Sudden increases in the background gamma-radiation dose may occur due to the removal of 222 Rn and 220 Rn progeny from the atmosphere by wet deposition mechanisms. This contribution has been measured using a Geiger-Muller detector at the Atomic Weapons Establishment (Aldermaston, UK) during July 2005-April 2006. The results are approximated by a log-normal distribution and there were nine separate occurrences of the gamma-radiation dose exceeding 125% of the geometric mean value. The increases were associated with periods of heavy rainfall, although no correlation was evident between the dose rate and the amount of rainfall, as increased rainfall dilutes the activity further rather than increasing its atmospheric removal. The events were preceded by periods of fine weather and atmospheric stability that allow for the build-up of 222 Rn and 220 Rn progeny. Similar increases in gamma-radiation dose have been measured at a nearby monitoring station situated approximately 11 miles from Aldermaston. Increases in gamma-radiation dose during heavy rainfall have also been observed throughout the UK, that followed the trajectory of an air mass. All events decreased to typical values within 1-2 h as the water permeated into the ground below and the radioactivity decayed away.

Sublimate reduction from the new bottom antireflective coating (BARC) and gap fill materials in bake process was investigated by means of absorption spectroscopy and the quantitative analysis of sublimation using the quartz crystal microbalance (QCM) sensing element. The small molecular components in BARC and gap fill materials were found to be related to a decrease in the number of sublimate defect. The application of the newly developed BARC and gap fill materials of the polymers with a self cross-link reaction system showed lower sublimate amount. In addition, good resist profiles and 130 nm via fill performance in the via-first dual damascene process were achieved using this self cross-link polymer system. This new system is one of the most promising systems ready to be tested for the mass production of 32 -45 nm node IC devices and beyond.

We determine the geometry of supersymmetric heterotic string backgrounds for which all parallel spinors with respect to the connection∇ with torsion H, the NS⊗NS three-form field strength, are Killing. We find that there are two classes of such backgrounds, the null and the timelike. The Killing spinors of the null backgrounds have stability subgroups K R 8 in Spin(9, 1), for K = Spin(7), SU (4), Sp(2), SU (2) × SU (2) and {1}, and the Killing spinors of the timelike backgrounds have stability subgroups G 2 , SU (3), SU (2) and {1}. The former admit a single null∇-parallel vector field while the latter admit a timelike and two, three, five and nine spacelike∇-parallel vector fields, respectively. The spacetime of the null backgrounds is a Lorentzian two-parameter family of Riemannian manifolds B with skew-symmetric torsion. If the rotation of the null vector field vanishes, the holonomy of the connection with torsion of B is contained in K. The spacetime of time-like backgrounds is a principal bundle P with fibre a Lorentzian Lie group and base space a suitable Riemannian manifold with skew-symmetric torsion. The principal bundle is equipped with a connection λ which determines the non-horizontal part of the spacetime metric and of H. The curvature of λ takes values in an appropriate Lie algebra constructed from that of K. In addition dH has only horizontal components and contains the Pontrjagin class of P . We have computed in all cases the Killing spinor bilinears, expressed the fluxes in terms of the geometry and determine the field equations that are implied by the Killing spinor equations.

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