[en] A variety of administrative subjects are discussed in this brief report. Among them are the awarding of the Louis Rosen prize, the election of officers to the group, discussions with new LAMPF management and the Technical Advisory Panel. Other matters outlined are U accounts, housing problems, schedule changes and open access to LAMPF facilities

No abstract available

No abstract available

[en] The study of quasi-free scattering of pions may lead to an improved understanding of the πN interaction in nuclear matter, provided that wave distortion effects on the incoming and outgoing particles are understood. Up to now, no (π,πN) coincidence data have been published with high enough resolution to determine the excited states of the residual nucleus. The present work provides information on ¹²C(π^-,π^-n)¹¹C, ¹²C(π^-,π^-p)¹¹B and ¹²C(π^-,π^-d)¹⁰B. (Auth.)

[en] The light vector mesons (ρ,ω, and φ) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the ρ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to e⁺e^-. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The ρ-meson mass spectrum was extracted after the ω and φ signals were removed in a nearly model-independent way. Comparisons were made between the ρ mass spectra from the heavy targets (A>2) with the mass spectrum extracted from the deuterium target. With respect to the ρ-meson mass, we obtain a small shift compatible with zero. Also, we measure widths consistent with standard nuclear many-body effects such as collisional broadening and Fermi motion

[en] For the first time, the reaction γd→ΛnK⁺ has been analyzed in order to search for the exotic pentaquark baryon Θ⁺(1540). The data were taken at Jefferson Laboratory, using the Hall-B tagged-photon beam of energy between 0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No statistically significant structures were observed in the nK⁺ invariant-mass distribution. The upper limit on the γd→ΛΘ⁺ integrated cross section has been calculated and found to be between 5 and 25 nb, depending on the production model assumed. The upper limit on the differential cross section is also reported

[en] A device has been developed with moveable liquid nitrogen and liquid helium volumes that is capable of reaching over two meters into the coldest regions of a cryostat or dilution refrigerator and reliably extracting or installing a target of solid, polarized hydrogen deuteride (HD). This Transfer Cryostat incorporates a cylindrical neodymium rare-earth magnet that is configured as a Halbach dipole, which is maintained at 77 K and produces a 0.1 T field around the HD target. Multiple layers provide a hermetic 77 K-shield as the device is used to maintain a target at 2 K during a transfer between cryostats. Tests with frozen-spin HD show negligible polarization loss for either H or D over typical transfer periods. Multiple target transfers with this apparatus have shown an overall reliability of about 95% per transfer, which is a significant improvement over earlier versions of the device

[en] The photoproduction of vector mesons on various nuclei has been studied using the CLAS detector at Jefferson Laboratory. The vector mesons, ρ, ω, and φ, are observed via their decay to e⁺e^-, in order to reduce the effects of final-state interactions in the nucleus. Of particular interest are possible in-medium effects on the properties of the ρ meson. The ρ mass spectrum is extracted from the data on various nuclei, ²H, C, Fe, and Ti. We observe no significant mass shift and some broadening consistent with expected collisional broadening for the ρ meson

[en] A new pp → K⁺X experiment has been performed at the Saturn National Laboratory with high resolution to study Λp and ΣN final interactions in a large range of momentum transfer and missing mass. This paper presents the first results obtained at an incident proton energy of 2.3 GeV in the mass region for X : 2055 < M_X < 2180 GeV and for kaon emission angles θ_K = 8⁰ and 10⁰. 16 refs.; 5 figs

[en] A pp → K⁺X experiment was performed with high resolution to study λp and σN in a large range of momentum transfer and missing mass, in order to study the cusp effect which hinders the characterisation of the structure near the σ⁺n threshold as dynamical or kinematical. The difficulty in explaining the cusp effect is related to the large SU(3) breaking. It is argued that the present experiment provides a good means of obtaining the information required, but detailed analysis of results is not yet complete