A5065870649- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- Nuclear physics research studies
- Atomic and Molecular Physics
- High-Energy Particle Collisions Research
- Advanced NMR Techniques and Applications
- Advanced Chemical Physics Studies
- Dark Matter and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Electron and X-Ray Spectroscopy Techniques
- Atomic and Subatomic Physics Research
- Crystallography and Radiation Phenomena
- High-pressure geophysics and materials
- Particle Detector Development and Performance
- Quantum, superfluid, helium dynamics
- Neutrino Physics Research
- Photocathodes and Microchannel Plates
- X-ray Spectroscopy and Fluorescence Analysis
- Computational Physics and Python Applications
- Advanced Electron Microscopy Techniques and Applications
- Silicon Carbide Semiconductor Technologies
- Radiation Therapy and Dosimetry
- Advanced Data Storage Technologies
- Astro and Planetary Science
Max Planck Institute for Nuclear Physics
2024
Johannes Gutenberg University Mainz
2014-2024
Campbell Collaboration
2023
Tel Aviv University
2018-2020
Tohoku University
2016
A massive, but light, Abelian U(1) gauge boson is a well-motivated possible signature of physics beyond the standard model particle physics. In this Letter, search for signal such in electron-positron pair production at spectrometer setup A1 Collaboration Mainz Microtron described. Exclusion limits mass range 40 MeV/c2 to 300 MeV/c2, with sensitivity squared mixing parameter as little ε2=8×10−7 are presented. large fraction space has been excluded where discrepancy measured anomalous...
A new exclusion limit for the electromagnetic production of a light $U(1)$ gauge boson ${\ensuremath{\gamma}}^{\ensuremath{'}}$ decaying to ${e}^{+}{e}^{\ensuremath{-}}$ was determined by A1 Collaboration at Mainz Microtron. Such bosons appear in several extensions standard model and are also discussed as candidates interaction dark matter with matter. In electron scattering from heavy nucleus, existing limits narrow state coupling were reduced nearly an order magnitude range lepton pair...
At the Mainz Microtron MAMI, first high-resolution pion spectroscopy from decays of strange systems was performed by electron scattering off a (9)Be target in order to study Λ binding energy light hypernuclei. Positively charged kaons were detected short-orbit spectrometer with broad momentum acceptance at 0° forward angles respect beam, efficiently tagging production strangeness nucleus. Coincidentally, negatively decay pions two independent spectrometers. About 10(3) pionic weak...
We perform a systematic study of the α-particle excitation from its ground state 0_{1}^{+} to 0_{2}^{+} resonance. The so-called monopole transition form factor is investigated via an electron scattering experiment in broad Q^{2} range (from 0.5 5.0 fm^{-2}). precision new data dramatically supersedes that older sets data, each covering only portion range. allow determination two coefficients low-momentum expansion, leading puzzle. By confronting state-of-the-art theoretical calculations, we...
We report on a new experimental method based initial-state radiation (ISR) in e–p scattering, which exploits the radiative tail of elastic peak to study properties electromagnetic processes and extract proton charge form factor (GEp) at extremely small Q2. The ISR technique was implemented an experiment three-spectrometer facility Mainz Microtron (MAMI). This led precise validation corrections far away from line provided first measurements GEp for 0.001≤Q2≤0.004(GeV/c)2.
Abstract We report on a comprehensive reinterpretation of the existing cross-section data for elastic electron-proton scattering obtained by initial-state radiation technique, resulting in significantly improved accuracy extracted proton charge radius. By refining external energy corrections we have achieved an outstanding description radiative tail, essential detailed investigation finite-size effects measured cross sections. This development, together with novel framework determining...
We report on the first ${Q}^{2}$-dependent measurement of beam-normal single spin asymmetry ${A}_{n}$ in elastic scattering 570 MeV vertically polarized electrons off $^{12}\mathrm{C}$. cover ${Q}^{2}$ range between 0.02 and $0.05\text{ }\text{ }{\mathrm{GeV}}^{2}/{c}^{2}$ determine at four different values. The experimental results are compared to a theoretical calculation that relates imaginary part two-photon exchange amplitude. result emphasizes behavior given by ratio Compton charge...
The helicity-dependent recoil proton polarizations ${P}_{x}^{\ensuremath{'}}$ and ${P}_{z}^{\ensuremath{'}}$ as well the helicity-independent component ${P}_{y}$ have been measured in $p(\stackrel{\ensuremath{\rightarrow}}{e},{e}^{\ensuremath{'}}\stackrel{\ensuremath{\rightarrow}}{p}){\ensuremath{\pi}}^{0}$ reaction at four-momentum transfer ${Q}^{2}\ensuremath{\simeq}0.1\text{ }\text{ }{\mathrm{GeV}}^{2}$, center-of-mass emission angle...
Abstract We present the findings of a study based on new inelastic electron-scattering experiment $${}^{12}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mn>12</mml:mn> </mml:mmultiscripts> </mml:math> C nucleus focusing kinematic region $$Q^2=0.8\,\textrm{GeV}^2/{c}^2$$ <mml:mrow> <mml:msup> <mml:mi>Q</mml:mi> <mml:mn>2</mml:mn> </mml:msup> <mml:mo>=</mml:mo> <mml:mn>0.8</mml:mn> <mml:mspace/> <mml:mtext>GeV</mml:mtext> <mml:mo>/</mml:mo>...
We measured the ratio $P_{x}/P_{z}$ of transverse to longitudinal components polarization transferred from electrons bound protons in $^{12}\mathrm{C}$ by $^{12}\mathrm{C}(\vec{e},e'\vec{p})$ process at Mainz Microtron (MAMI). observed consistent deviations unity this normalized free-proton ratio, $(P_{x}/P_{z})_{^{12}\mathrm{C}}/(P_{x}/P_{z})_{^{1}\mathrm{H}}$, for both $s$- and $p$-shell knocked out protons, even though they are embedded averaged local densities that differ about a factor...
In an attempt to contribute further insight into the discrepancy between Lamb shift and elastic scattering determinations of proton charge radius, a new experiment at MAMI is underway, aimed measuring form-factors very low momentum transfers by using technique based on initial state radiation. This paper reports conclusions pilot measurement performed in 2010, whose main goal was check feasibility proposed recognize overcome any obstacles before running full experiment. The modifications...
We report the measurement of ratio polarization-transfer components, Px/Pz, in H2(e→,e′p→)n reaction at low and high missing momenta, search differences between free bound protons. The observed deviation Px/Pz from that a proton, which is similar to 4He, indicates effect nuclei function virtuality knock-out proton momentum direction, but not average nuclear density. There general agreement data calculations, assume form factors, however, measurements are consistently about 10% higher.
Virtual Compton scattering on the proton has been investigated at three yet unexplored values of four-momentum transfer Q^{2}: 0.10, 0.20, and 0.45 GeV^{2}, Mainz Microtron. Fits performed using either low-energy theorem or dispersion relations allowed extraction structure functions P_{LL}-P_{TT}/ε P_{LT}, as well electric magnetic generalized polarizabilities α_{E1}(Q^{2}) β_{M1}(Q^{2}). These new results show a smooth rapid falloff α_{E1}(Q^{2}), in contrast to previous measurements...
We report the first measurements of transverse (Px and Py) longitudinal (Pz) components polarization transfer to a bound proton in deuteron via H2(e→,e′p→) reaction, over wide range missing momentum. A precise determination electron beam reduces systematic uncertainties on individual level that enables detailed comparison state-of-the-art calculation using free-proton electromagnetic form factors. observe very good agreement between measured calculated Px/Pz ratios, but deviations...
We present measurements of the polarization-transfer components in $^2$H$(\vec e,e'\vec p)$ reaction, covering a previously unexplored kinematic region with large positive (anti-parallel) missing momentum, $p_{\rm miss}$, up to 220 MeV$/c$, and $Q^2=0.65$ $({\rm GeV}/c)^2$. These measurements, performed at Mainz Microtron (MAMI), were motivated by theoretical calculations which predict small final-state interaction (FSI) effects these kinematics, making them favorable for searching medium...
We report the measurements of transverse (Px′) and longitudinal (Pz′) components polarization transfer to a bound proton in carbon via quasifree C12(e⃗,e′p⃗) reaction, over wide range missing momenta. determine these transfers separately for protons knocked out from s p shells. The electron-beam was measured individual with systematic uncertainties which allow detailed comparison theoretical calculations.Received 1 March 2020Accepted May...
A comparison between polarization-transfer to a bound proton in quasi-free kinematics by the A$(\vec{e},e'\vec p)$ knockout reaction and that elastic scattering off free can provide information on characteristics of proton. In past reported measurements have been compared those with zero initial momentum. We introduce, for first time, expressions components when is initially motion compare them $^2$H data measured at Mainz Microtron (MAMI). show ratios transverse ($P_x$) longitudinal ($P_z$)...
A precise measurement of the elastic electron-deuteron scattering cross section at four-momentum transfers 0.24 fm−1 ≤ Q 2.7 has been performed Mainz Microtron. In this paper we describe utilized experimental setup and necessary analysis procedure to precisely determine deuteron charge form factor from these data. Finally, radius rd can be extracted an extrapolation that Q2 = 0.
The cross section of the p(e,e′π+)n reaction has been measured for five kinematic settings at an invariant mass W=1094MeV and a four-momentum transfer Q2=0.078(GeV/c)2. measurement performed MAMI using new short-orbit spectrometer (SOS) A1 collaboration, intended detection low-energy pions. transverse longitudinal terms were separated Rosenbluth method transverse-longitudinal interference term determined from left-right asymmetry. experimental are compared with calculations three models:...