O. Miklukho - Academia.edu (original) (raw)

Papers by O. Miklukho

The European Physical Journal C, 2000

Production and decay angular distributions were extracted from measurements of exclusive electrop... more Production and decay angular distributions were extracted from measurements of exclusive electroproduction of the ρ 0 (770) meson over a range in the virtual photon negative four-momentum squared 0.5 < Q 2 < 4 GeV 2 and the photon-nucleon invariant mass range 3.8 < W < 6.5 GeV. The experiment was performed with the Hermes spectrometer, using a longitudinally polarized positron beam and a 3 He gas target internal to the HERA e ± storage ring. The event sample combines ρ 0 mesons produced incoherently off individual nucleons and coherently off the nucleus as a whole. The distributions in one production angle and two angles describing the ρ 0 → π + π − decay yielded measurements of eight elements of the spin-density matrix, including one that had not been measured before. The results are consistent with the dominance of helicity conserving amplitudes and natural parity exchange. The improved precision achieved at 4 < W < 7 GeV, in combination with other data at W > 7 GeV, reveals evidence for an energy dependence in the ratio R of the longitudinal to transverse cross sections at constant Q 2 .

The European Physical Journal C, 2000

Measurements of the cross section for exclusive virtual-photoproduction of ρ 0 mesons from hydrog... more Measurements of the cross section for exclusive virtual-photoproduction of ρ 0 mesons from hydrogen are reported. The data were collected by the HERMES experiment using 27.5 GeV positrons incident on a hydrogen gas target in the HERA storage ring. The invariant mass W of the photon-nucleon system ranges from 4.0 to 6.0 GeV, while the negative squared four-momentum Q 2 of the virtual photon varies from 0.7 to 5.0 GeV 2. The present data together with most of the previous data in the intermediate W-domain are well described by a model that infers the W-dependence of the cross section from the dependence on the Bjorken scaling variable x of the unpolarized structure function for deep-inelastic scattering. In addition, a model calculation based on Off-Forward Parton Distributions gives a fairly good account of the longitudinal component of the ρ 0 production cross section for Q 2 > 2 GeV 2 .

Physics Letters B, 2004

Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target t... more Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel pK 0 S → pπ + π −. A peak is observed in the pK 0 S invariant mass spectrum at 1528 ± 2.6(stat) ± 2.1(syst) MeV. Depending on the background model, the naïve statistical significance of the peak is 4-6 standard deviations and its width may be somewhat larger than the experimental resolution of σ = 4.3-6.2 MeV. This state may be interpreted as the predicted S=+1 exotic Θ + (uudds) pentaquark baryon. No signal for an hypothetical Θ ++ baryon was observed in the pK + invariant mass distribution. The absence of such a signal indicates that an isotensor Θ is excluded and an isovector Θ is unlikely.

Physics Letters B, 2005

Single-spin asymmetries in the semi-inclusive production of charged pions in deep-inelastic scatt... more Single-spin asymmetries in the semi-inclusive production of charged pions in deep-inelastic scattering from transversely and longitudinally polarized proton targets are combined to evaluate the subleading-twist contribution to the longitudinal case. This contribution is significantly positive for π + mesons and dominates the asymmetries on a longitudinally polarized target previously measured by Hermes. The subleading-twist contribution for π − mesons is found to be small.

The European Physical Journal A, 2015

Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on ha... more Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (πN) TDAs frompp → e + e − π 0 reaction with the futurePANDA detector at the FAIR facility. At high centerof-mass energy and high invariant mass squared of the lepton pair q 2 , the amplitude of the signal channel pp → e + e − π 0 admits a QCD factorized description in terms of πN TDAs and nucleon Distribution Amplitudes (DAs) in the forward and backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuringpp → e + e − π 0 with thePANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e.pp → π + π − π 0 were performed for the center-of-mass energy squared s = 5 GeV 2 and s = 10 GeV 2 , in the kinematic regions 3.0 < q 2 < 4.3 GeV 2 and 5 < q 2 < 9 GeV 2 , respectively, with a neutral pion scattered in the forward or backward cone | cos θ π 0 | > 0.5 in the proton-antiproton center-of-mass frame. Results of the simulation show that the particle identification capabilities of thePANDA detector will allow to achieve a background rejection factor of 5 • 10 7 (1 • 10 7) at low (high) q 2 for s = 5 GeV 2 , and of 1 • 10 8 (6 • 10 6) at low (high) q 2 for s = 10 GeV 2 , while keeping the signal reconstruction efficiency at around 40%. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 fb −1 of integrated luminosity. The cross sections obtained from the simulations are used to show that a test of QCD collinear factorization can be done at the lowest order by measuring scaling laws and angular distributions. The future measurement of the signal channel cross section withPANDA will provide a new test of the perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing πN TDAs.

arXiv (Cornell University), Dec 14, 2019

PANDA-Strong interaction studies with antiprotons Cover: The figure shows the PANDA Forward Spect... more PANDA-Strong interaction studies with antiprotons Cover: The figure shows the PANDA Forward Spectrometer Calorimeter placed on the Forward Spectrometer support. The region of a single module is zoomed, allowing a view into the calorimeter structure with the sandwich of scintillator and lead tiles and the bunches of traversing WLS fibres, funneled to photo detectors, one for each of the four cells of one module. The "LEGO"-type locks used to firmly join the tiles are zoomed even more. This document is devoted to the electromagnetic calorimeter of the Forward Spectrometer and describes the design considerations, the technical layout, the expected performance, and the production readiness.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2014

The OLYMPUS experiment was designed to measure the ratio between the positronproton and electron-... more The OLYMPUS experiment was designed to measure the ratio between the positronproton and electron-proton elastic scattering cross sections, with the goal of determining the contribution of two-photon exchange to the elastic cross section. Two-photon exchange might resolve the discrepancy between measurements of the proton form factor ratio, µ p G p E /G p M , made using polarization techniques and those made in unpolarized experiments. OLYMPUS operated on the DORIS storage ring at DESY, alternating between 2.01 GeV electron and positron beams incident on an internal hydrogen gas target. The experiment used a toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight detectors to measure rates for elastic scattering over the polar angular range of approximately 25 •-75 •. Symmetric Møller/Bhabha calorimeters at 1.29 • and telescopes of GEM and MWPC detectors at 12 • served as luminosity monitors. A total luminosity of approximately 4.5 fb −1 was collected over two running periods in 2012. 1

Journal of Physics G: Nuclear and Particle Physics

PANDA (anti-proton annihiliation at Darmstadt) is planned to be one of the four main experiments ... more PANDA (anti-proton annihiliation at Darmstadt) is planned to be one of the four main experiments at the future international accelerator complex FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. It is going to address fundamental questions of hadron physics and quantum chromodynamics using cooled antiproton beams with a high intensity and and momenta between 1.5 and 15 GeV/c. PANDA is designed to reach a maximum luminosity of 2 × 1032 cm−2 s. Most of the physics programs require an excellent particle identification (PID). The PID of hadronic states at the forward endcap of the target spectrometer will be done by a fast and compact Cherenkov detector that uses the detection of internally reflected Cherenkov light (DIRC) principle. It is designed to cover the polar angle range from 5° to 22° and to provide a separation power for the separation of charged pions and kaons up to 3 standard deviations (s.d.) for particle momenta up to 4 GeV/c in order to cover the imp...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2005

The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with ... more The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with the polarized electron beam of HERA at DESY to study the spin structure of the nucleon. Polarized atoms from a Stern-Gerlach Atomic Beam Source are injected into a storage cell internal to the HERA electron ring. Atoms diffusing from the center of the storage cell into a side tube are analyzed to determine the atomic fraction and the atomic polarizations. The atoms have a nuclear polarization, the axis of which is defined by an external magnetic holding field. The holding field was longitudinal during 1996-2000, and was changed to transverse in 2001. The design of the target is described, the method for analyzing the target polarization is outlined, and the performance of the target in the various running periods is presented.

Upgrading to the document High Energy Physics Esperiment (hep-ex/0505054). The document describes... more Upgrading to the document High Energy Physics Esperiment (hep-ex/0505054). The document describes the physics case of the PAX experiment using polarized antiprotons, which has recently been proposed for the new Facility for Antiprotons and Ions Research (FAIR) at GSI--Darmstadt. Polarized antiprotons provide access to a wealth of single-- and double--spin observables, thereby opening a new window to physics uniquely accessible at the HESR. The polarized antiprotons would be most efficiently produced by spin--filtering in a dedicated Antiproton Polarizer Ring (APR) using an internal polarized hydrogen gas target. In the proposed collider scenario of the PAX experiment, polarized protons stored in a COSY--like Cooler Storage Ring (CSR) up to momenta of 3.5 GeV/c are bombarded head--on with 15 GeV/c polarized antiprotons stored in the HESR. This asymmetric double--polarized antiproton--proton collider is ideally suited to map, e.g., the transversity distribution in the proton. The prop...

arXiv: Instrumentation and Detectors, 2012

This document illustrates the technical layout and the expected performance of the Micro Vertex D... more 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.

Physical review letters, 2021

We report the first measurement of the average of the electron-proton and positron-proton elastic... more We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading effects of hard two-photon exchange, giving more robust access to the proton's electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of Møller, Bhabha, and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits.

arXiv: Nuclear Experiment, 2020

We report the first measurement of the average of the electron-proton and positron-proton elastic... more We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading effects of hard two-photon exchange, giving more robust access to the proton's electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of M{\o}ller, Bhabha and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits.

arXiv: High Energy Physics - Experiment, 2009

To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with ... more 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.

arXiv: Instrumentation and Detectors, 2008

This document presents the technical layout and the envisaged performance of the Electromagnetic ... more 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.

arXiv: Instrumentation and Detectors, 2009

This document is the Technical Design Report covering the two large spectrometer magnets of the P... more 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.

The polarization of the secondary protons (P1,2) in the (p,2p) reaction with the S - shell proton... more The polarization of the secondary protons (P1,2) in the (p,2p) reaction with the S - shell protons of nuclei 4He, 6Li, 12C, 28Si, 40Ca was measured at 1 GeV unpolarized proton beam. The spin correlation parameters Cij for the 4He and 12C targets also were for the first time obtained. The polarization measurements were performed by means of a two - arm magnetic spectrometer each arm of which was equipped with multiwire - proportional chambers polarimeter.

The European Physical Journal C, 2000

Production and decay angular distributions were extracted from measurements of exclusive electrop... more Production and decay angular distributions were extracted from measurements of exclusive electroproduction of the ρ 0 (770) meson over a range in the virtual photon negative four-momentum squared 0.5 < Q 2 < 4 GeV 2 and the photon-nucleon invariant mass range 3.8 < W < 6.5 GeV. The experiment was performed with the Hermes spectrometer, using a longitudinally polarized positron beam and a 3 He gas target internal to the HERA e ± storage ring. The event sample combines ρ 0 mesons produced incoherently off individual nucleons and coherently off the nucleus as a whole. The distributions in one production angle and two angles describing the ρ 0 → π + π − decay yielded measurements of eight elements of the spin-density matrix, including one that had not been measured before. The results are consistent with the dominance of helicity conserving amplitudes and natural parity exchange. The improved precision achieved at 4 < W < 7 GeV, in combination with other data at W > 7 GeV, reveals evidence for an energy dependence in the ratio R of the longitudinal to transverse cross sections at constant Q 2 .

The European Physical Journal C, 2000

Measurements of the cross section for exclusive virtual-photoproduction of ρ 0 mesons from hydrog... more Measurements of the cross section for exclusive virtual-photoproduction of ρ 0 mesons from hydrogen are reported. The data were collected by the HERMES experiment using 27.5 GeV positrons incident on a hydrogen gas target in the HERA storage ring. The invariant mass W of the photon-nucleon system ranges from 4.0 to 6.0 GeV, while the negative squared four-momentum Q 2 of the virtual photon varies from 0.7 to 5.0 GeV 2. The present data together with most of the previous data in the intermediate W-domain are well described by a model that infers the W-dependence of the cross section from the dependence on the Bjorken scaling variable x of the unpolarized structure function for deep-inelastic scattering. In addition, a model calculation based on Off-Forward Parton Distributions gives a fairly good account of the longitudinal component of the ρ 0 production cross section for Q 2 > 2 GeV 2 .

Physics Letters B, 2004

Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target t... more Evidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel pK 0 S → pπ + π −. A peak is observed in the pK 0 S invariant mass spectrum at 1528 ± 2.6(stat) ± 2.1(syst) MeV. Depending on the background model, the naïve statistical significance of the peak is 4-6 standard deviations and its width may be somewhat larger than the experimental resolution of σ = 4.3-6.2 MeV. This state may be interpreted as the predicted S=+1 exotic Θ + (uudds) pentaquark baryon. No signal for an hypothetical Θ ++ baryon was observed in the pK + invariant mass distribution. The absence of such a signal indicates that an isotensor Θ is excluded and an isovector Θ is unlikely.

Physics Letters B, 2005

Single-spin asymmetries in the semi-inclusive production of charged pions in deep-inelastic scatt... more Single-spin asymmetries in the semi-inclusive production of charged pions in deep-inelastic scattering from transversely and longitudinally polarized proton targets are combined to evaluate the subleading-twist contribution to the longitudinal case. This contribution is significantly positive for π + mesons and dominates the asymmetries on a longitudinally polarized target previously measured by Hermes. The subleading-twist contribution for π − mesons is found to be small.

The European Physical Journal A, 2015

Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on ha... more Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (πN) TDAs frompp → e + e − π 0 reaction with the futurePANDA detector at the FAIR facility. At high centerof-mass energy and high invariant mass squared of the lepton pair q 2 , the amplitude of the signal channel pp → e + e − π 0 admits a QCD factorized description in terms of πN TDAs and nucleon Distribution Amplitudes (DAs) in the forward and backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuringpp → e + e − π 0 with thePANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e.pp → π + π − π 0 were performed for the center-of-mass energy squared s = 5 GeV 2 and s = 10 GeV 2 , in the kinematic regions 3.0 < q 2 < 4.3 GeV 2 and 5 < q 2 < 9 GeV 2 , respectively, with a neutral pion scattered in the forward or backward cone | cos θ π 0 | > 0.5 in the proton-antiproton center-of-mass frame. Results of the simulation show that the particle identification capabilities of thePANDA detector will allow to achieve a background rejection factor of 5 • 10 7 (1 • 10 7) at low (high) q 2 for s = 5 GeV 2 , and of 1 • 10 8 (6 • 10 6) at low (high) q 2 for s = 10 GeV 2 , while keeping the signal reconstruction efficiency at around 40%. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 fb −1 of integrated luminosity. The cross sections obtained from the simulations are used to show that a test of QCD collinear factorization can be done at the lowest order by measuring scaling laws and angular distributions. The future measurement of the signal channel cross section withPANDA will provide a new test of the perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing πN TDAs.

arXiv (Cornell University), Dec 14, 2019

PANDA-Strong interaction studies with antiprotons Cover: The figure shows the PANDA Forward Spect... more PANDA-Strong interaction studies with antiprotons Cover: The figure shows the PANDA Forward Spectrometer Calorimeter placed on the Forward Spectrometer support. The region of a single module is zoomed, allowing a view into the calorimeter structure with the sandwich of scintillator and lead tiles and the bunches of traversing WLS fibres, funneled to photo detectors, one for each of the four cells of one module. The "LEGO"-type locks used to firmly join the tiles are zoomed even more. This document is devoted to the electromagnetic calorimeter of the Forward Spectrometer and describes the design considerations, the technical layout, the expected performance, and the production readiness.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2014

The OLYMPUS experiment was designed to measure the ratio between the positronproton and electron-... more The OLYMPUS experiment was designed to measure the ratio between the positronproton and electron-proton elastic scattering cross sections, with the goal of determining the contribution of two-photon exchange to the elastic cross section. Two-photon exchange might resolve the discrepancy between measurements of the proton form factor ratio, µ p G p E /G p M , made using polarization techniques and those made in unpolarized experiments. OLYMPUS operated on the DORIS storage ring at DESY, alternating between 2.01 GeV electron and positron beams incident on an internal hydrogen gas target. The experiment used a toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight detectors to measure rates for elastic scattering over the polar angular range of approximately 25 •-75 •. Symmetric Møller/Bhabha calorimeters at 1.29 • and telescopes of GEM and MWPC detectors at 12 • served as luminosity monitors. A total luminosity of approximately 4.5 fb −1 was collected over two running periods in 2012. 1

Journal of Physics G: Nuclear and Particle Physics

PANDA (anti-proton annihiliation at Darmstadt) is planned to be one of the four main experiments ... more PANDA (anti-proton annihiliation at Darmstadt) is planned to be one of the four main experiments at the future international accelerator complex FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. It is going to address fundamental questions of hadron physics and quantum chromodynamics using cooled antiproton beams with a high intensity and and momenta between 1.5 and 15 GeV/c. PANDA is designed to reach a maximum luminosity of 2 × 1032 cm−2 s. Most of the physics programs require an excellent particle identification (PID). The PID of hadronic states at the forward endcap of the target spectrometer will be done by a fast and compact Cherenkov detector that uses the detection of internally reflected Cherenkov light (DIRC) principle. It is designed to cover the polar angle range from 5° to 22° and to provide a separation power for the separation of charged pions and kaons up to 3 standard deviations (s.d.) for particle momenta up to 4 GeV/c in order to cover the imp...

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2005

The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with ... more The HERMES hydrogen and deuterium nuclear-polarized gas targets have been in use since 1996 with the polarized electron beam of HERA at DESY to study the spin structure of the nucleon. Polarized atoms from a Stern-Gerlach Atomic Beam Source are injected into a storage cell internal to the HERA electron ring. Atoms diffusing from the center of the storage cell into a side tube are analyzed to determine the atomic fraction and the atomic polarizations. The atoms have a nuclear polarization, the axis of which is defined by an external magnetic holding field. The holding field was longitudinal during 1996-2000, and was changed to transverse in 2001. The design of the target is described, the method for analyzing the target polarization is outlined, and the performance of the target in the various running periods is presented.

Upgrading to the document High Energy Physics Esperiment (hep-ex/0505054). The document describes... more Upgrading to the document High Energy Physics Esperiment (hep-ex/0505054). The document describes the physics case of the PAX experiment using polarized antiprotons, which has recently been proposed for the new Facility for Antiprotons and Ions Research (FAIR) at GSI--Darmstadt. Polarized antiprotons provide access to a wealth of single-- and double--spin observables, thereby opening a new window to physics uniquely accessible at the HESR. The polarized antiprotons would be most efficiently produced by spin--filtering in a dedicated Antiproton Polarizer Ring (APR) using an internal polarized hydrogen gas target. In the proposed collider scenario of the PAX experiment, polarized protons stored in a COSY--like Cooler Storage Ring (CSR) up to momenta of 3.5 GeV/c are bombarded head--on with 15 GeV/c polarized antiprotons stored in the HESR. This asymmetric double--polarized antiproton--proton collider is ideally suited to map, e.g., the transversity distribution in the proton. The prop...

arXiv: Instrumentation and Detectors, 2012

This document illustrates the technical layout and the expected performance of the Micro Vertex D... more 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.

Physical review letters, 2021

We report the first measurement of the average of the electron-proton and positron-proton elastic... more We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading effects of hard two-photon exchange, giving more robust access to the proton's electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of Møller, Bhabha, and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits.

arXiv: Nuclear Experiment, 2020

We report the first measurement of the average of the electron-proton and positron-proton elastic... more We report the first measurement of the average of the electron-proton and positron-proton elastic scattering cross sections. This lepton charge-averaged cross section is insensitive to the leading effects of hard two-photon exchange, giving more robust access to the proton's electromagnetic form factors. The cross section was extracted from data taken by the OLYMPUS experiment at DESY, in which alternating stored electron and positron beams were scattered from a windowless gaseous hydrogen target. Elastic scattering events were identified from the coincident detection of the scattered lepton and recoil proton in a large-acceptance toroidal spectrometer. The luminosity was determined from the rates of M{\o}ller, Bhabha and elastic scattering in forward electromagnetic calorimeters. The data provide some selectivity between existing form factor global fits and will provide valuable constraints to future fits.

arXiv: High Energy Physics - Experiment, 2009

To study fundamental questions of hadron and nuclear physics in interactions of antiprotons with ... more 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.

arXiv: Instrumentation and Detectors, 2008

This document presents the technical layout and the envisaged performance of the Electromagnetic ... more 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.

arXiv: Instrumentation and Detectors, 2009

This document is the Technical Design Report covering the two large spectrometer magnets of the P... more 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.

The polarization of the secondary protons (P1,2) in the (p,2p) reaction with the S - shell proton... more The polarization of the secondary protons (P1,2) in the (p,2p) reaction with the S - shell protons of nuclei 4He, 6Li, 12C, 28Si, 40Ca was measured at 1 GeV unpolarized proton beam. The spin correlation parameters Cij for the 4He and 12C targets also were for the first time obtained. The polarization measurements were performed by means of a two - arm magnetic spectrometer each arm of which was equipped with multiwire - proportional chambers polarimeter.