0000000000125231

AUTHOR

Achim Richter

showing 52 related works from this author

The neutron-rich Mg isotopes: first results from MINIBALL at REX-ISOLDE

2004

After the successful commissioning of the Radioactive beam EXperiment (REX) at ISOLDE (CERN) in 2002, first physics experiments were performed in 2003 which focussed on the neutron-rich Mg isotopes in the vicinity of the “island of inversion”. After introducing the REX facility and the modern γ spectrometer MINIBALL first preliminary results will be presented showing the high potential and physics opportunities offered by this new radioactive beam facility.

PhysicsNuclear and High Energy PhysicsLarge Hadron ColliderIsotopeSpectrometer010308 nuclear & particles physicsPhysics::Instrumentation and DetectorsSHELL model[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]01 natural sciencesNuclear physics0103 physical sciencesPhysics::Accelerator PhysicsNeutron010306 general physicsNuclear ExperimentHigh potentialRadioactive beam
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Three-body correlations in electromagnetic dissociation of Borromean nuclei: The 6He case

2005

20 pages, 2 tables, 9 figures, 1 appendix.-- PACS nrs.: 25.60.-t; 27.20.+n; 25.70.De; 25.75.Gz.-- Printed version published Sep 5, 2005.

PhysicsNuclear and High Energy PhysicsParticle correlationsCoulomb excitationCoulomb excitationDissociation (chemistry)Coincidence[PACS] Reactions induced by unstable nucleiAmplitude6 ≤ A ≤ 19 [[PACS] Properties of specific nuclei listed by mass ranges]Fragmentation (mass spectrometry)[PACS] Particle correlations and fluctuationsNeutronHe-6[PACS] Properties of specific nuclei listed by mass ranges: 6 ≤ A ≤ 19Atomic physicsSeries expansionGround stateUnstable nucleiNuclear Physics A
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No evidence for medium effects in the12C(e, e'p)11Bg.s. reaction

1995

The12C(e, e'p)11B g.s reaction has been measured in parallel and anti-parallel kinematics over ap m range of −120<p m<120 MeV/c at a centralT p of 90 MeV. In contrast to previous measurements at NIKHEF, both kinematics can be described without enhancement of the transverse form factor of the bound proton (η=0.98(5)). The spectroscopic factor for this transition as determined with the new Mainz data (S α =1.54(5)) is 22% smaller than the NIKHEF value.

PhysicsNuclear and High Energy PhysicsNuclear magnetic resonanceProtonForm factor (quantum field theory)Analytical chemistryNuclear fusionZeitschrift für Physik A Hadrons and Nuclei
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Exclusive measurements of nuclear breakup reactions of 17Ne

2014

F. Wamers et al.; 4 pags.; 2 figs. Open Access funded by Creative Commons Atribution Licence 2.0

Nuclear reactionPhysicsIsotopePhysicsQC1-999HadronNuclear Theorychemistry.chemical_elementBreakup530Nuclear physicsBaryonchemistryIsotopes of neonPhysics::Accelerator Physicsddc:530Statistical physicsNucleonNuclear ExperimentCarbon
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Comparison of electromagnetic and nuclear dissociation of Ne-17

2018

8 pags., 10 figs., 3 tabs.

PhysicsCOLLISIONSInternal energy010308 nuclear & particles physics01 natural sciences7. Clean energySTATEDissociation (chemistry)CoincidenceCAPTUREReaction ratemedicine.anatomical_structureFragmentation (mass spectrometry)0103 physical sciencesmedicineHaloAtomic physics010306 general physicsGround stateDECAYNucleus
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Complete Electric Dipole Response and the Neutron Skin inPb208

2011

A benchmark experiment on Pb-208 shows that polarized proton inelastic scattering at very forward angles including 0 degrees is a powerful tool for high-resolution studies of electric dipole (E1) and spin magnetic dipole (M1) modes in nuclei over a broad excitation energy range to test up-to-date nuclear models. The extracted E1 polarizability leads to a neutron skin thickness r(skin) = 0.156(-0.021)(+0.025) fm in Pb-208 derived within a mean-field model [Phys. Rev. C 81, 051303 (2010)], thereby constraining the symmetry energy and its density dependence relevant to the description of neutron stars.

PhysicsDipoleProtonPolarizabilityGeneral Physics and AstronomyNeutronInelastic scatteringElectric dipole transitionAtomic physicsMagnetic dipoleExcitationPhysical Review Letters
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Invariant mass spectrum and α-n correlation function studied in the fragmentation of 6He on a carbon target

1998

13 pags, 5 figures.-- PACS nrs.: 24.60.−t; 25.70.Ef; 27.20.+n.

PhysicsNuclear and High Energy PhysicsReaction mechanismMomentum distributionsBreakupSpectral lineIon[PACS] Reactions induced by unstable nucleiBreakup reactions6 ≤ A ≤ 19 [[PACS] Properties of specific nuclei listed by mass ranges]Fragmentation (mass spectrometry)Halo nucleiFragmentation mechanism[PACS] ResonancesSecondary radioactive beamsInvariant massNeutronHe-5He-6Invariant mass spectra[PACS] Properties of specific nuclei listed by mass ranges: 6 ≤ A ≤ 19Atomic physicsGround stateExotic nucleiNuclear Physics A
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Systematic investigation of the drip-line nuclei 11Li and 14Be and their unbound subsystems 10Li and 13Be

2007

Fragmentation reactions in a carbon target with beams of 11Li and 14Be at relativistic energies have been studied in a kinematically complete experiment at the ALADIN-LAND setup at GSI. Excited states in 11Li and 14Be were obtained from the data in the inelastic channel. The measured cross sections with the core nucleus in the final state show that in the 14Be case core polarization plays an important role. In the one-neutron knockout channels the measured angular correlations between fragment and neutron are asymmetric, which demonstrates the presence of states with different parities in the 11Li and 14Be ground states. For 10Li a low-lying virtual s-state, a p-state and evidence for a d-s…

PhysicsNuclear physicsNuclear and High Energy PhysicsFragmentation (mass spectrometry)Excited stateHalo nucleusNeutronAtomic physicsNuclear ExperimentPolarization (waves)Ground stateNuclear Physics A
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Pygmy dipole resonance in208Pb

2012

Scattering of protons of several hundred MeV is a promising new spectroscopic tool for the study of electric dipole strength in nuclei. A case study of 208Pb shows that at very forward angles J^pi = 1- states are strongly populated via Coulomb excitation. A separation from nuclear excitation of other modes is achieved by a multipole decomposition analysis of the experimental cross sections based on theoretical angular distributions calculated within the quasiparticle-phonon model. The B(E1) transition strength distribution is extracted for excitation energies up to 9 MeV, i.e., in the region of the so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows sensitivity to…

PhysicsNuclear and High Energy PhysicsNuclear TheoryScatteringTransition dipole momentFOS: Physical sciencesCoulomb excitationResonance (particle physics)Nuclear Theory (nucl-th)DipoleNuclear Experiment (nucl-ex)Atomic physicsElectric dipole transitionNuclear ExperimentMultipole expansionNuclear ExperimentExcitationPhysical Review C
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Transverse spin effects in hadron-pair production from semi-inclusive deep inelastic scattering

2012

First measurements of azimuthal asymmetries in hadron-pair production in deep-inelastic scattering of muons on transversely polarised ^6LiD (deuteron) and NH_3 (proton) targets are presented. The data were taken in the years 2002-2004 and 2007 with the COMPASS spectrometer using a muon beam of 160 GeV/c at the CERN SPS. The asymmetries provide access to the transversity distribution functions, without involving the Collins effect as in single hadron production. The sizeable asymmetries measured on the NH_ target indicate non-vanishing u-quark transversity and two-hadron interference fragmentation functions. The small asymmetries measured on the ^6LiD target can be interpreted as indication …

Nuclear and High Energy PhysicsParticle physicsCOMPASS; SIDIS; two hadron azimuthal asymmetries; transversityHadronNuclear TheoryFOS: Physical sciencesCOMPASSSIDIS01 natural sciencesHigh Energy Physics - ExperimentNuclear physicsHigh Energy Physics - Experiment (hep-ex)0103 physical sciences010306 general physicsNuclear ExperimenttransversityPhysicsLarge Hadron ColliderMuonSpectrometerta114010308 nuclear & particles physicsScatteringtwo hadron azimuthal asymmetrietwo hadron azimuthal asymmetriesHigh Energy Physics::PhenomenologyDeep inelastic scatteringPair productionDistribution functionHigh Energy Physics::ExperimentParticle Physics - ExperimentPhysics Letters B
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Precise pion electroproduction in thep(e, e? ?+)n reaction at W=1125 MeV

1996

The reactione+p →> e+π ++n at c.m. energyW=1125MeV and momentum transfer Q2=0.117GeV2/c2 has been measured. The transverse and longitudinal structure functions have been separated by varying the polarization of the virtual photon (Rosenbluth plot) with a 3 to 4% error. In addition the longitudinal-transverse interference term has been determined measuring the right-left asymmetry with an accuracy of 3%. The experimental data are compared to model calculations, and the sensitivity of the results to the axial and pion formfactors is discussed.

PhysicsNuclear and High Energy Physicsmedia_common.quotation_subjectMomentum transferStructure functionVirtual particlePolarization (waves)AsymmetryNuclear physicsTransverse planePionNuclear fusionNuclear Experimentmedia_commonZeitschrift f�r Physik A: Hadrons and Nuclei
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Precise measurements of the neutron magnetic form factor

1998

Abstract The neutron magnetic form factor Gmn has been determined via a measurement of the ratio of cross sections D(e,e′n) and D(e,e′p). The absolute detection efficiency of the neutron detector was measured with high accuracy using tagged neutrons produced from H(n,p)n elastic scattering by means of a high intensity neutron beam. This approach minimizes the model dependence and improves upon the weakest points of previous experiments. Data in the range q2=0.2–0.8 (GeV/c)2 with uncertainties of

Elastic scatteringPhysicsNuclear physicsNuclear and High Energy PhysicsRange (particle radiation)Astrophysics::High Energy Astrophysical PhenomenaMagnetic form factorNeutron detectionNeutronAtomic physicsNeutron radiationNuclear ExperimentIntensity (heat transfer)Physics Letters B
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Two- and three-body correlations: breakup of halo nuclei

2004

4 pages, 2 figures.

Nuclear physicsPhysicsNuclear and High Energy PhysicsSpinsCoincidentNuclear TheoryNeutronHaloNuclear ExperimentGround stateBreakup
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Lithium isotopes beyond the drip line

2008

The unbound isotopes 10Li, 12Li and 13Li have been observed after nucleon-knockout reactions at relativistic energies with 11Li and 14Be beams impinging on a liquid hydrogen target. The channels , and were analysed in the ALADIN-LAND setup at GSI. The 10Li data confirm earlier findings, while the 12Li and 13Li nuclei were observed for the first time. The relative-energy spectrum shows that the ground state of 12Li can be described as a virtual s-state with a scattering length of -13.7(1.6) fm. A broad energy spectrum was found for the channel. Based on the assumption that the relative-energy spectrum is dominated by a correlated background presumably stemming from initial correlations in th…

PhysicsNuclear and High Energy PhysicsIsotopeIsotopes of lithiumNuclear TheoryScattering lengthResonance (particle physics)Nuclear physicsEnergy spectrumAtomic physicsNuclear ExperimentGround stateLiquid hydrogenLine (formation)Physics Letters B
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The horizontal drift chambers for the focal plane proton-polarimeter of the 3-spectrometer setup at MAMI

2002

Abstract Large-area horizontal drift chambers have been built for use in a proton polarimeter. A gas mixture of 20% argon and 80% ethane is used. The left–right assignment is achieved by measuring the difference of the signals induced on neighboring potential wires. A spatial resolution of 300 μm is achieved.

PhysicsNuclear and High Energy PhysicsArgonProtonSpectrometerPhysics::Instrumentation and Detectorsbusiness.industrychemistry.chemical_elementPolarimeterCardinal pointOpticschemistrybusinessInstrumentationImage resolutionNuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
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Study of M1 and E1 excitations by high-resolution proton inelastic scattering measurement at forward angles

2007

Experimental technique for measuring proton inelastic scattering with high‐resolution at 295 MeV and at forward angles including zero degrees is described. The method is useful for extracting spin part of the M1 strength via nuclear excitation as well as E1 strength via Coulomb excitation. An excitation energy resolution of 20 keV, good scattering angle resolution, and low background condition have been achieved. The experimental technique was applied for several sd and pf shell nuclei.

PhysicsProtonScatteringNuclear TheoryResolution (electron density)Coulomb excitationProton emissionMott scatteringInelastic scatteringAtomic physicsExcitationAIP Conference Proceedings
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“Safe” Coulomb Excitation ofMg30

2005

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)R 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the …

Physics010308 nuclear & particles physicsIsland of inversionProjectileGeneral Physics and AstronomyCoulomb barrierCoulomb excitation01 natural sciencesNuclear physics13. Climate actionExcited state0103 physical sciencesPhysics::Accelerator PhysicsNeutronAtomic physicsNuclear Experiment010306 general physicsIsotopes of magnesiumMagnesium ionPhysical Review Letters
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Continuum excitations in6He

1999

T. Aumann et al. ; 11 pags.; 6 figs.; 2 tabs. ; PACS number(s): 27.20.1n, 25.60.Gc, 25.70.De, 29.30.Hs

PhysicsNuclear and High Energy PhysicsAngular distributionContinuum (topology)Giant resonanceExcited stateQuantum mechanicsCoulomb excitationInelastic scatteringAtomic physicsIsotopes of heliumResonance (particle physics)Physical Review C
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Exclusive muoproduction on transversely polarised protons and deuterons

2012

The transverse target spin azimuthal asymmetry A(UT)(sin(phi-phi s)) in hard exclusive production of rho(0) mesons was measured at COMPASS by scattering 160 GeV/c muons off transversely polarised protons and deuterons. The measured asymmetry is sensitive to the nucleon helicity-flip generalised parton distributions E-q, which are related to the orbital angular momentum of quarks in the nucleon. The Q(2), x-B-j and p(T)(2) dependence of A(UT)(sin(phi-phi s)) is presented in a wide kinematic range: 1 (GeV/c)(2) < Q(2) < 10 (GeV/c)(2), 0.003 < xB(j) < 0.3 and 0.05 (GeV/c)(2) < p(T)(2) < 0.5 (GeV/c)(2) for protons or 0.10 (GeV/c)(2) < p(T)(2) < 0.5 (GeV/c)(2) for deuterons. Results for deuteron…

QuarkPhysicsNuclear and High Energy PhysicsParticle physicsAngular momentumMuonMeson010308 nuclear & particles physicsmedia_common.quotation_subjectNuclear TheoryParton01 natural sciencesAsymmetryNuclear physics0103 physical sciencesHigh Energy Physics::ExperimentNuclear Experiment010306 general physicsNucleonmedia_commonSpin-½Nuclear Physics B
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Investigation of the Li9+H2→Li8+t reaction at REX-ISOLDE

2006

The one-neutron transfer reaction Li-9 + H-2 -> Li-8 + t has been investigated in an inverse kinematics experiment by bombarding a deuterated polypropylene target with a 2.36 MeV/u Li-9 beam from the post-accelerator REX-ISOLDE at CERN. Excitation energies in Li-8 as well as angular distributions of the tritons were obtained and spectroscopic factors deduced. (c) 2006 Elsevier B.V. All rights reserved.

Nuclear reactionElastic scatteringPhysicsNuclear and High Energy PhysicsLight nucleusAngular distributionDeuteriumNuclear TheoryPhysics::Accelerator PhysicsAtomic physicsNuclear ExperimentBeam (structure)ExcitationPhysics Letters B
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Two-neutron removal reactions for very neutron-rich nuclei

1992

Abstract The two-neutron removal reactions of beams of 11 Li, 14 Be and 8 He upon Be, Ni and Au targets were studied at 30 MeV/u. The cross sections and the neutron forward angular distributions were measured; they correlate strongly with the two-neutron separation energy of the projectile. Even though the coverage of the neutron detectors was limited, a rough neutron-neutron distribution could be extracted. A simplified interpretation of the data is presented.

Nuclear reactionPhysicsNuclear and High Energy Physics010308 nuclear & particles physicsProjectileAstrophysics::High Energy Astrophysical PhenomenaNuclear Theory[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]01 natural sciencesNuclear physics0103 physical sciencesNeutron cross sectionNeutron detectionNeutronAtomic physicsNuclear Experiment010306 general physics
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Searching for the 5H resonance in the t+n+n system

2003

19 pages, 7 figures, 2 tables, 2 appendices.-- PACS nrs.: 27.10.+h; 25.60.Gc.-- Printed version published Jul 28, 2003.

PhysicsNuclear reactionNuclear and High Energy PhysicsComparisons with previous resultsMeasured triton and neutron relative energy spectra energy and angular correlationsHyperspherical harmonic expansion analysisResonance[PACS] Properties of specific nuclei listed by mass ranges: A ≤ 5Nuclear Reactions C(6Hent) (6He2nt) E=240 MeV/nucleonNuclear physicsNuclear magnetic resonanceA ≤ 5 [[PACS] Properties of specific nuclei listed by mass ranges]45H deduced resonance features[PACS] Breakup and momentum distributionsNuclear Physics A
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Investigation of short-range nucleon-nucleon correlations using the reaction in close to 4π geometry

1998

Abstract Two-proton correlations were studied in close to 4 π geometry using the reaction 12 C (e,e′pp) . The beam energy was 705 MeV, the energy transfer 225 MeV, and the three-momentum transfer 412 MeV/c. The electrons were observed in a large-acceptance magnetic spectrometer in coincidence with protons observed in a BGO crystal ball. Missing energy and momentum, relative momentum and angular distributions were derived and compared with a factorized two-nucleon emission model. Soft-core correlation functions are favoured by the data.

PhysicsNuclear and High Energy PhysicsRange (particle radiation)Missing energySpectrometerNuclear TheoryGeometryElectronCoincidenceNuclear physicsMomentumPhysics::Accelerator PhysicsAtomic physicsNuclear ExperimentNucleonCrystal BallPhysics Letters B
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Study of the $^{15}$O(2p, γ )$^{17}$Ne cross section by Coulomb dissociation of $^{17}$Ne for the rp process of nucleosynthesis

2014

Acta physica Polonica / B 45(2), 229 - 234 (2014). doi:10.5506/APhysPolB.45.229

PhysicsRadiative captureNuclear structureGeneral Physics and AstronomySigma25.40.Lw 25.70.De 26.30.Ca 27.20.+nrp-process[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]530Dissociation (chemistry)Nuclear physicsNucleosynthesisTheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITYCoulombddc:530Atomic physicsExcitationComputingMilieux_MISCELLANEOUS
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The three-spectrometer facility at the Mainz microtron MAMI

1998

Abstract A set-up of three high-resolution magnetic spectrometers, for simplicity named A, B and C, has been built as the central facility for the precise determination of double and triple coincidence cross sections of hadron knock-out and meson production through the scattering of electrons at the Mainz microtron MAMI. The spectrometers A and C with point-to-point optics in the dispersive plane and parallel-to-point optics in the non-dispersive plane have a solid angle of 28 msr and a momentum acceptance of 20 and 25%, respectively. They each consist of a quadrupole, a sextupole and two dipole magnets, reaching maximum momenta of 735 and 550 MeV/c, respectively. The spectrometer B has a s…

PhysicsNuclear and High Energy PhysicsSpectrometerCherenkov detectorSolid angleElectronlaw.inventionNuclear physicsDipoleDipole magnetlawQuadrupoleNuclear ExperimentInstrumentationMicrotronNuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
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The spin-dependent structure function of the proton g1p and a test of the Bjorken sum rule

2010

Abstract The inclusive double-spin asymmetry, A 1 p , has been measured at COMPASS in deep-inelastic polarised muon scattering off a large polarised NH3 target. The data, collected in the year 2007, cover the range Q 2 > 1 ( GeV / c ) 2 , 0.004 x 0.7 and improve the statistical precision of g 1 p ( x ) by a factor of two in the region x 0.02 . The new proton asymmetries are combined with those previously published for the deuteron to extract the non-singlet spin-dependent structure function g 1 NS ( x , Q 2 ) . The isovector quark density, Δ q 3 ( x , Q 2 ) , is evaluated from a NLO QCD fit of g 1 NS . The first moment of Δ q 3 is in good agreement with the value predicted by the Bjorken su…

Quantum chromodynamicsPhysicsCoupling constantNuclear and High Energy PhysicsParticle physicsMuonIsovectorProton010308 nuclear & particles physicsDeep inelastic scattering01 natural sciencesNuclear physics0103 physical sciencesSum rule in quantum mechanics010306 general physicsSpin-½Physics Letters B
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The electronion scattering experiment ELISe at the International Facility for Antiproton and Ion Research (FAIR) - A conceptual design study

2011

The electronion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented. © 2011 Elsevier B.V. All rights reserved.

Nuclear and High Energy PhysicselectronscatteringFORM-FACTORS[PHYS.PHYS.PHYS-ACC-PH]Physics [physics]/Physics [physics]/Accelerator Physics [physics.acc-ph]Electron[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]DATA-ACQUISITION SYSTEMNUCLEAR-STRUCTURE01 natural sciencesBINDING-ENERGIESCHARGE-DENSITY DISTRIBUTIONSIonCROSS-SECTIONSNuclear physicsNuclei far off stabilityConceptual designeA collider0103 physical sciencesCENTRAL DEPRESSIONElectron scattering010306 general physicsInstrumentationPhysics010308 nuclear & particles physicsScattering29.27.-a 25.30.Bf25.30.Dh21.10.Ft29.20.Dh29.30.-hRELATIVISTIC HEAVY-IONSEXOTIC NUCLEIFacility for Antiproton and Ion ResearchGIANT-RESONANCESStorage ring
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Flavour Separation of Helicity Distributions from Deep Inelastic Muon-Deuteron Scattering

2009

We present a LO evaluation of helicity densities of valence, \Delta u_v+\Delta d_v, non-strange sea, \Delta\bar{u}+\Delta\bar{d}, and strange quarks, \Delta s (assumed to be equal to \Delta\bar{s}). They have been obtained from the inclusive asymmetry A_{3,d} and the semi-inclusive asymmetries A^{\pi+}_{1,d}, A^{\pi-}_{1,d}, A^{K+}_{1,d}, A^{K-}_{1,d} measured in polarised deep inelastic muon-deuteron scattering. The full deuteron statistics of COMPASS (years 2002-2004 and 2006) has been used. The data cover the range Q^2 > 1 (GeV/c)^2 and 0.004<x<0.3. Both non-strange densities are found to be in a good agreement with previous measurements. The distribution of \Delta s(x) is compatible wit…

Strange quarkPOLARIZED TARGETNuclear TheoryVALENCE QUARK DISTRIBUTION; PARTON DISTRIBUTIONS; POLARIZED TARGET; NUCLEON; PROTON; DISPolarised DIS and SIDISPROTON01 natural sciencesCOMPASSParton distribution functionHigh Energy Physics - ExperimentCOMPASS; double-spin asymmetry; helicity density; parton distribution function; flavour sep- aration analysis; polarised DIS and SIDIS reactions; charged kaon asymmetrypolarised DIS and SIDIS reactionHigh Energy Physics - Experiment (hep-ex)Helicity densityVALENCE QUARK DISTRIBUTIONNUCLEONNuclear Experimentmedia_commonQuantum chromodynamicsPhysicsFlavour separation analysisHelicityCharged kaon asymmetryNucleondouble-spin asymmetryParticle Physics - Experimentcharged kaon asymmetryParticle physicsNuclear and High Energy Physicsreactionsflavour sep- aration analysismedia_common.quotation_subjectFOS: Physical sciencesparton distribution functionAsymmetryNuclear physics0103 physical sciencesflavour sep- aration analysiPolarised DIS and SIDIS reactions010306 general physicsfunctionDISMuonValence (chemistry)010308 nuclear & particles physicsScatteringParton distributionPARTON DISTRIBUTIONSHigh Energy Physics::Experimenthelicity densityDouble-spin asymmetry
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The Polarised Valence Quark Distribution from semi-inclusive DIS

2007

The semi-inclusive difference asymmetry A^{h^{+}-h^{-}} for hadrons of opposite charge has been measured by the COMPASS experiment at CERN. The data were collected in the years 2002-2004 using a 160 GeV polarised muon beam scattered off a large polarised ^6LiD target and cover the range 0.006 &lt; x &lt; 0.7 and 1 &lt; Q^2 &lt; 100 (GeV/c)^2. In leading order QCD (LO) the asymmetry A_d^{h^{+}-h^{-}} measures the valence quark polarisation and provides an evaluation of the first moment of Delta u_v + Delta d_v which is found to be equal to 0.40 +- 0.07 (stat.) +- 0.05 (syst.) over the measured range of x at Q^2 = 10 (GeV/c)^2. When combined with the first moment of g_1^d previously measured …

QuarkNuclear and High Energy PhysicsParticle physicsmagnetic spectrometer: COMPASSStructure functionsmedia_common.quotation_subjectHadronpolarization: longitudinalFOS: Physical sciencespolarized targetcross section: ratioDeep inelastic scattering; Structure functionsmuon deuteron: deep inelastic scattering01 natural sciencesAsymmetryx-dependenceHigh Energy Physics - ExperimentNuclear physicsHigh Energy Physics - Experiment (hep-ex)charged particle: multiple productionnegative particle: electroproductionExperiment-HEP13.88.+e0103 physical sciencesstructure function: moment010306 general physicsNuclear Experimentmedia_commonPhysicsQuantum chromodynamicsMuonValence (chemistry)010308 nuclear & particles physicsHigh Energy Physics::Phenomenologycross section: differenceCERN SPSDeep inelastic scatteringpositive particle: electroproductionDeuteriumquark: valenceHigh Energy Physics::Experimentmuon: polarized beamquark: polarization140-180 GeVspin: asymmetry13.60.HbDeep inelastic scatteringParticle Physics - Experimentexperimental results
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Collins and Sivers asymmetries for pions and kaons in muon-deuteron DIS

2008

The measurements of the Collins and Sivers asymmetries of identified hadrons produced in deep-inelastic scattering of 160 GeV/c muons on a transversely polarised 6LiD target at COMPASS are presented. The results for charged pions and charged and neutral kaons correspond to all data available, which were collected from 2002 to 2004. For all final state particles both the Collins and Sivers asymmetries turn out to be small, compatible with zero within the statistical errors, in line with the previously published results for not identified charged hadrons, and with the expected cancellation between the u- and d-quark contributions.

QuarkNuclear and High Energy PhysicsParticle physicsSivers asymmetryHadronNuclear TheoryFOS: Physical sciences01 natural sciencesCOMPASSHigh Energy Physics - ExperimentNuclear physicsHigh Energy Physics - Experiment (hep-ex)PionIdentifiedCompass0103 physical sciencesTransverse spin effects; Deuteron; Collins asymmetry; Sivers asymmetry; COMPASSDeuteronTransverse spin effect010306 general physicsNuclear ExperimentPhysicsMuon010308 nuclear & particles physicsScatteringHigh Energy Physics::PhenomenologyTransverse single-spin asymmetryTransverse spin effectsCollins asymmetryhadronsDeuteriumTransversityHigh Energy Physics::Experiment
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Invariant-mass spectroscopy of $^{10}$Li and $^{11}$Li

1997

Break-up of secondary Li-11 ion beams (280 MeV/nucleon) on C and Pb targets into Li-9 and neutrons is studied experimentally. Cross sections and neutron multiplicity distributions are obtained, characterizing different reaction mechanisms. Invariant-mass spectroscopy for Li-11 and Li-10 is performed. The E1 strength distribution, deduced from electromagnetic excitation of Li-11 up to an excitation energy of 4 MeV comprises similar to 8% of the Thomas-Reiche-Kuhn energy-weighted sumrule strength. Two low-lying resonance-like structures are observed for Li-10 at decay energies of 0.21(5) and 0.62(10) MeV, the former one carrying 26(10)% of the strength and likely to be associated with an s-wa…

PhysicsNuclear reactionNuclear and High Energy Physics010308 nuclear & particles physics[PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex]Nuclear Theory[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]01 natural sciencesIon0103 physical sciencesInvariant massNeutronAtomic physicsMultiplicity (chemistry)Nuclear Experiment010306 general physicsNucleonSpectroscopyExcitationNuclear Physics
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Model-independent separation of structure functions over an extended kinematical region

1994

A method for the separation of structure functions in (e, e′ p) experiments is proposed, which is an extension of the traditional Rosenbluth-type techniques of [1,2]. In our approach, we use a very flexible Ansatz to describe the structure functions within an extended kinematical regionG and determine its free parameters with a x2 minimization. The procedure is tested by pseudo data (12C(e, e′p)11Bg.s.) in the quasi-free region.

PhysicsNuclear and High Energy PhysicsMathematical analysisHadronElementary particleMinificationExtension (predicate logic)FermionNucleonFree parameterAnsatzZeitschrift f�r Physik A Hadrons and Nuclei
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Neutron momentum distributions from "core break-up" reactions of halo nuclei

1995

Neutron angular distributions from violent break-up reactions of Li-11 and Be-11 have been measured at 28 MeV/u and 280 MeV/u and at 41 MeV/u and 460 MeV/u, respectively. The derived neutron momentum distributions show a narrow component in transverse momentum that is within uncertainties independent of beam energy and target charge. This component is suggested to be simply related to the momentum distribution of the loosely bound halo neutron(s) in the projectiles.

PhysicsBreak-UpProjectileAstrophysics::High Energy Astrophysical PhenomenaNuclear TheoryGeneral Physics and AstronomyNuclear physicsTransverse momentumPhysics::Accelerator PhysicsNeutronHaloAtomic physicsNuclear ExperimentBeam energyNuclear Physics
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Pion electroproduction in the 3He(e,é π+)3H reaction at intermediate energies

1997

Abstract The differential coincident pion electroproduction cross section in the 3 He(e,e π + ) 3 H reaction has been measured with high resolution with the three-spectrometer set-up at the Mainz Microtron (MAMI) electron accelerator. Measurements were performed at the four incident energies E 0 = 855, 675, 600, and 555 MeV at fixed four-momentum transfer Q 2 = 0.045 GeV 2 , with the pions detected in parallel kinematics. This enables a separation of the measured cross section into the transverse and longitudinal structure functions by means of the Rosenbluth method. The experimental data are compared to model calculations, in which the elementary pion production amplitude includes the stan…

PhysicsNuclear and High Energy PhysicsParticle physicsNuclear TheoryParticle acceleratorResonance (particle physics)law.inventionNuclear physicsCross section (physics)AmplitudePionCoincidentlawHigh Energy Physics::ExperimentNuclear ExperimentWave functionMicrotronNuclear Physics A
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Experimental study of the 15O(2p, γ)17Ne cross section by Coulomb Dissociation for the rp process

2016

6th Nuclear Physics in Astrophysics Conference (NPA), Lisbon, Portugal, 19 May 2013 - 24 May 2013; Journal of physics / Conference Series 665, 012046 (2016). doi:10.1088/1742-6596/665/1/012046

HistoryChemistryNuclear structurechemistry.chemical_elementrp-process[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]530Dissociation (chemistry)Computer Science ApplicationsEducationIonSubatomär fysikFragmentation (mass spectrometry)Subatomic PhysicsCoulombNuclear Physics - ExperimentBerylliumAtomic physicsNuclear Experiment[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]Excitation
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The Miniball spectrometer

2013

The Miniball germanium detector array has been operational at the REX (Radioactive ion beam EXperiment) post accelerator at the Isotope Separator On-Line facility ISOLDE at CERN since 2001. During the last decade, a series of successful Coulomb excitation and transfer reaction studies have been performed with this array, utilizing the unique and high-quality radioactive ion beams which are available at ISOLDE. In this article, an overview is given of the technical details of the full Miniball setup, including a description of the γ-ray and particle detectors, beam monitoring devices and methods to deal with beam contamination. The specific timing properties of the REX-ISOLDE facility are hi…

Radioactive ion beamsNuclear and High Energy PhysicsIon beamREX-ISOLDEONLINECoulomb excitation[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex]01 natural sciencesNuclear physicsSETUPCOULOMB-EXCITATION0103 physical sciencesNuclear fusionSILICON STRIP DETECTOR[PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det]RELATIVISTIC ENERGIES010306 general physicsNuclear ExperimentNEUTRON KNOCKOUTPhysicsNuclear Physics; Heavy Ions; Hadrons; Particle and Nuclear Physics; Nuclear FusionLarge Hadron ColliderSpectrometerNUCLEI010308 nuclear & particles physicsDetectorRADIOACTIVE ION-BEAMSemiconductor detectorPhysics::Accelerator PhysicsGE DETECTORS
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Nonquenched Isoscalar Spin-M1Excitations insd-Shell Nuclei

2015

Differential cross sections of isoscalar and isovector spin-M1 (0(+)→1(+)) transitions are measured using high-energy-resolution proton inelastic scattering at E(p)=295  MeV on (24)Mg, (28)Si, (32)S, and (36)Ar at 0°-14°. The squared spin-M1 nuclear transition matrix elements are deduced from the measured differential cross sections by applying empirically determined unit cross sections based on the assumption of isospin symmetry. The ratios of the squared nuclear matrix elements accumulated up to E(x)=16  MeV compared to a shell-model prediction are 1.01(9) for isoscalar and 0.61(6) for isovector spin-M1 transitions, respectively. Thus, no quenching is observed for isoscalar spin-M1 transi…

PhysicsMatrix (mathematics)IsovectorProtonIsospinIsoscalarNuclear TheoryStochastic matrixGeneral Physics and AstronomyInelastic scatteringAtomic physicsNuclear ExperimentSpin (physics)Physical Review Letters
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Large recoil momenta in the D(e,e′p)n reaction

1998

Abstract The D(e,e′p)n reaction cross section has been measured for recoil momenta ranging from 17 MeV/c up to 950 MeV/c at momentum transfers between 600 MeV/c and 700 MeV/c. At recoil momenta above 400 MeV/c, the gross features of the cross section are only reproduced if virtual nucleon excitations are included in the calculations.

PhysicsNuclear physicsMomentumNuclear and High Energy PhysicsParticle physicsCross section (physics)RecoilNuclear TheoryPhysics::Accelerator PhysicsNuclear ExperimentNucleonPhysics Letters B
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A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target

2007

New high precision measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised 6LiD target are presented. The data were taken in 2003 and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. Both the Collins and Sivers asymmetries turn out to be compatible with zero, within the present statistical errors, which are more than a factor of 2 smaller than those of the published COMPASS results from the 2002 data. The final results from the 2002, 2003 and 2004 runs are compared with naive expectations and with existing model calculations.

QuarkdeuteronNuclear and High Energy PhysicsParticle physicsPhysics::Instrumentation and DetectorsSivers asymmetryHadrontransversity and Sivers functionFOS: Physical sciencesCOMPASS01 natural sciencesHigh Energy Physics - ExperimentNuclear physicsHigh Energy Physics - Experiment (hep-ex)nucleon structure; transverse spin and transverse momentum; transversity and Sivers functions; deuteron; COMPASS experimentCompass0103 physical sciencesCOMPASS experimentCollins010306 general physicsNuclear ExperimentCOMPASS experimenttransversityPhysicsLarge Hadron ColliderMuonSpectrometer010308 nuclear & particles physicsScatteringtransversity and Sivers functionsnucleon structureHigh Energy Physics::Experimenttransverse spin and transverse momentumasymmetryParticle Physics - Experimenttransverse single-spin asymmetry
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Study of the Unstable NucleusL10iin Stripping Reactions of the Radioactive ProjectilesB11eandL11i

1995

Reactions of the halo systems Be-11 and Li-11 (at 460 and 280 MeV/nucleon) with a carbon target demonstrate that (n + Li-9) has an (unbound) l = 0 ground state very close to the threshold. The neutron halo of Li-11 has appreciable (1s(1/2))(2) and (0p(1/2))(2) components.

PhysicsStripping (chemistry)ProjectileAnalytical chemistryGeneral Physics and Astronomychemistry.chemical_elementmedicine.anatomical_structurechemistrymedicineNeutronHaloAtomic physicsNucleonGround stateNucleusCarbonPhysical Review Letters
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Accelerated radioactive beams from REX-ISOLDE

2003

In 2001 the linear accelerator of the Radioactive beam EXperiment (REX-ISOLDE) delivered for the first time accelerated radioactive ion beams, at a beam energy of 2 MeV/u. REX-ISOLDE uses the method of charge-state breeding, in order to enhance the charge state of the ions before injection into the LINAC. Radioactive singly-charged ions from the on-line mass separator ISOLDE are first accumulated in a Penning trap, then charge bred to an A/q < 4.5 in an electron beam ion source (EBIS) and finally accelerated in a LINAC from 5 keV/u to energies between 0.8 and 2.2 MeV/u. Dedicated measurements with REXTRAP, the transfer line and the EBIS have been carried out in conjunction with the first co…

PhysicsNuclear and High Energy PhysicsPhysics::Instrumentation and DetectorsDetectorPenning trapParticle detectorIon sourceLinear particle acceleratorSemiconductor detectorNuclear physicsPhysics::Accelerator PhysicsNeutronAtomic physicsNuclear ExperimentInstrumentationBeam (structure)
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Halo excitations in fragmentation of He at 240 MeV/u on carbon and lead targets

2000

Dissociation of a 240 MeV/u beam of He-6, incident on carbon and lead targets, has been studied in kinematically complete experiments to investigate low-lying excitation modes in the halo nucleus He-6. It is shown that alignment effects characterize the inelastic scattering and allow an unambiguous assignment of the spin of a narrow resonance observed in the excitation energy spectrum. The differential cross sections for the He-6 inelastic scattering on carbon and lead targets were deduced from the measured moments of the two neutrons and the a-particle. An analysis of these distributions shows that quadrupole and, possibly, monopole excitations characterize the hadronic interaction, while …

PhysicsNuclear and High Energy PhysicsFragmentation (mass spectrometry)QuadrupoleCoulombHalo nucleusNeutronAtomic physicsInelastic scatteringResonance (particle physics)ExcitationNuclear Physics A
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High-momentum components in the 1p orbitals of 16O

1995

Abstract We have investigated that part of the proton momentum distribution of 16O that is linked through the (e, e′p) reaction to low-lying discrete states in 15N. The MAMI facility with its new generation of 100%-duty-cycle electron accelerator has allowed to cover in this experiment the previously not accessible momentum range of 265

PhysicsNuclear reactionNuclear and High Energy PhysicsRange (particle radiation)ProtonDistribution (number theory)Particle acceleratorHigh momentumlaw.inventionMomentumNuclear physicsAtomic orbitallawPhysics::Accelerator PhysicsAtomic physicsNuclear ExperimentPhysics Letters B
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8He-6He: a comparative study of nuclear fragmentation reactions

2001

19 pages, 3 tables, 6 figures.-- PACS nrs.: 27.20.+n; 24.70.+s; 25.06.-t.-- Available online Dec 4, 2000.

PhysicsNuclear and High Energy Physics[PACS] Polarization phenomena in reactionsResonanceHalo nucleusInelastic scatteringDissociation (chemistry)6 ≤ A ≤ 19 [[PACS] Properties of specific nuclei listed by mass ranges]Fragmentation (mass spectrometry)NeutronAtomic physics[PACS] Properties of specific nuclei listed by mass ranges: 6 ≤ A ≤ 19Ground stateExcitation
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First Observation of the Unbound NucleusNe15

2014

We report on the first observation of the unbound proton-rich nucleus Ne-15. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u Ne-17. The Ne-15 ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to O-13 with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2(-) and 1(-) states in F-14 is observed. The Ne-15 ground state is shown to have a strong configuration with two protons in the (sd) shell around O-13 with a 63(5)% (1s(1/2))(2) component.

Physicsmedicine.anatomical_structureExcited stateNuclear TheorymedicineShell (structure)Physics::Accelerator PhysicsGeneral Physics and AstronomyAtomic physicsNuclear ExperimentGround stateNucleusBeam (structure)Physical Review Letters
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He-8 - He-6: a comparative study of electromagnetic fragmentation reactions

2002

14 pages, 1 table, 2 figures.-- PACS nrs.:27.20.+n; 24.70.+.-- Available online Oct 8, 2001.

PhysicsNuclear and High Energy PhysicsNuclear Reactions: Pb(He-8xn He-6) E=227 MeV/nucleonNuclear TheoryHalo nucleusElectromagnetic fragmentationB(E1)Dissociation (chemistry)Nuclear physics6 ≤ A ≤ 19 [[PACS] Properties of specific nuclei listed by mass ranges]Measured σ σ(Θ) σ(E)He-8 deduced resonance energyPb(He-6xnα) E=240 MeV/nucleonNeutronAtomic physics[PACS] Properties of specific nuclei listed by mass ranges: 6 ≤ A ≤ 19Nuclear ExperimentPb(He-8xn He-6) E=227 MeV/nucleon [Nuclear Reactions]
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Measurement of the Collins and Sivers asymmetries on transversely polarised protons

2010

The Collins and Sivers asymmetries for charged hadrons produced in deeply inelastic scattering on transversely polarised protons have been extracted from the data collected in 2007 with the CERN SPS muon beam tuned at 160 GeV/c. At large values of the Bjorken x variable non-zero Collins asymmetries are observed both for positive and negative hadrons while the Sivers asymmetry for positive hadrons is slightly positive over almost all the measured x range. These results nicely support the present theoretical interpretation of these asymmetries, in terms of leading-twist quark distribution and fragmentation functions.

QuarkNuclear and High Energy PhysicsParticle physicsProtonmedia_common.quotation_subjectSivers asymmetryNuclear TheoryHadronFOS: Physical sciencesInelastic scattering01 natural sciencesAsymmetryCOMPASSHigh Energy Physics - ExperimentNuclear physicsHigh Energy Physics - Experiment (hep-ex)0103 physical sciencesTransverse spin effectNuclear Experiment010306 general physicsmedia_commonPhysicsMuonLarge Hadron Collider010308 nuclear & particles physicsHigh Energy Physics::PhenomenologyTransverse spin effectsCollins asymmetryPhysics::Accelerator PhysicsHigh Energy Physics::ExperimentTransverse spin effects; Proton; Collins asymmetry; Sivers asymmetry; COMPASSProtonParticle Physics - Experiment
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Forward-AngleH3e(e,e′π±)Coincident Electroproduction and the Search forΔ's in the Ground State ofH3e

1996

Forward-angle coincident electroproduction cross sections of charged pions from ${}^{3}\mathrm{He}$ have been measured at electron energies ${E}_{0}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}855$, 675, 600, and 555 MeV. The overall features of the data for energy transfers of $\ensuremath{\omega}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}370$ to 430 MeV with pions detected along the momentum transfer axis are reproduced in terms of a microscopic model, including pole terms, final state rescattering and produced and preformed $\ensuremath{\Delta}$ resonances. Separation of the cross section into its longitudinal and transverse parts was performed at ${Q}^{2}\phantom{\rule{0ex…

Nuclear reactionPhysicsParticle physicsPionMesonHadronGeneral Physics and AstronomyElementary particleGround stateOmegaDelta baryonPhysical Review Letters
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Coulomb and nuclear excitations of narrow resonances in 17Ne

2016

Physics letters / B 759, 200 - 205 (2016). doi:10.1016/j.physletb.2016.05.073

PhysicsNuclear and High Energy PhysicsTeoría de los quantaInternal energySpins010308 nuclear & particles physicsProjectile310601 natural sciences530lcsh:QC1-999Mass formulaNuclear physics0103 physical sciencesPhysical SciencesCoulombIsobaric processFysikddc:530Atomic physics010306 general physicsMultipletExcitationlcsh:PhysicsPhysics Letters B
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Longitudinal and transverse momentum distributions of 9Li fragments from break-up of 11Li

1995

7 pages, 3 figures, 1 table.

PhysicsNuclear and High Energy PhysicsTransverse planeFull width at half maximumMomentum (technical analysis)Break-UpSignificant differenceTransverse momentumSigmaHaloAtomic physicsNuclear Physics
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New experimental method for investigation of the nucleon polarizabilities

2010

Abstract At the continuous wave (cw) Superconducting Darmstadt Electron Linear Accelerator S-DALINAC, a new method has been developed for the determination of the electric ( α ¯ ) and magnetic ( β ¯ ) polarizabilities of the proton and the deuteron. For that purpose the energy and angular dependence of the differential cross-section for elastic γ p and γ d scattering of bremsstrahlung photons in the energy range between 20 and 100 MeV is measured by detecting the recoiling proton (deuteron) in coincidence with the scattered bremsstrahlung photon. α ¯ and β ¯ are then found by means of a best fit to a theoretical description of the scattering cross-section with these quantities as open param…

PhysicsNuclear and High Energy PhysicsPhotonProtonScatteringBremsstrahlungCompton scatteringNuclear physicsDeuteriumIonizationPhysics::Accelerator PhysicsAtomic physicsNuclear ExperimentNucleonInstrumentationNuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
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Low energy reactions with radioactive ions at REX-ISOLDE-the 9Li + 2H case

2005

19 pages, 12 figures, 2 tables.-- PACS nrs.: 25.60.-t; 25.45.-z; 27.20.+n.-- et al. ISOLDE Collaborattion and REX-ISOLDE Collaboration.

PhysicsNuclear and High Energy PhysicsExcitation energyC3D6 targetRex-Isolde post-acceleratorIonNuclear physicsLow energyDeduced reaction channelsDeuteriumReaction radioactiveDSSSD detectorAtomic physicsBeam (structure)Radioactive beam
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