Quasi-free photoproduction of eta-mesons off 3He nuclei

Abstract

Quasi-free photoproduction of $\eta$-mesons has been measured off nucleons bound in ${}^3$He nuclei for incident photon energies from the threshold region up to 1.4 GeV. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with an almost $4\pi$ covering electromagnetic calorimeter, combining the TAPS and Crystal Ball detectors. The $\eta$-mesons were detected in coincidence with the recoil nucleons. This allowed a comparison of the production cross section off quasi-free protons and quasi-free neutrons and a full kinematic reconstruction of the final state, eliminating effects from nuclear Fermi motion. In the $S_{11}$(1535) resonance peak, the data agree with the neutron/proton cross section ratio extracted from measurements with deuteron targets. More importantly, the prominent structure observed in photoproduction off quasi-free neutrons bound in the deuteron is also clearly observed. Its parameters (width, strength) are consistent with the expectations from the deuteron results. On an absolute scale the cross sections for both quasi-free protons and neutrons are suppressed with respect to the deuteron target pointing to significant nuclear final state interaction effects.

accepted for publication in Eur. Phys. J. A

References in corpus (14)

• Upgrade of the Glasgow photon tagging spectrometer for Mainz MAMI-C
• Study of the gp-->etap reaction with the Crystal Ball detector at the Mainz Microtron(MAMI-C)
• Evidence for a narrow structure at W~1.68 GeV in eta photoproduction on the neutron
• Measurement of eta photoproduction on the proton from threshold to 1500 MeV
• Measurement of the beam asymmetry in eta-photoproduction off the proton
• Quasi-free photoproduction of eta-mesons of the neutron
• eta-photoproduction in the resonance energy region
• Photoproduction of eta-mesons on the deuteron above S11(1535) in the presence of a narrow P11(1670) resonance
• Photoproduction of $\eta$ mesons off neutrons from a deuteron target
• Photoproduction of eta meson within a coupled-channels K-matrix approach
• A narrow structure in the excitation function of eta-photoproduction off the neutron
• Photoproduction of pi0pi0 and pi0pi+-pairs off the proton from threshold to the second resonance region
• Radiative pi0 photoproduction on protons in the Delta+(1232) region
• Photoproduction of eta-mesons off nuclei for Eg < 2.2 GeV

Cited by in corpus (21)

• Quasifree photoproduction of $\eta$ mesons off protons and neutrons
• Light Baryon Spectroscopy
• Measurement of the transverse target and beam-target asymmetries in $\eta$ meson photoproduction at MAMI
• Insight into the narrow structure in {\boldmath{$\eta$}}-photoproduction on the neutron from helicity dependent cross sections
• First measurement of the polarization observable $E$ and helicity-dependent cross sections in single ${\pi }^0$ photoproduction from quasi-free nucleons
• Helicity-dependent cross sections and double-polarization observable E in eta photoproduction from quasi-free protons and neutrons
• Measurement of the beam-helicity asymmetry $I^{\odot }$ in the photoproduction of ${\pi }^0{\pi }^{\pm }$-pairs off protons and off neutrons
• Experimental study of the $\gamma p\to K^0{\Sigma }^{+}$, $\gamma n\to K^0\Lambda$, and $\gamma n\to K^0{\Sigma }^0$ reactions at the Mainz Microtron
• Photoproduction ofeta-pi pairs off nucleons and deuterons
• Photoproduction of eta mesons from the neutron: cross sections and double polarization observable E
• Photoproduction of {\boldmath{${\pi }^0$}} Mesons off Protons and Neutrons in the Second and Third Nucleon Resonance Region
• Comment on "Evidence for narrow resonant structures at $W\approx$ 1.68 GeV and $W\approx$ 1.72 GeV in real Compton scattering off the proton"
• Observation of Narrow $N^{+}(1685)$ and $N^0(1685)$ Resonances in $\gamma N\to \eta \pi N$ Reactions
• First measurement of helicity-dependent cross sections in pi0-eta photoproduction from quasi-free nucleons
• Effects of nucleon resonances on $\eta$ photoproduction off the neutron reexamined
• Energy dependent analysis of eta-meson photoproduction on protons and neutrons without background in the energy region up to 3.4 GeV
• Feasibility study of the $K^{+}d\to K^{0}pp$ reaction for the "${\Theta }^{+}$" pentaquark
• New Narrow $N(1685)$ and $N(1726)$? Remarks on the Interpretation of the Neutron Anomaly as an Interference Phenomenon
• Search for the $N$(1685) in $\eta \pi$-Photoproduction
• New narrow nucleon resonances $N^{\ast }(1685)$ and $N^{\ast }(1726)$ within the chiral quark-soliton model
• New narrow N*(1685) resonance: review of observations