M. Weinriefer - Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany

M. Weinriefer
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Name
M. Weinriefer
Affiliation
Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany
City
Mainz
Country
Germany

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Nuclear Experiment (16)
 
High Energy Physics - Experiment (5)
 
Physics - Instrumentation and Detectors (2)

Publications Authored By M. Weinriefer

We report on a new experimental method based on initial-state radiation (ISR) in e-p scattering, in which the radiative tail of the elastic e-p peak contains information on the proton charge form factor ($G_E^p$) at extremely small $Q^2$. The ISR technique was validated in a dedicated experiment using the spectrometers of the A1-Collaboration at the Mainz Microtron (MAMI). This provided first measurements of $G_E^p$ for $0. Read More

A massive, but light abelian U(1) gauge boson is a well motivated possible signature of physics beyond the Standard Model of particle physics. In this paper, the search for the signal of such a U(1) gauge boson in electron-positron pair-production at the spectrometer setup of the A1 Collaboration at the Mainz Microtron (MAMI) is described. Exclusion limits in the mass range of 40 MeV up to 300 MeV with a sensitivity in the mixing parameter of down to $\epsilon^2 = 8\times 10^{-7}$ are presented. Read More

A measurement of beam helicity asymmetries in the reaction 3He(e,e'n)pp has been performed at the Mainz Microtron in quasielastic kinematics in order to determine the electric to magnetic form factor ratio of the neutron, GEn/GMn, at a four momentum transfer Q2 = 1.58 GeV2. Longitudinally polarized electrons were scattered on a highly polarized 3He gas target. Read More

The paper describes a precise measurement of electron scattering off the proton at momentum transfers of $0.003 \lesssim Q^2 \lesssim 1$\ GeV$^2$. The average point-to-point error of the cross sections in this experiment is $\sim$ 0. Read More

The Kaos spectrometer is maintained by the A1 collaboration at the Mainz Microtron MAMI with a focus on the study of (e,e'K^+) coincidence reactions. For its electron-arm two vertical planes of fiber arrays, each comprising approximately 10 000 fibers, are operated close to zero degree scattering angle and in close proximity to the electron beam. A nearly dead-time free DAQ system to acquire timing and tracking information has been installed for this spectrometer arm. Read More

Cross section measurements of the exclusive p(e,e'K+)Lambda,Sigma^0 electroproduction reactions have been performed at the Mainz Microtron MAMI in the A1 spectrometer facility using for the first time the Kaos spectrometer for kaon detection. These processes were studied in a kinematical region not covered by any previous experiment. The nucleon was probed in its third resonance region with virtual photons of low four-momenta, Q^2= 0. Read More

Wire chambers are routinely operated as tracking detectors in magnetic spectrometers at high-intensity continuous electron beams. Especially in experiments studying reactions with small cross-sections the reaction yield is limited by the background rate in the chambers. One way to determine the track of a charged particle through a multi-wire proportional chamber (MWPC) is the measurement of the charge distribution induced on its cathodes. Read More

A new exclusion limit for the electromagnetic production of a light U(1) gauge boson {\gamma}' decaying to e^+e^- was determined by the A1 Collaboration at the Mainz Microtron. Such light gauge bosons appear in several extensions of the standard model and are also discussed as candidates for the interaction of dark matter with standard model matter. In electron scattering from a heavy nucleus, the existing limits for a narrow state coupling to e^+e^- were reduced by nearly an order of magnitude in the range of the lepton pair mass of 210 MeV/c^2 < m_e^+e^- < 300 MeV/c^2. Read More

New precise results of a measurement of the elastic electron-proton scattering cross section performed at the Mainz Microtron MAMI are presented. About 1400 cross sections were measured with negative four-momentum transfers squared up to Q^2=1 (GeV/c)^2 with statistical errors below 0.2%. Read More

Cross sections for the ^{3}He(e,e'pn)p reaction were measured for the first time at energy transfers of 220 and 270 MeV for several momentum transfers ranging from 300 to 450 MeV/c. Cross sections are presented as a function of the momentum of the recoil proton and the momentum transfer. Continuum Faddeev calculations using the Argonne V18 and Bonn-B nucleon-nucleon potentials overestimate the measured cross sections by a factor 5 at low recoil proton momentum with the discrepancy becoming much smaller at higher recoil momentum. Read More

2008Feb
Affiliations: 1Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 2Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 3Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 4Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 5Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 6Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 7Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 8Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 9Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 10Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 11Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 12Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 13Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 14Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 15Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz, Germany, 16University of Ljubljana and Jozef Stefan Institute, Ljubljana, Slovenia, 17University of Ljubljana and Jozef Stefan Institute, Ljubljana, Slovenia, 18University of Ljubljana and Jozef Stefan Institute, Ljubljana, Slovenia, 19GSI, Darmstadt, Germany, 20GSI, Darmstadt, Germany, 21GSI, Darmstadt, Germany, 22GSI, Darmstadt, Germany, 23GSI, Darmstadt, Germany, 24GSI, Darmstadt, Germany, 25GSI, Darmstadt, Germany, 26GSI, Darmstadt, Germany, 27KEK, Japan, 28Graduate School of Science, Osaka University, Japan, 29Graduate School of Science, Osaka University, Japan, 30Division of Electronics and Applied Physics, Osaka Electro-Communication University, Japan

The performance of scintillating fibre detectors was studied with electrons at the spectrometer facility of the Mainz microtron MAMI, as well as in a C-12 beam of 2 AGeV energy and in a beam of different particle species at GSI. Multi-anode photomultipliers were used to read out one or more bundles of 128 fibres each in different geometries. For electrons a time resolution of FWHM = 1 ns was measured in a single detector plane with a detection efficiency epsilon > 99%. Read More

The beam-recoil double polarization P_{x'}^h and P_{z'}^h and the recoil polarization P_{y'} were measured for the first time for the p(\vec{e},e'\vec{p})\eta reaction at a four-momentum transfer of Q^2=0.1 GeV^2/c^2 and a center of mass production angle of \theta = 120^\circ at MAMI C. With a center of mass energy range of 1500 MeV < W < 1550 MeV the region of the S_{11}(1535) and D_{13}(1520) resonance was covered. Read More

One contribution to the time resolution of a scintillation detector is the signal time spread due to path length variations of the detected photons from a point source. In an experimental study a rectangular scintillator was excited by means of a fast pulsed ultraviolet laser at different positions along its longitudinal axis. Timing measurements with a photomultiplier tube in a detection plane displaced from the scintillator end face showed a correlation between signal time and tube position indicating only a small distortion of photon angles during transmission. Read More