A5080051133- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- Nuclear physics research studies
- High-Energy Particle Collisions Research
- Advanced NMR Techniques and Applications
- Atomic and Subatomic Physics Research
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Vascular Procedures and Complications
- Aortic aneurysm repair treatments
- Computational Physics and Python Applications
- Abdominal vascular conditions and treatments
- Technology Assessment and Management
- Graphite, nuclear technology, radiation studies
- Medical Imaging Techniques and Applications
- Dark Matter and Cosmic Phenomena
- Nuclear Physics and Applications
University Hospital of Bern
2024
University of Bern
2024
University of Basel
2014-2020
Johannes Gutenberg University Mainz
2020
Istituto Nazionale di Fisica Nucleare, Sezione di Pavia
2017-2018
University of Pavia
2018
The reactions γp→ηp and γp→η^{'}p are measured from their thresholds up to the center-of-mass energy W=1.96 GeV with tagged-photon facilities at Mainz Microtron, MAMI. Differential cross sections obtained unprecedented statistical accuracy, providing fine binning full production-angle coverage. A strong cusp is observed in total section for η photoproduction energies vicinity of η^{'} threshold, W=1896 MeV (E_{γ}=1447 MeV). Within framework a revised ηMAID isobar model, cusp, connection...
The Dalitz decays eta -> e^+e^-g and omega pi^0 e^+e^- have been measured in the g p reactions, respectively, with A2 tagged-photon facility at Mainz Microtron, MAMI. value obtained for slope parameter of electromagnetic transition form factor eta, Lambda^{-2}_eta=(1.97+/-0.11_tot) GeV^{-2}, is good agreement previous measurements mu^+mu^-g decays. uncertainty Lambda^{-2}_eta lower than results based on decay. parameter, Lambda^{-2}_omega_pi^0 = (1.99+/-0.21_tot) somewhat mu^+mu^-, but are...
The spin polarizabilities of the nucleon describe how responds to an incident polarized photon. most model-independent way extract is through Compton scattering. Double-polarized scattering asymmetries on proton were measured in $\mathrm{\ensuremath{\Delta}}(1232)$ region using circularly photons and a transversely target at Mainz Microtron. Fits asymmetry data performed dispersion model calculation baryon chiral perturbation theory calculation, separation all four multipole basis was...
Differential cross sections for the gamma p -> pi^0 reaction have been measured with A2 tagged-photon facilities at Mainz Microtron, MAMI C, up to center-of-mass energy W=1.9 GeV. The new results, obtained a fine and angular binning, increase existing quantity of photoproduction data by ~47%. Owing unprecedented statistical accuracy full coverage, results are sensitive high partial-wave amplitudes. This is demonstrated decomposition differential in terms Legendre polynomials further...
We present new data for the transverse target asymmetry T and very first beam-target F in →γ→p→ηp reaction up to a center-of-mass energy of W=1.9 GeV. The were obtained with Crystal-Ball/TAPS detector setup at Glasgow tagged photon facility Mainz Microtron MAMI. All existing model predictions fail reproduce indicating significant impact on our understanding underlying dynamics η meson photoproduction. peculiar nodal structure observed close threshold is not confirmed.Received 12 June...
The double polarization observable E and the helicity dependent cross sections σ_{1/2} σ_{3/2} were measured for η photoproduction from quasifree protons neutrons. circularly polarized tagged photon beam of A2 experiment at Mainz MAMI accelerator was used in combination with a longitudinally deuterated butanol target. almost 4π detector setup Crystal Ball TAPS is ideally suited to detect recoil nucleons decay photons η→2γ η→3π^{0}. results show that narrow structure previously observed...
The Dalitz decay π0→e+e−γ has been measured in the γp→π0p reaction with A2 tagged-photon facility at Mainz Microtron, MAMI. value obtained for slope parameter of π0 electromagnetic transition form factor, aπ=0.030±0.010tot, is agreement existing measurements this and recent theoretical calculations. uncertainty aπ lower than previous results based on decay.Received 16 November 2016DOI:https://doi.org/10.1103/PhysRevC.95.025202©2017 American Physical SocietyPhysics Subject Headings...
A new measurement of the rare, doubly radiative decay $\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}\ensuremath{\gamma}$ was conducted with Crystal Ball and TAPS multiphoton spectrometers together photon tagging facility at Mainz Microtron MAMI. New data on dependence partial width, $\ensuremath{\Gamma}(\ensuremath{\eta}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}\ensuremath{\gamma})$, two-photon invariant-mass squared,...
Precise helicity-dependent cross sections and the double-polarization observable $E$ were measured for $\ensuremath{\eta}$ photoproduction from quasifree protons neutrons bound in deuteron. The $\ensuremath{\eta}\ensuremath{\rightarrow}2\ensuremath{\gamma}$ $\ensuremath{\eta}\ensuremath{\rightarrow}3{\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}6\ensuremath{\gamma}$ decay modes used to optimize statistical quality of data estimate systematic uncertainties. measurement A2 detector setup at...
The double-polarization observable $E$ and the helicity-dependent cross sections $\sigma_{1/2}$ $\sigma_{3/2}$ have been measured for first time single $\pi^{0}$ photoproduction from protons neutrons bound in deuteron at electron accelerator facility MAMI Mainz, Germany. experiment used a circularly polarized photon beam longitudinally deuterated butanol target. reaction products, recoil nucleons decay photons $\pi^0$ meson were detected with Crystal Ball TAPS electromagnetic calorimeters....
The γp→π0p reaction was studied at laboratory photon energies from 425 to 1445 MeV with a transversely polarized target and longitudinally beam. beam-target asymmetry F measured for the first time new high precision data T were obtained. experiment performed tagging facility of Mainz Microtron (MAMI) using Crystal Ball TAPS spectrometers. cross sections expanded in terms associated Legendre functions compared recent predictions several partial-wave analyses. impact on our understanding...
Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of $ \pi^{0}\pi^{0}$ pairs off free protons nucleons bound in deuteron. The experiments were performed at MAMI accelerator facility Mainz using Glasgow photon tagging spectrometer Crystal Ball/TAPS detector. delivered electron beams 1508 1557MeV, which produced bremsstrahlung thin radiator foils. tagged beam covered energies up to 1400MeV. data from proton target are good...
The largest, at the moment, statistics of 7x10^6 eta->3pi^0 decays, based on 6.2x10^7 eta mesons produced in gamma p -> reaction, has been accumulated by A2 Collaboration Mainz Microtron, MAMI. It allowed a detailed study dynamics beyond its conventional parametrization with just quadratic slope parameter alpha and enabled, for first time, measurement second-order term better understanding cusp structure neutral decay. present data are also compared to recent theoretical calculations that...
Polarisation-dependent differential cross sections σT associated with the target asymmetry T have been measured for reaction γp→→pπ0 transverse polarisation from π0 threshold to photon energies of 190 MeV. The data were obtained using a frozen-spin butanol Crystal Ball / TAPS detector set-up and Glasgow tagging system at Mainz Microtron MAMI. Results used in combination our previous measurements unpolarised section σ0 beam Σ model-independent determination S- P-wave multipoles region, which...
The data available from the A2 Collaboration at MAMI were analyzed to select γp→π0ηp reaction on an event-by-event basis, which allows for partial-wave analyses of three-body final states obtain more reliable results, compared fits measured distributions. These provide world's best statistical accuracy in energy range threshold Eγ=1.45 GeV, allowing a finer binning measurement all observables needed understanding dynamics. results obtained are existing models, and impact new is checked by...
The Compton double-polarization observable ${\mathrm{\ensuremath{\Sigma}}}_{2z}$ has been measured for the first time in $\mathrm{\ensuremath{\Delta}}(1232)$ resonance region using a circularly polarized photon beam incident on longitudinally proton target at Mainz Microtron. This paper reports these results, together with model-dependent extraction of four spin polarizabilities from fits to additional asymmetry data either dispersion relation calculation or baryon chiral perturbation theory...
We report the first large-acceptance measurement of beam-spin asymmetry for deuteron photodisintegration ($\vec{\gamma} d\to pn$) in photon energy range $400<E_{\gamma}<630$~MeV. The provides important new constraints on mechanisms above delta resonance and photocoupling recently discovered $d^*(2380)$ hexaquark.
High-statistics measurements of the photon asymmetry $\Sigma$ for $\overrightarrow{\gamma}p\rightarrow\pi^{0}p$ reaction have been made in center-of-mass energy range $W=1214-1450$ MeV. The data were measured with MAMI A2 real beam and Crystal Ball/TAPS detector systems Mainz, Germany. results significantly improve existing world are shown to be good agreement previous measurements, MAID, SAID, Bonn-Gatchina predictions. We also combined recent cross-section from Mainz calculate profile...
Artificial intelligence (AI) is increasingly employed in radiation protection, encompassing both medical devices and software. These technologies are integrated with AI throughout their manufacturing application processes. This article underscores the imperative for comprehensive regulation utilization of AI. Decisions regarding should not solely rest manufacturers, professionals, or patients. Instead, an overarching "neutral" authority must be engaged to regulate, review, enforce adherence...
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. measurements were performed using Crystal Ball TAPS detector setup Glasgow tagged facility of Mainz Microtron MAMI. general assumption that is dominated by $\Delta 3/2^-$ amplitude confirmed. in particular sensitive small contributions other partial waves.
Background: Photoproduction of mesons off quasifree nucleons bound in the deuteron allows us to study electromagnetic excitation spectrum neutron and isospin structure nucleon resonances. The database for such reactions is much more sparse than free proton targets.Purpose: Study experimentally single ${\ensuremath{\pi}}^{0}$ photoproduction from deuteron. Investigate nuclear effects by a comparison results protons protons. Use data (corrected effects) test predictions reaction models partial...
An experimental study of the η′→π0π0η→6γ decay has been conducted with best up-to-date statistical accuracy, by measuring η′ mesons produced in γp→η′p reaction A2 tagged-photon facility at Mainz Microtron, MAMI. The results obtained for standard parametrization η′→π0π0η matrix element are consistent most recent η′→ππη decays, but have smaller uncertainties. available statistics and resolution allowed, first time, an observation a structure below π+π− mass threshold, magnitude sign which,...
The helicity-dependent cross sections for the photoproduction of $\pi^0\eta$ pairs have been measured first time. experiment was performed at tagged photon facility Mainz MAMI accelerator with combined Crystal Ball - TAPS calorimeter. used a polarized deuterated butanol target and circularly beam. This arrangement allowed $\sigma_{1/2}$ (photon spin antiparallel) $\sigma_{3/2}$ (parallel spins) components to be quasi-free production off protons neutrons. main finding is that two helicity...