Heavy Meson Production at COSY - 11

The COSY-11 collaboration has measured the total cross section for the pp --> pp eta-prime and pp --> pp eta reactions in the excess energy range from Q = 1.5 MeV to Q = 23.6 MeV and from Q = 0.5 MeV to Q = 5.4 MeV, respectively. Measurements have been performed with the total luminosity of 73 nb^(-1) for the pp --> pp eta reaction and 1360 nb^(-1) for the pp --> pp eta-prime one. Recent results are presented and discussed.Comment: Invited talk at 4th International Conference on Physics at Storage Rings (STORI 99), Bloomington, Indiana, USA, September 12-16, 199

Near-Threshold eta Meson Production in Proton-Proton Collisions

The production of eta mesons has been measured in the proton-proton interaction close to the reaction threshold using the COSY-11 internal facility at the cooler synchrotron COSY. Total cross sections were determined for eight different excess energies in the range from 0.5 MeV to 5.4 MeV. The energy dependence of the total cross section is well described by the available phase-space volume weighted by FSI factors for the proton-proton and proton-eta pairs.Comment: 9 pages, 1 table, 5 figure

Total Cross Section of the Reaction pp \to pK^+\Lambda Close to Threshold

The energy dependence of the total cross section for the pp \to pK^+\Lambda reaction was measured in the threshold region covering the excess energy range up to 7MeV. Existing model calculations describe the slope of the measured cross sections well, but are too low by a factor of two to three in rate. The data were used for a precise determination of the beam momentum of the COSY-synchrotron.Comment: 11 pages, 5 figure

η′\eta^{\prime} production in proton-proton scattering close to threshold}

The $pp \to pp \eta^{\prime}$ (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{$Q = ~1.5 ~MeV, ~1.7 ~MeV, ~2.9 ~MeV,$ and $~4.1 MeV$} have been evaluated to be \mbox{$\sigma = 2.5 \pm 0.5~nb$, $~~~ 2.9 \pm 1.1~nb$, $~~~ 12.7 \pm 3.2~nb$, ~ and $~~~ 25.2 \pm 3.6 ~nb$}, respectively. In this region of excess energy the $\eta^{\prime}$ (958) cross sections are much lower compared to those of the $\pi ^0$ and $\eta$ production.Comment: 11 pages, 3 figure

Comparison of Lambda and Sigma(0) Threshold Production in Proton-Proton Collisions

Threshold measurements of the associated strangeness production reactions pp --> p K(+) Lambda and pp --> p K(+) Sigma(0) are presented. Although slight differences in the shapes of the excitation functions are observed, the most remarkable feature of the data is that at the same excess energy the total cross section for the Sigma(0) production appears to be about a factor of 28 smaller than the one for the Lambda particle. It is concluded that strong Sigma(0)-p final state interactions, and in particular the Sigma-N --> Lambda-p conversion reaction, are the likely cause of the depletion for the yield in the Sigma signal. This hypothesis is in line with other experimental evidence in the literature.Comment: 13 pages, 3 figures, 1 tabl

New Optimized PWM VSC Control Structures and Strategies Under Unbalanced Voltage Transients

International audienc

Excitation function of proton induced nuclear reaction on strontium: Special relevance to the production of 88Y

Excitation functions were measured by the activation method using stacked-foil technique for the natSr (p,xn)88,87m,g,86m,gY reactions up to 18 MeV. The experimental results were compared with the theoretical data from EMPIRE-3.2 code and TENDL. Integral yields of 88,87m,g,86m,gY were estimated based on the measured cross sections. The optimum energy range for the production of the important isotope 88Y is Ep=16→11 MeV, 88Y yield amounts to about 3 MBq/μAh

Force constants from thermal diffusion in the He-C2H4 and Ne-C2H4 gas mixtures

SIGLEITItal

Activation cross-section data for α-particle-induced nuclear reactions on natural vanadium for practical applications

Excitation functions for α-induced reactions on natural vanadium were measured in the energy range up to 20 MeV. The stacked-foil activation technique was used. The experimental results were compared with the theoretical calculations using EMPIRE-3.1, EMPIRE-3.2.2 and TENDL 2015, and with earlier experimental results. Thick target yields were calculated for the production of 54Mn and for the associated impurity 52M