0000000000740375

AUTHOR

C. Bradtke

showing 6 related works from this author

Measurement of Helicity-Dependent Photoabsorption Cross Sections on the Neutron from 815 to 1825 MeV

2005

Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of [33.9 +/- 5.5(stat) +/- 4.5(syst)] microb is extracted.

PhysicsRange (particle radiation)Photon010308 nuclear & particles physicsNuclear TheoryGeneral Physics and AstronomyPhoton energy7. Clean energy01 natural sciencesHelicityNuclear physicsDeuterium0103 physical sciencesNeutronAtomic physicsNuclear Experiment010306 general physicsMultipole expansionCircular polarizationPhysical Review Letters
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A new frozen-spin target for 4π particle detection

1999

Abstract A new frozen-spin target has been developed, that allows the detection of emitted particles in an angular acceptance of almost 4π in the laboratory frame. The central part of this new target represents a 3He/4He dilution refrigerator that is installed horizontally along the beam axis. The refrigerator includes an internal superconducting holding coil to maintain the nucleon polarization in the frozen-spin mode longitudinally to the beam. The design of the dilution refrigerator and the use of an internal holding coil enabled for the first time the measurement of a spin-dependent total cross section in combination with a polarized solid state target. This new frozen-spin target was u…

PhysicsNuclear and High Energy Physicsmedia_common.quotation_subjectRefrigerator carPolarization (waves)AsymmetryHelicityNuclear physicsElectromagnetic coilSum rule in quantum mechanicsDilution refrigeratorNucleonInstrumentationmedia_commonNuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
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Measurement of the Gerasimov-Drell-Hearn Integrand forH2from 200 to 800 MeV

2006

A measurement of the helicity dependence of the total inclusive photoabsorption cross section on the deuteron was carried out at MAMI (Mainz) in the energy range $200l{E}_{\ensuremath{\gamma}}l800\text{ }\text{ }\mathrm{MeV}$. The experiment used a $4\ensuremath{\pi}$ detection system, a circularly polarized tagged photon beam and a frozen-spin target which provided longitudinally polarized deuterons. The contribution to the Gerasimov-Drell-Hearn sum rule for the deuteron determined from the data is $407\ifmmode\pm\else\textpm\fi{}20(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}24(\mathrm{syst})\text{ }\text{ }\ensuremath{\mu}\mathrm{b}$ for $200l{E}_{\ensuremath{\gamma}}l800\text{ }\text{ }\m…

PhysicsParticle physicsMeson production010308 nuclear & particles physicsNuclear TheoryGeneral Physics and AstronomyComputer Science::Computation and Language (Computational Linguistics and Natural Language and Speech Processing)01 natural sciencesHelicityNuclear physics0103 physical sciencesSum rule in quantum mechanicsPhoton beamNuclear Experiment010306 general physicsEnergy (signal processing)Physical Review Letters
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Helicity Dependence ofγp→Nπbelow 450 MeV and Contribution to the Gerasimov-Drell-Hearn Sum Rule

2000

The helicity dependence of the single pion photoproduction on the proton has been measured in the energy range from 200 to 450 MeV for the first time. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a frozen-spin target. The data obtained provide new information for multipole analyses of pion photoproduction and determine the main contributions to the Gerasimov-Drell-Hearn sum rule and the forward spin polarizability gamma(0).

PhysicsParticle physicsProtonNuclear TheoryGeneral Physics and AstronomyHelicityNuclear physicsPionPolarizabilityPhysics::Accelerator PhysicsHigh Energy Physics::ExperimentSum rule in quantum mechanicsNuclear ExperimentMultipole expansionMicrotronSpin-½Physical Review Letters
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Experimental Check of the Gerasimov-Drell-Hearn Sum Rule for H1

2004

For the first time we checked the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the proton experimentally in the photon energy range from 0.2-2.9 GeV with the tagged photon facilities at MAMI (Mainz) and ELSA (Bonn). New data of the doubly polarized total cross section difference are presented in the energy range from 1.6 to 2.9 GeV. The contribution to the GDH integral from 0.2-2.9 GeV yields [254+/-5(stat)+/-12(syst)] microb with negative contributions in the Regge regime at photon energies above 2.1 GeV. This trend supports the validity of the GDH sum rule.

PhysicsRange (particle radiation)PhotonProton010308 nuclear & particles physicsAstrophysics::High Energy Astrophysical PhenomenaNuclear TheoryGeneral Physics and AstronomyPhoton energy01 natural sciencesNuclear physicsRegge theory0103 physical sciencesHigh Energy Physics::ExperimentSum rule in quantum mechanicsNuclear Experiment010306 general physicsAstrophysics::Galaxy AstrophysicsPhysical Review Letters
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Measurement of proton and nitrogen polarization in ammonia and a test of equal spin temperature

1998

The 1996 data taking of the SMC experiment used polarized protons to measure the spin-dependent structure function g(1) of the proton. Three liters of solid granular ammonia were irradiated at the Bonn electron linac in order to create the paramagnetic radicals which are needed for polarizing the protons. Proton polarizations of +/- (90 +/- 2.5)% were routinely reached. An analysis based on a theoretical line shape for spin-1. systems with large quadrupolar broadening was developed which allowed the nitrogen polarization in the ammonia to be determined with a 10% relative error. The measured quadrupolar coupling constant of N-14 agrees well with earlier extrapolated values. The polarization…

Nuclear and High Energy Physicsspin resonanceProtonp polarized targetNuclear Theorychemistry.chemical_elementAmmoniachemistry.chemical_compoundParamagnetismIrradiationDetectors and Experimental TechniquesNuclear ExperimentInstrumentationPhysicsCoupling constantpolarizationquadrupolar interactionsPolarization (waves)Nitrogennitrogen polarized targetdynamic nuclearnuclear magnetic resonancechemistryDeuteriump polarized target; nitrogen polarized target; spin resonanceAtomic physics
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