O. Hartmann

New results on mesonic weak decay of p-shell Lambda-hypernuclei

Abstract The FINUDA experiment performed a systematic study of the charged mesonic weak decay channel of p -shell Λ -hypernuclei. Negatively charged pion spectra from mesonic decay were measured with magnetic analysis for the first time for 7 Λ Li, 9 Λ Be, 11 Λ B and 15 Λ N. The shape of the π − spectra was interpreted through a comparison with pion distorted wave calculations that take into account the structure of both hypernucleus and daughter nucleus. Branching ratios Γ π − / Γ tot were derived from the measured spectra and converted to π − decay rates Γ π − by means of known or extrapolated total decay widths Γ tot of p -shell Λ -hypernuclei. Based on these measurements, the spin-parity assignment 1 / 2 + for 7 Λ Li and 5 / 2 + for 11 Λ B ground-state are confirmed and a spin-parity 3 / 2 + for 15 Λ N ground-state is assigned for the first time.

Proton spectra from Non-Mesonic Weak Decay of p-shell Λ-hypernuclei and evidence for the two-nucleon induced process

Abstract New spectra from the FINUDA experiment of the Non-Mesonic Weak Decay (NMWD) proton kinetic energy for Be Λ 9 , B Λ 11 , C Λ 12 , C Λ 13 , N Λ 15 and O Λ 16 are presented and discussed along with the published data on He Λ 5 and Li Λ 7 . Exploiting the large mass number range and the low energy threshold (15 MeV) for the proton detection of FINUDA, an evaluation of both Final State Interactions (FSI) and the two-nucleon induced NMWD contributions to the decay process has been done. Based on this evaluation, a linear dependence of FSI on the hypernuclear mass number A is found and for the two-nucleon stimulated decay rate the experimental value of Γ 2 / Γ p = 0.43 ± 0.25 is determined for the first time. A value for the two-nucleon stimulated decay rate to the total decay rate Γ 2 / Γ NMWD = 0.24 ± 0.10 is also extracted.

Measurement of the proton spectra from non-mesonic weak decay of 5ΛHe, 7ΛLi and 12ΛC

Abstract The results of a measurement of the proton spectra following the non-mesonic weak decay of 5ΛHe, 7ΛLi and 12ΛC are presented and discussed. The experiment was performed at the ( e + e − ) collider DAΦNE at Laboratori Nazionale di Frascati of INFN. It is the first measurement for 7ΛLi, and for all the spectra the lower limit on the energy of the protons is 15 MeV, never reached before. All the spectra show a similar shape, namely a peak at around 80 MeV as expected for the free Λ p → n p weak reaction, with a low energy rise that should be due to final state interactions and/or two-nucleon induced weak processes. The decay spectrum of 5ΛHe is somehow similar to the ones reported by previous measurements and theoretical calculations, but the same does not happen for the 12ΛC one.

Recent results on mesonic weak decay of Lambda-Hypernuclei

The FINUDA experiment has performed a systematic study of mesonic weak decay of p-shell Λ-hypernuclei. Recent results on the mesonic decay spectra and ratios are illustrated and discussed.

New results on nonmesonic weak decay of Lambda hypernuclei with FINUDA

The FINUDA experiment has performed a systematic study of the NonMesonic Weak Decay (NMWD) of Λ hypernuclei analizing all the data collected from 2003 up to 2007. The results of a measurement of the spectra of protons coming from the NMWD of , , , , , , and are the subject of this paper.

Recent results on mesonic weak decay of Lambda-hypernuclei

The FINUDA experiment has performed a systematic study of mesonic weak decay of p-shell Λ-hypernuclei. Recent results on the mesonic decay spectra and ratios are illustrated and discussed.

THE SEARCH FOR ANTIKAON NUCLEAR BOUND STATES, RECENT RESULTS FROM FINUDA

Novel data from the absorption reaction in light nuclei are presented. The data were collected by the FINUDA spectrometer running at the DAΦNE ϕ-facility, Laboratori Nazionali di Frascati (LNF), Italy.

The A(Kstop−, Λd)A′ reaction, a tool to observe [\overline K NNN] clusters

This work presents experimental results obtained from a study of the K stop − A → ΛdA′ reaction, where A = 6Li. The study concerns the distributions of the Λd invariant mass, which allows us to determine the structure of bound [K − ppn] systems in nuclei. A candidate of such clusters is identified in the present measurement, and its mass (binding energy), decay width and yield are reported. The experiment was performed at the DAΦNE o-facility (LNF) by using the FINUDA spectrometer. The study depended on the capability of FINUDA to reconstruct the traces of all the particles involved in the decay of the nuclear cluster.

A study of Λ 7 Li production with FINUDA

The FINUDA experiment studies the production and decay of Λ-hypernuclei by stopping in thin targets the K −s coming from the decay of the Φ (1020) meson at the DAΦNE e + − e − collider at INFN Laboratori Nazionali di Frascati. In this paper we report the results concerning the production of Λ 7 Li. The absolute production rates for bound states and the best up-to-date hypernuclear spectrum obtained by means of the production π − spectroscopy, with an energy resolution of 1.1 MeV (FWHM), are unveiled.