[en] This paper describes a new videometric technique designed to monitor the deformations and misalignments of large vital components in the centre of a future particle detector. It relies on a geometrical principle called 'reciprocal collimation' of two CCD cameras: the combination of the video devices in pair gives rise to a network of well located reference lines that surround the object to be surveyed. Each observed point, which in practice is a bright point-like light-source, is accurately located with respect to this network of neighbouring axes. Adjustment calculations provide the three-dimensional position of the object fitted with various light-sources. An experimental test-bench, equipped with four cameras, has corroborated the precision predicted by previous simulations of the system

[en] We report on the first measurement of exclusive Ξ^-(1321) hyperon photoproduction in γp → K⁺K⁺Ξ^- for 3.2 < E_γ < 3.9 GeV. The final state is identified by the missing mass in p(γ, K⁺K⁺)X measured with the CLAS detector at Jefferson Laboratory. We have detected a significant number of the ground-state Ξ^-(132)1/2⁺, and have estimated the total cross section for its production. We have also observed the first excited state Ξ^-(1530)3/2⁺. Photoproduction provides a copious source of Ξ's. We discuss the possibilities of a search for the recently proposed Ξ₅^-- and Ξ₅⁺ pentaquarks

[en] The U.S. Department of Energy (DOE) Hanford Site in south central Washington State lies along the Columbia River and is one of DOE's largest legacy waste management sites. Enormous radionuclide and chemical inventories exist below-ground. These include Resource Conservation and Recovery Act (RCRA) storage facilities where hazardous and radioactive contaminants were discharged and leaked to the soil surface and to the deep vadose zone and groundwater. The vadose zone is also contaminated from facilities regulated by the RCRA and Comprehensive Environmental Response Compensation and Liability Act (CERCLA) Act. Hanford now contains as much as 28,300 cubic meters of soil contaminated with radionuclides from liquid wastes released near processing facilities. The Hanford Federal Facility Agreement and Consent Order, Tri-Party Agreement (TPA) has set the completion of the cleanup of these sites by 2024. There are numerous technical and regulatory challenges to cleanup of the vadose zone at the Hanford site. This paper attempts to identify the categories of deep vadose zone problem and identifies a few possible regulatory options to clean up the site under the mix of state and federal regulatory authorities. There are four major categories of vadose contamination areas at the Hanford Site. The first is laterally extensive with intermediate depth (ground surface to about 45 meters depth) mostly related to high volume effluent discharge into cribs, ponds and ditches of designated CERCLA facilities. The second is dominated by laterally less extensive mostly related to leaks from RCRA tank farms. The later contamination is often commingled at depth with wastes from adjacent CERCLA facilities. The third category is from the high volume CERCLA facilities extending from the surface to more than 60 meters below ground. Contamination from the later category crosses the entire thickness of the vadose zone and reached groundwater. The fourth category is the lower volume waste sites. There are multiple management options to clean up the above four categories of vadose zones sites. The following are some of the options considered for detailed evaluation: - Maintain separate decision processes for each RCRA and CERCLA units/waste sites with a more accommodating schedule. - Create new vadose zone operable units with limited geographical boundaries regardless of site category/origin and make an integrated decision. - Expand the existing CERCLA groundwater operable units to include the deep vadose zone - Use a combination of the above. Each option has pros and cons and regulatory limitations. Detailed evaluation of these options is required to support a cost effective expedited cleanup. (authors)

[en] The role of resonance electroproduction at high Q² is discussed in the context of exclusive reactions, as well as the alternative theoretical models which are proposed to treat exclusive reactions in the few GeV²/c² region of momentum transfer. Jefferson Lab experiment 94-014, which measured the excitation of the Delta (1232) and S₁₁(1535) via the reactions p(e,e^'p)pi⁰ and p(e,e^'p)eta respectively at Q² ∼ 2.8 and 4 GeV²/c² is described, and the state of analysis reported

[en] Jefferson Lab experiment E94-014 measured the excitation of the Delta (1232) resonance via the reaction p(e,e(prime)p)π⁰ at Q² near 2.8 and 4 Gev². This is the highest Q² for which exclusive resonance electroproduction has ever been observed. Decay distributions of the Delta (1232) resonance into the ppi⁰ final state were measured over a wide range of barycentric decay angles and energies. The goal of this experiment is to assess the transition in Q² from the constituent quark model (CQM) to the regime where hard processes become important. At Q² ∼ few GeV²/c² the ratio E₁₊/M₁₊ depends dramatically on the theoretical description, varying from a few 10^-2 in the CQM limit, to about 1 in the pQCD limit. Preliminary analysis of the data shows that the ratio E₁₊/M₁₊ remains small at Q² up to 4 Gev²/c². After first pass analysis we obtain E₁₊/M₁₊ = -4.1 ± 1.2 at Q² = 2.8 Gev²/c² and E₁₊/M₁₊ = -7.9 ± 0.8 at Q² = 4 Gev²/c² (statistical errors only)

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[en] We report measurements of cross sections for the reaction ¹H(e,e(prime) K⁺)Y, for both the Λ and Σ⁰ hyperon states, at an invariant mass of W = 1.84 GeV and four-momentum transfers 0.5 < Q² < 2 (GeV/c)². Data were taken for three values of virtual photon polarization ε, allowing the decomposition of the cross sections into longitudinal and transverse components. The Λ data are a revised analysis of prior work, whereas the Σ⁰ results have not been previously reported

[en] We report measurements of cross sections for the reaction p(e,e(prime)K⁺)Y, for both the Lambda and Sigma₀ hyperon states, at an invariant mass of W = 1.84 GeV and four-momentum transfers 0.5 < Q² < 2 (GeV/c)². Data were taken for three values of virtual photon polarization, allowing the decomposition of the cross sections into longitudinal and transverse components. The Lambda data is a revised analysis of prior work, whereas the Sigma₀ results have not been previously reported

[en] The first measurements of differential cross sections for deuteron photo-disintegration at photon energies up to 4 GeV were performed at the Thomas Jefferson National Accelerator Facility early in 1996. Cross section results for D(gamma,p)n at proton center of mass angle of 35^o, 53^o and 90^o will be presented. These results are in good agreement with previous measurements at low energy and extend to higher energies where data were previously unavailable. The 90^o degree data show behavior consistent with the constituent counting rules up to 4 GeV and are also in fair agreement with the asymptotic meson exchange model. The 37^o and 53^o data do not show clear signs of counting rule behavior, although a threshold in transverse momentum for the onset of scaling cannot be excluded