48,577 research outputs found
THz fingerprinting of biomolecules supported by Ab initio molecular modelling
No full textIn this paper we explore various ab initio molecular approaches and their usefulness for the prediction of vibrational spectra of biomolecules.Jones, I. ; Rainsford, T. ; Fischer, B. ; Abbott, D
T-ray imaging and tomography
No full textThe original publication is available at www.springerlink.comWe demonstrate two algorithms used for reconstructing the target's structure based on the diffracted pulses and additionally show that a three-dimensional target can be reconstructed using the broadband pulses and a Fresnel lens by virtue of its frequency dependent focal length. One advantage of T-ray imaging is the ability to measure the far-infrared spectral response of the target. To highlight the importance of this spectral information, we demonstrate T-ray classification imaging with different biological samples using a simple classification algorithm and two dimensional T-ray spectroscopic images.S. Wang, B. Ferguson, D. Abbott and X.-C. Zhan
T-ray tomographic imaging
No full text© 2003 COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.We present three T-ray (terahertz wave) tomographic imaging modalities: T-ray computed tomography, T-ray diffraction tomography, and tomographic imaging with a Fresnel binary lens. Each of these techniques uses pulses of broadband terahertz radiation to obtain 3-dimensional images of targets with wide potential application. We present images demonstrating the performance of each technique and discuss their relative advantages.Bradley Ferguson, Shaohong Wang, Douglas A. Gray, Derek Abbott, and Xi-Cheng Zhan
Inclusive and differential cross-sections for dilepton t t ¯ production measured in s = 13 TeV pp collisions with the ATLAS detector
No full textDifferential and double-differential distributions of kinematic variables of leptons from decays of top-quark pairs ( t t ¯ ) are measured using the full LHC Run 2 data sample collected with the ATLAS detector. The data were collected at a pp collision energy of s = 13 TeV and correspond to an integrated luminosity of 140 fb−1. The measurements use events containing an oppositely charged eμ pair and b-tagged jets. The results are compared with predictions from several Monte Carlo generators. While no prediction is found to be consistent with all distributions, a better agreement with measurements of the lepton pT distributions is obtained by reweighting the t t ¯ sample so as to reproduce the top-quark pT distribution from an NNLO calculation. The inclusive top-quark pair production cross-section is measured as well, both in a fiducial region and in the full phase-space. The total inclusive cross-section is found to be σ t t ¯ = 829 ± 1 stat ± 13 syst ± 8 lumi ± 2 beam pb , where the uncertainties are due to statistics, systematic effects, the integrated luminosity and the beam energy. This is in excellent agreement with the theoretical expectation
Search for production in the multilepton final state in proton–proton collisions at = 13 TeV with the ATLAS detector
No full textA search for a new heavy scalar or pseudo-scalar Higgs boson (H/A) produced in association with a pair of top quarks, with the Higgs boson decaying into a pair of top quarks (H/A → ) is reported. The search targets a final state with exactly two leptons with same-sign electric charges or at least three leptons. The analysed dataset corresponds to an integrated luminosity of 139 fb−1 of proton–proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Two multivariate classifiers are used to separate the signal from the background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of a type-II two-Higgs-doublet model. The observed (expected) upper limits at 95% confidence level on the production cross-section times the branching ratio of H/A → range between 14 (10) fb and 6 (5) fb for a heavy Higgs boson with mass between 400 GeV and 1000 GeV, respectively. Assuming that only one particle, either the scalar H or the pseudo-scalar A, contributes to the final state, values of tan β below 1.2 or 0.5 are excluded for a mass of 400 GeV or 1000 GeV, respectively. These exclusion ranges increase to tan β below 1.6 or 0.6 when both particles are considered
Signal processing for T-ray bio-sensor systems
No full text© 2001 COPYRIGHT SPIE--The International Society for Optical EngineeringPulsed terahertz (T-ray) imaging systems represent an extremely promising method of obtaining sub-millimetre spectroscopic measurements for a wide range of applications. This paper investigates a number of techniques for optimally processing terahertz data. Specifically we consider wavelet de-noising and Wiener deconvolution algorithms. A goal of this research is the design and implementation of a high speed, compact and portable T-ray imaging system. This system will draw heavily on MOEMS technology. A significant challenge in the development of such a system is the development of efficient software algorithms to perform signal recognition and imaging operations in real time. This paper takes the example application of a smart bio-sensor for surface tumours and investigates the signal processing techniques amenable to the tasks of efficiently de-convolving the system response, de-noising and extracting the salient features from the terahertz response waveform.Bradley Ferguson and Derek Abbot
Search for leptoquark pair production decaying into or in multi-lepton final states in pp collisions at with the ATLAS detector
No full textA search for leptoquark pair production decaying into or in final states with multiple leptons is presented. The search is based on a dataset of pp collisions at recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb . Four signal regions, with the requirement of at least three light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from a b-hadron, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into (), the corresponding lower limit on the scalar mixed-generation leptoquark mass is at 1.58 (1.59) TeV and on the vector leptoquark mass at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang–Mills scenario
Highly birefringent, low loss and low dispersion THz waveguides with sub-wavelength porous structure
No full textS. Atakaramians, S. Afshar V., B. M. Fischer, D. Abbott and T. M. Monr
Towards an apertureless electro-optic T-ray microscope
No full textWe use an ultrafast laser which is focused to a very small spot on a ZnTe electro optical crystal so that THz waves are only generated in this region. The idea spatial resolution is close to the focus spot size.Tao Yuan Mickan, S. JinZhou Xu Abbott, D. Zhang, X.-C
- …
