Hypernuclear structure from gamma-ray spectroscopy

The energies of p-shell hypernuclear gamma rays obtained from recent experiments using the Hyperball at BNL and KEK are used to constrain the YN interaction which enters into shell-model calculations that include both Lambda and Sigma configurations.Comment: 10 pages, 5 figures; HYP2003, Jefferson Lab, October 14-18, 2003; proceedings to appear in Nuclear Physics

Shell-model calculations for p-shell hypernuclei

The interpretation of hypernuclear gamma-ray data for p-shell hypernuclei in terms of shell-model calculations that include the coupling of Lambda- and Sigma-hypernuclear states is briefly reviewed. Next, Lambda 8Li, Lambda 8Be, and Lambda 9Li are considered, both to exhibit features of Lambda-Sigma coupling and as possible source of observed, but unassigned, hypernuclear gamma rays. Then, the feasibility of measuring the ground-state doublet spacing of Lambda 10Be, which, like Lambda 9Li, could be studied via the (K-,pi0 gamma) reaction, is investigated. Structural information relevant to the population of states in these hypernuclei in recent (e,e'K+) studies is also given. Finally, the extension of the shell-model calculations to sd-shell hypernuclei is briefly considered.Comment: 17 pages, 3 figures. Contribution to special volume on Strangeness Nuclear Physic

pi^- decay rates of p-shell hypernuclei revisited

Explicit expressions for the parity-violating s-wave and the parity-conserving p-wave contributions to pi- weak-decay rates of Lambda hypernuclei in the 1p shell are given in the weak-coupling limit, to update previous shell-model calculations and to compare with recent pi- spectra and total decay rates measured by the FINUDA Collaboration. A useful sum rule for the summed strength of Lambda_{1s} --> pi- + proton_{1p} weak decays is derived. Fair agreement between experiment and calculations is reached, using the primary s-wave amplitude and Cohen-Kurath nuclear wavefunctions. The role of the p-wave amplitude is studied in detail for Lambda-15N and found to be secondary. Previous assignments of ground-state spin-parity values are confirmed and a new assignment is made, spin-parity 3/2+ for Lambda-15N, based on the substantial suppression calculated here for spin-parity 1/2+.Comment: published version; new footnote 2 added in proof; related to recent FINUDA data, arXiv:0905.0623 [nucl-ex] submitted to Phys. Lett.

Radio Communication with Moving Trains

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Structure of unstable light nuclei

The structure of light nuclei out to the drip lines and beyond up to Z = 8 is interpreted in terms of the shell model. Special emphasis is given to the underlying supermultiplet symmetry of the p-shell nuclei which form cores for neutrons and protons added in sd-shell orbits. Detailed results are given on the wave functions, widths, and Coulomb energy shifts for a wide range of non-normal parity states in the p-shell.Comment: 21 pages, to appear in Nuclear Physics