12509407
An international intercomparison of environmental dosimeters.
137898852
MECHANISMS AND APPLICATIONS OF NUCLEAR TRACK REGISTRATION IN POLYMERS.
43029702
Nuclear track registration in dosimeter glasses for neutron dosimetry in mixed radiation fields.
Abstract : The fission track detection in fission foil/glass combinations avoids most of the disadvantages of the conventional methods (nuclear track evaluations and activation foils) for integrating neutron measurements. These systems are insensitive to gamma radiation, temperature, climatic and chemical disturbances, easy to evaluate, have no directional dependence, an extended dose and energy range, superior accuracy, etc. The method has been investigated, using different dosimeter glasses, etching conditions, fissionable materials and neutron energies between thermal and 14 MeV. The fission track detection efficiency is 100%, the sensitivity for fissionable metals thicker than ca. 5 microns is 0.000013 tracks/neutron/barn. Simple evaluation techniques and practical applications, mainly for fast neutron personnel dosimetry, are described. (Author)
6918482
Faint Scattering Around Pulsars: Probing the Interstellar Medium on Solar System Size Scales
We have made high-resolution, high-sensitivity dynamic spectra of a sample of strong pulsars at 430 MHz with the Arecibo radio telescope. For four pulsars we find faint but sharply delineated features in the secondary spectra. These are examples of the previously observed "crisscross" or "multiple drift slope" phenomenon presumed to be due to multiple imaging of the pulsar by the interstellar medium (ISM). The unprecedented resolution and dynamic range of our observations allow a deeper level of analysis. Distances to the dominant scattering screen along the line of sight are determined and are shown to agree well with those inferred from other scintillation phenomena. Multiple imaging of the pulsar by the ISM is required. A compact central image surrounded by a faint scattering halo, roughly circularly symmetric, is consistent with the data. Scattering from filaments may also be consistent. The angular extent of the scattering material parallel to the direction of the pulsar velocity is ~5 mas, corresponding to a linear extent of ~2 AU. Further observations of these features should allow better discrimination between models and an identification of the scattering structures.
109075983
Development of a new first level trigger for the surface array in the Pierre Auger Observatory based on the CycloneTM Altera® FPGA
Abstract The development of a new first level trigger for the surface array in the Pierre Auger Observatory is described. It utilizes the new Altera ® family Cyclone TM which is available since March 2003. Different from previous and the currently used design based on the APEX TM and ACEX ® families, respectively, it offers much higher capacity of logic registers and memories, a simplified board design, lower power consumption, and lower cost. The paper describes the board design, internal structures of the programming routines, various trigger implementations and test results obtained in the laboratory.
17056116
A two-loop test of M(atrix) theory
Abstract We consider the scattering of two Dirichlet zero-branes in M(atrix) theory. Using the formulation of M(atrix) theory in terms of ten-dimensional super Yang-Mills theory dimensionally reduced to (0+1) dimensions, we obtain the effective (velocity-dependent) potential describing these particles. At one loop we obtain the well-known result for the leading order of the effective potential V eff ∼ v 4 / r 7 , where v and r are the relative velocity and distance between the two zero-branes, respectively. A calculation of the effective potential at two loops shows that no renormalizations of the v 4 term of the effective potential occur at this order.
119274731
Four-derivative brane couplings from string amplitudes
A bstractWe evaluate the string theory disc amplitude of one Ramond-Ramond field C(p−3) and two Neveu-Schwarz B-fields in the presence of a single Dp-brane in type II string theory. From this amplitude we extract the four-derivative (or equivalently order α′2) part of the Dp-brane action involving these fields. We show that the new couplings are invariant under R-R and NS-NS gauge transformations and compatible with linear T-duality.
14657506
A note on compactifications on spin(7)-holonomy manifolds
In this note we consider compactifications of Script M-theory on Spin(7)-holonomy manifolds to three-dimensional Minkowski space. In these compactifications a warp factor is included. The conditions for unbroken N = 1 supersymmetry give rise to determining equations for the 4-form field strength in terms of the warp factor and the self-dual 4-form of the internal manifold.