Proceedings (PRO)

The hadron identification in the PANDA experiment at FAIR will be done with DIRC detectors. Because of design and space reasons the sensors of the DIRCs have to be placed inside the strong magnetic field of the solenoid. As the favored photon sensors microchannel-plate photomultipliers (MCP-PMTs) were identified. However, these devices showed serious aging problems until very recently, which manifest themselves by a fast degrading quantum efficiency (QE) of the photo cathode (PC). This is mainly due to feedback ions from the residual gas. In this paper we discuss the recently accomplished huge improvements in the lifetime of MCP-PMTs. With innovative countermeasures applied to the MCP-PMTs in the attempt to reduce the aging effects the manufacturers were able to increase the lifetime of MCP-PMT prototypes by almost two orders of magnitude compared to the former commercially available devices. Our group has studied the aging of MCP-PMTs for more than four years by simultaneously illuminating different types of lifetime-enhanced MCP-PMTs at the same photon rate. Gain, dark count rate, and QE as a function of the wavelength and the PC surface were measured in regular time intervals and studied in dependence of the integrated anode charge. We observe that MCP-PMTs treated with an atomic layer deposition (ALD) technique are by far the best devices available now. A lifetime of up to 10
C/cm2 integrated anode charge was reached with these sensors. This is sufficient for both PANDA DIRCs.

The charged particle identification at the PANDA experiment will be mainly performed with DIRC detectors. Because of their advantageous properties the preferred photon sensors are MCP-PMTs. However, until recently these devices showed serious aging problems which resulted in a diminishing quantum efficiency (QE) of the photo cathode. By applying innovative countermeasures against the aging causes, the manufacturers recently succeeded in drastically improving the lifetime of MCP-PMTs. Especially the application of an ALD coating technique to seal the material of the micro-channels proves very powerful and results in a lifetime of ~6 C/cm2 integrated anode charge without a substantial QE degradation for the latest PHOTONIS XP85112. This paper will present a comparative measurement of the lifetime of several older and recent MCP-PMTs demonstrating this progress.

PANDA is an experiment at the new FAIR facility at GSI and will, among other physics goals,
perform charmonium spectroscopy and search for gluonic excitations using high luminosity antiproton
beams up to 15 GeV/c. A high performance particle identification system applying DIRC
detectors will allow pion/kaon separation up to 4 GeV/c. A Barrel DIRC with fused silica radiator
bars or plates will surround the target at a radial distance of 48 cm and will cover a polar
angle range of 22 to 140 degrees; a novel Endcap Disk DIRC built of a segmented fused silica
disk of 210 cm diameter will be installed in the forward region to cover the polar angles from
5 to 22 degrees. The design of the optics and the readout of both DIRCs will be presented in
this paper. Different prototypes were tested in particle beams. The performance of the latest prototypes,
which are close to the final DIRC design, are discussed and compared to the PANDA
requirements.

DIRC Cherenkov detectors will be the main devices for pi/K separation at the PANDA experiment at
FAIR. Due to their advantageous properties in terms of time resolution and especially inside magnetic
fields micro-channel plate photo multipliers (MCP-PMTs) are very attractive sensor candidates. In this
paper we present the investigation of several types of multi-anode MCP-PMTs. The darkcount rate, the
behavior inside a magnetic field of up to 2 T, the time resolution, the gain homogeneity and crosstalk of
multi-pixel MCP-PMTs were found to be well suitable for the PANDA requirements. Even the rate
capability of the latest models from Burle-Photonis and Hamamatsu is satisfactory. Although a big step
forward was accomplished with these recently available MCP-PMTs, the lifetime is still not sufficient for
the photon densities expected for the PANDA DIRCs.

Proceedings of CHEP2013 - In 2018 data taking for hadronphysics facility PANDA is planned to commence. It will be build at the antiproton accelerator HESR, which itself is a part of the FAIR complex (GSI, Darmstadt, Germany). The luminosity at PANDA will be measured by a dedicated subdetector, which will register scattered antiproton tracks from ̄pp elastic scattering. From a software point of view, the Luminosity Detector is a tracking system. Therefore the most of its offline software parts are typical for a track reconstruction. The basic concept and Monte Carlo based performance studies of each reconstruction step is presented in this paper.

The PANDA experiment at the new Facility for Antiproton and Ion Research in Europe (FAIR)
at GSI, Darmstadt, will study fundamental questions of hadron physics and QCD using
high-intensity cooled antiproton beams with momenta between 1.5 and 15 GeV/c.
Efficient Particle Identification (PID) for a wide momentum range and the full solid angle
is required for reconstructing the various physics channels of the PANDA program.
Hadronic PID in the barrel region of the detector will be provided by a DIRC (Detection of
Internally Reflected Cherenkov light) counter.
The design is based on the successful BABAR DIRC with important improvements, such as
focusing optics and fast photon timing.
Several of these improvements, including different radiator geometries and optics, were tested
in particle beams at GSI and at CERN.
We will discuss the design and performance of the prototypes in the 2011 and 2012 test beam
campaigns.

The charged particle identification in the barrel region of the detector in the future FAIR facility at GSI is planned with a very thin Cherenkov detector using the DIRC principle. Due to a very compact design of the barrel DIRC with focusing optics, the reconstruction of the Cherenkov angle is quite challenging. In this contribution, the possible reconstruction algorithm of the barrel DIRC will be discussed, with emphasis on the possibility to include the DIRC in the trigger decision and the correction of the chromatic dispersion with fast timing information.

The PANDA experiment at the future Facility for Antiproton and Ion Research (FAIR) at GSI, Darmstadt, aims at studying the strong interacting matter by precision spectroscopy. A detector system with excellent particle identification over a large range of solid angle and momentum is therefore mandatory. Charged hadron identification in the barrel region will be performed by a compact ring imaging Cherenkov detector based on the DIRC principle (Detection of Internally Reflected Cherenkov light), designed to separate pions from kaons with at least 3 standard deviations in the momentum range from 0.5 GeV/c to 3.5 GeV/c. We present details of the simulation of the PANDA Barrel DIRC and a study of the detector performance using a fast reconstruction algorithm to determine the single photon Cherenkov angle resolution and photon yield for several design options.

Cooled antiproton beams of unprecedented intensities in the momentum range of 1.5-15 GeV/c will be used for the PANDA experiment at FAIR to perform high precision experiments in the charmed quark sector. The PANDA detector will investigate antiproton annihilations with beams in the momentum range of 1.5 GeV/c to 15 GeV/c on a fixed target. An almost 4π acceptance double spectrometer is divided in a forward spectrometer and a target spectrometer. The charged particle identification in the latter is performed by ring imaging Cherenkov counters employing the DIRC principle.