[en] The Pearson VII function, which is more general than the Gaussian, Lorentzian and other profiles, is used to fit the x-ray spectral lines produced in a laser-generated plasma, instead of the more usual, but computationally expensive, Voigt function. The mean full-width half-maximum of the fitted lines is 0.102±0.014 nm, entirely consistent with the value expected from geometrical considerations, and the fitted line profiles are generally inconsistent with being either Lorentzian or Gaussian. (author)

[en] The King's College laboratory scanning x-ray microscope has been used on the laser plasma source at the Rutherford Appleton Laboratory, which has been extensively characterized. Resolution and contrast in the initial images are limited by electrical noise in the detector system

[en] Radiation micro-beams represent a unique and powerful tool to study and quantify the effects of precise doses of radiation delivered with micron precision to selected biological samples. The Gray Cancer Institute has developed two independent but complementary micro-irradiation facilities, specifically developed for the targeted irradiation of cells and structured tissues; a charged-particle microbeam that uses collimated protons or helium ions and an ultra-soft X-ray microprobe. The ultra-soft X-ray facility employs a focused electron bombardments source to produce a near monochromatic CK X-ray beam. Highly efficient zone plates optimised for the appropriate wavelength are used to focus the characteristic X-rays into a sub-micron spot. The facility is also equipped with a three-axis micro-positioning stage, an epi-fluorescent UV microscope with intensified CCD camera coupled to a fast PC for a automatic, fast and accurate samples recognition and alignment with the probe. Recent experiments have been directed to investigate the bystander effect by irradiating only one cell within a population of V79 cells that are subsequently individually revisited for colony formation. A clear bystander effect has been detected (∼ 10 % reduction in survival) when a single cell has been irradiated. The effect is triggered by very low doses ((∼ 100 mGy) and it is largely dose independent. (authors)

[en] A 129EM electron multiplier has been modified to detect soft x-rays by coating the first dynode with CsI. The prototype detector was tested at the X1a beamline of the NSLS synchrotron source at Brookhaven Lab and at the laser plasma source at the Rutherford Lab. Initial tests have shown that the detector type is suitable for use in soft x-ray microscopy

[en] An x-ray microprobe, which utilizes a small laboratory x-ray source with a carbon target and a zone plate to form a fine focus, has been used for initial studies of cellular radiation response. It is not yet clear whether carbon K x-rays exhibit the hypersensitivity at very low doses for 240 kVp x-rays, which manifests itself predominately with sparsely ionizing radiation. There is some evidence to support the phenomenon of radiation induced bystander effects whereby unexposed neighbors of irradiated cells also exhibit a response