108 research outputs found
Proton-deuteron radiative capture cross sections at intermediate energies
Differential cross sections of the reaction have been
measured at deuteron laboratory energies of 110, 133 and 180 MeV. The data were
obtained with a coincidence setup measuring both the outgoing He and the
photon. The data are compared with modern calculations including all possible
meson-exchange currents and two- and three- nucleon forces in the potential.
The data clearly show a preference for one of the models, although the shape of
the angular distribution cannot be reproduced by any of the presented models.Comment: 6 pages, 6 figures, accepted for publication in EPJ
Systematic investigation of the elastic proton-deuteron differential cross section at intermediate energies
To investigate the importance of three-nucleon forces (3NF) systematically
over a broad range of intermediate energies, the differential cross sections of
elastic proton-deuteron scattering have been measured at proton bombarding
energies of 108, 120, 135, 150, 170 and 190 MeV at center-of-mass angles
between and . Comparisons with Faddeev calculations show
unambiguously the shortcomings of calculations employing only two-body forces
and the necessity of including 3NF. They also show the limitations of the
latest few-nucleon calculations at backward angles, especially at higher beam
energies. Some of these discrepancies could be partially due to relativistic
effects. Data at lowest energy are also compared with a recent calculation
based on \chipt
Investigation of the quasi-free domain in deuteron-deuteron break-up using spin observables
Precision measurements of vector and tensor analyzing powers of the 2H(d, dp)n break-up process
for configurations in the vicinity of the quasi-free scattering regime with the neutron as spectator
are presented. These measurements are performed with a polarized deuteron-beam with an energy of
65MeV/nucleon impinging on a liquid-deuterium target. The experiment was conducted at the AGOR
facility at KVI using the BINA 4π-detection system. Events for which the final-state deuteron and proton
are coplanar have been analyzed and the data have been sorted for various momenta of the missing
neutron. In the limit of vanishing neutron momentum and at large deuteron-proton momentum transfer,
the data agree well with the measured and theoretically predicted spin observables of the elastic deuteronproton
scattering process. The agreement deteriorates rapidly with increasing neutron momentum and/or
decreasing momentum transfer from the deuteron beam to the outgoing proton. This study reveals the
presence of a significant contribution of final-state interactions even at very small neutron momenta
Comprehensive measurements of cross sections and spin observables of the three-body break-up channel in deuteron-deuteron scattering at 65 MeV/nucleon
Detailed measurements of five-fold differential cross sections and a rich set
of vector and tensor analyzing powers of the 2H(d; dp)n break-up process using
polarized deuteron-beam energy of 65 MeV/nucleon with a liquid-deuterium target
are presented. The experiment was conducted at the AGOR facility at KVI using
the BINA 4Pi-detection system. We discuss the analysis procedure including a
thorough study of the systematic uncertainties. The results can be used to
examine upcoming state-of-the-art calculations in the four-nucleon scattering
domain, and will, thereby, provide further insights into the dynamics of three-
and four-nucleon forces in few-nucleon systems. The results of coplanar
configurations are compared with the results of recent theoretical calculations
based on the Single-Scattering Approximation (SSA). Through these comparisons,
the validity of SSA approximation is investigated in the Quasi-Free (QF)
region.Comment: 33 pages, 30 figure
Evidence of the Coulomb force effects in the cross sections of the deuteron-proton breakup at 130 MeV
High precision cross-section data of the deuteron-proton breakup reaction at
130 MeV deuteron energy are compared with the theoretical predictions obtained
with a coupled-channel extension of the CD Bonn potential with virtual
Delta-isobar excitation, without and with inclusion of the long-range Coulomb
force. The Coulomb effect is studied on the basis of the cross-section data
set, extended in this work to about 1500 data points by including breakup
geometries characterized by small polar angles of the two protons. The
experimental data clearly prefer predictions obtained with the Coulomb
interaction included. The strongest effects are observed in regions in which
the relative energy of the two protons is the smallest.Comment: 9 pages, 3 figures, submitted to Physics Letters
Search for Three-Nucleon Force Effects in Analyzing Powers for p→d Elastic Scattering
A series of measurements have been performed at KVI to obtain the vector analyzing power Ay of the 2H(p→,pd) reaction as a function of incident beam energy at energies of 120, 135, 150, and 170 MeV. For all these measurements, a range of ϑc.m. from 30° to 170° has been covered. The purpose of these investigations is to observe possible spin-dependent effects beyond two-nucleon forces. When compared to the predictions of Faddeev calculations, based on two-nucleon forces only, significant deviations are observed at all energies and at center-of-mass angles between 70° and 130°. The addition of present-day three-nucleon forces does not improve the description of the data, demonstrating the still insufficient understanding of the properties of three-nucleon systems
Cross Sections of the Deuteron-Proton Breakup at 130 MeV:A Probe of Three-Nucleon System Dynamics
Three-nucleon system dynamics can be investigated quantitatively by comparing observables calculated with the use of Faddeev equations with results of precise measurements. Proper description of the experimental data can be achieved only if the dynamical models include, in addition to the nucleon-nucleon interaction, subtle effects of suppressed degrees of freedom, effectively introduced by means of genuine three-nucleon forces. A large set of high precision, exclusive cross-section data for the (1)H(d,pp)n breakup reaction at 130 MeV contributes significantly to constrain the physical assumptions underlying the theoretical interaction models. Comparison of nearly 1,800 cross section data points with the predictions using nuclear interactions generated in various ways, allowed to establish importance of including both, the three-nucleon and the Coulomb forces to significantly improve the description of the whole data set
Systematic investigation of three-nucleon force effects in elastic scattering of polarized protons from deuterons at intermediate energies
The question, whether the high-quality nucleon-nucleon potentials can successfully describe the three-nucleon system, and to what extent three-nucleon forces (3NFs) play a role, has become very important in nuclear few-body physics. One kinematic region where effects because of 3NFs show up is in the minimum of the differential cross section of elastic nucleon-deuteron scattering. Another observable, which could give an indication about the contribution of the spin to 3NFs, is the vector analyzing power. To investigate the importance of 3NFs systematically over a broad range of intermediate energies, both observables of elastic proton-deuteron scattering have been measured at proton bombarding energies of 108, 120, 135, 150, 170, and 190 MeV, covering an angular range in the center-of-mass system between 30° and 170°. The results show unambiguously the shortcomings of calculations employing only two-body forces and the necessity of the inclusion of 3NFs. They also show the limitations of the results of the present day models for few-nucleon systems at backward angles, especially at higher beam energies. New calculations based on chiral perturbation theory are also presented and compared with the data at the lowest energy
Proton-proton bremsstrahlung towards the elastic limit at 190 MeV incident beam energy
AbstractA series of nucleon–nucleon bremsstrahlung (NNγ) experiments at 190 MeV incident beam energy have been performed at KVI in order to gain more insight into the dynamics governing the bremsstrahlung reaction. After initial measurements wherein the bremsstrahlung process was studied far away from the elastic limit, a new study was used to probe the process nearer to the elastic limit by measuring at lower photon energies. Measured cross sections and analyzing powers are compared with the predictions of a microscopic model and those of two soft-photon models. The theoretical calculations overestimate the data by up to ≈30%, for some kinematics
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