Paper

The PANDA experiment represents the central part of the hadron physics
programme at the new Facility for Antiproton and Ion Research (FAIR) under
construction at GSI/Darmstadt (Germany). The multi-purpose PANDA detector in
combination with an intense and high-quality antiproton beam allows for coverage
of a broad range of different aspects of QCD, and it is best suited for charmonium
spectroscopy. We present a comprehensive PANDA Monte Carlo simulation study for
precision resonance energy scan measurements, using the example of the charmonium-like
$X(3872)$ state discussed to be exotic. Apart from the proof of principle for
natural decay width and line-shape measurements of very narrow resonances, the
achievable sensitivities are quantified for the concrete example of the $X(3872)$.
The discussed measurement is uniquely possible with a $\bar{p}p$ annihilation
experiment such as PANDA at FAIR.

At the international FAIR laboratory, an upcoming significant enlargement of the GSI installations near Darmstadt, Germany, the PANDA antiproton experiment will investigate fundamental questions of hadron physics in the charm quark energy range. Antiprotons in the 1.5 to15 GeV/c momentum range will interact with gas jet or pellet fixed targets. The Endcap Disc DIRC (Detection of Internally Reflected Cherenkov light) covers the forward endcap solid angle of the PANDA target spectrometer to positively identify charged kaons. Monte-Carlo simulations indicate that from 1 up to 4 GeV/c one can achieve kaon-pion separation with a separation power of at least 3 standard deviations. For the upcoming CERN test beam in August 2018 the read-out electronics has been upgraded to the TOFPET-ASIC Version 2.

This paper summarises a comprehensive Monte Carlo simulation study for precision resonance energy scan measurements. Apart from the proof of principle for natural width and line-shape measurements of very narrow resonances with PANDA, the achievable sensitivities are quantified for the concrete example of the charmonium-like $X(3872)$ state discussed to be exotic, and for a larger parameter space of various assumed signal cross-sections, input widths and luminosity combinations. PANDA is the only experiment that will be able to perform a precision resonance energy scan of such a narrow state with quantum numbers of spin and parities that differs from $J^{PC} = 1^{--}$.

Microchannel-plate (MCP) PMTs were identified as the only suitable photon sensors for the two DIRC detectors of the PANDA experiment at FAIR. As the long-standing aging problem of MCP-PMTs was recently overcome by coating the MCP pores with an atomic layer deposition (ALD) technique, further improved 2-inch MCP-PMTs were investigated. The best PHOTONIS device has reached a lifetime of >20 C/cm2 integrated anode charge without any sign of aging. Also the newly developed 2-inch MCP-PMTs of Hamamatsu are maturing and are usable in high rate environments. The status of our long-term lifetime measurements and the performance parameters of the currently most advanced ALD-coated MCP-PMTs from PHOTONIS and Hamamatsu are presented. In addition, first results obtained with a new quality assurance setup for MCP-PMTs are discussed. This setup consists of a high performance DAQ system to measure the response of >=64 anode pixels simultaneously. The system allows to study and quantify background parameters like position dependent dark count rates and ion afterpulsing as well as temporal and spacial distributions of recoil electrons and the effects of electronic and charge-sharing crosstalk among the anode pixels.

Proceedings for the CHEP 2018. Deadline for initial submission is October 31st, 2018.

The Endcap Disc DIRC has been developed to provide an excellent particle identification
for the future PANDA experiment by separating pions and kaons up to a momentum of 4 GeV/c with
a separation power of 3 standard deviations in the polar angle region from 5 ◦ to 22 ◦ . This goal will
be achieved using dedicated particle identification algorithms based on likelihood methods and will
be applied in an offline analysis and online event filtering. This paper evaluates the resulting PID
performance using Monte-Carlo simulations to study basic single track PID as well as the analysis
of complex physics channels. The online reconstruction algorithm has been tested with a Virtex4
FGPA card and optimized regarding the resulting constraints.

The Endcap Disc DIRC (EDD) has been developed to provide an excellent particle identification in the future PANDA experiment by separating pions and kaons up to a momentum of 4\,GeV/c with a separation power of 3\,s.d.. The detector is placed in the forward endcap of the PANDA target spectrometer. It consists of a fused silica plate and focusing elements placed at the outer rim, which focus the Cherenkov light on the photo cathodes of the attached MCP-PMTs. A compact and fast readout of the signals is realized with special ASICs. The performance has been studied and validated with different prototype setups in various testbeam facilities.

The PANDA detector at the future FAIR facility at GSI is planned as a fixed- target experiment for proton-antiproton collisions at momenta between 1.5 and 15 GeV/c. It will be used to address open questions in hadronic physics. In order to achieve a sufficient particle identification, two different DIRC detector concepts have been developed. This talk will cover the Endcap Disc DIRC detector which is placed at the forward endcap of the PANDA target spectrometer and will provide a 3σ separation of pions and kaons up to a momentum of 4 GeV/c for polar angles from 5° to 22°. The most important component of the DIRC detector is a 2 cm thin fused silica radiator plate that is divided into 4 identical quadrants. The surfaces are polished with high precision in order to guarantee little photon losses by total reflection and conserve the Cherenkov angle during propagation through the optical system. Intrinsic chromatic errors will be minimized by the implementation of an optical filter. The readout system consists of 96 readout elements with focusing optics and attached MCP-PMTs to focus the photons that are produced by the Cherenkov cone of the traversing particle and acquire their position and timing information. This new detector concept requires the development of dedicated reconstruction and particle identification algorithms which permit an efficient analysis of the measured time-correlated photon patterns. Time and event based simulations with dedicated Monte-Carlo simulation frameworks have been used to validate the PID requirements of the DIRC counter. Additionally, the Monte-Carlo simulations have been used to estimate the radiation dose in different detector volumes in order to compare these values with actual measurement results.

The PANDA experiment at FAIR will use DIRC detectors for the separation of hadrons. The compactness of the PANDA detector requires the image planes of these detectors to be placed inside the magnetic field of the solenoid. Due to this and other boundary conditions MCP-PMTs were identified as the only suitable photon sensors. Until recently the major obstacle for an application of MCP-PMTs in high rate experiments like PANDA were serious aging problems which led to damage at the photo-cathode and a fast declining quantum efficiency as the integrated anode charge (IAC) increased. With new countermeasures against the aging, in particular due to the application of an atomic layer deposition (ALD) technique to coat the MCP pores, the lifetime of MCP-PMTs has meanwhile increased by a factor >50 which is fully sufficient for PANDA. The recent results of our long-term lifetime measurements are discussed. New 2-inch MCP-PMT prototypes from Hamamatsu show an encouraging behavior. However, the currently best performing MCP-PMT is a 2-inch PHOTONIS tube with two ALD-layers which reaches an IAC of >16 C/cm2 without any visible sign of aging. In the second part of these proceedings a new data acquisition system of the PADIWA/TRB type is presented which allows a quasi-parallel measurement of many MCP-PMT performance parameters. Especially unwanted effects like dark-count rate, crosstalk, ion afterpulsing, and recoil electrons can be studied in more detail than ever before. Exemplary results for these parameters are shown. The discussed DAQ system will be used for the comprehensive data quality checks of the MCP-PMTs being built into the DIRCs.