Neutron powder diffraction based atomic pair distribution functions (PDFs) are reported from the new wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The spectrometer was run in white-beam mode with no Fermi chopper. The PDF patterns of Ni and Al2O3 were refined using the PDFfit method and the results compared to data c...

A modern physics facility must synchronize the operation of equipment over a wide area. The primary purpose of the site wide SNS synchronization and timing system is to synchronize the operation of the LINAC, accumulator ring and neutron choppers and to distribute appropriate timing signals to accelerator systems, including the Injector, LINAC, Accumulator Ring and Experimental Facilities. Sign...

Oldowan lithic assemblages are often portrayed as a product of the need to obtain sharp flakes for cutting into animal carcases. However, ethnographic and experimental research indicates that the optimal way to produce flakes for such butchering purposes is via bipolar reduction of small cryptocrystalline pebbles rather than from larger crystalline cores resembling choppers. Ethnographic observ...

We describe the Disk Chopper Spectrometer (DCS) at the NIST Center for Neutron Research (NCNR). The maximum measured flux at the sample, averaged over the 3 cm width and 10 cm height of the beam, with all choppers turning at 20,000 revolutions per minute and phased to transmit neutrons through the widest slots on each disk, is approximately 3 10 n cm 2 s . In this configuration the elastic reso...

In this paper, we have developed an explicit analytical drain current model comprising surface channel potential and threshold voltage in order to explain the advantages of the proposed Gate Stack Double Diffusion (GSDD) MOSFET design over the conventional MOSFET with the same geometric specifications that allow us to use the benefits of the incorporation of the high-k layer between the oxide l...

A low power and low noise front end chopped instrumentation amplifier for portable electrocardiogram recording system is presented. The circuit is based on the chopper technique which is implemented using folded cascode structure that has significant lower power consumption than the predecessor’s approaches while keeping the performance unchanged. The chopper switches modulate noise from a low ...

ABSTRACT: The wind turbine generator is operated such that the rotor speed varies according to wind speed to adjust the duty cycle of power converter and maximizes wind energy conversion system efficiency. The rotating speed of permanent-magnet generator should be adjusted in the real time to capture maximum wind power. This paper proposes a quite simple maximum power point tracking control sch...

A new current structure for the fast traveling-wave 2.5MeV beam chopper in the front end of the Spallation Neutron Source (SNS) has been suggested in [1]. The structure is based on the meander-folded notched stripline with dielectric supports and separators. Its design has been optimized using electromagnetic 3-D modeling with the MAFIA code package to provide rise and fall times in the range o...

High current and severe restrictions on beam losses, below 1 nA/m, in the designed linac for the National Spallation Neutron Source (NSNS) require clean and fast — with the rise time from 2% to 98% less than 2.5 ns to accommodate a 402.5-MHz beam structure — beam chopping in its front end, at the beam energy 2.5 MeV. The R&D program includes both modification of the existing LANSCE coax-plate c...

We present Chopper, a tool that efficiently explores the vast input space of file system policies to find behaviors that lead to costly performance problems. We focus specifically on block allocation, as unexpected poor layouts can lead to high tail latencies. Our approach utilizes sophisticated statistical methodologies, based on Latin Hypercube Sampling (LHS) and sensitivity analysis, to expl...