Submitted by ken.suzuki on Fri, 24/02/2017 - 13:50.
The triggerless detector system PANDA which is being built at the FAIR facility. The versatile detector system will enable us to study open questions in hadron physics, by doing charmonium spectroscopy with precision measurements of mass, width and decay branches, investigating possible exotic states, search for modifications of charmed hadrons in nuclear matter and gamma-ray spectroscopy of hypernuclei by using antiprotons on a cluster jet or a pellet target in the momentum range of 1.5 to 15 GeV/c.
The barrel-TOF subdetector is one of the outer layers of the multi-layer design of the PANDA barrel. It is designed with a minimal material budget in mind mainly consisting of 90x30x5 mm^3 thin plastic scintillator tiles read out on each end by a serial connection of 4 SiPMs. 120 such tiles are placed on 16 2460 x 180 mm^2 PCB boards forming a barrel covering an azimuthal angle from 22.5° to 150°. The detector is designed to achieve a time resolution below 100 ps (sigma) which allows for good event separation as well as particle identification below the Cherenkov threshold via the time-of-flight, simultaniously providing the interaction times of events. The current prototype achieved ~60 ps, well below the design goal.
The R&D is in a matured stage and a technical design report is currently being reviewed by the collaboration. In this contribution the whole project from the design concept to the latest result of test beamtime as well as the future outlook will be presented.
The PANDA detector 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 (PID) over a large range of solid angles and particle momenta will be essential to meet the objectives of the rich physics program, which includes charmonium spectroscopy, the search for hybrids and glueballs, and the study of the interaction of hidden and open charm particles with nucleons and nuclei.
Charged PID for the barrel section of the target spectrometer will be provided by a DIRC (Detection of Internally Reflected Cherenkov light) detector.
This counter will cover the angular range of 22-140 degrees and will need to cleanly separate charged pions from kaons for momenta between 0.5 GeV/c and 3.5 GeV/c with a separation power of at least 3 standard deviations.
The design of the PANDA Barrel DIRC detector is based on the successful BABAR DIRC and the SuperB FDIRC R&D with several important improvements to optimize the performance for PANDA, such as a focusing lens system, fast timing, and a compact fused silica prism as expansion region.
We will discuss the baseline design of the PANDA Barrel DIRC, based on narrow bars made of synthetic fused silica, and a complex multi-layer spherical lens system, and the potentially cost-saving design option using wide fused silica plates and
will present the result of tests of a large system prototype with a mixed hadron beam at CERN.
In the PANDA experiment, for momentum analysis of forward scattered charged particles, a large gap dipole magnet and the Forward Tracker (FT) will be used.
The main requirements for the FT include a high rate capability corresponding to particle fluxes reaching up to 2.5x10^4 cm^-2 s^-1 close to the beam pipe and a total counting rate of about 5x10^7 s^-1.
A momentum acceptance extending down to at least 3% of the beam momentum and a momentum resolution better than 1.5% is expected.
To meet these requirements, a tracking system based on 10 mm in diameter straw tubes, made of a thin (27 um) aluminized Mylar film, has been designed.
It consists of 6 tracking stations, each comprising 4 planar double-layers of the straws with a total material budget of only 2% X0.
The straws are made self-supporting by a 1 bar over-pressure of the working gas mixture (Ar/CO2). This allows to use lightweight and compact rectangular support frames for the double-layers and to split the frames into pairs of C-shaped half-frames for an easier installation on the beam line.
The double-layers are built of separate modules consisting of 32 straws arranged in two staggered layers.
The modular construction allows for fast repair and/or replacement of the modules suffering from aging effects or broken straws during the detector lifetime.
The read out of the FT is based on the newly developed PASTTREC ASIC (0.35 um CMOS) providing configurable
gain and shaping time, an ion tail cancelation and a baseline holder circuits appropriate for the high rate applications.
The drift time as well as a Time-Over-Threshold (TOT) of the detector signals is measured using Trigger Readout Boards v3 (TRBv3) containing 64 TDC channels implemented in FPGA
and serving also as nodes of the readout platform and data processing.
Tests of prototype modules, performed with proton beams at high counting rates of up to 1 MHz/straw, demonstrated a tracking capability with a good spatial resolution of 150 um per straw and the applicability of the TOT technique for the identification of the particles species by means of their specific energy losses.