Cintiladores Gasosos Activos F. A. F. Fraga, P. Mendes, L. M. S. Margato, M. M. F. R. Fraga, S. T....
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Transcript of Cintiladores Gasosos Activos F. A. F. Fraga, P. Mendes, L. M. S. Margato, M. M. F. R. Fraga, S. T....
Cintiladores Gasosos Activos
F. A. F. Fraga, P. Mendes, L. M. S. Margato , M. M. F. R. Fraga, S. T. G. Fetal, Filipa Balau, R. Ferreira Marques, A.
J. P. L. Policarpo
LIP Coimbra, Universidade de Coimbra
Resumo
• Cintilação do GEM
• Operação de GEMs com conversores de comprimento de onda
• TPCs com GEMs com leitura óptica
• Simulação de um sistema de leitura de luz para GEMs com PMTs
• Polarímetro de raios-X
• Testes GEMs da 3M
• Projecto MILAND
The GEM - gas electron multiplier - a pre-amplifying structure
See http://gdd.web.cern.ch/GDD/
Pulse analysis of light signals• Our previous work has shown that light
pulses in He-CF4 are very fast (rise time less than ns)
• Can we estimate alpha track orientation from the light pulse structure collected with PMTs?
• System allows – precise definition of track angle
– simultaneous recording of
– CCD image - track oriention
– digitized light pulse
H.V.
47
mm
GEM 1
3 m
mTransparentWindow
5.
5mm
2 m
m
2 m
m
GEM 2GEM 3
CCD - Hamamatsu512x512 Pixel
24x24m
Drift Plane
241 Am
5mm
P-terphenyl absorption and emission
p-terphenyl
0
5000
10000
15000
20000
25000
30000
35000
40000
200 220 240 260 280 300 320 340 360 380 400 420 440
(nm)
Mo
lar
ext
inct
ion
co
eff.
(cm
-1/M
)
0
0.2
0.4
0.6
0.8
1
1.2
Fluorescence intensity (a.u.)
Conical GEMs
• Electron microscope cross-section of the double-conical or standard (a), conical (b) GEMs
Spectrum of Ar-TEA with GEMs coated and not coated with p-terphenyl
0%10%20%30%40%50%60%70%80%90%
100%110%
200 240 280 320 360 400 440 480 520 560 600 640 680 720 760 800 840 880
Wavelength (nm)
#PM
T/s
e no
rmal
ised
to T
EA
m
axim
um p
eak
Ar5%TEA 26-11-2002
Ar5%TEA p-terphenyl19-12-2002
No p-terphenylStep = 2 nm; Dl = 4,65 nm;Ed = 1kV/cm;Vgem = 260 V;Ei = 0 kV/cm;VRX = 10 kV;
IRX = 0,100 mA
P-terphenylStep = 2 nm; Dl = 4,65 nm;Ed = 1kV/cm;Vgem = 330 V;Ei = 0 kV/cm;VRX = 10 kV;
IRX = 0,500 mA
CCD images of uniformly irradiated GEMs
a) full spectrum
b) bandpass filter
Simulation of light signals in a PMT readout
• Monte Carlo simulation of localization by light centroid
• Light is emitted at the GEM plane and is punctual - no light diffusion and/or reflexion!
• Only the four nearby PMTs are considered
Light collection simulation3cm diameter PMTs
y
x
z
dPMT plane
GEM plane
3 2
14
PMT(1,3) assimetry
PMT(1,4) assimetry
Assimetry(1,3) statistics106 photons
Assimetry(1,4) statistics106 photons
Next steps
• Avalanche dimmensions
• PMT noise and non uniformity will be added
• Assembly of a system with four PMTs and a sweeping source
3M GEMs preliminary tests
• A First Mass Production of Gas Electron Multipliers , P.S. Barbeau J.I. Collar , J.D. Geissinger , J. Miyamoto , I. Shipsey and R. Yang
3M’s roll to roll flexible circuit manufacture in clean room conditions.
First tests using Ar -5% CO2
1
10
100
1000
200 250 300 350 400 450
Vgem (V)
Ga
in
CCD setup
-Vdrift
Front electrode Back electrode
GEM
Glass window
Scintillation image of a 2.5 cm diameter 3M GEM
• Ar5%CO2;
• IRX=1.000 mA;
• Lens detector distance = 21 cm
• Drift lenght= 7 mm;
• Ed= 1 kV/cm;
• Vgem=420 V(G~94)
• Kodak CCD
Scintillation image (zoom)
MIDLAND, Millimetre Resolution Large Area Neutron Detector
• 6th Framework Programme (FP6), (JRA2 Integrated Infrastructure Initiative for Neutron Scattering and Muon Spectroscopy (NMI3)