C.D. Goodman

COSY- 11, an internal experimental facility for threshold measurements

Abstract The COSY-11 installation is an internal experiment at the cooler synchrotron and storage ring COSY Julich. It has been designed for full geometrical acceptance close to threshold for meson production studies, especially in the 1 GeV/ c 2 mass range. The experimental setup makes use of a regular C-type COSY dipole magnet, following a cluster target, to separate reaction products from the beam and to analyze their momenta, thus allowing the observation of charged reaction products at small angles with beam energies close to threshold. Resonances will be identified by missing mass reconstructions from measured four-momenta of two outgoing protons in the predominantly studied pp → ppX reaction. In addition, charged mesons either produced directly or from decays of X will be detected. The different components of the experimental facility are presented.

ETA ' PRODUCTION IN PROTON-PROTON SCATTERING CLOSE TO THRESHOLD

The

Comparison of Lambda and Sigma**0 threshold production in proton proton collisions

pp to pp eta^{prime}

Total cross section of the reaction pp→pK+Λ close to threshold

(958) reaction has been measured at COSY using the internal beam and the COSY-11 facility. The total cross sections at the four different excess energies mbox{

Gamow-Teller resonances

Q = ~1.5 ~MeV, ~1.7 ~MeV, ~2.9 ~MeV,

Λ-hyperon production via the pp → pK+Λ reaction 2 MeV above threshold

and

The 19F(p, n)19Ne and 39K(p, n)39Ca reactions at intermediate energies and quenching of the Gamow-Teller strength

~4.1 MeV

INPOL – the Indiana University Neutron Polarimeter☆

} have been evaluated to be mbox{

Spin-longitudinal and spin-transverse cross sections for Δ production in the 12C(p, n) reaction

sigma = 2.5 pm 0.5~nb

Data analysis techniques for extracting Gamow–Teller strengths from data

,