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PID Cherenkov Session at CM 17/2

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  Minutes PID-Cherenkov group June 2017 
 
Marvin Krebs, Uni Frankfurt, GSI
Optical Quality of the PANDA Barrel DIRC Prototype Radiator Plates
 
The optical lab setup for measuring the plates is shown and explained.
Bulk transmission and reflection coefficients were measured.
Results of the optical measurements of the Nikon plate were shown.
He finds an attenuation length of about 20m for 266nm. The internal
reflection measurements show results in agreement with a
surface roughness of 0.6 nm (InSync 0.85nm).
 
 
Mustafa Schmidt, Uni Giessen
Disc DIRC Performance Analysis and Test beam Results
 
After an explanation of the detector concept of the DISK DIRC he shows
how to determine the Cherenkov angle with an analytical formula.
He shows a backward reconstruction algorithm calculating the Cherenkov angle.
He gets 2 mrad track Cherenkov angle resolution. The forward
reconstruction algorithm makes a particle assumption and yields the likelihood.
He shows that for a minimum wave length of 360 a Cherenkov angle resolution of
1.16 mrad is achieved.
backward 5.11
forward 5.27 likelihood difference
The DESY test beam was done with a prototype with elements  like in the
final PANDA setup with a rectangular NIKON plate made from fused silica.
Simulation results agree with the measured quantities single photon resolution
and charge sharing.  A single photon resolution of 7.75 mrad was achieved.
Averaged their yields 2.5 mrad.
 
 
 
 
Markus Pfaffinger, Uni Erlangen
 
Accelerate measurements by measuring the current at the first MCP, since
the integrated anode current is linear to th photon yield at higher intensities.
A potential free pico-amp meter can measure the current at the first MCP.
First measurements are promising. A QE measurement traditional and
with the picoamp meter shows the same result. In future a picoamp meter with
a potential of 4kV is foreseen.
Markus shows the update of PC damage as function of the integrated
anode current.
The double ALD coated PHOTONIS tube is at 13.6 C/cm2 without PC damage.
 
 
Merlin Boehm, Uni Erlangen
First measurements in the quality assurance test box
 
This copper shielded setup measures gain, QE (wavelength dependent),
dark count rate for the MCP-PMT. The laser spot must not focused too sharp,
otherwise the PC saturates. The PC current and the anode current is measured.
The ratio yields the gain independent on the QE. Also after-pulsing of some
percent is measured. The Photonis tubes show with the PADIWA-TRB chain
about 150-200 ps (Scope 50ps) and a charge sharing of 0.6mm. 
 
There are minutes attached to this event. Show them.
    • 14:00 → 14:20
      Optical Quality of the PANDA Barrel DIRC Prototype Radiator Plates 20m
      Speaker: Mr Marvin Krebs (GSI, Darmstadt)
      Slides
    • 14:20 → 14:50
      Disc DIRC Performance Analysis and Testbeam Results 30m
      Speaker: Mr Mustafa Schmidt (JLU)
      Slides
    • 14:50 → 15:10
      Update on Picoamp and Lifetime Measurements 20m
      Speaker: Mr Markus Pfaffinger (Universität Erlangen(UErl))
      Slides
    • 15:10 → 15:25
      First results of quality assurance measurements 15m
      Speaker: Mr Merlin Böhm (Uni Erlangen)
      Slides
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