Martin R. Barnes

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We report on a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers. The search focused on binary systems with component masses between 3 and 20M. Optimally oriented binaries with distances up to 1 Mpc could be detected with efficiency of at least 90%. We found no events that(More)
A new analytically and numerically manageable model collision operator is developed specifically for turbulence simulations. The like-particle collision operator includes both pitch-angle scattering and energy diffusion and satisfies the physical constraints required for collision operators: it conserves particles, momentum, and energy, obeys Boltzmann's(More)
Sheared toroidal flows can cause bifurcations to zero-turbulent-transport states in tokamak plasmas. The maximum temperature gradients that can be reached are limited by subcritical turbulence driven by the parallel velocity gradient. Here it is shown that q/ϵ (magnetic field pitch/inverse aspect ratio) is a critical control parameter for sheared tokamak(More)
A set of key properties for an ideal dissipation scheme in gyrokinetic simulations is proposed, and implementation of a model collision operator satisfying these properties is described. This operator is based on the exact linearized test-particle collision operator, with approximations to the field-particle terms that preserve conservation laws and an(More)
Beam emission spectroscopy (BES) measurements of ion-scale density fluctuations in the MAST tokamak are used to show that the turbulence correlation time, the drift time associated with ion temperature or density gradients, the particle (ion) streaming time along the magnetic field, and the magnetic drift time are consistently comparable, suggesting a(More)
The effect of small deviations from a Maxwellian equilibrium on turbulent momentum transport in tokamak plasmas is considered. These non-Maxwellian features, arising from diamagnetic effects, introduce a strong dependence of the radial flux of cocurrent toroidal angular momentum on collisionality: As the plasma goes from nearly collisionless to weakly(More)
Does visual processing influence mental arithmetic? The relationship between high and low visual similarity and horizontal versus vertical presentation was examined in three-digit addition problems with two carries (ex. 518 + 294). Adults (20 female, 20 male) solved vertically presented problems faster than horizontally presented problems and solved(More)
The LHC [1] will be supplied, via the SPS, with protons from the pre-injector chain comprising Linac2, PS Booster (PSB) and PS. These accelerators have undergone a major upgrading programme [2] during the last five years so as to meet the stringent requirements of the LHC. These imply that many high-intensity bunches of small emittance and tight spacing (25(More)