Development of EM-CCD-based X-ray detector for synchrotron applications

A high speed, low noise camera system for crystallography and X-ray imaging applications is developed and successfully demonstrated. By coupling an electron-multiplying (EM)-CCD to a 3:1 fibre-optic taper and a CsI(Tl) scintillator, it was possible to detect hard X-rays. This novel approach to hard X-ray imaging takes advantage of sub-electron equivalent readout noise performance at high pixel readout frequencies of EM-CCD detectors with the increase in the imaging area that is offered through the use of a fibre-optic taper. Compared with the industry state of the art, based on CCD camera systems, a high frame rate for a full-frame readout (50 ms) and a lower readout noise (<1 electron root mean square) across a range of X-ray energies (6–18 keV) were achieved

Apparatus for measuring electric field strength on the surface of a model vehicle Patent

Space environment simulation system for measuring spacecraft electric field strength in plasma sheat

Singlet baryons in the graded symmetry approach to partially quenched QCD

Progress in the calculation of the electromagnetic properties of baryon excitations in lattice QCD is presenting new challenges in the determination of sea-quark loop contributions to matrix elements. A reliable estimation of the sea-quark loop contributions presents a pressing issue in the accurate comparison of lattice QCD results with experiment. In this article, an extension of the graded symmetry approach to partially quenched QCD is presented, which builds on previous theory by explicitly including flavor-singlet baryons in its construction. The formalism takes into account the interactions among both octet and singlet baryons, octet mesons, and their ghost counterparts; the latter enables the isolation of the quark-flow disconnected sea-quark loop contributions. The introduction of the flavor-singlet states anticipates the application of the method to baryon excitations such as the lowest-lying odd-parity Lambda baryon, the Lambda(1405), which is considered in detail as a worked example.Comment: arXiv copy updated to published version: Phys. Rev. D 94, 094004 (2016

Field Release of Virus-Sprayed Adult Parasitoids of the European Pine Sawfly (Hymenoptera: Diprionidae) in Wisconsin

Rapid field release of adult parasitoids sprayed with the nucleopolyhedrosis virus of the European pine sawfly successfully transferred the virus to feeding larval colonies

Optical transfer cavity stabilization using current-modulated injection-locked diode lasers

It is demonstrated that RF current modulation of a frequency stabilized injection-locked diode laser allows the stabilization of an optical cavity to adjustable lengths, by variation of the RF frequency. This transfer cavity may be used to stabilize another laser at an arbitrary wavelength, in the absence of atomic or molecular transitions suitable for stabilization. Implementation involves equipment and techniques commonly used in laser cooling and trapping laboratories, and does not require electro- or acousto-optic modulators. With this technique we stabilize a transfer cavity using a RF current-modulated diode laser which is injection locked to a 780 nm reference diode laser. The reference laser is stabilized using polarization spectroscopy in a Rb cell. A Ti:sapphire ring laser at 960 nm is locked to this transfer cavity and may be precisely scanned by varying the RF modulation frequency. We demonstrate the suitability of this system for the excitation of laser cooled Rb atoms to Rydberg states

Chiral extrapolations for nucleon magnetic moments

Lattice QCD simulations have made significant progress in the calculation of nucleon electromagnetic form factors in the chiral regime in recent years. With simulation results achieving pion masses of order ~180 MeV, there is an apparent challenge as to how the physical regime is approached. By using contemporary methods in chiral effective field theory, both the quark-mass and finite-volume dependence of the isovector nucleon magnetic moment are carefully examined. The extrapolation to the physical point yields a result that is compatible with experiment, albeit with a combined statistical and systematic uncertainty of 10%. The extrapolation shows a strong finite-volume dependence; lattice sizes of L > 5 fm must be used to simulate results within 2% of the infinite-volume result for the magnetic moment at the physical pion mass.Comment: 7 pages, 12 figures, 1 tabl

Power Counting Regime of Chiral Effective Field Theory and Beyond

Chiral effective field theory complements numerical simulations of quantum chromodynamics (QCD) on a space-time lattice. It provides a model-independent formalism for connecting lattice simulation results at finite volume and a variety of quark masses to the physical world. The asymptotic nature of the chiral expansion places the focus on the first few terms of the expansion. Thus, knowledge of the power-counting regime (PCR) of chiral effective field theory, where higher-order terms of the expansion may be regarded as negligible, is as important as knowledge of the expansion itself. Through the consideration of a variety of renormalization schemes and associated parameters, techniques to identify the PCR where results are independent of the renormalization scheme are established. The nucleon mass is considered as a benchmark for illustrating this general approach. Because the PCR is small, the numerical simulation results are also examined to search for the possible presence of an intrinsic scale which may be used in a nonperturbative manner to describe lattice simulation results outside of the PCR. Positive results that improve on the current optimistic application of chiral perturbation theory beyond the PCR are reported.Comment: 18 pages, 55 figure