0000000000679716
AUTHOR
J.r.m. Annand
Measurement of the decay η′→π0π0η at MAMI
An experimental study of the eta' -> pi(0)pi(0)eta -> 6 gamma decay has been conducted with the best up-to-date statistical accuracy, by measuring. 0 mesons produced in the gamma p -> eta'p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The results obtained for the standard parametrization of the eta' -> pi(0)pi(0)eta matrix element are consistent with the most recent results for eta' -> pi pi eta decays, but have smaller uncertainties. The available statistics and experimental resolution allowed, for the first time, an observation of a structure below the pi(+)pi(-) thorn p-mass threshold, the magnitude and sign of which, checked within the framewo…
Insight into the narrow structure in η-photoproduction on the neutron from helicity\ud dependent cross sections
The double polarization observable E and the helicity dependent cross sections σ1/2 and σ3/2 were measured for η photoproduction from quasifree protons and neutrons. The circularly polarized tagged photon beam of the A2 experiment at the Mainz MAMI accelerator was used in combination with a longitudinally polarized deuterated butanol target. The almost 4π detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from η→2γ and η→3π0. The results show that the narrow structure previously observed in η photoproduction from the neutron is only apparent in σ1/2 and hence, most likely related to a spin-1/2 amplitude. Nucleon resonances that …
First measurement of helicity-dependent cross sections in Photoproduction From Quasi-free Nucleons
The helicity-dependent cross sections for the photoproduction of π0η pairs have been measured for the first time. The experiment was performed at the tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball – TAPS calorimeter. The experiment used a polarized deuterated butanol target and a circularly polarized photon beam. This arrangement allowed the σ1/2 (photon and target spin antiparallel) and σ3/2 (parallel spins) components to be measured for quasi-free production of π0η pairs off protons and neutrons. The main finding is that the two helicity components contribute identically, within uncertainties, for both participant protons and neutrons. The absolute cou…
Study of η and η' Photoproduction at MAMI
The reactions γp → ηp and γp → η0\ud p are measured from their thresholds up to the center-of-mass\ud energy W ¼ 1.96 GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross\ud sections are obtained with unprecedented statistical accuracy, providing fine energy binning and full\ud production-angle coverage. A strong cusp is observed in the total cross section for η photoproduction at the\ud energies in the vicinity of the η0 threshold, W ¼ 1896 MeV (Eγ ¼ 1447 MeV). Within the framework of a\ud revised ηMAID isobar model, the cusp, in connection with a steep rise of the η0 total cross section from its\ud threshold, can only be explained by a strong coupling of …
First measurement of target and beam-target asymmetries in the γp→π0ηp reaction
The first data on target and beam-target asymmetries for the γp→π0ηp reaction at photon energies from 1050 up to 1450 MeV are presented. The measurements were performed using the Crystal Ball and TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. The general assumption that the reaction is dominated by the Δ3/2− amplitude is confirmed. The data are in particular sensitive to small contributions from other partial waves.
"Table 1" of "Differential cross section for the reaction $^2$H(��,p)n from 133 to 158 MeV"
No description provided.
"dcs09" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7891 GeV
"dcs02" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7319 GeV
"Table 2" of "C-12 (gamma,p) B-11 cross-section from 80 to 157 MeV"
EX = 7 (FROM 6.5 TO 8.0 MEV). ANGULAR BINS OF 5 DEG WIDTH.
"Table 3" of "Scaling of the $^{4}$He(��,p)t reaction in the $E_\gamma$ = 80���160 MeV region"
No description provided.
"Table 2" of "The 16O(��, 2N) reaction measured with tagged photons"
PROPOSED THAT THE REACTION IS DUE TO A QUASI DEUTERON MECHANISM AND P N PAIRS E]ECT FROM THE 1P SHELL.
"dcs13" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8192 GeV
"Table 6" of "Scaling of the $^{4}$He(��,p)t reaction in the $E_\gamma$ = 80���160 MeV region"
No description provided.
"dcs04" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7490 GeV
"Table 3" of "Quasi-free Compton Scattering and the Polarizabilities of the Neutron"
Energy dependence of the triple differential cross section w.r.t. the scattered proton.
"Table 3" of "C-12 (gamma,p) B-11 cross-section from 80 to 157 MeV"
EX = 13 (FROM 12.0 TO 13.5 MEV). ANGULAR BINS OF 5 DEG WIDTH.
"dcs05" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7568 GeV
"Table 4" of "Scaling of the $^{4}$He(��,p)t reaction in the $E_\gamma$ = 80���160 MeV region"
No description provided.
"dcs19" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8657 GeV
"dcs06" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7645 GeV
"Table 1" of "Scaling of the $^{4}$He(��,p)t reaction in the $E_\gamma$ = 80���160 MeV region"
No description provided.
"Table 1" of "Double pi0 photoproduction off the proton at threshold."
Total cross section measurement. Statistical errors only.
"Table 2" of "Quasi-free Compton Scattering and the Polarizabilities of the Neutron"
Energy dependence of the quasi-free proton differential cross section.
"Table 7" of "Scaling of the $^{4}$He(��,p)t reaction in the $E_\gamma$ = 80���160 MeV region"
No description provided.
"dcs11" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8045 GeV
"dcs12" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8119 GeV
"Table 1" of "First measurement of the polarization transfer on the proton in the reactions H (e (polarized), e-prime p (polarized)) and D (e (polarized), e-prime p (polarized))"
No description provided.
"tcs" of "Photoproduction of the omega meson off the proton near threshold"
Total cross section as a function of c.m. energy W.
"dcs17" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8504 GeV
"dcs01" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7245 GeV
"dcs20" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8720 GeV
"Table 1" of "C-12 (gamma,p) B-11 cross-section from 80 to 157 MeV"
EX IN 0 MEV REGION (FROM 0 TO 1.5 MEV). ANGULAR BINS OF 5 DEG WIDTH.
"Table 2" of "Differential cross section for the reaction $^2$H(��,p)n from 133 to 158 MeV"
No description provided.
"Table 2" of "Scaling of the $^{4}$He(��,p)t reaction in the $E_\gamma$ = 80���160 MeV region"
No description provided.
"Table 5" of "Quasi-free Compton Scattering and the Polarizabilities of the Neutron"
Energy dependence of the free neutron differential cross section.
"Table 4" of "Quasi-free Compton Scattering and the Polarizabilities of the Neutron"
Energy dependence of the triple differential cross section w.r.t. the scattered neutron.
"dcs18" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8581 GeV
"dcs16" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8424 GeV
"dcs07" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7729 GeV
"dcs03" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7401 GeV
"dcs14" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8269 GeV
"dcs10" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7968 GeV
"dcs08" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.7811 GeV
"Table 1" of "Quasi-free Compton Scattering and the Polarizabilities of the Neutron"
Energy dependence of the free-proton differential cross section.
"Table 5" of "Scaling of the $^{4}$He(��,p)t reaction in the $E_\gamma$ = 80���160 MeV region"
No description provided.
"Table 1" of "The 16O(��, 2N) reaction measured with tagged photons"
PROPOSED THAT THE REACTION IS DUE TO A QUASI DEUTERON MECHANISM AND P N PAIRS E]ECT FROM THE 1P SHELL.
"dcs15" of "Photoproduction of the omega meson off the proton near threshold"
Differential cross section at W= 1.8348 GeV