[en] Precise measurement of the neutron scalar polarizabilities has been a lasting challenge because of the lack of a free-neutron target. Led by the University of Glasgow and the Mount Allison University groups of the A2 collaboration in Mainz, Germany, preparations have begun to test a recent theoretical model with an active helium target with the hope of determining these elusive quantities with small statistical, systematic, and model-dependent errors. Apparatus testing and background-event simulations have been carried out, with the full experiment projected to run in 2015. Once determined, these values can be applied to help understand quantum chromodynamics in the nonperturbative region

[en] Since its upgrade in 2007, the Glasgow-Mainz spectrometer has provided a state-of-the-art photon tagger for a series of photo-production experiments at electron beam energies from 200 to 1508 MeV. We report on the operational status of the tagging spectrometer, refitted with a new focal-plane detector to extend its rate capability and improve its timing resolution by a factor 2. This complements the Crystal Ball and TAPS calorimeters, which provide almost 4π detection of both neutral and charged particles. These systems have very high detection efficiency for multi-photon final states. Measurement of pseudo-scalar-meson photo production on the nucleon is a major component of the experimental programme. We have data on π⁰, π⁺, η, η^', K⁰, K⁺ (single and multiple-meson) final states for ¹H and ²H targets. The eventual goal is to make complete measurements of the helicity amplitudes, which require at least 8 observables chosen properly from unpolarised, single-spin and double-spin possibilities. The possibilities in Mainz will extend when polarised targets become available in 2009. In December 2008 the maximum MAMI-C energy was raised to 1557 MeV and data taken with an open trigger at tagged-photon energies from 80 to 1447 MeV. We show some first analyses of these tests.

[en] The University of Glasgow and its spinout Lynkeos Technology are pioneers of muography for radioactive waste management and nuclear decommissioning applications. This passive non-destructive testing technique uses charged particles called muons that are produced in the upper atmosphere from cosmic-ray interactions. Dozens of muons harmlessly pass through the human body every second. By tracking these particles through an unknown structure using pairs of position-sensitive detectors on opposite sides, a 3D density distribution of the constituent materials can be reconstructed with positional accuracy and resolution of several millimetres. Lynkeos Technology spun out from a seven-year research programme funded by the UK Nuclear Decommissioning Authority, in collaboration with the UK National Nuclear Laboratory, to develop a passive assay system, initially for Intermediate Level Waste (ILW) container characterisation. In 2018, the Lynkeos Muon Imaging System was commercialised under Innovate UK funding and the first unit was installed on the Sellafield site. This technology has subsequently been used for a range of nuclear waste management research applications. Selected results are presented in this paper. These confirm the potential of muography to play a significant role in global nuclear waste management for a variety of different containers and encapsulation techniques, and to underpin the safety cases for long-term waste storage. Presented results include world first 3D images of uranic material within 500 litre, stainless-steel, concrete-filled ILW containers and extensive results from a quality assurance campaign on GeoMelt^R In-Container Vitrification R and D Product Blocks, which show the potential to assess the homogeneity of the product melt as well as characterising and locating small metallic inclusions. Current experimental and simulated studies are presented showing the optimisation of muography for future 3 m³ boxed wastes from the Magnox Swarf Storage Silo on the Sellafield site. These confirm the ability to identify sub-centimetre deformations in the steel liners and the evolution of waste and water layer boundaries to less than a centimetre accuracy. Sellafield Ltd is currently undertaking a comparison between muography and X-ray technologies for this 3 m³ box application. Engineering viability studies and shielding requirements are now being assessed as part of the design process for a bespoke muography system. The passive monitoring, low maintenance, low service requirements and robustness of muography has been identified as a very attractive technology for nuclear waste applications. Results from detailed simulations carried out by Lynkeos Technology and Bundesgesellschaft fur Endlagerung, the German federal company for radioactive waste disposal, are also presented. This study investigated the feasibility of muography to characterise waste packages retrieved from the Asse II mine, in particular concrete shielded 200 litre drums. Results of different waste containers and their encapsulants are presented to highlight the flexibility of the inspection technique and its ability to detect small voids in concrete fill materials. Discussion of muography studies, including those funded as part of the Advanced Nuclear Systems Innovation Campus pilot scheme, is presented into other aspects of nuclear decommissioning including spent fuel dry storage casks for international safeguarding, alongside an outlook into the use of muography in structural health and integrity monitoring for ageing reinforced concrete infrastructure. All results highlight the vast potential of muography to impact upon current and future waste management and decommissioning practices. (authors)

[en] A high-resolution (σ_instr. = 1.5 MeV) search for narrow states (Λ < 10 MeV) with masses of M_x ∼ 1500-1850 MeV in ep → e' K⁺ X, e' K^- X and e' π⁺ X electroproduction at small angles and low Q² was performed. These states would be candidate partner states of the reported Θ⁺(1540) pentaquark. No statistically significant signal was observed in any of the channels at 90% C.L. Upper limits on forward production were determined to be between 0.7% and 4.2% of the Λ(1520) production cross section, depending on the channel and the assumed mass and width of the state

[en] New possibilities of hypernuclear studies at modern electron accelerators based on recently developed radio frequency photomultiplier tubes are discussed.

[en] A multi-cell He gas scintillator active target, designed for the measurement of photoreaction cross sections, is described. The target has four main chambers, giving an overall thickness of 0.103 g/cm"3 at an operating pressure of 2 MPa. Scintillations are read out by photomultiplier tubes and the addition of small amounts of N_2 to the He, to shift the scintillation emission from UV to visible, is discussed. First results of measurements at the MAX IV Laboratory tagged-photon facility show that the target has a timing resolution of around 1 ns and can cope well with a high-flux photon beam. The determination of reaction cross sections from target yields relies on a Monte Carlo simulation, which considers scintillation light transport, photodisintegration processes in "4He, background photon interactions in target windows and interactions of the reaction-product particles in the gas and target container. The predictions of this simulation are compared to the measured target response. (orig.)

[en] The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.