Coherent photoproduction of pi^0- and eta-mesons off 7Li

Abstract

Coherent photoproduction of ${\pi }^0$-mesons from threshold ($E_{th}\approx$ 136 MeV) throughout the $\Delta$-resonance region and of $\eta$-mesons close to the production threshold ($E_{th}\approx$ 570 MeV for $\eta$) has been measured for ${}^7$Li nuclei. The experiment was performed using the tagged-photon beam of the Mainz MAMI accelerator with the Crystal Ball and TAPS detectors combined to give an almost 4$\pi$ solid-angle electromagnetic calorimeter. The reactions were identified by a combined invariant-mass and missing-energy analysis. A comparison of the pion data to plane-wave impulse modelling tests the nuclear mass form factor. So far coherent $\eta$-production had been only identified for the lightest nuclear systems (${}^2$H and ${}^3$He). For ${}^3$He a large enhancement of the cross section above plane-wave approximations had been reported, indicating the formation of a quasi-bound state. The present Li-data for $\eta$-production agree with a plane-wave approximation. Contrary to ${}^3$He, neither a threshold enhancement of the total cross section nor a deviation of the angular distributions from the expected form-factor dependence were observed.

accepted for publication in Eur. Phys. J. A

References in corpus (8)

• Study of the gp-->etap reaction with the Crystal Ball detector at the Mainz Microtron(MAMI-C)
• Measurement of the dp -->3He eta reaction near threshold
• Photoproduction of pi0-mesons from nuclei
• 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
• Precision study of the d+p->3He+eta reaction for excess energies between 20 and 60 MeV
• Incoherent pion photoproduction on ${}^{12}$C

Cited by in corpus (7)

• Neutron skin of ${}^{208}$Pb from Coherent Pion Photoproduction
• Search for Quasi Bound $\eta$ Mesons
• Coherent pi0-pi0 photoproduction on lightest nuclei
• Coherent π0η photoproduction on s-shell nuclei
• Double pion photoproduction off nuclei - are there effects beyond final-state interaction?
• Coherent photoproduction of the neutral pion and eta meson on the deuteron at incident energies below 1.15 GeV
• Study of the eta meson production with polarized proton beam