155 research outputs found
Recommended from our members
Quench performance of superconducting quadrupole magnets for the new Fermilab low beta insertion
Construction and testing of the components for the new Tevatron D0/B0 low beta insertion has been nearly completed. The devices include superconducting cold iron quadrupoles utilizing a 2-shell, cos2{theta} coil geometry with a 7.6 cm aperture. The maximum design gradient is 1.41 T/cm at an operating current of 4832 A. They have the highest current density with the highest peak field on the winding of any quadrupole yet built. This paper summarizes the quench performance and ramp rate sensitivity of the 2-shell design and relates the performance characteristics to the relevant aspects of design and fabrication. 8 refs., 6 figs., 3 tabs
\textsc{MaGe} - a {\sc Geant4}-based Monte Carlo Application Framework for Low-background Germanium Experiments
We describe a physics simulation software framework, MAGE, that is based on
the GEANT4 simulation toolkit. MAGE is used to simulate the response of
ultra-low radioactive background radiation detectors to ionizing radiation,
specifically the MAJORANA and GERDA neutrinoless double-beta decay experiments.
MAJORANA and GERDA use high-purity germanium detectors to search for the
neutrinoless double-beta decay of 76Ge, and MAGE is jointly developed between
these two collaborations. The MAGE framework contains the geometry models of
common objects, prototypes, test stands, and the actual experiments. It also
implements customized event generators, GEANT4 physics lists, and output
formats. All of these features are available as class libraries that are
typically compiled into a single executable. The user selects the particular
experimental setup implementation at run-time via macros. The combination of
all these common classes into one framework reduces duplication of efforts,
eases comparison between simulated data and experiment, and simplifies the
addition of new detectors to be simulated. This paper focuses on the software
framework, custom event generators, and physics lists.Comment: 12 pages, 6 figure
ELEVATED PHENYLACETIC ACID LEVELS DO NOT CORRELATE WITH ADVERSE EVENTS IN PATIENTS WITH UREA CYCLE DISORDERS OR HEPATIC ENCEPHALOPATHY AND CAN BE PREDICTED BASED ON THE PLASMA PAA TO PAGN RATIO
Background Phenylacetic acid (PAA) is the active moiety in sodium phenylbutyrate (NaPBA) and glycerol phenylbutyrate (GPB, HPN-100), both are approved for treatment of urea cycle disorders (UCDs) - rare genetic disorders characterized by hyperammonemia. PAA is conjugated with glutamine in the liver to form phenylacetyleglutamine (PAGN), which is excreted in urine. PAA plasma levels ≥500 μg/dL have been reported to be associated with reversible neurological adverse events (AEs) in cancer patients receiving PAA intravenously. Therefore, we have investigated the relationship between PAA levels and neurological AEs in patients treated with these PAA pro-drugs as well as approaches to identifying patients most likely to experience high PAA levels. Methods The relationship between nervous system AEs, PAA levels and the ratio of plasma PAA to PAGN were examined in 4683 blood samples taken serially from: [1] healthy adults [2], UCD patients ≥2 months of age, and [3] patients with cirrhosis and hepatic encephalopathy (HE). The plasma ratio of PAA to PAGN was analyzed with respect to its utility in identifying patients at risk of high PAA values. Results Only 0.2% (11) of 4683 samples exceeded 500 ug/ml. There was no relationship between neurological AEs and PAA levels in UCD or HE patients, but transient AEs including headache and nausea that correlated with PAA levels were observed in healthy adults. Irrespective of population, a curvilinear relationship was observed between PAA levels and the plasma PAA:PAGN ratio, and a ratio > 2.5 (both in μg/mL) in a random blood draw identified patients at risk for PAA levels > 500 μg/ml. Conclusions The presence of a relationship between PAA levels and reversible AEs in healthy adults but not in UCD or HE patients may reflect intrinsic differences among the populations and/or metabolic adaptation with continued dosing. The plasma PAA:PAGN ratio is a functional measure of the rate of PAA metabolism and represents a useful dosing biomarker
Detection of Atmospheric Muon Neutrinos with the IceCube 9-String Detector
The IceCube neutrino detector is a cubic kilometer TeV to PeV neutrino
detector under construction at the geographic South Pole. The dominant
population of neutrinos detected in IceCube is due to meson decay in cosmic-ray
air showers. These atmospheric neutrinos are relatively well-understood and
serve as a calibration and verification tool for the new detector. In 2006, the
detector was approximately 10% completed, and we report on data acquired from
the detector in this configuration. We observe an atmospheric neutrino signal
consistent with expectations, demonstrating that the IceCube detector is
capable of identifying neutrino events. In the first 137.4 days of livetime,
234 neutrino candidates were selected with an expectation of 211 +/-
76.1(syst.) +/- 14.5(stat.) events from atmospheric neutrinos
On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes
The sensitivity of a search for sources of TeV neutrinos can be improved by
grouping potential sources together into generic classes in a procedure that is
known as source stacking. In this paper, we define catalogs of Active Galactic
Nuclei (AGN) and use them to perform a source stacking analysis. The grouping
of AGN into classes is done in two steps: first, AGN classes are defined, then,
sources to be stacked are selected assuming that a potential neutrino flux is
linearly correlated with the photon luminosity in a certain energy band (radio,
IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino
production in AGN, this correlation is motivated by hadronic AGN models, as
briefly reviewed in this paper.
The source stacking search for neutrinos from generic AGN classes is
illustrated using the data collected by the AMANDA-II high energy neutrino
detector during the year 2000. No significant excess for any of the suggested
groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic
Recommended from our members
Results on Fermilab main injector dipole measurements
Measurements of the Productions run of Fermilab Main Injector Dipole magnets is underway. Redundant strength measurements provide a set of data which one can fit to mechanical and magnetic properties of the assembly. Plots of the field contribution from the steel supplement the usual plots of transfer function (B/I) vs. I in providing insight into the measured results
Mathematical Representation of Viscosity of Ionic Liquid + Molecular Solvent Mixtures at Various Temperatures Using the Jouyban–Acree Model
Article on mathematical representation of viscosity of ionic liquid and molecular solvent mixtures at various temperatures using the Jouyban-Acree model
MaGe: A Monte Carlo framework for the Gerda and Majorana double beta decay experiments
The Gerda [1] and Majorana [2] projects, both searching for the neutrinoless double beta-decay of 76Ge, are developing a joint Monte-Carlo simulation framework called MaGe. Such an approach has many benefits: the workload for the development of general tools is shared between more experts, the code is tested in more detail, and more experimental data is made available for validation
- …