R. Codling - A2 Collaboration at MAMI

R. Codling
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Name
R. Codling
Affiliation
A2 Collaboration at MAMI
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Nuclear Experiment (16)
 
High Energy Physics - Experiment (11)
 
Nuclear Theory (4)
 
High Energy Physics - Phenomenology (3)

Publications Authored By R. Codling

The reactions $\gamma p\to \eta p$ and $\gamma p\to \eta' p$ have been measured from their thresholds up to the center-of-mass energy $W=1.96$GeV with the tagged-photon facilities at the Mainz Microtron, MAMI. Differential cross sections were obtained with unprecedented accuracy, providing fine energy binning and full production-angle coverage. Read More

An experimental study of $\omega$ photoproduction on the proton was conducted by using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. The $\gamma p\to\omega p$ differential cross sections are measured from threshold to the incident-photon energy $E_\gamma=1.40$ GeV ($W=1. Read More

2014May
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI, 77A2 Collaboration at MAMI, 78A2 Collaboration at MAMI, 79A2 Collaboration at MAMI

A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0. Read More

Information on the size and shape of the neutron skin on $^{208}$Pb has been extracted from coherent pion photoproduction cross sections measured using the Crystal Ball together with the Glasgow tagger at the MAMI electron beam facility. On exploitation of an interpolated fit of a theoretical model to the measured cross sections the half-height radius and diffuseness of the neutron distribution are found to be 6.70$\pm 0. Read More

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon, pioneering a novel polarimetry technique with wide application to future nuclear and hadronic physics experiments. The commissioning measurement of polarization transfer in the $^{1}H$($\vec{\gamma}$,$\vec{p}$)$\pi^{0}$ reaction in the range $0.4Read More

2013Sep
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI

The Dalitz decay eta -> e^+ e^- gamma has been measured in the gamma p -> eta p reaction with the Crystal Ball and TAPS multiphoton spectrometers, together with the photon tagging facility at the Mainz Microtron MAMI. The experimental statistic used in this work is one order of magnitude greater than in any previous measurement of eta -> e^+ e^- gamma. The value obtained for the slope parameter 1/Lambda^2 of the eta transition form factor, 1/Lambda^2 = (1. Read More

2013Jun
Affiliations: 1A2 Collaboration at MAMI, 2A2 Collaboration at MAMI, 3A2 Collaboration at MAMI, 4A2 Collaboration at MAMI, 5A2 Collaboration at MAMI, 6A2 Collaboration at MAMI, 7A2 Collaboration at MAMI, 8A2 Collaboration at MAMI, 9A2 Collaboration at MAMI, 10A2 Collaboration at MAMI, 11A2 Collaboration at MAMI, 12A2 Collaboration at MAMI, 13A2 Collaboration at MAMI, 14A2 Collaboration at MAMI, 15A2 Collaboration at MAMI, 16A2 Collaboration at MAMI, 17A2 Collaboration at MAMI, 18A2 Collaboration at MAMI, 19A2 Collaboration at MAMI, 20A2 Collaboration at MAMI, 21A2 Collaboration at MAMI, 22A2 Collaboration at MAMI, 23A2 Collaboration at MAMI, 24A2 Collaboration at MAMI, 25A2 Collaboration at MAMI, 26A2 Collaboration at MAMI, 27A2 Collaboration at MAMI, 28A2 Collaboration at MAMI, 29A2 Collaboration at MAMI, 30A2 Collaboration at MAMI, 31A2 Collaboration at MAMI, 32A2 Collaboration at MAMI, 33A2 Collaboration at MAMI, 34A2 Collaboration at MAMI, 35A2 Collaboration at MAMI, 36A2 Collaboration at MAMI, 37A2 Collaboration at MAMI, 38A2 Collaboration at MAMI, 39A2 Collaboration at MAMI, 40A2 Collaboration at MAMI, 41A2 Collaboration at MAMI, 42A2 Collaboration at MAMI, 43A2 Collaboration at MAMI, 44A2 Collaboration at MAMI, 45A2 Collaboration at MAMI, 46A2 Collaboration at MAMI, 47A2 Collaboration at MAMI, 48A2 Collaboration at MAMI, 49A2 Collaboration at MAMI, 50A2 Collaboration at MAMI, 51A2 Collaboration at MAMI, 52A2 Collaboration at MAMI, 53A2 Collaboration at MAMI, 54A2 Collaboration at MAMI, 55A2 Collaboration at MAMI, 56A2 Collaboration at MAMI, 57A2 Collaboration at MAMI, 58A2 Collaboration at MAMI, 59A2 Collaboration at MAMI, 60A2 Collaboration at MAMI, 61A2 Collaboration at MAMI, 62A2 Collaboration at MAMI, 63A2 Collaboration at MAMI, 64A2 Collaboration at MAMI, 65A2 Collaboration at MAMI, 66A2 Collaboration at MAMI, 67A2 Collaboration at MAMI, 68A2 Collaboration at MAMI, 69A2 Collaboration at MAMI, 70A2 Collaboration at MAMI, 71A2 Collaboration at MAMI, 72A2 Collaboration at MAMI, 73A2 Collaboration at MAMI, 74A2 Collaboration at MAMI, 75A2 Collaboration at MAMI, 76A2 Collaboration at MAMI, 77A2 Collaboration at MAMI, 78A2 Collaboration at MAMI

The g p -> K^0 Sigma^+ reaction has been measured from threshold to Eg=1.45 GeV (W_cm=1.9 GeV) using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. Read More

Photoproduction of $\pi^{0}\pi^{0}$ and $\pi^{0}\pi^{\pm}$ pairs from nuclei has been measured over a wide mass range ($^2$H, $^{7}$Li, $^{12}$C, $^{40}$Ca, and $^{\rm nat}$Pb) for photon energies from threshold to 600 MeV. The experiments were performed at the MAMI accelerator in Mainz, using the Glasgow photon tagging spectrometer and a 4$\pi$ electromagnetic calorimeter consisting of the Crystal Ball and TAPS detectors. A shift of the pion-pion invariant mass spectra for heavy nuclei to small invariant masses has been observed for $\pi^0$ pairs but also for the mixed-charge pairs. Read More

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. Read More

A new precise determination of the {\eta} meson mass is presented. It is based on a measurement of the threshold for the {\gamma}p -> p{\eta} reaction using the tagger focal-plane microscope detector at the MAMI-B facility in Mainz. The tagger microscope has a higher energy resolution than the standard tagging spectrometer and, hence, allowed an improvement in the accuracy compared to the previous {\eta} mass measurement at MAMI-B. Read More

Precise total cross-sections and invariant-mass distributions have been measured for photoproduction of pion pairs off the proton producing $p\pi^0\pi^0$ and $n\pi^+\pi^0$ final states from the threshold region up to 800 MeV incident photon energy. Additionally, beam helicity asymmetries have been measured in the second resonance region (550 MeV - 820 MeV). The experiment was performed at 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. Read More

The gamma p --> pi0 pi0 p reaction has been measured from threshold to 1.4 GeV using the Crystal Ball and TAPS photon spectrometers together with the photon tagging facility at the Mainz Microtron. The experimental results include total and differential cross sections as well as specific angular distributions, which were used to extract partial-wave amplitudes. Read More

2010Sep
Affiliations: 1The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 2The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 3The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 4The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 5The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 6The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 7The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 8The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 9The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 10The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 11The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 12The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 13The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 14The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 15The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 16The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 17The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 18The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 19The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 20The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 21The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 22The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 23The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 24The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 25The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 26The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 27The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 28The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 29The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 30The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 31The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 32The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 33The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 34The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 35The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 36The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 37The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 38The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 39The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 40The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 41The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 42The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 43The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 44The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 45The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 46The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 47The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 48The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 49The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 50The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 51The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 52The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 53The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 54The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 55The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 56The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 57The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 58The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 59The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 60The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 61The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 62The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 63The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 64The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 65The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 66The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 67The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 68The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 69The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 70The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 71The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 72The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 73The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 74The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 75The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 76The Crystal Ball at MAMI, TAPS, and A2 Collaborations, 77The Crystal Ball at MAMI, TAPS, and A2 Collaborations

The circular photon asymmetry for pi0 eta photoproduction on the proton was measured for the first time at the tagged photon facility of the MAMI C accelerator using the Crystal Ball/TAPS photon spectrometer. The experimental results are interpreted within a phenomenological isobar model that confirms the dominant role of the Delta(1700)D33 resonance. The measured asymmetry allows us to identify small contributions from positive-parity resonances via interference terms with the dominant D33 amplitude. Read More

2010Jul
Affiliations: 1Crystal Ball Collaboration at MAMI, 2Crystal Ball Collaboration at MAMI, 3Crystal Ball Collaboration at MAMI, 4Crystal Ball Collaboration at MAMI, 5Crystal Ball Collaboration at MAMI, 6Crystal Ball Collaboration at MAMI, 7Crystal Ball Collaboration at MAMI, 8Crystal Ball Collaboration at MAMI, 9Crystal Ball Collaboration at MAMI, 10Crystal Ball Collaboration at MAMI, 11Crystal Ball Collaboration at MAMI, 12Crystal Ball Collaboration at MAMI, 13Crystal Ball Collaboration at MAMI, 14Crystal Ball Collaboration at MAMI, 15Crystal Ball Collaboration at MAMI, 16Crystal Ball Collaboration at MAMI, 17Crystal Ball Collaboration at MAMI, 18Crystal Ball Collaboration at MAMI, 19Crystal Ball Collaboration at MAMI, 20Crystal Ball Collaboration at MAMI, 21Crystal Ball Collaboration at MAMI, 22Crystal Ball Collaboration at MAMI, 23Crystal Ball Collaboration at MAMI, 24Crystal Ball Collaboration at MAMI, 25Crystal Ball Collaboration at MAMI, 26Crystal Ball Collaboration at MAMI, 27Crystal Ball Collaboration at MAMI, 28Crystal Ball Collaboration at MAMI, 29Crystal Ball Collaboration at MAMI, 30Crystal Ball Collaboration at MAMI, 31Crystal Ball Collaboration at MAMI, 32Crystal Ball Collaboration at MAMI, 33Crystal Ball Collaboration at MAMI, 34Crystal Ball Collaboration at MAMI, 35Crystal Ball Collaboration at MAMI, 36Crystal Ball Collaboration at MAMI, 37Crystal Ball Collaboration at MAMI, 38Crystal Ball Collaboration at MAMI, 39Crystal Ball Collaboration at MAMI, 40Crystal Ball Collaboration at MAMI, 41Crystal Ball Collaboration at MAMI, 42Crystal Ball Collaboration at MAMI, 43Crystal Ball Collaboration at MAMI, 44Crystal Ball Collaboration at MAMI, 45Crystal Ball Collaboration at MAMI, 46Crystal Ball Collaboration at MAMI, 47Crystal Ball Collaboration at MAMI, 48Crystal Ball Collaboration at MAMI, 49Crystal Ball Collaboration at MAMI, 50Crystal Ball Collaboration at MAMI, 51Crystal Ball Collaboration at MAMI, 52Crystal Ball Collaboration at MAMI, 53Crystal Ball Collaboration at MAMI, 54Crystal Ball Collaboration at MAMI, 55Crystal Ball Collaboration at MAMI, 56Crystal Ball Collaboration at MAMI, 57Crystal Ball Collaboration at MAMI, 58Crystal Ball Collaboration at MAMI, 59Crystal Ball Collaboration at MAMI, 60Crystal Ball Collaboration at MAMI, 61Crystal Ball Collaboration at MAMI, 62Crystal Ball Collaboration at MAMI, 63Crystal Ball Collaboration at MAMI, 64Crystal Ball Collaboration at MAMI, 65Crystal Ball Collaboration at MAMI, 66Crystal Ball Collaboration at MAMI, 67Crystal Ball Collaboration at MAMI, 68Crystal Ball Collaboration at MAMI, 69Crystal Ball Collaboration at MAMI, 70Crystal Ball Collaboration at MAMI, 71Crystal Ball Collaboration at MAMI, 72Crystal Ball Collaboration at MAMI, 73Crystal Ball Collaboration at MAMI, 74Crystal Ball Collaboration at MAMI, 75Crystal Ball Collaboration at MAMI, 76Crystal Ball Collaboration at MAMI, 77Crystal Ball Collaboration at MAMI, 78Crystal Ball Collaboration at MAMI, 79Crystal Ball Collaboration at MAMI, 80Crystal Ball Collaboration at MAMI, 81Crystal Ball Collaboration at MAMI, 82Crystal Ball Collaboration at MAMI, 83Crystal Ball Collaboration at MAMI, 84Crystal Ball Collaboration at MAMI

The gp-->etap reaction has been measured with the Crystal Ball and TAPS multiphoton spectrometers in the energy range from the production threshold of 707 MeV to 1.4 GeV (1.49 =< W >= 1. Read More

The reaction gamma p -> p pi0 gamma' has been measured with the Crystal Ball / TAPS detectors using the energy-tagged photon beam at the electron accelerator facility MAMI-B. Energy and angular differential cross sections for the emitted photon gamma' and angular differential cross sections for the pi0 have been determined with high statistics in the energy range of the Delta+(1232) resonance. Cross sections and the ratio of the cross section to the non-radiative process gamma p -> p pi0 are compared to theoretical reaction models, having the anomalous magnetic moment kappa_Delta+ as free parameter. Read More

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz in the three isospin channels $\vec{\gamma}p\to \pi^{+}\pi^0n$, $\vec{\gamma}p\to \pi^{0}\pi^0p$ and $\vec{\gamma}p\to \pi^{+}\pi^{-}p$ . The circularly polarized photons, produced from bremsstrahlung of longitudinally polarized electrons, were tagged with the Glasgow magnetic spectrometer. Charged pions and the decay photons of $\pi^0$ mesons were detected in a $~4\pi$ electromagnetic calorimeter which combined the Crystal Ball detector with the TAPS detector. Read More

We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The $^{12}$C$(\gamma,\pi^{0})^{12}$C$^{*}_{4.4MeV}$ reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a $\pi^{0}$ spectrometer and to detect decay photons from the excited residual nucleus. Read More