112 research outputs found
A New Measurement of the 1S0 Neutron-Neutron Scattering Length using the Neutron-Proton Scattering Length as a Standard
The present paper reports high-accuracy cross-section data for the 2H(n,nnp)
reaction in the neutron-proton (np) and neutron-neutron (nn)
final-state-interaction (FSI) regions at an incident mean neutron energy of
13.0 MeV. These data were analyzed with rigorous three-nucleon calculations to
determine the 1S0 np and nn scattering lengths, a_np and a_nn. Our results are
a_nn = -18.7 +/- 0.6 fm and a_np = -23.5 +/- 0.8 fm. Since our value for a_np
obtained from neutron-deuteron (nd) breakup agrees with that from free np
scattering, we conclude that our investigation of the nn FSI done
simultaneously and under identical conditions gives the correct value for a_nn.
Our value for a_nn is in agreement with that obtained in pion-deuteron capture
measurements but disagrees with values obtained from earlier nd breakup
studies.Comment: 4 pages and 3 figure
Few Body Reserch - Summary
Few-body research history, achievements, current development and challenges
are presented.Comment: 21 pages, 2 tables, Summary talk at 18th International IUPAP
Conference on Few-Body Problems in Physics August 21-26. 2006 Santos SP
Brazil; to be published in Nuclear Physic
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superseded by more complete meson production investigations at the nucleon beam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
Recommended from our members
BREAKDOWN OF TIME REVERSAL INVARIANCE IN THE INTERACTION OF NUCLEAR PARTICLES
Recommended from our members
THE 1S0 p-p SCATTERING PARAMETERS OBTAINED PROM A REANALYSIS OF EXPERIMENTAL DATA
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