arXiv subjects

H. -G. Zaunick

Publications and source records attributed to H. -G. Zaunick.

10 recordsLinked to original sources

arXiv2023

The new APD-Based Readout of the Crystal Barrel Calorimeter -- An Overview

The Crystal Barrel is an electromagnetic calorimeter consisting of 1380 CsI(Tl) scintillators, and is currently installed at the CBELSA/TAPS experiment where it is used to detect decay products from photoproduction of mesons. The readout of the Crystal Barrel has been upgraded in order to integrate the detector into the first level of the trigger and to increase its sensitivity for neutral final states. The new readout uses avalanche photodiodes in the front-end and a dual back-end with branches optimized for energy and time measurement, respectively. An FPGA-based cluster finder processes the whole hit pattern within less than 100 ns. The important downside of APDs -- the temperature dependence of their gain -- is handled with a temperature stabilization and a compensating bias voltage supply. Additionally, a light pulser system allows the APDs' gains to be measured during beamtimes.

physics.ins-det↗

arXiv2020

The BGOOD experimental setup at ELSA

The BGOOD experiment at the ELSA facility in Bonn has been commissioned within the framework of an international collaboration. The experiment pursues a systematic investigation of non-strange and strange meson photoproduction, in particular $t$-channel processes at low momentum transfer. The setup uniquely combines a central almost $4π$ acceptance BGO crystal calorimeter with a large aperture forward magnetic spectrometer providing excellent detection of both neutral and charged particles, complementary to other setups such as Crystal Barrel, Crystal Ball, LEPS and CLAS.

physics.ins-det↗

arXiv2018

The η'-carbon potential at low meson momenta

The production of $η^\prime$ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on $^{12}$C and on a liquid hydrogen (LH$_2$) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The $η^\prime$ mesons have been identified via the $η^\prime\rightarrow π^0 π^0η\rightarrow 6 γ$ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF$_2$ array at polar angles of $2^{\circ} \le θ_{p} \le 11^{\circ}$. Under these kinematic constraints the $η^\prime$ mesons are produced with relatively low kinetic energy ($\approx$ 150 MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the $η^\prime$-carbon potential at low meson momenta by comparing with collision model calculations of the $η^\prime$ kinetic energy distribution and excitation function. Fitting the latter data for $η^\prime$ mesons going backwards in the center-of-mass system yields a potential depth of V = $-$(44 $\pm$ 16(stat)$\pm$15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average $η^\prime$ momenta of $\approx$ 1.1 GeV/$c$. Within the experimental uncertainties, there is no indication of a momentum dependence of the $η^\prime$-carbon potential. The LH$_2$ data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for $η^\prime$ photoproduction off the free proton.

nucl-ex↗

arXiv2016

Momentum dependence of the imaginary part of the $ω$- and $η^\prime$-nucleus optical potential

The photoproduction of $ω$ and $η^\prime$ mesons off carbon and niobium nuclei has been measured as a function of the meson momentum for incident photon energies of 1.2-2.9 GeV at the electron accelerator ELSA. The mesons have been identified via the $ω\rightarrow π^0 γ\rightarrow 3 γ$ and $η^\prime\rightarrow π^0 π^0η\rightarrow 6 γ$ decays, respectively, registered with the CBELSA/TAPS detector system. From the measured meson momentum distributions the momentum dependence of the transparency ratio has been determined for both mesons. Within a Glauber analysis the in-medium $ω$ and $η^\prime$ widths and the corresponding absorption cross sections have been deduced as a function of the meson momentum. The results are compared to recent theoretical predictions for the in-medium $ω$ width and $η^\prime$-N absorption cross sections. The energy dependence of the imaginary part of the $ω$- and $η^\prime$-nucleus optical potential has been extracted. The finer binning of the present data compared to the existing data allows a more reliable extrapolation towards the production threshold. The modulus of the imaginary part of the $η^\prime$ nucleus potential is found to be about three times smaller than recently determined values of the real part of the $η^\prime$-nucleus potential, which makes the $η^\prime$ meson a suitable candidate for the search for meson-nucleus bound states. For the $ω$ meson, the modulus of the imaginary part near threshold is comparable to the modulus of the real part of the potential. As a consequence, only broad structures can be expected which makes the observation of $ω$ mesic states very difficult experimentally.

nucl-ex↗

arXiv2016

Determination of the real part of the η'-Nb optical potential

The excitation function and momentum distribution of η' mesons have been measured in photoproduction off 93^Nb in the energy range of 1.2-2.9 GeV. The experiment has been performed with the combined Crystal Barrel and MiniTAPS detector system, using tagged photon beams from the ELSA electron accelerator. Information on the sign and magnitude of the real part of the η'-Nb potential has been extracted from a comparison of the data with model calculations. An attractive potential of -(41 \pm 10(stat) \pm 15(syst)) MeV depth at normal nuclear matter density is deduced within model uncertainties. This value is consistent with the potential depth of -(37 \pm 10(stat) \pm 10(syst)) MeV obtained in an earlier measurement for a light nucleus (carbon). This relatively shallow η'-nucleus potential will make the search for η'-nucleus bound states more difficult.

nucl-ex↗

arXiv2012

Technical Design Report for the: PANDA Micro Vertex Detector

This document illustrates the technical layout and the expected performance of the Micro Vertex Detector (MVD) of the PANDA experiment. The MVD will detect charged particles as close as possible to the interaction zone. Design criteria and the optimisation process as well as the technical solutions chosen are discussed and the results of this process are subjected to extensive Monte Carlo physics studies. The route towards realisation of the detector is outlined.

physics.ins-det↗

arXiv2009

Development of a GEM-TPC prototype

The use of GEM foils for the amplification stage of a TPC instead of a con- ventional MWPC allows one to bypass the necessity of gating, as the backdrift is suppressed thanks to the asymmetric field configuration. This way, a novel continuously running TPC, which represents one option for the PANDA central tracker, can be realized. A medium sized prototype with a diameter of 300 mm and a length of 600 mm will be tested inside the FOPI spectrometer at GSI using a carbon or lithium beam at intermediate energies (E = 1-3AGeV). This detector test under realistic experimental conditions should allow us to verify the spatial resolution for single tracks and the reconstruction capability for displaced vertexes. A series of physics measurement implying pion beams is scheduled with the FOPI spectrometer together with the GEM-TPC as well.

physics.ins-det↗

arXiv2009

Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.

physics.ins-det↗

arXiv2009

Physics Performance Report for PANDA: Strong Interaction Studies with Antiprotons

To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with nucleons and nuclei, the universal PANDA detector will be built. Gluonic excitations, the physics of strange and charm quarks and nucleon structure studies will be performed with unprecedented accuracy thereby allowing high-precision tests of the strong interaction. The proposed PANDA detector is a state-of-the art internal target detector at the HESR at FAIR allowing the detection and identification of neutral and charged particles generated within the relevant angular and energy range. This report presents a summary of the physics accessible at PANDA and what performance can be expected.

hep-ex↗

arXiv2008

Technical Design Report for PANDA Electromagnetic Calorimeter (EMC)

This document presents the technical layout and the envisaged performance of the Electromagnetic Calorimeter (EMC) for the PANDA target spectrometer. The EMC has been designed to meet the physics goals of the PANDA experiment, which is being developed for the Facility for Antiproton and Ion Research (FAIR) at Darmstadt, Germany. The performance figures are based on extensive prototype tests and radiation hardness studies. The document shows that the EMC is ready for construction up to the front-end electronics interface.

physics.ins-det↗