33 research outputs found
Interaction of Cooled Ion Beams with Internal Fiber Targets
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Study of the production mechanism of the eta meson by means of analysing power measurements
Information about the production mechanism of the eta meson in proton-proton
collisions can be inferred by confronting the experimental studies on the
analysing power for the p(pol)p --> pp eta reaction with the theoretical
predictions of this observable. Results show that the predictions of pure
pseudoscalar- or vector meson exchange model are insufficient to describe the
analysing powers.Comment: 4 pages, 4 figures, Presented at MESON 2006: 9th International
Workshop on Meson Production, Properties and Interactions, Cracow, Poland,
9-13 Jun 200
A Precision Measurement of pp Elastic Scattering Cross Sections at Intermediate Energies
We have measured differential cross sections for \pp elastic scattering with
internal fiber targets in the recirculating beam of the proton synchrotron
COSY. Measurements were made continuously during acceleration for projectile
kinetic energies between 0.23 and 2.59 GeV in the angular range deg. Details of the apparatus and the data analysis are
given and the resulting excitation functions and angular distributions
presented. The precision of each data point is typically better than 4%, and a
relative normalization uncertainty of only 2.5% within an excitation function
has been reached. The impact on phase shift analysis as well as upper bounds on
possible resonant contributions in lower partial waves are discussed.Comment: 23 pages 29 figure
The cross section minima in elastic Nd scattering: a ``smoking gun'' for three nucleon force effects
Neutron-deuteron elastic scattering cross sections are calculated at
different energies using modern nucleon-nucleon interactions and the
Tucson-Melbourne three-nucleon force adjusted to the triton binding energy.
Predictions based on NN forces only underestimate nucleon-deuteron data in the
minima at higher energies starting around 60 MeV. Adding the three-nucleon
forces fills up those minima and reduces the discrepancies significantly.Comment: 11 pages, 6 figure
Spin‐Flipping Polarized Deuterons At COSY
We recently stored a 1.85 GeV/c vertically polarized deuteron beam in the COSY Ring in Jülich; we then spin‐flipped it by ramping a new air‐core rf dipole’s frequency through an rf‐induced spin resonance to manipulate the polarization direction of the deuteron beam. We first experimentally determined the resonance’s frequency and set the dipole’s rf voltage to its maximum; then we varied its frequency ramp time and frequency range. We used the EDDA detector to measure the vector and tensor polarization asymmetries. We have not yet extracted the deuteron’s tensor polarization spin‐flip parameters from the measured data, since our short run did not provide adequate tensor analyzing‐power data at 1.85 GeV/c. However, with a 100 Hz frequency ramp and our longest ramp time of 400 s, the deuterons’ vector polarization spin‐flip efficiency was 48±1%. © 2004 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87592/2/763_1.pd
Cooler Target Development
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Cooler Experiment Preparation
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Close-to-threshold Meson Production in Hadronic Interactions
Studies of meson production at threshold in the hadron--hadron interaction
began in the fifties when sufficient energies of accelerated protons were
available. A strong interdependence between developments in accelerator
physics, detector performance and theoretical understanding led to a unique
vivid field of physics. Early experiments performed with bubble chambers
revealed already typical ingredients of threshold studies, which were
superseded by more complete meson production investigations at the nucleon beam
facilities TRIUMF, LAMPF, PSI, LEAR and SATURNE. Currently, with the advent of
the new cooler rings as IUCF, CELSIUS and COSY the field is entering a new
domain of precision and the next step of further progress.
The analysis of this new data in the short range limit permits a more
fundamental consideration and a quantitative comparison of the production
processes for different mesons in the few--body final states. The
interpretation of the data take advantage of the fact that production reactions
close-to-threshold are characterized by only a few degrees of freedom between a
well defined combination of initial and exit channels. Deviations from
predictions of phase-space controlled one-meson-exchange models are indications
of new and exciting physics. Precision data on differential cross sections,
isospin and spin observables -- partly but by no means adequately available --
are presently turning up on the horizon. There is work for the next years and
excitement of the physics expected. Here we try to give a brief and at the same
time comprehensive overview of this field of hadronic threshold production
studies.Comment: 100 pages, Review article to be published in Prog. Part. Nucl. Phys.
Vol. 49, issue 1 (2002
A new form of three-body Faddeev equations in the continuum
We propose a novel approach to solve the three-nucleon (3N) Faddeev equation
which avoids the complicated singularity pattern going with the moving
logarithmic singularities of the standard approach. In this new approach the
treatment of the 3N Faddeev equation becomes essentially as simple as the
treatment of the two-body Lippmann-Schwinger equation. Very good agreement of
the new and old approaches in the application to nucleon-deuteron elastic
scattering and the breakup reaction is found.Comment: 20 pages, 3 eps figure