C. Collicott - A2 Collaboration at MAMI

C. Collicott
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Name
C. Collicott
Affiliation
A2 Collaboration at MAMI
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Nuclear Experiment (18)
 
High Energy Physics - Experiment (11)
 
Nuclear Theory (2)
 
High Energy Physics - Phenomenology (2)
 
Physics - Instrumentation and Detectors (1)

Publications Authored By C. Collicott

The double-polarization observable $E$ and the helicity-dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ have been measured for the first time for single $\pi^{0}$ photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the $\pi^0$ meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Read More

Precise helicity-dependent cross sections and the double-polarization observable $E$ were measured for $\eta$ photoproduction from quasi-free protons and neutrons bound in the deuteron. The $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0\rightarrow 6\gamma$ decay modes were used to optimize the statistical quality of the data and to estimate systematic uncertainties. The measurement used the A2 detector setup at the tagged photon beam of the electron accelerator MAMI in Mainz. Read More

The double polarization observable $E$ and the helicity dependent cross sections $\sigma_{1/2}$ and $\sigma_{3/2}$ were measured for $\eta$ photoproduction from quasi-free 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 $4\pi$ detector setup of the Crystal Ball and TAPS is ideally suited to detect the recoil nucleons and the decay photons from $\eta\rightarrow 2\gamma$ and $\eta\rightarrow 3\pi^0$. Read More

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

The Dalitz decay pi^0 -> e^+e^-gamma has been measured in the gamma p -> pi^0 p reaction with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the pi^0 electromagnetic transition form factor, a_pi = 0.030+/-0. Read More

The scalar dipole polarizabilities, $\alpha_{E1}$ and $\beta_{M1}$, are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton polarizabilities were determined by fitting to unpolarized proton Compton scattering cross section data. The measurement of the beam asymmetry $\Sigma_{3}$ in a certain kinematical range provides an alternative approach to the extraction of the scalar polarizabilities. Read More

The Dalitz decays eta -> e^+e^-g and omega -> pi^0 e^+e^- have been measured in the g p -> eta p and g p -> omega p reactions, respectively, with the A2 tagged-photon facility at the Mainz Microtron, MAMI. The value obtained for the slope parameter of the electromagnetic transition form factor of eta, Lambda^{-2}_eta=(1.97+/-0. Read More

High statistics measurements of the photon asymmetry $\mathrm{\Sigma}$ for the $\overrightarrow{\gamma}$p$\rightarrow\pi^{0}$p reaction have been made in the center of mass energy range W=1214-1450 MeV. The data were measured with the MAMI A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly improve the existing world data and are shown to be in good agreement with previous measurements, and with the MAID, SAID, and Bonn-Gatchina predictions. Read More

Low energy Compton scattering allows the investigation of one of the fundamental properties of the nucleon -- how its internal structure deforms under an applied electromagnetic field. We review recent developments in the investigation of proton polarizabilities, and our plans for future measurement at the Mainz Microtron (MAMI). Read More

Differential cross sections for the gamma p -> pi^0 p reaction have been measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C, up to the center-of-mass energy W=1.9 GeV. The new results, obtained with a fine energy and angular binning, increase the existing quantity of pi^0 photoproduction data by ~47%. Read More

The first data on target and beam-target asymmetries for the $\gamma p\to\pi^0\eta p$ 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 $\Delta 3/2^-$ amplitude is confirmed. Read More

We report on a measurement of the neutron detection efficiency in NaI crystals in the Crystal Ball detector obtained from a study of single p0 photoproduction on deuterium using the tagged photon beam at the Mainz Microtron. The results were obtained up to a neutron energy of 400 MeV. They are compared to previous measurements made more than 15 years ago at the pion beam at the BNL AGS. Read More

We present new data for the transverse target asymmetry T and the very first data for the beam-target asymmetry F in the $\vec \gamma \vec p\to\eta p$ reaction up to a center-of-mass energy of W=1.9 GeV. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. Read More

The spin polarizabilities of the nucleon describe how the spin of the nucleon responds to an incident polarized photon. The most model-independent way to measure the nucleon spin polarizabilities is through polarized Compton scattering. Double-polarized Compton scattering asymmetries on the proton were measured in the $\Delta(1232)$ region using circularly polarized incident photons and a transversely polarized proton target at the Mainz Microtron. 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

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