Detector software

The PANDA experiment will study a wide range of physics topics with beams of antiprotons incident on fixed proton or complex nuclear targets. One issue is the Ds semileptonic decay, which is governed by the weak and strong forces. The interaction can be parameterized by a transition form factor. The performance of PANDA to measure the decay form factor of Ds + → νe η e+ is evaluated via Monte Carlo simulation. This thesis concentrates on describing the software development and the evaluation of the expected precision. A preliminary estimate of the expected count rate is obtained. In this measurement, it is essential to reconstruct the Ds semileptonic decay with high efficiency and purity in order to overcome the many orders of magnitude higher background. The Micro-Vertex-Detector plays an import role in the whole tracking system. The rate capability and tracking performance of the recent ASIC prototype for the readout of the MVD is tested using a beam of high-energy protons.

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 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.

Hadronic particle identification (PID) in the barrel region of the PANDA experiment at the new Facility for Antiproton and Ion Research in Europe (FAIR) at GSI, Darmstadt will be provided by a DIRC (Detection of Internally Reflected Cherenkov light) counter. To optimize the performance and reduce the detector cost, detailed simulations of different design elements, such as the width of the radiators, the shape of the expansion volume, and the type of focusing system, were performed using Geant. Custom reconstruction algorithms were developed to match the detector geometry. We will discuss the single photon resolution and photon yield as well as the PID performance for the Barrel DIRC baseline design and several detector design options.

The forward tracking system (FTS) is a straw-tube based detector in
the forward-part of the PANDA-detector. It is specializing in reconstruc-
tion of particle trajectories. The FTS consists of six stations. Each station
consists of four doublelayer straw-tubes. The second doublelayer is skewed
5 to the right and the third doublelayer is skewed 5 to the left. The first
and the fourth doublelayer are not skewed. The stations are numbered
with FTS1-FTS6. Between FTS2 and FTS5 is a magnetic field located so
charged particles will be distracted to the left or to the right. If a particle
fly through the FTS there will be FTS-hits at the position of the taken
straw-tubes created. It is necessary to reconstruct the trajectories of the
particles which are crossing the FTS. In this thesis an algorithm has been
developed which gets FTS-hits and creates PndTracks for the trajectory
in the FTS.

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. FRICH will have a multilayer focusing aerogel radiator to achieve the required resolution on Cherenkov angle. A set of precisely aligned flat mirrors will collect light on the multi-anode photomultipliers which are located outside of the detector’s effective aperture. The PANDA Forward RICH R&D relies on experience of other modern RICH detectors. A baseline design of the PANDA Forward RICH is presented including results of the full Monte-Carlo simulation, optical measurements and prototype beam tests.

The Panda experiment, currently under construction at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, addresses fundamental questions in hadron and nuclear physics via interactions of antiprotons with nucleus / nuclei. The High Energy Storage Ring will provide an antiproton beam with a momentum range of 1.5 – 15 GeV/c and an average collision rate of 20~MHz on a fixed target. Due to a missing hardware trigger and a continuous data acquisition in the \panda experiment, a highly advanced online analysis is needed to achieve an online data reduction of a factor 100 – 1000 before storage. A missing collision time (\t0), high interaction rates and overlapping event data in the sub detector systems further increases the difficulty of the event reconstruction.

The Barrel Time-of-Flight detector (Barrel TOF) for Panda, being developed at the Stefan Meyer Institute, will be one of the key components in Panda to determine the origin time of particle tracks, to ensure a disentanglement of overlapped hits from neighboring collisions and to provide information about \t0. Another important task of the Barrel TOF is to provide particle identification (PID) for charged particles together with the Cherenkov-based PID detectors, which is especially important for particle momenta below 700 MeV. In order to achieve a time resolution of < 100 ps, required for the mentioned disentanglement of the data, while keeping a minimal material budget, the detector will be realized as a barrel-shaped scintillator tile hodoscope. It covers the central region of the detector with a diameter of about 1~m and a length of about 2~ m. The sensitive area of about 6~ m² consists of 1920 scintillating tiles with a dimension of 90 x 30 x 5 mm³ each, readout by 8 Silicon Photomultipliers (SiPMs), with 4 on each end connected in series. The signal transmission lines are embedded in a multilayer PCB backplane. It also serves as the mechanical frame to minimize the material budget. During beam tests a single tile time resolution of about 55 ps in standard deviation has been achieved.

It was a crucial and challenging task to implement the Barrel TOF in the simulation framework, PandaRoot. This allowed the optimization of the detector geometry using Monte Carlo simulations and the investigation of the requirements for the readout electronics and led to the described design. In the second phase the performance of the Barrel TOF was evaluated and optimized for the entire experiment. For this purpose software algorithms based on the Barrel TOF system were developed and implemented in PandaRoot, i.e. triggering, event sorting, start time reconstruction and particle identification. Among other work this allowed the submission of the Technical Design Report for the Barrel TOF in February 2017 to FAIR, which has been accepted. After this the developed and implemented algorithms as well as the acquired knowledge were used to advance the general \panda reconstruction chain. Together with our international collaborators the first steps towards a dynamical tracking and event reconstruction algorithm, which combines the signal of all sub detector systems of Panda, were developed.

PANDA Management Quarterly Report 18Q2

PANDA Collaboration Meeting 18/2 Minutes