33 citations · 67 across the 15 of their papers we have counts for
15 papers
Temperature Dependent Optical Response Of High- Tc Yba2cu3o7-δ (Ybco) Thin Films
Vivek Khichar, V. A. Chirayath, Jonathan Asaadi +5
We report on the temperature-dependent optical response of thin films of YBa2Cu3O7-δ (YBCO) in the visible spectral range under cryogenic conditions. Specifically, we observe an in…
Measurement and analysis of the Doppler broadened energy spectra of annihilation gamma radiation originating from clean and adsorbate-covered surfaces
S. Lotfimarangloo, V. A. Chirayath, P. A. Sterne +8
We present measurements and theoretical modeling demonstrating the capability of Doppler Broadened annihilation gamma Spectroscopy (DBS) to provide element-specific information fro…
Monte Carlo analysis of the contributions of long-lived positronium to the spectra of positron-impact-induced secondary electrons measured using an annihilation-gamma-triggered time-of-flight spectrometer
S. Lotfimarangloo, V. A. Chirayath, S. Mukherjee +5
Magnetic bottle Time-of-Flight (ToF) spectrometers can measure the energy spectra of all electrons emitted into a 2 sr solid angle simultaneously, greatly reducing data collecti…
Design and fabrication guide for a new metamaterial as an absorber of visible light with exceptionally high absorption efficiency
Vivek Khichar, Nader Hozhabri, Ali R. Koymen
We present a guide for the design and fabrication of a CMOS-compatible metamaterial microstructure as an absorber of visible light with exceptionally high absorption efficiency (~…
Photoemission spectroscopy using virtual photons emitted by positron sticking: a new probe of the top layer surface electronic structure
Alexander J Fairchild, Varghese A. Chirayath, Bernardo Barbiellini +3
We present a spectroscopic method which utilizes virtual photons to selectively measure the electronic structure of the top-most atomic layer. These virtual photons are created whe…
Identification of Auger mechanisms responsible for low energy electron emission from graphene on copper using Auger-gamma coincidence spectroscopy
R. W. Gladen, V. A. Chirayath, P. A. Sterne +3
We present a novel method for the analysis of the Doppler broadened spectrum of gamma photons emitted following the annihilation of surface trapped positrons with the electrons of…
Efficient Machine Learning Approach for Optimizing the Timing Resolution of a High Purity Germanium Detector
R. W. Gladen, V. A. Chirayath, A. J. Fairchild +3
We describe here an efficient machine-learning based approach for the optimization of parameters used for extracting the arrival time of waveforms, in particular those generated by…
Direct evidence for low-energy electron emission following O LVV Auger transitions at oxide surfaces
Alexander J. Fairchild, Varghese A. Chirayath, Philip A. Sterne +3
Oxygen, the third most abundant element in the universe, plays a key role in the chemistry of condensed matter and biological systems. Here, we report evidence for a hitherto unexp…
A multi-stop time-of-flight spectrometer for the measurement of positron annihilation-induced electrons in coincidence with the Doppler-shifted annihilation gamma photon
V. A. Chirayath, R. W. Gladen, A. D. McDonald +12
Here we describe an advanced multi functional, variable-energy positron beam system capable of measuring the energies of multiple positron-induced electrons in coincidence with the…
Positron Induced Electron Emission from Graphite
A. J. Fairchild, V. A. Chirayath, R. W. Gladen +2
In this paper, we present and analyze measurements of the positron induced electron spectra (PIES) from highly oriented pyrolytic graphite (HOPG). The spectra were obtained using a…
Coincident Measurement of the Energy Spectra of Doppler-Shifted Annihilation Gamma Quanta and Positron-Induced Secondary Electrons
R W Gladen, V A Chirayath, A J Fairchild +3
Preliminary results are presented from a new positron beam system currently under development at the University of Texas at Arlington for the coincident energy measurement of Doppl…
Application of Doppler Broadened Gamma Spectroscopy to Study the Surface of Graphene
A. H. Weiss, V. A. Chirayath, R. W. Gladen +4
We present Doppler broadened gamma spectra, obtained using the newly developed advanced positron beam at the University of Texas at Arlington, from a sample consisting of 6 to 8 la…
Positronium formation in graphene and graphite
V. A. Chirayath, A. J. Fairchild, R. W. Gladen +3
Positronium (Ps) formation on the surface of clean polycrystalline copper (Cu), highly oriented pyrolytic graphite (HOPG) and multi layer graphene (MLG) grown on a polycrystalline…
Direct observation of electron emission as a result of a VVV Auger transition in the valence band of Graphene
V. A. Chirayath, V. Callewaert, M. D. Chrysler +11
We report the first direct observation of electron emission into the vacuum as a result of a VVV Auger transition resulting from the relaxation of a deep hole in the valence band.…
Giant magnetic broadening of ferromagnetic resonance in a GMR Co/Ag/Co/Gd quadlayer
Sezen Demirtas, Ali R. Koymen, Myron B. Salamon
Both magnetic-resonance damping and the giant magnetoresistance effect have been predicted to be strongly affected by the local density of states in thin ferromagnetic films. We em…