D. Garreta

Σ hypernuclear states in (K−, π±) reactions on 12C

Abstract Using negative kaons of momenta 400 and 450 MeV/c, Σ hypernuclear states have been produced in (K−, π−) and (K−, π+) reactions on 12C. The observed states are interpreted as the recoilless production of Σ particles on carbon. The upper limit for the widths of these states is estimated to be 5 MeV, independent of the charge of the Σ particle.

The (K−, π+) strangeness exchange reaction on 16O

Abstract Using negative kaons of 450 MeV/c momentum, Σ hypernuclear states have been produced in the (K−, π+) reaction on 16O. The observed states are interpreted as the recoilless production of Σ− particles in the p 3 2 and p 1 2 orbits of the Σ16C hypernucleus. Their energy splitting gives a constraint to the magnitude of the spin-orbit coupling for the Σ− particles in the nucleus.

Hypernuclear production in the

Abstract Cross sections for the production of hypernuclei were measured in the reaction A(K − , π − ) Λ A. on light and heavy nuclear targets, using a separated K − beam at the CERN Proton Synchrotron. The pions were detected in the forward direction. The results are compared with cross sections calculated under the assumption that the reaction took place on a single neutron. The good agreement between the measured and the calculated cross sections justifies the use of the (K − , π − ) reaction in order to obtain spectroscopic information on hypernuclei.

(K^−, π^−)

Abstract Neutron hole states in the 1s shell have been studied in the n(K−, π−)Λ strangeness-exchange reaction on 6Li, 7Li, 9Be, and 12C targets at the CERN Proton Synchrotron. The excitation energy and the width of the states as well as the differential cross section have been determined. The clear similarity with the 1s proton hole states observed in (p, 2p) reactions indicates that the presence of the Λ-particle can be taken into account within the weak-coupling model. In this way the (K−, π−) reaction can be used for the study of Λ -states as well as for the investigation of neutron hole states produced at very low momentum transfer.

reaction

Abstract Elastic scattering of 178.4 MeV p has been measured on 16 O and 18 O isotopes. Both macroscopic and microscopic analyses of the data show differences which can be related to the neutron excess in 18 O

Neutron hole states in Λ6Li, Λ7Li, Λ9Be and Λ12C hypernuclei

Abstract The angular distributions of the inelastic scattering of antiprotons for a few collective states of 12C and 18O have been measured. They exhibit a diffractive pattern, typical of strong absorption. Coupled channel analysis of these data has been carried out. The derived multipole moments agree fairly well with those obtained with other probes. Microscopic calculations performed in the framework of the DWIA formalism, using either the Paris or the Dover-Richard NN interaction are in good agreement with the data for the low-lying collective states. The present status of the experimental study of the unnatural parity levels is discussed.

Comparative study of the elastic scattering of 178.4 MeV antiprotons by the 16O and 18O isotopes

Abstract The knock-out reaction A( p , p)X has been used to search for narrow p -nucleus states. The experiment was performed using the 600 MeV/ c antiproton beam at LEAR and the high-resolution and large-acceptance magnetic spectrometer SPES II. The A -dependence of the annihilation-induced proton spectra has been studied on 2 H, 6 Li, 12 C, 63 Cu, 208 Pb and 209 Bi. The quasi-free elastic p p scattering observed in the lighter targets, and the comparison with the free p p scattering, also observed in this experiment, determine an effective proton number N eff for 1s- and 1p-shell protons. No evidence for narrow bound or resonant p -nucleus states could be found. Upper limits for their production are one order of magnitude lower than certain theoretical predictions, but consistent with the properties of the p -nucleus interaction, as established from recent elastic and inelastic scattering as well as from studies of antiprotonic atoms.

Inelastic scattering of antiprotons from 12C and 18O at 50 and 180 MeV

Abstract We have studied (p, p) reactions on 12 C , 63 Cu, and 209 Bi to search for possible nuclear states formed ny antiprotons and nuclei. The experiments used the 180 MeV antiproton beam from LEAR, and the high-resolution magnetic spectrometer, SPES II, to detect the outgoing protons. No evidence of antiproton-nucleus states was found. The gross features of the proton spectra are reasonably well described by intranuclear cascade model calculations, which consider proton emission following antiproton annihilations in the target nucleus.

Search for p-nucleus states using the (p, p) knock-out reaction at 600 MeV/c

Abstract Proton-induced pion production at intermediate energies, leaving the final nucleus in discrete, resolved states, has been measured at the Saclay Synchrotron Saturne I, using the high resolution spectrometer facility SPES I. The (p, π+) reaction has been investigated on 9Be at proton energies of 410 and 605 MeV, and on 10B at incident energies of 320,410, 483 and 605 MeV. These data are presented and analysed in a coherent way, together with previous results at intermediate energies, by means of a pion exchange model. It is found that all the characteristic features of the data are reproduced satisfactorily.

Search for antiproton-nucleus states with (p̄p) reactions

Abstract Neutron hole states in the 1s shell have been studied in the n(K−, π−)Λ strangeness-exchange reaction on 6Li, 7Li, 9Be, and 12C targets at the CERN Proton Synchrotron. The excitation energy and the width of the states as well as the differential cross section have been determined. The clear similarity with the 1s proton hole states observed in (p, 2p) reactions indicates that the presence of the Λ-particle can be taken into account within the weak-coupling model. In this way the (K−, π−) reaction can be used for the study of Λ -states as well as for the investigation of neutron hole states produced at very low momentum transfer.