Energetic Protons and Deuterons Emitted Following μ⁻ Capture by ³He Nuclei

Spectra of energetic protons and deuterons emitted following negative muon capture from rest in 3He have been measured for the first time. Significant capture strength is observed at high energy transfers (mμ- Ev \u3e60 MeV) for the two-body and three-body breakup channels, indicative of the importance of nucleon-nucleon correlations and meson exchange currents in the capture process. A simple plane wave impulse approximation calculation reproduces the proton spectrum reasonably well, but underpredicts the deuteron rate at the highest energies by a large factor

First Neutrino Observations from the Sudbury Neutrino Observatory

The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed.Comment: Latex, 7 pages, 10 figures, Invited paper at Neutrino 2000 Conference, Sudbury, Canada, June 16-21, 2000 to be published in the Proceeding

ENERGY DEPENDENCE OF THE CHARGE ASYMMETRY A (T (pi), THETA) IN pi d ELASTIC SCATTERING

Angular distributions of charge asymmetry A(T\u3c0,\u3b8), have been measured for \u3c0d elastic scattering. Data were obtained in the backward hemisphere for pion bombarding energies of 143, 180, 220, and 256 MeV. The results are compared with predictions employing different mass and width parameters for the delta isobars

MEDIUM EFFECTS ON KNOCKOUT OF DEEPLY BOUND NUCLEONS

Le pouvoir d'analyse de diffusion quasi-libre nucléon-nucléon est nettement différent de celui de l'interaction libre. Cette modification due au milieu nucléaire a été observé pour la première fois dans les expériences de diffusion inclusive. Nous montrons ici que des expériences en cinématique totalement exclusive permettent de mettre cet effet en évidence encore plus clairement. Cet avantage réside dans le fait de pouvoir sélectionner des nucléons liés dans des états bien définis à l'intérieur du noyau.The analyzing power for quasi-free nucleon-nucleon scattering has been found to differ substantially from that for the free interaction. This medium modification was first noticed in inclusive scattering experiments. In the present work, it has been demonstrated that kinematically complete exclusive measurements are capable of demonstrating this effect more clearly. This advantage arises by virtue of the possibility of selecting nucleons bound in states localized in the nuclear interior

Multinucleon Effects in Muon Capture on ³He at High Energy Transfer

Energy spectra of both protons and deuterons emitted following the capture of negative muons by 3He nuclei have been measured for energies above 15 MeV. A limited number of proton-neutron pairs emitted in coincidence were also observed. A simple plane wave impulse approximation (PWIA) model calculation yields fair agreement with the measured proton energy spectra, but underpredicts the measured rate of deuteron production above our energy threshold by a large factor. A more sophisticated PWIA calculation for the two-body breakup channel, based on a realistic three-body wave function for the initial state, is closer to the deuteron data at moderate energies, but still is significantly lower near the kinematic end point. The proton-neutron coincidence data also point to the presence of significant strength involving more than one nucleon in the capture process at high energy transfer. These results indicate that additional terms in the capture matrix element beyond the impulse approximation contribution may be required to explain the experimental data. Specifically, the inclusion of nucleon-nucleon correlations in the initial or final state and meson exchange current contributions could bring calculations into better agreement with our data. A fully microscopic calculation would thus open the possibility for a quantitative test of multinucleon effects in the weak interaction

Spin-dependent scattering of deeply bound nucleons

Exclusive measurements of the analyzing power and two spin-transfer observables for nucleon knockout from a

Role of the pi n P(11) interaction in pi d elastic scattering at 50-MeV

Measurements of the vector analyzing power iT11 in \u3c0+d elastic scattering at 50 MeV have been made at pion laboratory scattering angles between 60\ub0 and 130\ub0 using a dynamically polarized target and a magnetic spectrometer. In contrast to measurements of spin observables at higher energies, we find agreement with models that include the \u3c0N P11 amplitude and disagreement with models that exclude or suppress it