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Abstract: A new sub-micron beamline for high-resolution nuclear microprobe applications has been constructed at the Lund nuclear microprobe facility. The design and construction of the main experimental chamber, sample viewing system and computer controlled precision sample stage movement is presented in this paper. The chamber is especially designed for using a large area annular HPGe detector. The advantages with such a large area detector are discussed and illustrated. In addition the quality of the optical viewing and the precision sample stage is discussed. [Copyright &y& Elsevier]

Abstract: Hydrogen has been shown to occur as a trace element in many nominally anhydrous minerals. The presence of hydrogen in several of the major minerals in the Earth’s mantle has received attention, due to the possibility that these phases provide a significant hydrogen reservoir. Recently an experimental and analytical procedure for hydrogen measurements in thin mineral samples by proton–proton scattering has been developed at the Lund Nuclear Microprobe facility. An annular surface barrier detector, divided in two insulated halves, is used to detect the scattered proton and the recoiled proton in coincidence. The summed energy of each detected proton pair can be used to produce depth profiles if the individual scattering angles are known. The easiest case is when only a small difference in energy between each detected proton pair is allowed, i.e. scattering angles very close to 45°. This limitation criterion considerably reduces the statistics. For this reason the analytical method has been expanded to use the full detector area (35–55°) and to identify the scattering angles individually for each hydrogen event. Nominally anhydrous minerals, both synthesized and of natural occurrence, with hydrogen concentrations from 10 to 100ppm have been analysed. Hydrous minerals, as well as Mylar foils were used as standards. Depth profiles show that intrinsic hydrogen can be distinguished from surface contaminations, e.g. water adsorbed on the sample surfaces. [Copyright &y& Elsevier]

The response of a position-sensitive Li-glass based scintillation detector being developed for thermal-neutron detection with 6 mm position resolution has been investigated using focused beams of 2.5 MeV protons and deuterons. The beams were scanned across the detector in 0.5 mm horizontal and vertical steps perpendicular to the beams. Scintillation light was registered using an 8 × 8 pixel multi-anode photomultiplier tube. The signal amplitudes were recorded for each pixel on an event-by-event basis. Several pixels generally registered considerable signals at each beam location. To optimize planned detector operation at the European Spallation Source, the number of pixels above set thresholds was investigated, with the maximization of the single-hit efficiency over the largest possible area as the primary goal. For both beams, at a threshold of ∼ 50% of the mean of the full-deposition peak, ∼ 80% of the events were registered in a single pixel, resulting in an effective position resolution of ∼ 5 mm in X and Y. Lower thresholds resulted in higher pixel multiplicities. These events could also be localized with the same effective position resolution. [ABSTRACT FROM AUTHOR]