PID Cherenkov Session at CM 22/3

Daniel Miehling, FAU Erlangen,
"Update on the most recent Photonis MCPPMTs for the PANDA Barrel DIRC "

The required specifications of 5 C/cm² is reached by most ALD-coated
MCP-PMTs. The test of 5 new PHOTONIS tubes revealed a uniformity below
1.4 for all tubes for 100% active area. The gain uniformity is better 3
for all tubes for > 90% active area. It was emphasized that the combined
information of gain, quantum efficiency and collection efficiency needs
to be included in MC-studies. To take care of only the quantum efficiency
might be misleading. The escalation mode, where the tube starts to emit
light by itself is further studied. By optimizing the ALD process Photonis
was able to shift the ”escalation” starting point to higher gains for the
newest tubes.

In the following discussion about the ratio of the resistors within the
HV-divider it was agreed on to follow the 4:10:1 ratio in order to get the
best RMS for the timing precision.

Utkarsh Verma, GSI, "Timing precision of the DiRICH at GSI"

Carsten gave a short oral update of developments in the electronic lab. Together
with the summer student Davide Pannico  and the Get-INvolved-Student Utkarsh
Verma they addressed a polarity problem of the DiRICH. With the right polarity
the timing precision of the DAQ-system is now in the order of 60ps for
single photons consistent with the results of the Erlangen group.

Ahmed Ali, HIM, "Status of the gluing lab at HIM"

Ahmed addresses the  task to glue radiator bars. Two radiator pieces
to be glued end-to-end to form a long bar, covering the full length of the
Barrel DIRC 17mm (T) x 53mm (W) x 2400mm (L). He showed the lab space with
the optical tables. He is performing gluing tests and procedures to remove air
bubbles from the glue.