J. Žofka

Supermultiplet structure and decay properties of hypernuclear 1+ resonances in Λ6Li

Abstract The excitation function for the 0 ℏω and 1 ℏω levels of Λ6Li, populated in the (K−, π−) reaction at ϑ π= 0°, is calculated in the framework of the translationally invariant shell model. One-baryon and cluster widths for the decay of resonance hypernuclear states are estimated. The decay properties of those states are shown to be essentially given by the Young tableaux selection rules. Very good agreement with recent experimental data at pK = 790 MeV/c at CERN is achieved. The decay of Λ 6 Li ∗ into exicted Λ 4 He ∗ ( Λ 4 H ∗ ) with subsequent hypernuclear γ-emission is discussed as well.

Effective λN-interaction and spectroscopy of low-lying states of 1p-shell hyernuclei

A new set of the shell-model two-particle potential parametersδ,SΛ,SN andT forp-shell hypernuclei is proposed. The set is consistent with the available data on the excited levels ofΛ7Li,Λ9Be,Λ10B,Λ12B andΛpO. The classification of low lying states andγ-transitions in the 1p-shell hypernuclei is discussed in terms of the {s4pn*sΛ:JT} configurations. The feasibility for the excited bound states and for theγ-transitions to be observed in the spin-flip and non spin-flip single-nucleon reactions is examined in detail.

On nucleon decays of hypernuclear resonances — Population of bound hypernuclear levels

Abstract Hypernuclear resonances excited in ( K − ,π 0 ) reactions decay also via the nucleon channel and the low lying part of hypernuclear spectra is thus populated. The analysis — quantitative for A = 14- suggests to measure neutron line spectra and hypernuclear γ-quanta. The novel spectroscopy should reveal new information on the structure (deviations from the weak coupling scheme), on the NΛ effective interaction (its possible long-rangedness) and on decay mechanisms.

Excitation and structure of hypernuclear resonances in (K−,π¯0)-reactions on 1p-shell nuclei

The available experimental data on the excitation functions (EF) of the 1p-shellΛ-hy-pernuclei in (K−, π−) reactions atθπ = 0° has been analysed in terms of shell model and weak coupling scheme. It is substantiated by the experimental data on the neutron spectroscopic factors and on the fragmentation of nuclear hole excitations. The pronounced nuclear spectroscopic characteristics in the hypernuclear spectra are indicative of a weak coupling ofΛ-hyperon with nuclear subsystem. The analysis has made it possible to determine the difference is single-particle energies ofΛ-hyperon in the 1p- and 1s-states and to obtain additional evidence for the smallness of theΛ-nucleus spin-orbit interaction. The resonance structure of EF of hypernuclei, which were not studied in (K−,π0−) reactions, is predicted. The interrelated aspects of the studies of the (K−,π0−), (K−,π0− β′), and (K−, π+) reactions which are of interest to spectroscopy ofΛ-andΣ-hypernuclei are discussed.

Molecular three-body approach to Λ9Be and Σ9Be hypernuclei

Abstract The dependence of the low-lying spectra of Λ, Σ 9 Be hypernuclei on hyperon- α interaction in the molecular α + α + Λ ( Σ ) scheme has been studied. A suggestion is made for obtaining the strengths of both p-wave and spin-orbit Λ - α interactions from the experimental Λ 9 Be spectrum. A relation between the Σ 0 -binding energies B Σ ( Σ 9 Be ) and B Σ ( Σ 9 He ) has been established and on its basis a prediction is made about a possible binding energy of Σ 5 He .

A note on the origin of secondary hypernuclear γ-quanta from Λ 10 B

An alternative interpretation ofΛ10B secondaryγ-quanta due toΛ10B →Λ7Li+3He channel is proposed. Its impact on effectiveΛN interaction properties and on understanding of (s−1sΛ) configurations is discussed and some verifying experiments are put forward.

On the production of the lightest hypernucleus Λ3H in high energy nuclear collisions

Abstract The production of lightest and extremely weak-bound hypernucleus Λ3H in high-energy nuclear collisions is studied for two different mechanisms; (1) coalescence of a deuteron fragment from peripheral collisions and the Λ-hyperon, and (2) coalescence of Λ, neutron and proton, all from central collisions. The respective cross sections are found to be comparable but with distinct rapidity distributions.

Hypernuclear magnetic moments

Abstract Magnetic moments of Λ-hypernuclei λ 13 C , λ 17 O , λ 21 Ne , λ 41 Ca , λ 91 Zr , λ 209 Pb have been calculated in the mean field model with deformation. The relativistic effects in them may reach up to 20% in the Pb region, the spatial components of the ω-field are important and a sensitivity to the nuclear densities has been encountered.

On the spectroscopy of the Λ13C hypernucleus

Abstract The spectrum of {s 4 p 8 ⊗ s Λ } and {s 4 p 8 ⊗ p Λ } states of Λ 13 C from the reaction (K − , π − ), their baryon decays, the resulting neutron spectra and the nuclear and hypernuclear γ-spectra are studied, displayed and discussed. Specifically, the isospin selection rule leads to narrow states of Λ 13 C high in the continuum, decaying via hard γ-quanta ( E ≈ 15 MeV).

Non-mesonic hypernuclear weak decays-systematic testing in the shell model testing in the shell model

The nuclear input into the non-mesonic weak decay of p-shell Λ-hypernuclei is analyzed and the systematics of delayed γ-quanta from (A − 2) daughter nuclei is given.