A5033617037- Particle accelerators and beam dynamics
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Gyrotron and Vacuum Electronics Research
- Plasma Diagnostics and Applications
- Magnetic confinement fusion research
- Muon and positron interactions and applications
- Advanced Condensed Matter Physics
- Graphite, nuclear technology, radiation studies
- Advancements in Battery Materials
- Physics of Superconductivity and Magnetism
- Radiation Therapy and Dosimetry
- Crystallography and Radiation Phenomena
- ZnO doping and properties
- Metal and Thin Film Mechanics
- Magnetic properties of thin films
- Radiation Detection and Scintillator Technologies
- Astronomical Observations and Instrumentation
- Advanced Memory and Neural Computing
- Digital Rights Management and Security
- Acoustic Wave Resonator Technologies
- Ion-surface interactions and analysis
- Advanced NMR Techniques and Applications
- Metallurgy and Material Science
University of British Columbia
2018-2024
TRIUMF
2018-2024
Simon Fraser University
2023
University of Victoria
2023
National University of Singapore
2013
A new high field spectrometer has been built to extend the capabilities of $\beta$-detected nuclear magnetic resonance ($\beta$-NMR) facility at TRIUMF. This beamline extension allows $\beta$-NMR spectroscopy be performed with fields up 200 mT parallel a sample's surface (perpendicular ion beam), allowing depth-resolved studies local electromagnetic spin polarized probes much higher applied than previously available in this configuration. The primary motivation and application is allow...
The performance of superconducting radiofrequency (SRF) cavities used for particle accelerators depends on two characteristic material parameters: field first flux entry ${H}_{\text{entry}}$ and pinning strength. former sets the limit maximum achievable accelerating gradient, while latter determines how efficiently can be expelled related to quality factor. In this paper, a method based muon spin rotation ($\ensuremath{\mu}\mathrm{SR}$) is developed probe these parameters samples. It...
Abstract We report measurements of the first-flux-penetration field in surface-treated and coated Nb samples using <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mi>μ</mml:mi> <mml:mtext>SR</mml:mtext> stretchy="false">)</mml:mo> </mml:mrow> </mml:math> . Using thin Ag foils as energy moderators for implanted muon spin-probes, we ‘profile’ vortex penetration <mml:msub> <mml:mn>0</mml:mn> </mml:msub>...
We report measurements of the first-flux-penetration field in surface-treated and coated Nb samples using muon spin rotation ($\mu$SR). Using thin Ag foils as energy moderators for implanted spin-probes, we "profile" vortex penetration $\mu_{0} H_{\mathrm{vp}}$ at sub-surface depths on order $\sim 10$ $\mathrm{\mu}$m to 100$ $\mathrm{\mu}$m. In a sample [Nb$_3$Sn(2 $\mathrm{\mu}$m)/Nb], find that is depth-independent with value 234.5(35) mT, consistent Nb's metastable superheating suggestive...
We study the temperature dependence as well anisotropy of optical conductivity ($\sigma_1$) in pseudocubic single crystal Pr$_{0.5}$Ca$_{1.5}$MnO$_{4}$ using spectrocopic ellipsometry. Three transition temperatures are observed and can be linked to charge-orbital ($T_{\rm CO/OO}$ $\sim$ 320 K), two-dimensional-antiferromagnetic (2D-AFM) ($\sim$ 200 three-dimensional AFM N} \sim$ 125 K) orderings. Below $T_{\rm CO/OO}$, $\sigma_1$ shows a charge ordering peak ($\sim$0.8 eV) with significant...
We report measurements of the Meissner screening profile in a Nb(300 nm)/Al2O3 thin film using 8Liβ-detected nuclear magnetic resonance (β-NMR). The NMR probe 8Li was ion-implanted into Nb at energies ≤ 20 keV, corresponding to mean stopping depths comparable Nb’s penetration depth λ. 8Li’s strong dipole–dipole coupling with host 93Nb nuclei provided “cross-relaxation” channel that dominated low fields, which conferred indirect sensitivity local field via spin-lattice relaxation (SLR) rate...
We report on the stability and magnetic state of ion implanted $^{8}\mathrm{Li}$ in single crystals semiconductor ZnO using $\ensuremath{\beta}$-detected nuclear resonance. At ultradilute concentrations, spectra reveal distinct Li sites from 7.6 to 400 K. Ionized shallow donor interstitial is stable across entire temperature range, confirming its ability self-compensate acceptor character (Zn) substitutional counterpart. Above 300 K, spin-lattice relaxation indicates onset correlated local...
<title>Abstract</title> We report direct measurements of the magnetic field screening at limits Meissner phase for two superconducting Nb samples. The samples are processed with different surface treatments that have been developed radio-frequency cavity applications — a “baseline” treatment and an oxygen-doping (“O-doping” ) treatment. show: 1) length is significantly longer in “O-doping” sample compared to sample; 2) near increases applied field; 3) evolution profile as material...
We report direct measurements of the magnetic field screening at limits Meissner phase for two superconducting Nb samples. The samples are processed with different surface treatments that have been developed radio-frequency cavity applications -- a "baseline" treatment and an oxygen-doping ("O-doping") treatment. show: 1) length is significantly longer in "O-doping" sample compared to sample; 2) near increases applied field; 3) evolution profile as material transitions from mixed phase; 4)...
We report $\ensuremath{\beta}$-detected nuclear magnetic resonance of ultradilute $^{8}\mathrm{Li}^{+}$ implanted in highly oriented pyrolytic graphite (HOPG). The absence motional narrowing and diffusional spin-lattice relaxation implies ${\mathrm{Li}}^{+}$ is not appreciably mobile up to 400 K, sharp contrast the lithiated stage compounds. However, remarkably fast persists down cryogenic temperatures. Ruling out extrinsic paramagnetic impurities intrinsic ferromagnetism, we conclude due...
The electron source in the TRIUMF ARIEL project is a gridded dispenser cathode. cathode biased at -300kV, and grid requires RF control signal of up to 150V 650 MHz. required power approximately 20 W provided by an amplifier located outside gun vessel. This coupled into circuit through ceramic transmission line. design this line, as well impedance transformation which provides both matching dc powers assembly are described.
We report $\beta$-detected nuclear magnetic resonance of ultra-dilute $^{8}$Li$^{+}$ implanted in highly oriented pyrolytic graphite (HOPG). The absence motional narrowing and diffusional spin-lattice relaxation implies Li$^+$ is not appreciably mobile up to 400 K, sharp contrast the lithiated stage compounds. However, remarkably fast persists down cryogenic temperatures. Ruling out extrinsic paramagnetic impurities intrinsic ferromagnetism, we conclude due centers correlated with...
Abstract In our prior work, we showed that β -detected nuclear magnetic resonance ( -NMR) was a good probe of bulk room temperature ionic liquid (RTIL) dynamics and dynamic heterogeneity. We now investigate how the surface modifies these properties, presenting first depth-resolved -NMR measurements in 1-ethyl-3-methylimidazolium acetate as liquid, supercooled glass. This interfacial region is important for understanding constrained dimensionality affects dynamics. show both glass transition...
Abstract The inverse perovskite Sr 3 SnO is a 3D cubic Dirac semimetal with very small energy gap[1]. Its unusual electronic structure confers variety of novel properties, such as chiral topological surface states, and strong itinerant electron orbital magnetism. Remarkably, when doped it also becomes superconducting[2]. In the lowest carrier density samples, Fermi level lies close to points, magnetism maximal. Here we report results ion-implanted 8 Li + β NMR in Au-capped epitaxial thin...