A5101566516- Radio Astronomy Observations and Technology
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Laser-Plasma Interactions and Diagnostics
- Superconducting and THz Device Technology
- Gyrotron and Vacuum Electronics Research
- Antenna Design and Optimization
- Gamma-ray bursts and supernovae
- Particle accelerators and beam dynamics
- Pulsed Power Technology Applications
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Astrophysics and Star Formation Studies
- Magnetic confinement fusion research
- Scientific Research and Discoveries
- Particle Accelerators and Free-Electron Lasers
- Ionosphere and magnetosphere dynamics
- Plasma Diagnostics and Applications
- Dust and Plasma Wave Phenomena
- Laser-induced spectroscopy and plasma
- Laser Design and Applications
- Astrophysical Phenomena and Observations
- Electromagnetic Launch and Propulsion Technology
University of Oxford
2013-2024
University of Brighton
2017
Cranfield University
2012
University of Cambridge
1995-2008
Los Alamos National Laboratory
1985-2005
Cavendish Hospital
2002
Bridge University
2001
Sussex Eye Hospital
1991-1998
Los Alamos Medical Center
1997
Computational Physics (United States)
1996
A novel method of frequency upshifting short (\ensuremath{\le}1 ps) pulses laser light, which makes use relativistic plasma waves, is described. This the fact that a pulse moving in can be thought as packet photons, each possessing an effective mass ${m}_{\ensuremath{\gamma}}$=\ensuremath{\Elzxh}${\ensuremath{\omega}}_{\mathrm{pe}}$/${c}^{2}$ and with group velocity pulse. These photons experience force acting on them when presence gradient density. By using wave (i.e., density gradient)...
The Arcminute Microkelvin Imager is a pair of interferometer arrays operating with six frequency channels spanning 13.9-18.2 GHz, very high sensitivity to angular scales 30''-10'. telescope aimed principally at Sunyaev-Zel'dovich imaging clusters galaxies. We discuss the design and describe explain its electronic mechanical systems.
We present deep Ka-band (ν≈ 33 GHz) observations of the cosmic microwave background (CMB) made with extended Very Small Array (VSA). This configuration produces a naturally weighted synthesized FWHM beamwidth ∼11 arcmin, which covers an ℓ range 300 to 1500. On these scales, foreground extragalactic sources can be major source contamination CMB anisotropy. problem has been alleviated by identifying at 15 GHz Ryle Telescope and then monitoring using single-baseline interferometer collocated...
A general analysis of the electromagnetic wakefields for an axisymmetric charge distribution moving through a cold uniform plasma is presented. Particular attention given to and relativistic effects influencing waves. It shown that provides shielding transverse on scale length few skin depths (c/ωp). The implications wakefield accelerators are driving beams with radii will experience severe pinching, whereas larger be subject filamentation instabilities. These conclusions supported by...
We present new measurements of the power spectra E-mode CMB polarization, temperature T, cross-correlation E and upper limits on B-mode from 2.5 years dedicated Cosmic Background Imager (CBI) observations. Both raw maps optimal signal images in uv-plane real space show strong detections (11.7 sigma for EE spectrum overall) no detection B-mode. The are used to constrain parameters flat tilted adiabatic Lambda-CDM models: those determined TE bandpowers agree with TT, a powerful consistency...
The Q/U Imaging ExperimenT (QUIET) employs coherent receivers at 43GHz and 95GHz, operating on the Chajnantor plateau in Atacama Desert Chile, to measure anisotropy polarization of CMB. QUIET primarily targets B modes from primordial gravitational waves. combination these frequencies gives sensitivity foreground contributions diffuse Galactic synchrotron radiation. Between 2008 October 2010 December, >10,000hours data were collected, first with 19-element array (3458hours) then 90-element...
The drift of plasma ions relative to charged grains in a dusty can give rise dust/ion acoustic instability. We investigate the linear properties instability by numerically solving an appropriate dispersion equation and examine nonlinear behavior through one‐dimensional electrostatic particle simulations, which dust are treated as discrete particles electrons modeled Boltzmann fluid. saturates trapping some ions. is slightly weaker when have range sizes, corresponding charges masses. It...
The fields chosen for the first observations of cosmic microwave background with Very Small Array have been surveyed Ryle Telescope at 15 GHz. We covered three regions around RA 00h20m Dec +30deg, 09h40m +32deg and 15h40m +43deg (J2000), an area 520 deg^2. There are 465 sources above current completeness limit approximately 25 mJy, although a total ~760 detected, some as faint 10 mJy. This paper describes our techniques observation data analysis; it also includes source counts discussion...
The Q/U Imaging ExperimenT (QUIET) has observed the cosmic microwave background (CMB) at 43 and 95GHz. 43-GHz results have been published in QUIET Collaboration et al. (2011), here we report measurement of CMB polarization power spectra using 95-GHz data. This data set comprises 5337 hours observations recorded by an array 84 polarized coherent receivers with a total sensitivity 87 uK sqrt(s). Four low-foreground fields were observed, covering ~1000 square degrees effective angular...
The Q/U Imaging ExperimenT (QUIET) is designed to measure polarization in the Cosmic Microwave Background, targeting imprint of inflationary gravitational waves at large angular scales (~ 1 degree). Between 2008 October and 2010 December, two independent receiver arrays were deployed sequentially on a 1.4 m side-fed Dragonian telescope. polarimeters which form focal planes use highly compact design based High Electron Mobility Transistors (HEMTs) that provides simultaneous measurements...
The C-Band All-Sky Survey (C-BASS) is an all-sky full-polarisation survey at a frequency of 5 GHz, designed to provide complementary data the surveys WMAP and Planck, future CMB B-mode polarization imaging surveys. observing has been chosen signal that dominated by Galactic synchrotron emission, but suffers little from Faraday rotation, so measured directions good template for higher observations, carry direct information about magnetic field. Telescopes in both northern southern hemispheres...
Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application future satellite CMB polarization experiments. LiteBIRD is most advanced phase among such satellites, targeting its launch Japanese Fiscal Year 2027 (2027FY) with JAXA's H3 rocket. It will accommodate more than 4000 TESs focal planes reflective low-frequency and refractive medium-and-high-frequency...
We estimate cosmological parameters using data obtained by the Very Small Array (VSA) in its extended configuration, conjunction with a variety of other cosmic microwave background (CMB) and external priors. Within flat Λ cold dark matter (ΛCDM) model, we find that inclusion high-resolution from VSA modifies limits on as compared to those suggested Wilkinson Microwave Anisotropy Probe (WMAP) alone, while still remaining compatible their estimates. Ωbh2= 0.0234+0.0012−0.0014, Ωdmh2=...
The Very Small Array (VSA) is a synthesis telescope designed to image faint structures in the cosmic microwave background on degree and sub-degree angular scales. VSA has key differences from other CMB interferometers with result that different systematic errors are expected. We have tested operation of variety blank-field calibrator observations, cross-checked its calibration scale against independent measurements. find effects can be suppressed below thermal noise level long observations;...
We have observed a 2° × area of sky at frequencies 15.5 and 16.5 GHz with the Cambridge Cosmic Anisotropy Telescope (CAT). Comparison earlier measurements 13.5 shows that structure arises predominantly from cosmic microwave background. The broadband power, averaged over spherical harmonic multipole orders between 330 680, is (ΔT/T) = 2.0+ 0.4−0.4 10-5, which consistent predictions standard COBE-normalized, cold dark matter model.
We present evidence for anomalous microwave emission in the RCW175 \hii region. Motivated by 33 GHz $13\arcmin$ resolution data from Very Small Array (VSA), we observed at 31 with Cosmic Background Imager (CBI) a of $4\arcmin$. The region consists two distinct components, G29.0-0.6 and G29.1-0.7, which are detected high signal-to-noise ratio. integrated flux density is $5.97\pm0.30$ Jy GHz, good agreement VSA. $3.28\pm0.38$ ($8.6\sigma$) above expected value optically thin free-free based on...
Accurate calibration of data is essential for the current generation CMB experiments. Using from Very Small Array (VSA), we describe procedures which will lead to an accuracy 1 percent or better experiments such as VSA and CBI. Particular attention paid stability receiver systems, quality site frequent observations reference sources. At 30 GHz careful correction atmospheric emission absorption shown be achieving precision. The sources a relative flux density was achieved included Cas A, Cyg...
We discuss prospects for cluster detection via the Sunyaev–Zel'dovich (SZ) effect in a blank field survey with interferometer array, Arcminute MicroKelvin Imager (AMI). Clusters of galaxies selected SZ probe cosmology and structure formation little observational bias, because measures integrated gas pressure directly, does so independently redshift.
Rigorously sufficient and approximately necessary conditions for the absence of beam-Weibel instability are derived. These include previously known stability criteria resolve seeming contradiction that these modes can be stabilized by beam temperature when plasma is cold, but they cannot has infinitesimally small temperature.
We present an analysis of the diffuse emission at 5 GHz in first quadrant Galactic plane using two months preliminary intensity data taken with C-Band All Sky Survey (C-BASS) northern instrument Owens Valley Radio Observatory, California. Combining C-BASS maps ancillary to make temperature-temperature plots we find synchrotron spectral indices $\beta = -2.65 \pm 0.05$ between 0.408 and $ \beta -2.72 0.09$ 1.420 for $-10^{\circ} < |b| -4^{\circ}$, $20^{\circ} l 40^{\circ}$. Through...
Anomalous Microwave Emission (AME) is a significant component of Galactic diffuse emission in the frequency range $10$-$60\,$GHz and new window into properties sub-nanometre-sized grains interstellar medium. We investigate morphology AME $\approx10^{\circ}$ diameter $\lambda$ Orionis ring by combining intensity data from QUIJOTE experiment at $11$, $13$, $17$ $19\,$GHz C-Band All Sky Survey (C-BASS) $4.76\,$GHz, together with 19 ancillary datasets between $1.42$ $3000\,$GHz. Maps physical...
The effect of the finite charging time on spherical and cylindrical particulates in an RF discharge is considered. Using probe theory, analytical expressions for rate under various conditions are derived compared with numerical solutions. Scaling parameters, particular electron temperature, demonstrated. a one-dimensional fluid model rf discharge, equilibrium electric ion drag forces particulates. dynamics sizes discussed. Overall, long particle same mass as charges up more slowly to larger...