A new concept for the PANDA Endcap DIRC was proposed by the Giessen group in June 2006, incorporating both the time-of-propagation (TOP) technique and a chromatic correction based on dichroic mirrors which split the spectral range of the Cherenkov photons. This combination of technologies allows both to avoid the decrease of resolution usually connected with dispersion and to lengthen the travel path of light inside the radiator, thus leading to larger time differences in the TOP measurement which makes it less challenging to discriminate different particle species at large momenta.

A detailed description of this concept can be found in the attached file giessendirc.pdf as well as under the link http://www.physik.uni-giessen.de/dueren/giessendirc.pdf

The time-of-propagation concept obviously requires extremely fast photon detectors which are capable of measuring the travel time of cherenkov photons through the radiator material. At the moment especially micro-channel plate photomultiplier tubes (MCP-PMTs) seem to be a very promising technology. There is a group at the University of Nagoya, Japan, which works in collaboration with HAMAMATSU and KEK on the development of MCP-PMTs for a TOP DIRC intended for the BELLE / Super-B factory upgrade. Details about their results can be found in the attached NIM papers. BELLE has to make a technology decision concerning the TOP technique well before PANDA. In case they decide for a TOP Cherenkov counter with MCP-PMTs those photon detectors will probably become commercially available within the timescale of our project.

-- MarkusEhrenfried - 10 Aug 2006

• giessendirc.pdf: Conceptual Design of a Multi-Chromatic Time-of-Propagation Endcap DIRC for PANDA

• MCP-PMT-A528-763-2004.pdf: MCP-PMT timing property for single photons, NIM A 528 (2004) 763-775

• TOP-Counter-NIM-A453-331-2000.pdf: Test result of time-of-propagation Cherenkov counter, NIM A 453 (2000) 331-335

• TOP-Counter-NIM-A440-124-2000.pdf: Time-of-propagation Cherenkov counter for particle identification, NIM A 440 (2000) 124-135