Transcript A new Sci-Fi tracker for the COMPASS experiment Marcin Ziembicki Institute of Radioelectronics

A new Sci-Fi tracker for the
COMPASS experiment
Marcin Ziembicki
Institute of Radioelectronics
Warsaw University of Technology
VSAT Detectors
Tracking inside the beam:
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Capability of withstanding high count
rates without significant loss of detection
efficiency.
Considerable radiation hardness and
reasonable effects of aging.
Small radiation length in order to avoid
track distortions.
Sufficient space and time resolution.
Possible detector types:
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Fast scintillators.
Semiconductors.
Detector concept
2 inclined planes
(u, v)
4 layers per channel
176 channels
(each plane)
0.7 mm pitch
1.0 mm fibers
0,7 mm
1,0 mm
Layer
Beam
Column
LVDS
Scintillators
(12,5 cm)
Clear fibers
(100 - 130 cm)
PMT
Discriminator
PMT
Discriminator
PMT
Discriminator
PMT
Discriminator
Components
Double cladding fibers
16-channel photomultipliers (Hamamatsu
H8711-10)
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Booster base - separate power supply for last
three dynodes.
Discriminators
Time resolution
Need to correlate hits in different detectors as
belonging to the same particle.
Average time between particles – 12.9 ns.
Time resolution – fibers
Statistical fluctuations of ionization,
UV-emission, UV-absorption and re-emission in
visible light
Attenuation
Different path lengths – time spread ~ 200 ps
Time resolution – photomultiplier
Different paths of electrons
Dependence on the number of initial
photoelectrons
t ~
1
N PE
Higher light yield = better time resolution
Time resolution – electronics
„Time walk”
Different rise times,
equal amplitudes
Equal rise times,
different amplitudes
1
2
0.9
1.8
0.8
1.6
0.7
1.4
0.6
1.2
0.5
1
0.4
0.8
Threshold
0.3
0.6
0.2
0.4
0.1
0.2
0
0
100
200
300
400
Time spread
500
600
700
800
900
1000
0
Threshold
0
100
200
Time spread
300
400
500
600
700
800
900
1000
Current research
Joint technology
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Welding
Gluing
Heating wire
Clear fiber
Neddle with glue
UV Power LED
Centering sleeve
Glass pipe
Scintillating fiber
Current research
Light yield from
scintillator
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Mirrors at the free end
of the fiber
Scattering covering
Current research
Plane assembly
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As little mass as possible
As good geometry as possible