Download - December 10, 2008 1 The Parallel Plate Chamber CERN Presentation Wout Kremers Detector R&D NIKHEF
December 10, 2008
1
The Parallel Plate Chamber
CERN Presentation
Wout Kremers
Detector R&DNIKHEF
December 10, 2008 2
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Introduction
• Electron Emmission Foil• Parallel Plate Chamber (PPC)• Preliminary Results• Simulation• Conclusion
December 10, 2008 3
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Electron Emmission Foil
• Incident MIP hits foil• Thin foil (atm 68 micron)• MIP frees electrons in foil• Few electrons will be close to surface of
foil• These can be amplified
FoilFoil
MIP
electron
December 10, 2008 4
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Parallel Plate Chamber
Copper coated Kapton Foil Cathode
Messing Block Anode
Mylar Foil Spacer
50 micron
68 micron
December 10, 2008 5
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Parallel Plate Chamber
• Gas amplification potential causes electrostatic force
• Spacer to keep distance and define active area detector
• Foil cathode placed under tension to limit bending effect
• To stabilise gas flow and pressure a perspex clamp was mounted on the pcb
December 10, 2008 6
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Parallel Plate Chamber
December 10, 2008 7
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Preliminary Results
• The pcb was connected to a high voltage supply, a 10dB output amplifier and a scope
• The chamber was flushed with 97,5% Argon and 2,5% Iso-butane
• Chamber was tested with Fe 55 and Sr 90 sources
December 10, 2008 8
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Preliminary Results
0,008 0,010 0,012 0,014 0,016 0,018 0,020 0,022 0,024 0,0260
20
40
60
80
100
120Vo
ltage
(V)
Count
Fe 55 Spectrum at -361,4 V Applied Voltage
December 10, 2008 9
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Preliminary Results
0,000 0,005 0,010 0,015 0,020 0,025 0,0300
20
40
60
80
100
120
140
Volta
ge (V
)
C ount
-351,1 V -354,2 V -361,4 V -365,3 V
F e 55 S pectrum at multiple A pplied V oltages
December 10, 2008 10
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Preliminary Results
0,008 0,010 0,012 0,014 0,016 0,018 0,020 0,022 0,024 0,0260
20
40
60
80
100
120
140Vo
ltage
(V)
Count
Sr 90 Spectrum at -362.4 V Applied Voltage
December 10, 2008 11
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Preliminary Results
• Some signals were below noise level• No gain could be directly seen from
spectrum• Measurement made of signal current• Current on the order of pico ampere
December 10, 2008 12
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Preliminary Results
350 355 360 365 370 375 380 385 390 39550
100
150
200
250
300
Curre
nt (p
A)
Applied Voltage (V)
Signal Current vs Applied Voltage
December 10, 2008 13
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Simulation
• So far only for Fe 55• Assumption all electrons created in gas
gap• Simple statistical approximation of
interactions• Monte Carlo simulation
December 10, 2008 14
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Simulation
0 1 2 3 4 5 6 7 8 9 10
x 104
0
50
100
150
200
250
300
350
400
Number of electrons collected at anode
Coun
ts
Simulation of 5.9 KeV X-Rays in PPC
December 10, 2008 15
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Conclusion
• Working chamber with small avalanche only gap
• Chamber which can be used to test foils• Different types of foils, eg carbon
nanotube coated foil• Foil efficiency will be determined through
beam test
December 10, 2008 16
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results
Conclusion
• Future possibilities:• Electron emission
foil and micro channel amplification
• Electron emission foil and multi grid amplification
electron emission foil
CMOS pixel chip
electron emission foil
CMOS pixel chip
December 10, 2008 17
IntroductionElectron Emmission Foil
Parallel PlateChamber
SimulationConclusion
Preliminary Results ?