The PANDA experiment at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) near GSI, Darmstadt, Germany will address fundamental questions of hadron physics. Excellent particle identification is required to achieve the PANDA physics goals. Hadronic particle identification (PID) in the PANDA target spectrometer will be delivered by two DIRC (Detection of Internally Reflected Cherenkov light) counters. The Barrel DIRC will cover the polar angle range of 22−140 degree and is designed to provide pion/kaon separation for momenta between 0.5 GeV/c and 3.5 GeV/c with a separation power of at least 3 standard deviations. Several reconstruction algorithms have been developed to determine the performance of the detector. The "geometrical reconstruction" determines the Cherenkov angle relying primarily on the position of the detected photons. The "time imaging", however, utilizes both position and time measurements by directly performing the maximum likelihood fit. GEANT4 simulations and experimental data from prototype tests at the CERN PS were used to optimize the performance of the algorithms. We will discuss detailed aspects of both reconstruction approaches.
High event rates of up to 20 MHz and continuous detector readout makes the event filtering at PANDA a challenging task. In addition, no hardware-based event selection will be possible due to the similarities between signal and background. This makes PANDA among a new generation of experiments utilizing a fully software-based event filtering. Classically, detector hits are pre-sorted into events by the hardware filter before being passed to the software-based event filter with track reconstruction and event building. Track reconstruction will play a key part in the online filtering at PANDA where it will be used iteratively together with the event building.
To ensure the quality of the track reconstruction, the existing quality assurance task has been modified to be able to cope with free streaming data. This talk will address the data stream at PANDA as well as the candidates for online track reconstruction algorithms for free streaming data based e.g. on the Cellular Automaton. The quality assurance procedure and the results from the tracking at different event rates and level of event mixing is presented.
Submitted by c.schwarz on Thu, 12/12/2019 - 14:09.
The PANDA experiment of the FAIR facility will address open
questions in hadron physics using antiproton beams in the
momentum range of 1.5-15 GeV/c.
The antiprotons are stored and cooled in the High Energy
Storage Ring (HESR) and allow high precision spectroscopy in
the energy range of closed and open charm.
Two Cherenkov detectors using the principle of Detection of
Internally Reflected Cherenkov light (DIRC) will provide
excellent PID in the PANDA target spectrometer.
The Endcap Disc DIRC separates pions from kaons better than
3σ up to momenta of 4 GeV/c in the forward direction, for polar
angles from 5∘ to 22∘.
It uses a fused silica radiator disk, consisting of four
optically isolated quadrants.
The Cherenkov photons are imaged on Microchannel-Plate PMTs
(MCP-PMTs) by focusing lightguides.
The Barrel DIRC cleanly separates pions from kaons for polar
angles in the range of 22∘ - 140∘ and momenta up to 3.5 GeV/c.
The barrel is formed by 16 sectors, each comprising three narrow
fused silica radiator bars, with a flat mirror attached to
one end and a spherical lens attached to the other, and a
large fuse silica prism, coupled to each group of three lenses.
The Cherenkov light is focused on the back side of the prism,
where an array of lifetime-enhanced MCP-PMTs detects the photons.
The designs are simulated and validated in test beams with
prototypes and the Technical Design Reports of both devices
have recently been completed.
While mass production of some of the components has already
started, the R&D for other important items, like the readout
electronics or the shape and materials of the mechanical support,
is still ongoing.
This talk describes the status of the two DIRC projects and will
discuss the remaining R&D activities.
PANDA is one of the four experimental pillars of the upcoming FAIR facility in Darmstadt, Germany. In PANDA, an antiproton beam with an energy between 1.5 and 15 GeV/c will interact in a hydrogen or nuclear target, allowing for studies of various aspects of non-perturbative QCD. Motivated by the high interaction rates and the diverse physics goals of the experiment, a triggerless readout approach will be employed. In this approach, each detector subsystem will be equipped with intelligent front-end electronics that independently identify signals of interest in real time. In order to detect the most forward-directed photons, electrons and positrons in PANDA, a shashlyk-type calorimeter is being constructed. This detector consists of 1512 individual cells of interleaved plastic scintillators and lead plates, and has been optimised to have a relative energy resolution of approximately 3%/sqrt(GeV) and a time resolution of approximately 100 ps/sqrt(GeV). The signals from this detector will be digitised by sampling ADCs and processed in real time by FPGAs. As part of the triggerless approach, these FPGAs will perform so-called feature extraction on the digitised signals, where the pulse-height and time of incoming pulses are extracted in real time. A substantial pileup rate is expected, and it is foreseen that the chosen algorithm should enable reconstruction of such events. The work presented here has consisted of developing a detailed Geant4-based model of the shashlyk calorimeter and readout system, calibrating this model against testbeam data, and using it to evaluate potential feature-extraction algorithms for the PANDA shashlyk calorimeter.