43,761 research outputs found
A Study for a Tracking Trigger at First Level for CMS at SLHC
It is expected that the LHC accelerator and experiments will undergo a
luminosity upgrade which will commence after several years of running. This
part of the LHC operations is referred to as Super-LHC (SLHC) and is expected
to provide beams of an order of magnitude larger luminosity (1035cm-2sec-1)
than the current design. Preliminary results are presented from a feasibility
study for a First Level Tracking Trigger for CMS at the SLHC using the data of
the inner tracking detector. As a model for these studies the current CMS pixel
detector with the same pixel size and radial distances from the beam has been
used. Monte Carlo studies have been performed using the full CMS simulation
package (OSCAR) and the occupancy of such a detector at SLHC beam conditions
has been calculated. The design of an electron trigger which uses both the
calorimeter energy depositions and the pixel data to identify isolated
electrons and photons has been investigated. Results on the tracker occupancy
and the electron trigger performance are presentedComment: Presented at LECC, Heidelberg 200
Spin Coherence and N ESEEM Effects of Nitrogen-Vacancy Centers in Diamond with X-band Pulsed ESR
Pulsed ESR experiments are reported for ensembles of negatively-charged
nitrogen-vacancy centers (NV) in diamonds at X-band magnetic fields
(280-400 mT) and low temperatures (2-70 K). The NV centers in synthetic
type IIb diamonds (nitrogen impurity concentration ~ppm) are prepared with
bulk concentrations of cm to cm
by high-energy electron irradiation and subsequent annealing. We find that a
proper post-radiation anneal (1000C for 60 mins) is critically
important to repair the radiation damage and to recover long electron spin
coherence times for NVs. After the annealing, spin coherence times of T~ms at 5~K are achieved, being only limited by C nuclear spectral
diffusion in natural abundance diamonds. At X-band magnetic fields, strong
electron spin echo envelope modulation (ESEEM) is observed originating from the
central N nucleus. The ESEEM spectral analysis allows for accurate
determination of the N nuclear hypefine and quadrupole tensors. In
addition, the ESEEM effects from two proximal C sites (second-nearest
neighbor and fourth-nearest neighbor) are resolved and the respective C
hyperfine coupling constants are extracted.Comment: 10 pages, 5 figure
Summary of all cycle II.5 shear and boundary layer measurements, aerodynamics
The two measurement systems were used to measure mean velocity and velocity, mass flux, and total temperature fluctuations in the turbulent boundary on the fuselage of a KC-135 aircraft. The boundary layer thickness ranged between about 20 and 30 cm for the range of flight Mach numbers from about 0.25 to 0.85 and Reynolds numbers between 3 and 6 x 10 to the 6th power/m. The adaptation of each system for use in airborne applications is discussed. The data obtained from each system are given and compared with each other and they indicate that the two systems represent viable ones for use in future airborne turbulence experiments
Trends in Outcomes for Young People with Disabilities: Are We Making Progress?
This paper uses the Current Population Survey (CPS) from 1981-2000 to compare long term trends in socio-economic outcomes for youth (aged 15-21) and young adults (aged 22-29) with work limitations to those for youth and young adults without work limitations. We focus on the years 1988 and 1999: years that roughly correspond to the peaks of successive business cycles. We find that prevalence of work limitations declined for males but increased for females, mostly accounted for by growth for African American females. Despite a substantial reduction in the educational attainment gap between young adults with and without disabilities, gaps in employment, earnings, dependency on public programs and poverty widened substantially. These trends could be due to factors that determine whether individuals report themselves to be work-limited, factors that affect individual outcomes regardless of self-reported work limitation status, or both sets of factors
The use of honey in healing a recalcitrant wound following surgical treatment of hidradenitis suppurativa
Ancient civilizations used honey to heal wounds. Despite the rediscovery of honey by modern physicians1 its use in conventional medicine, unlike in complementary medicine, remains limited. Much anecdotal evidence, some clinical observations, some animal models and some randomised controlled trials support the efficacy of honey in managing wounds2,3 , but few detailed descriptions of the use of honey in healing difficult surgical wounds have previously been published
The LHC di-photon excess and Gauge Coupling Unification in Extra Heterotic-String Derived Models
The di-photon excess observed at the LHC can be explained as a Standard Model
singlet that is produced and decays by heavy vector-like colour triplets and
electroweak doublets in one-loop diagrams. The characteristics of the required
spectrum are well motivated in heterotic-string constructions that allow for a
light . Anomaly cancellation of the symmetry
requires the existence of the Standard Model singlet and vector-like states in
the vicinity of the breaking scale. In this paper we show
that the agreement with the gauge coupling data at one-loop is identical to the
case of the Minimal Supersymmetric Standard Model, owing to cancellations
between the additional states. We further show that effects arising from heavy
thresholds may push the supersymmetric spectrum beyond the reach of the LHC,
while maintaining the agreement with the gauge coupling data. We show that the
string inspired model can indeed account for the observed signal and discuss
the feasibility of obtaining viable scalar mass spectrum.Comment: 26 pages. 11 figures. Published versio
Addressing spin transitions on 209Bi donors in silicon using circularly-polarized microwaves
Over the past decade donor spin qubits in isotopically enriched Si
have been intensely studied due to their exceptionally long coherence times.
More recently bismuth donor electron spins have become popular because Bi has a
large nuclear spin which gives rise to clock transitions (first-order
insensitive to magnetic field noise). At every clock transition there are two
nearly degenerate transitions between four distinct states which can be used as
a pair of qubits. Here it is experimentally demonstrated that these transitions
are excited by microwaves of opposite helicity such that they can be
selectively driven by varying microwave polarization. This work uses a
combination of a superconducting coplanar waveguide (CPW) microresonator and a
dielectric resonator to flexibly generate arbitrary elliptical polarizations
while retaining the high sensitivity of the CPW
Estimation of Delamination Crack Depth Using Passive Thermography
Passive thermography is used to monitor small increases in temperature resulting from delamination damage formation in a composite hat-stiffened panel during quasi-static loading. The heating is composed of two heat generation components. The first component is an instantaneous response due to a strain release during quasi-static loading. The second component is mechanical heating, at the interface of failure, due to fracture damage. This second component produces a transient rise in temperature that is a function of the damage depth and thermal diffusivity. The first component defines the thermal start time for the transient response. A one-dimensional thermal model is used to determine the damage depth. The results are compared to ultrasonic and X-ray CT data. The advantages and limitations of the thermal technique for damage depth detection are discussed
Comments on Anomaly Cancellations by Pole Subtractions and Ghost Instabilities with Gravity
We investigate some aspects of anomaly cancellation realized by the
subtraction of an anomaly pole, stressing on some of its properties in
superspace. In a local formulation these subtractions can be described in terms
of a physical scalar, an axion and related ghosts. They appear to be necessary
for the unitarization of the theory in the ultraviolet, but they may generate
an infrared instability of the corresponding effective action, signalled by
ghost condensation. In particular the subtraction of the superanomaly multiplet
by a pole in superspace is of dubious significance, due to the different nature
of the chiral and conformal anomalies. In turn, this may set more stringent
constraints on the coupling of supersymmetric theories to gravity.Comment: 18 pages. Revised version. To appear in "Classical and Quantum
Gravity
High Accuracy Fuel Flowmeter, Phase 1
Technology related to aircraft fuel mass - flowmeters was reviewed to determine what flowmeter types could provide 0.25%-of-point accuracy over a 50 to one range in flowrates. Three types were selected and were further analyzed to determine what problem areas prevented them from meeting the high accuracy requirement, and what the further development needs were for each. A dual-turbine volumetric flowmeter with densi-viscometer and microprocessor compensation was selected for its relative simplicity and fast response time. An angular momentum type with a motor-driven, spring-restrained turbine and viscosity shroud was selected for its direct mass-flow output. This concept also employed a turbine for fast response and a microcomputer for accurate viscosity compensation. The third concept employed a vortex precession volumetric flowmeter and was selected for its unobtrusive design. Like the turbine flowmeter, it uses a densi-viscometer and microprocessor for density correction and accurate viscosity compensation
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