0000000000191381
AUTHOR
G. Caselotti
Compton scattering from the free and bound proton at backward angles above π-threshold
Differential cross sections for Compton scattering from the free proton at Theta(gamma)(lab) = 130.7 degrees in the energy region from 200 MeV to 410 MeV and far quasi-free Compton scattering from the proton bound in the deuteron at Theta(gamma)(lab) = 148.8 degrees in the energy region from 200 MeV to 290 MeV have been measured. The free proton data are in agreement with dispersion-theory predictions based on standard parameters. The difference of the proton polarizabilities has been extracted from the quasi-free data. Our result, - = [9.1 +/- 1.7(stat + syst) +/- 1.2(mod)] x 10(-4) fm(3), is in reasonable agreement with the world average of the free proton data if the backward spin polari…
Quasi-free Compton Scattering and the Polarizabilities of the Neutron
Differential cross sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz tagging spectrometer at the Mainz MAMI accelerator together with the Mainz 48 cm $\oslash$ $\times$ 64 cm NaI(Tl) photon detector and the G\"ottingen SENECA recoil detector. The data cover photon energies ranging from 200 MeV to 400 MeV at $\theta^{LAB}_\gamma=136.2^\circ$. Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction $p(\gamma,\pi^+ n)$. The "free" proton Compton scattering cross sect…
In-medium modifications of the pi pi interaction in photon-induced reactions
Differential cross sections of the reactions $(\gamma,\pi^\circ\pi^\circ)$ and $(\gamma,\pi^\circ\pi^++\pi^\circ\pi^-)$ have been measured for several nuclei ($^1$H,$^{12}$C, and $^{\rm nat}$Pb) at an incident-photon energy of $E_{\gamma}$=400-460 MeV at the tagged-photon facility at MAMI-B using the TAPS spectrometer. A significant nuclear-mass dependence of the $\pi\pi$ invariant-mass distribution is found in the $\pi^\circ\pi^\circ$ channel. This dependence is not observed in the $\pi^\circ\pi^{+/-}$ channel and is consistent with an in-medium modification of the $\pi\pi$ interaction in the $I$=$J$=0 channel. The data are compared to $\pi$-induced measurements and to calculations within …
Neutron polarizabilities investigated by quasi-free Compton scattering from the deuteron
Measuring Compton scattered photons and recoil neutrons in coincidence, quasifree Compton scattering by the neutron has been investigated at MAMI (Mainz) at ${\ensuremath{\theta}}_{\ensuremath{\gamma}}^{\mathrm{lab}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}136\ifmmode^\circ\else\textdegree\fi{}$ in an energy range from 200 to 400 MeV. From the data a polarizability difference of ${\ensuremath{\alpha}}_{n}\ensuremath{-}{\ensuremath{\beta}}_{n}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}9.8\ifmmode\pm\else\textpm\fi{}3.6(\mathrm{stat}{)}_{\ensuremath{-}1.1}^{+2.1}(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}2.2(\mathrm{model})$ in units of ${10}^{\ensuremath{-}4}{\mathrm{fm}}^{…
Backward spin polarizabilityγπof the proton
Using the Mainz $48\mathrm{cm}\ensuremath{\emptyset}\ifmmode\times\else\texttimes\fi{}64\mathrm{cm}$ NaI(Tl) detector and the segmented G\"ottingen recoil detector SENECA in coincidence, Compton scattering by the proton at ${\ensuremath{\theta}}_{\ensuremath{\gamma}}^{\mathrm{lab}}=136\ifmmode^\circ\else\textdegree\fi{}$ has been measured at MAMI (Mainz) in the energy range from 200 to 470 MeV. The new data confirm the previous observation that there is a systematic discrepancy between MAMI and LEGS (Brookhaven) data leading to different spin polarizabilities ${\ensuremath{\gamma}}_{\ensuremath{\pi}}=\ensuremath{-}38.7\ifmmode\pm\else\textpm\fi{}1.8$ and $\ensuremath{-}27.2\ifmmode\pm\else\…
Compton scattering from the free and bound proton above π-threshold
The differential cross sections for Compton scattering from the proton have been measured at MAMI with three different detector setups. There is a good agreement among all the results. The theoretical calculation based on dispersion relations shows that there is no drastic change necessary in the parameters of this approach.
The Reactionγp→π0γ′pand the Magnetic Dipole Moment of theΔ+(1232)Resonance
The reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\gamma}}^{\ensuremath{'}}p$ has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between $\sqrt{s}=1221--1331\text{ }\text{ }\mathrm{M}\mathrm{e}\mathrm{V}$. The cross section's differential in angle and energy have been determined for the photon ${\ensuremath{\gamma}}^{\ensuremath{'}}$ in three bins of the excitation energy. This reaction channel provides access to the magnetic dipole moment of the ${\ensuremath{\Delta}}^{+}(1232)$ resonance and, for the first time, a value of ${\ensuremath{\mu}}_{{\ensuremath{\Delta}}^{+}}=\mathbf{[}{2.7}_{\ensu…
"Table 6" of "In-medium modifications of the pi pi interaction in photon-induced reactions."
Differential cross section for PI0PI+/- production with a Lead target. Errors are statistical only.
"Table 2" of "In-medium modifications of the pi pi interaction in photon-induced reactions."
Differential cross section for PI0PI0 production with a Carbon target. Errors are statistical only.
"Table 1" of "In-medium modifications of the pi pi interaction in photon-induced reactions."
Differential cross section for PI0PI0 production with a proton target. Errors are statistical only. Note that the data given in this table are sightly different (newer) than the data points presented in the paper.
"Table 4" of "In-medium modifications of the pi pi interaction in photon-induced reactions."
Differential cross section for PI0PI+ production with a proton target. Errors are statistical only. Note that the data given in this table are sightly different (newer) than the data points presented in the paper.
"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 "In-medium modifications of the pi pi interaction in photon-induced reactions."
Differential cross section for PI0PI0 production with a Lead target. Errors are statistical only.
"Table 1" of "Compton scattering from the free and bound proton at backward angles above pi threshold."
No description provided.
"Table 2" of "Quasi-free Compton Scattering and the Polarizabilities of the Neutron"
Energy dependence of the quasi-free proton differential cross section.
"Table 5" of "In-medium modifications of the pi pi interaction in photon-induced reactions."
Differential cross section for PI0PI+/- production with a Carbon target. Errors are statistical only.
"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.
"Table 1" of "Quasi-free Compton Scattering and the Polarizabilities of the Neutron"
Energy dependence of the free-proton differential cross section.