Strange nuclear physics - a brief status report

This paper briefly reviews the present status of strange nuclear physics. Recently, significant progress has been made. One example to be discussed is a new, electroproduction experiment which offers the possibility of obtaining hypernuclear spectra with at least a factor of 3 better resolution than previously. However, many different experiments impact a spectrum of problems from weak interactions to astrophysics. Although in this short paper it is not possible to cover many topics in depth, sufficient information is provided so that the interested reader can obtain all of the most relevant material

Strana nuklearna fizika – kratak pregled

This paper briefly reviews the present status of strange nuclear physics. Recently, significant progress has been made. One example to be discussed is a new, electroproduction experiment which offers the possibility of obtaining hypernuclear spectra with at least a factor of 3 better resolution than previously. However, many different experiments impact a spectrum of problems from weak interactions to astrophysics. Although in this short paper it is not possible to cover many topics in depth, sufficient information is provided so that the interested reader can obtain all of the most relevant material.Kratko se raspravlja o stranoj nuklearnoj fizici. Nedavno je načinjen važan napredak. Primjer koji se raspravlja je novo mjerenje elektrotvorbe koje pruža mogućnost za dobivanje Λ hiperjezgri s razlučivanjem boljim barem tri puta od dosadašnjih. Međutim, mnoga se različita mjerenja sučeljavaju s nizom teškoća od slabih međudjelovanja do astrofizike. Ovdje se ne raspravljaju podrobnije mnoge teme, ali se izlažu podaci kojima se može dobiti najveći dio povezane građe

Strange nuclear physics - a brief status report

This paper briefly reviews the present status of strange nuclear physics. Recently, significant progress has been made. One example to be discussed is a new, electroproduction experiment which offers the possibility of obtaining hypernuclear spectra with at least a factor of 3 better resolution than previously. However, many different experiments impact a spectrum of problems from weak interactions to astrophysics. Although in this short paper it is not possible to cover many topics in depth, sufficient information is provided so that the interested reader can obtain all of the most relevant material

Experiments with the High Resolution Kaon Spectrometer at JLab Hall C and the new spectroscopy of 12B-Λ hypernuclei

Since the pioneering experiment E89-009 studying hypernuclear spectroscopy using the (e, e’K+) reaction was completed, two additional experiments, E01-011 and E05-115, were performed at Jefferson Lab. These later experiments used a modified experimental design, the "tilt method", to dramatically suppress the large electromagnetic background, and allowed for a substantial increase in luminosity. Additionally, a new kaon spectrometer, HKS (E01-011), a new electron spectrometer, HES, and a new splitting magnet (E05-115) were added to produce new data sets of precision, high-resolution hypernuclear spectroscopy. All three experiments obtained a spectrum for 12B-Λ, which is the most characteristic p-shell hypernucleus and is commonly used for calibration. Independent analyses of these different experiments demonstrate excellent consistency and provide the clearest level structure to date of this hypernucleus as produced by the (e, e’K+) reaction. This paper presents details of these experiments, and the extraction and analysis of the observed 12B-Λ spectrum

Nucleon pairing in μ- capture by 40Ca

Spectra of energetic protons above 35 MeV have been measured following negative muon capture from rest in Ca. The spectrum extends to the kinematic limit near 93 MeV, with a branching ratio of (2.3±0.3)×10-4 per capture above 40 MeV. Nuclear cascade calculations of the proton and neutron spectra in this energy region are presented and are consistent with the measured proton spectrum when capture on correlated pp and np pairs in the nucleus is included. The ratio of capture on np to pp pairs is 6.7±1.6, which is consistent with results from pion capture

Pion absorption in ^4He

This paper presents a large solid angle measurement of the positive pion absorption cross section on ^4He and its decomposition into partial channels. A large fraction of the absorption cross section at incident pion kinetic energies of T_π+ =70, 118, 162, 239, and 330 MeV is due to multinucleon channels

Transverse-spin dependence of the p-p total cross section ΔσT from 0.8 to 2.5 GeV/c

The difference ΔσT=σ(↓↑)-σ(↑↑) between the proton-proton total cross sections for protons in pure transverse-spin states, was measured at incident momenta 0.8 to 2.5 GeV/c in experiments performed at the Los Alamos Clinton P. Anderson Meson Physics Facility and the Argonne Zero Gradient Synchrotron. In agreement with other data, peaks were observed at center-of-mass energies of 2.14 and 2.43 GeV/c2, where 1D2 and 1G4 dibaryon resonances have been proposed

Measurement of the imaginary part of the I=1 N-barN S-wave scattering length

The survival time spectrum of slow antineutrons produced in a liquid-hydrogen target has been measured. From these data the imaginary part of the I=1 spin-averaged S-wave antineutron proton scattering length has been deduced to be Ima1=-0.83±0.07 fm. The result lies within the range of values calculated from current potential models. In addition, by combining a1 with the antiproton-proton scattering length deduced from antiprotonic atoms, the imaginary part of the I=0 spin-averaged N¯N scattering length was calculated to be Ima0=-1.07±0.16 fm

High resolution spectroscopic study of 10Be-Λ

Spectroscopy of a 10Be-Λ hypernucleus was carried out at JLab Hall C using the (e, e′K+) reaction. A new magnetic spectrometer system (SPL+HES+HKS), specifically designed for high resolution hypernuclear spectroscopy, was used to obtain an energy spectrum with a resolution of ∼0.78 MeV (FWHM). The well-calibrated spectrometer system of the present experiment using p(e, e′K+)Λ, Σ0 reactions allowed us to determine the energy levels ; and the binding energy of the ground-state peak (mixture of 1− and 2− states) was found to be B- Λ=8.55±0.07(stat.)±0.11(sys.) MeV. The result indicates that the ground-state energy is shallower than that of an emulsion study by about 0.5 MeV which provides valuable experimental information on the charge symmetry breaking effect in the ΛN interaction