摘要:

Recent experimental results on the &pgr;d breakup, the &pgr;d elastic scattering, the &pgr;d charge exchange and the &pgr;d absorption reactions are presented. The data are compared with predictions from different few body theories. Open questions and future experiments are being discussed.

ISSN:0094-243X    

DOI:10.1063/1.36918

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The theoretical understanding of elastic &pgr;d scattering, break‐up and pp↔&pgr;d as a multi‐channel system is reviewed. The sensitivity of cross sections and spin observables to the &pgr;N off‐mass‐shell extrapolation, to the splitting of the P11 &pgr;N partial wave and to the input is discussed for the &Dgr;‐resonance range. Some remarks for very low pion energies and for the GeV range are made.

ISSN:0094-243X    

DOI:10.1063/1.36929

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The theory of pion double charge exchange (DCX) to the double isobaric analog resonance is discussed. Emphasis is placed on the role of shell‐model correlations in the description of the (&pgr;+, &pgr;−) cross section. The DCX is discussed in the framework of the seniority scheme and also of the generalized seniority scheme. In the last part of this presentation the possibility of observing giant resonances built on excited states in pion DCX reactions is explored.

ISSN:0094-243X    

DOI:10.1063/1.36921

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Double‐charge‐exchange reactions induced by pions are shown to furnish a direct means of detecting nucleon‐nucleon correlations in nuclei. For the particular case of double isobaric analog transitions the effect of correlations is easily isolated and quite strong. Examination of the properties of the position correlations implicit in the nuclear shell model provides an explanation of several experimentally observed features of double‐charge‐exchange reactions, including in particular, their dependence on the number of valence neutrons present. An explicit demonstration of the role played by nucleon‐nucleon correlations is presented for the double‐charge‐exchange cross sections of the isotopes42Ca,44Ca and48Ca, recently measured at LAMPF. Our analysis explains why the cross section for the double‐charge‐exchange reaction on48Ca, in which 28 neutron pairs participate, is comparable and indeed smaller than the corresponding cross‐section for42Ca with its single valence neutron pair. It also predicts the variation of angular distributions over the family of isotopes.

ISSN:0094-243X    

DOI:10.1063/1.36906

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Forward‐angle differential cross sections for the (&pgr;+, &pgr;0) reaction to isobaric analog states were measured at 300, 425, 500, and 550 MeV on targets ranging in mass from7Li to208Pb. The 0° cross sections are found to rise markedly between 300 and 425 MeV, contrary to the behavior of the free &pgr;N process. The mass and energy dependence of the cross sections at the higher energies are discussed within the framework of the Glauber model.

ISSN:0094-243X    

DOI:10.1063/1.36908

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Results of extensive observation of inclusive double charge exchange in ten nuclei ranging in A from 3 to 208 are presented. Possible mechanisms for the reaction suggested by the systematics of these data are discussed.

ISSN:0094-243X    

DOI:10.1063/1.36909

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We discribe all the inclusive pionic reactions in a variety of nuclei around the resonance region by means of a microscopic many‐body calculation that evaluates reaction probabilities, followed by a Monte Carlo simulation which follows the evolution of the pions. We also make an intrusion into the higher energy domain by paying attention to the absorption mechanisms and their repercussions in exclusive single‐charge exchange reactions.

ISSN:0094-243X    

DOI:10.1063/1.36923

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The design of an updated version of the LAMPF based high‐resolution &pgr;0spectrometer which is based upon the opening angle of the 2‐gamma &pgr;oradiative decay is presented. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.36924

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Two issues in hypernuclear physics, highlighted by recent experiments at the Brookhaven AGS, are discussed: (i) the nature and systematics of &Lgr; single‐particle levels revealed in (&pgr;+, K+) spectra on several nuclear targets from9Beto89Y, particularly for the 1 s&Lgr;ground‐state configuration where Pauli repulsion effects arising from quark deconfinement have been conjectured; and (ii) the spin‐isospin dependence of the nonmesonic weak decay &Lgr;N → NNas extracted from partial decay rates measured for5&Lgr;He and12&Lgr;C, a dependence which has defied so far any explanation, perhaps due to its extreme sensitivity to short‐range behavior. Additional issues bearing on future directions in hypernuclear physics, such as the spin dependence of the &Lgr;‐nuclear interaction, the interpretation of &Sgr;‐hypernuclear spectra and (strangeness) S=−2 physics, are only briefly mentioned.

ISSN:0094-243X    

DOI:10.1063/1.36925

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The subject of meson productions in nuclei, a new direction in pion‐nucleus physics, is discussed. Recent experimental results at LAMPF and AGS on the (&pgr;, &eegr;) and (&pgr;+, K+) reactions in nuclei are presented.

ISSN:0094-243X    

DOI:10.1063/1.36926

出版商:AIP    

年代:1987

数据来源: AIP