5
Design of Beam Catcher – Single Module
• Lead converter– Size : 30 x 30 cm , 2mm thick
• Aerogel– Size : 30 x 30 cm , 5 cm thick– Refractive index : n ~ 1.05
• Mirror– flat mirror
• Funnel– Winston cone type
• PMT– 5 inch PMT
2. Basic Design
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 6
Top View
Design of Beam Catcher - Configuration
• Tapered configuration– 10 modules (front layer)
– 20 modules (back layer)
– 25 layers
• Number of modules– 370 modules
• Coincidence condition
2. Basic Design
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 7
Simulation – Efficiency for • Coincidence efficiency for
energy (GeV)
e
ffic
ienc
y
efficiency for
Y position (cm)
effi
cien
cy
3. Expected Performance
vertical position dependence
efficient region :±7cm
beam size
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Simulation – Insensitivity to neutrons (1)
e
ffic
ienc
y
neutron kinetic energy (GeV)
coincidence efficiency for n
• Insensitivity to neutronsnumber of false veto
neutron yield
→2.8 % false veto prob.
coincidence count
3. Expected Performance
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 9
Simulation – Insensitivity to neutrons (2)
• Single count rate by neutronssingle count rate by n
neutron spectrum
single count rate
→single rate ~ : 600kHz / module
3. Expected Performance
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 10
Aerogel Quality Control System
(i) Transmittance– LED (light source) + PMT (photo detector)
(ii) Cherenkov light Yield– Solenoid Spectrometer (as source) + mirror + PMT
It is important to control optical properties of aerogel
4. Aerogel Quality Control System
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 11
Masked by black paper with a
2mmX2mm hole
UV,BLUE,GREEN,
YELLOW,RED
5-COLORS
•PMT with 2mm hole mask detects LED lightPMT with 2mm hole mask detects LED light•30mm x 30mm area is scanned at 2mm interval30mm x 30mm area is scanned at 2mm interval
by moving X-Y stageby moving X-Y stage
•position dependence of transmittance can be measuredposition dependence of transmittance can be measured
Setup for Transmittance Measurement
ApertureAperture ApertureAperturePMT on XY stage
Aerogel on X-Y stage
4. Aerogel Quality Control System : (i) transmittance
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 12
Transmittance -Rayleigh scattering-
λ(nm)(nm)
A=0.93
CT=0.0088m4
A=0.82
CT=0.0094m4
)exp(4CT
A Fit the function 1-A:Absorption CT:Rayleigh Scattering parameterA:Absorption CT:Rayleigh Scattering parameter
Absorption also increaseAbsorption also increase
The Tile with rough surface n=1.03
The tile with Clean surface n=1.03
tran
smitt
anc
e tran
smitt
anc
e
4
2cos1
dd
Note that Rayleigh scattering is dominant in Aerogel
Two parameters, A and CT, are used as the input to our MC simulation .
Can it predict correct light yield?
4. Aerogel Quality Control System : (i) transmittance
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 13
Measurement of Cherenkov Light Yield4. Aerogel Quality Control System : (ii) light yield
To measure Cherenkov light yield…
• Solenoid Magnet Spectrometer– source + gap type solenoid magnet
• Setup for light yield measurement– Spectrometer + mirror + PMT
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 14
Solenoid Magnet Spectrometersource+ Gap-type Solenoid Magnet ==> Spectrometer
r
IRON
Electron rotate by Bz
COIL
GAP
Concept of Electron trajectory in this magnet
RuRu
0.8 m0.8 mMagnetic Field is strong near the gap
POINTTWO MAGNETS
•Large acceptance •High Resolution•parallel e- beam along Z-axis
We can get monochromatic electron beam
Variable Energy up to a few MeV
Beam intensity of ~30 Hz @2.5MeV
4. Aerogel Quality Control System :(ii) light yield
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 15
Spec of the Spectrometer
5.7
2670
7.5
2010 2400
13.7
820
10.1Resolution(%)
1460Energy(KeV)6. 310.1Resolution(%)
Energy(KeV)
Spectrum of Spectrum of focused electronfocused electron
[[ keVkeV ]]Energy spectrum of 106Ru
with and without magnet
[[ AA]]
Magnet Current VS peak e- energy
●● datadata▲▲ ExpectationExpectation
[[ keVkeV ]]
4. Aerogel Quality Control System : (ii) light yield
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 16
from Spectrometer
Measurement of Cherenkov Yield by the Spectrometer
Cherenkov image on PMTCherenkov image on PMT
sourcesource
106Ru(3.541MeV)Ru(3.541MeV)
Setup
MCMC
5inchPMT5inchPMT
Two trigger Scintillators are placed downstream of 10f hole at the mirror surface
4. Aerogel Quality Control System : (ii) light yield
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 17
Cherenkov Yield Energy Dependence Measurement1
▲▲ GEANT GEANT●● DATA DATA
▲▲ GEANT GEANT●● DATA DATA
n=n=1.01.033
TR=67TR=67%%@470nm@470nm
n=n=1.01.05 5
TR=69TR=69%%@470nm@470nm
We measure the Cherenkov light yield We measure the Cherenkov light yield with changing the energy of electronwith changing the energy of electron
Incident Energy of electronIncident Energy of electron Incident Energy of electronIncident Energy of electron
P.EP.E P.EP.E
Example of the results for two aerogel samples (thickness=11mm)Example of the results for two aerogel samples (thickness=11mm)
with similar transmittance but different refractive indexwith similar transmittance but different refractive index
4. Aerogel Quality Control System : (ii) light yield
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 18
Summary• Beam Catcher
– Photon detector positioned in neutral beam Need to have enough g efficiency Need to insensitive to neutrons
• Design– Pb + Aerogel Cherenkov counter with distributed geometry
• Expected Performance– 99% @ 300MeV / 0.3% @ 800MeV ~3% false veto prob.
• Aerogel quality control system– Transmittance– Cherenkov light yield
Summary
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 19
Extras
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 20
Beam Catcher – Prototype Test• Light yield – using +
• Neutron inefficiency
- using proton in place of neutrons
Prototype Module
Light Yield Proton Efficiency
Data matches MC very well
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 21
Simulation – Insensitivity to KL (1)
Coincidence efficiency for KL False veto probability by KL
→ ~2.3% false veto prob.
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 22
Simulation – Insensitivity to KL (2)
→ single rate : ~330 kHz
Single count rate by KL
Nov. 07 2004 Beam Catcher in KOPIO (H. Morii) @ Mikata Kaon mini worksyop 23
Cherenkov Yield Energy Dependence Measurement2
n=1.03n=1.03TR=67%@470nmTR=67%@470nm
▲▲ GEANT GEANT●● DATA DATA
n=1.03n=1.03TR=85TR=85%%@470nm@470nm
▲▲ GEANT GEANT●● DATA DATA
1.5 P.E1.5 [email protected]@2.4MeV
A=0.82
CT=0.0094μm4
A=0.94
CT=0.0044μm4
1.9 P.E1.9 [email protected]@2.4MeV
Incident Energy of electronIncident Energy of electronIncident Energy of electronIncident Energy of electron
P.EP.E P.EP.E
Example of the results for two aerogel samples (thickness=11mm)Example of the results for two aerogel samples (thickness=11mm)
with the same refractive index but different transmittancewith the same refractive index but different transmittance
4. Aerogel Quality Control System