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.
The PANDA detector at the international accelerator Facility for Antiproton and Ion Research in Europe (FAIR) in Darmstadt (Germany)
will address fundamental questions of hadron physics in high-energy antiproton collisions with fixed hydrogen and nuclear targets.
The PANDA Forward RICH (FRICH) is intended for identification of charged particles with forward polar angles below 5°–10°
and momenta from 3 to 15 GeV/c. PANDA FRICH will feature a multilayer focusing aerogel radiator, photon detection by Hamamatsu H12700 MaPMTs
read out by DiRICH front-end electornics. Precisely aligned flat mirrors will collect Cherenkov light on the photon detector.
Results of optical measurements of the detector components are presented.
The PANDA Forward RICH prototype was tested at 3GeV electron beam at the Budker INP in 2019.
Single photon resolution was obtained that agrees with expectations.