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Realtime calibration of the A4 electromagnetic lead fluoride calorimeter  [PDF]
S. Baunack,D. Balaguer Ríos,L. Capozza,J. Diefenbach,R. Frascaria,B. Gl?ser,D. v. Harrach,Y. Imai,R. Kothe,R. Kunne,J. H. Lee,F. E. Maas,M. C. Mora Espí,M. Morlet,S. Ong,E. Schilling,J. van de Wiele,C. Weinrich
Physics , 2011, DOI: 10.1016/j.nima.2011.02.099
Abstract: Sufficient energy resolution is the key issue for the calorimetry in particle and nuclear physics. The calorimeter of the A4 parity violation experiment at MAMI is a segmented calorimeter where the energy of an event is determined by summing the signals of neighbouring channels. In this case the precise matching of the individual modules is crucial to obtain a good energy resolution. We have developped a calibration procedure for our total absorbing electromagnetic calorimeter which consists of 1022 lead fluoride (PbF_2) crystals. This procedure reconstructs the the single-module contributions to the events by solving a linear system of equations, involving the inversion of a 1022 x 1022-matrix. The system has shown its functionality at beam energies between 300 and 1500 MeV and represents a new and fast method to keep the calorimeter permanently in a well-calibrated state.
A Monitor of Beam Polarization Profiles for the TRIUMF Parity Experiment  [PDF]
A. R. Berdoz
Physics , 2000, DOI: 10.1016/S0168-9002(00)00767-1
Abstract: TRIUMF experiment E497 is a study of parity violation in pp scattering at an energy where the leading term in the analyzing power is expected to vanish, thus measuring a unique combination of weak-interaction flavour conserving terms. It is desired to reach a level of sensitivity of 2x10^-8 in both statistical and systematic errors. The leading systematic errors depend on transverse polarization components and, at least, the first moment of transverse polarization. A novel polarimeter that measures profiles of both transverse components of polarization as a function of position is described.
A high power liquid hydrogen target for the Mainz A4 parity violation experiment  [PDF]
I. Altarev,E. Schilling,S. Baunack,L. Capozza,J. Diefenbach,K. Grimm,Th. Hammel,D. vonHarrach,Y. Imai,E. M. Kabuss,R. Kothe,J. H. Lee,A. LopesGinja,F. E. Maas,A. SanchezLorente,G. Stephan,C. Weinrich
Physics , 2005, DOI: 10.1016/j.nima.2006.03.022
Abstract: We present a new powerful liquid hydrogen target developed for the precise study of parity violating electron scattering on hydrogen and deuterium. This target has been designed to have minimal target density fluctuations under the heat load of a 20$\mu$A CW 854.3 MeV electron beam without rastering the electron beam. The target cell has a wide aperture for scattered electrons and is axially symmetric around the beam axis. The construction is optimized to intensify heat exchange by a transverse turbulent mixing in the hydrogen stream, which is directed along the electron beam. The target is constructed as a closed loop circulating system cooled by a helium refrigerator. It is operated by a tangential mechanical pump with an optional natural convection mode. The cooling system supports up to 250 watts of the beam heating removal. Deeply subcooled liquid hydrogen is used for keeping the in-beam temperature below the boiling point. The target density fluctuations are found to be at the level 10$^{-3}$ at a beam current of 20 $\mu$A.
eta and eta' Physics at MAMI  [PDF]
Marc Unverzagt
Physics , 2009, DOI: 10.1016/j.nuclphysbps.2009.12.034
Abstract: The Crystal Ball at MAMI setup offers an excellent possibility to study decays of the eta and eta' meson. Here, recent results of the Crystal Ball at MAMI experiment from eta meson decays are presented. Furthermore, future perspectives of this experiment in the field of eta and eta' physics are described.
The Physics Program at MAMI-C  [PDF]
Patrick Achenbach
Physics , 2008,
Abstract: In February 2007, the fourth stage of the Mainz Microtron, MAMI-C, started operations with a first experiment. The new Harmonic Double-Sided Microtron delivers an electron beam with energies up to 1.5 GeV while preserving the excellent beam quality of the previous stages. The experimental program at MAMI is focused on studies of the hadron structure in the domain of non-perturbative QCD. In this paper, a few prominent selections of the extensive physics program at MAMI-C will be presented.
The Crystal Ball programme at MAMI  [cached]
Watts D.P.
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20123701027
Abstract: This contribution will outline the physics programme exploiting the intense energy tagged polarised real photon beam at MAMI-C. The coupling of an intense photon beam and close to complete detector acceptance offers unique opportunities for precision measurements to challenge our understanding of the structure of the nucleon and the nucleus as well as the underlying theory of Quantum Chromo Dynamics (QCD). The experimental facility and the physics programme will be outlined and selected recent preliminary analyses will be presented.
Strangeness physics with Kaos at MAMI  [PDF]
Patrick Achenbach,for the A1 Collaboration
Physics , 2011,
Abstract: At the Institut f\"ur Kernphysik in Mainz, Germany, the microtron MAMI has been upgraded to 1.5-GeV electron beam energy. The magnetic spectrometer Kaos is now operated by the A1 collaboration to study strangeness electro-production. Its compact design and its capability to detect negative and positive charged particles simultaneously under forward scattering angles complements the existing spectrometers. In 2008 kaon production off a liquid hydrogen target was measured at = 0.050 (GeV/c)^2 and 0.036 (GeV/c)^2. Associated Lambda and Sigma hyperons were identified in the missing mass spectra. Major modifications to the beam-line are under construction and a new electron arm focal-surface detector system was built in order to use Kaos as a double-arm spectrometer under zero degree scattering angle.
Correlated forward-backward dissociation and neutron spectra as a luminosity monitor in heavy ion colliders  [PDF]
Anthony J. Baltz,Chellis Chasman,Sebastian N. White
Physics , 1998, DOI: 10.1016/S0168-9002(98)00575-0
Abstract: Detection in zero degree calorimeters of the correlated forward-backward Coulomb or nuclear dissociation of two colliding nuclei is presented as a practical luminosity monitor in heavy ion colliders. Complementary predictions are given for total correlated Coulomb plus nuclear dissociation and for correlated forward-backward single neutrons from the giant dipole peak.
Strange form factors in the context of SAMPLE, HAPPEX, and A4 experiments  [PDF]
António Silva,Hyun-Chul Kim,Klaus Goeke
Physics , 2001, DOI: 10.1103/PhysRevD.66.039902
Abstract: The strange properties of the nucleon are investigated within the framework of the SU(3) chiral quark-soliton model assuming isospin symmetry and applying the symmetry conserving SU(3) quantization. We present the form factors $G^0_{E,M}(Q^2)$, $G^Z_M(Q^2)$ and the electric and magnetic strange form factors $G^s_{E,M}(Q^2)$ incorporating pion and kaon asymptotics. The results show a fairly good agreement with the recent experimental data from the SAMPLE and HAPPEX collaborations. We also present predictions for future measurements including the A4 experiment at MAMI (Mainz).
A Scintillating Fiber Hodoscope for a Bremstrahlung Luminosity Monitor at an Electron$-$Positron Collider  [PDF]
D. H. Brown,D. H. Orlov,G. S. Varner,W. A. Worstell,S. I. Redin
Physics , 1996, DOI: 10.1063/1.1147108
Abstract: The performance of a scintillating fiber (2mm diameter) position sensitive detector ($4.8 \times 4.8$ cm$^2$ active area) for the single bremstrahlung luminosity monitor at the VEPP-2M electron-positron collider in Novosibirsk, Russia is described. Custom electronics is triggered by coincident hits in the X and Y planes of 24 fibers each, and reduces 64 PMT signals to a 10 bit (X,Y) address. Hits are accumulated (10 kHz) in memory and display (few Hz) the VEPP-2M collision vertex. Fitting the strongly peaked distribution ( $\sim$ 3-4 mm at 1.6m from the collision vertex of VEPP-2M ) to the expected QED angular distribution yields a background in agreement with an independent determination of the VEPP-2M luminosity.
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