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[en] The PANDA experiment is one of the major projects in preparation at the upcoming FAIR facility in Darmstadt, Germany. A multipurpose high energy physics detector is currently under construction and will be operated at the High Energy Storage Ring of FAIR. High intensity antiproton beams will be available in the momentum range between 1.5 GeV/c and 15 GeV/c and will allow to address a broad physics program including hadron spectroscopy, study of charm and strangeness in nuclei, hypernuclear physics and other QCD topics. In addition, the PANDA experiment will offer unique possibilities to investigate the structure of the proton using different electromagnetic processes. In this contribution, the PANDA physics program related to the nucleon structure aspects is discussed. Feasibility studies of electromagnetic processes for the measurements of proton electromagnetic form factors in the time-like region and the nucleon-to-meson transition distribution amplitudes at PANDA, are reported.
Journal
EPJ. Web of Conferences; ISSN 2100-014X; 
; v. 204; vp
; v. 204; vp
[en] The first measurements of baryonic form factors were performed six decades ago by Robert Hofstadter for the proton via electron scattering in atomic nuclei and led to many breakthough results for undestanding the structure of nuclei. Since then the space-like domain was examined over a large energy range by many different experiments for both protons and neutrons. In contrast, the time-like region is almost unknown until now, especially in case of the neutron. The Beijing Electron Positron Collider II (BEPCII) is designed for center of mass energies between 2 and 5 GeV and therefore offers with the included Beijing Electron Spectrometer III (BESIII) experiment a unique possibility to measure nucleon form factors in the time-like domain with high precision. In particular measurement of the time-like form factors of the neutron would offer a significant improvement to existing results. We report on the use of modern approaches like initial state radiation (ISR) and multivariate analysis methods as a general strategy in the analysis of the channel e+e-→ nnγISR.
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; CODEN VDPEAZ; (Frankfurt 2014 issue); [1 p.]
; CODEN VDPEAZ; (Frankfurt 2014 issue); [1 p.]
[en] In this contribution the latest status of the feasibility studies for the measurement of time-like proton electromagnetic form factors (FF's) using reactions of the type anti pp → μ+μ- at the PANDA experiment at FAIR is presented. Electromagnetic form factors are fundamental quantities which parameterize the electric and magnetic structure of hadrons. In the time-like region, the FF's can be accessed through reactions of the type p anti p → l+l-, where l = e, μ, under the assumption of one photon exchange. It is the first time that muon pairs in the final state are used for the measurement of the TL em FF's of the proton. One advantage of using this channel is that radiative corrections due to final state radiation are suppressed by the heavy mass of the muon. Measuring anti pp → μ+μ- also serves as a consistency check of the TL em FF data from anti pp → e+e-. In frame of the PANDARoot software, which encompasses full detector simulation and event reconstruction, the statistical precision at which the proton FF's will be determined at PANDA is estimated for the signal reaction p anti p → μ+μ- at different antiproton beam momenta. The signal identification and the suppression of the main background process (p anti p → π+π-) are studied. For the analysis of the processes of interest, different methods have been used and are compared.
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; CODEN VDPEAZ; (Darmstadt 2016 issue); [1 p.]
; CODEN VDPEAZ; (Darmstadt 2016 issue); [1 p.]
[en] The measurement of the phase between the electric and the magnetic form factors of the proton can be measured using a polarized interaction. A feasible possibility to allow this kind of reactions would be to develop a transversely polarized proton target to be used in the PANDA experiment. The first step to achieve the transverse target polarization is to study the feasibility of shielding the target region from the external 2 T longitudinal magnetic field generated by the PANDA solenoid. BSCOO-2212, a new high-temperature superconductor material, has been identified as a possible candidate to be used for shielding this external magnetic field. Tests at 4 K have taken place in the Helmholtz Institute Mainz with this material, and the first preliminary results are shown here.
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; CODEN VDPEAZ; (Darmstadt 2016 issue); [1 p.]
; CODEN VDPEAZ; (Darmstadt 2016 issue); [1 p.]
[en] One of the main goals of the future PANDA experiment at FAIR (Darmstadt, Germany) is the investigation of the proton structure. Electromagnetic form factors (FF's) are fundamental quantities which parameterize the electric and magnetic structure of hadrons. In the time-like region, proton FF's can be accessed experimentally in anti pp → l+l- (l = e,μ) annihilation processes, assuming that the interaction takes place through the exchange of one virtual photon. The expected statistical precision for the measurement of time-like electromagnetic proton form factors with PANDA was investigated in the framework of the PANDARoot software for detector simulation and event reconstruction for both muon and electron channels. These studies investigated the possibility to achieve an optimal signal-background separation and sufficient background suppression of the relevant background channels. Different methods have been used to generate and analyse the processes of interest. The results show, that time-like electromagnetic proton form factors can be measured at PANDA with high statistical accuracy over a large kinematical region.
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; CODEN VDPEAZ; (Bochum 2018 issue); [1 p.]
; CODEN VDPEAZ; (Bochum 2018 issue); [1 p.]
[en] We study the generalization of QED synchrotron radiation to the QCD case with a chromomagnetic field using the Schwinger et al. source method. It is shown that the QED case can be obtained as a special limit. The comparison with the path integral approach of Zakharov has shown consistent results.
Journal
[en] For the construction of the Backward End-Cap (BWEC) of the PANDA Electromagnetic Calorimeter (EMC) various tests regarding the mechanics and the monitoring system are necessary and will be discussed. In addition, a full prototype of the supporting system is under construction, comprising insertion rails, alignment feet, base and test arm supports, test mounting plates and basalt feet. This will allow testing the moving trajectory and insertion of the whole detector, including the specifications for the alignment. A customized solution for the monitoring and positioning of optical fibers for calibration and the insertion in the cold volume will be carried out. The status and the prospects of this development work is shown and discussed.
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; CODEN VDPEAZ; (Darmstadt 2016 issue); [1 p.]
; CODEN VDPEAZ; (Darmstadt 2016 issue); [1 p.]
[en] The neutron structure and dynamics can be understood via the study of its electro- magnetic form factors. In the time-like region few experiments had been performed so far, none of them had the possibility to determinate the ratio of the electric and magnetic form factors. Therefore, a large data sample in a wide range of center of mass energies [2.0-3.08 GeV] has been collected in Beijing Spectrometer III (BESIII) at the Beijing Electron Positron Collider II (BEPCII). With the collected data, it is expected to determine the electric and the magnetic FFs of neutron separately, determine Born cross section with higher precision and therefore enhance the knowledge of neutron structure. In this contribution, we will present our strategy of selecting e+e- → n anti n signal and the expected precision in the determination of Born cross section and electro-magnetic form factors.
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; CODEN VDPEAZ; (Bochum 2018 issue); [1 p.]
; CODEN VDPEAZ; (Bochum 2018 issue); [1 p.]
[en] The PANDA experiment wants to achieve a deeper understanding of the strong interaction. It is built at the new accelerator facility FAIR in Darmstadt. The electromagnetic process group in Mainz is developing the backward end-cap (BWEC) of the electromagnetic calorimeter. The prototype (PROTO16) serves for testing the final BWEC components for cooling, insulating, place consumption, photon read-out, electronics and signal transmission. PROTO16 got some major updates in the last year. The aim of these updates has been to improve the signal transmission for a better signal to noise ratio. New line driver boards have been developed. In the frame work of the signal enhancement, the latest version of the PANDA calorimeter preamplifier (APFEL-ASIC 1.5) has been introduced. Besides using geographical addressing, the key advantage is the individual biasing of the avalanche photodiodes. Furthermore, the slow control monitoring has been improved and detector stability has been enhanced. Two beam times with an 855 MeV electron beam at the Mainz Microtron Facility served for testing the improvements. This contribution discusses the results in terms of signal quality and detector stability.
Journal
Verhandlungen der Deutschen Physikalischen Gesellschaft; ISSN 0420-0195; ; CODEN VDPEAZ; (Darmstadt 2016 issue); [1 p.]
; CODEN VDPEAZ; (Darmstadt 2016 issue); [1 p.]
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