580 research outputs found
Recent Progress of RF Cavity Study at Mucool Test Area
In order to develop an RF cavity that is applicable for a muon beam cooling
channel, a new facility, called Mucool Test Area (MTA) has been built at
Fermilab. MTA is a unique facility whose purpose is to test RF cavities in
various conditions. There are 201 and 805 MHz high power sources, a 4-Tesla
solenoid magnet, a cryogenic system including a Helium liquifier, an explosion
proof apparatus to operate gaseous/liquid Hydrogen, and a beam transport line
to send an intense H- beam from the Fermilab Linac accelerator to the MTA hall.
Recent activities at MTA will be discussed in this document.Comment: 4 pp. 13th International Workshop on Neutrino Factories, Superbeams
and Beta beams (NuFact11) 1-6 Aug 2011: Geneva, Switzerlan
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Bone mineral density in patients with inherited bone marrow failure syndromes.
BackgroundPatients with inherited bone marrow failure syndromes (IBMFS) may have several risk factors for low bone mineral density (BMD). We aimed to evaluate the prevalence of low BMD in IBMFS and determine the associated risk factors.MethodsPatients with IBMFS with at least one dual-energy X-ray absorptiometry (DXA) scan were evaluated. Diagnosis of each IBMFS, Fanconi anemia (FA), dyskeratosis congenita, Diamond-Blackfan anemia, and Shwachman-Diamond syndrome was confirmed by syndrome-specific tests. Data were gathered on age, height, and clinical history. DXA scans were completed at the lumbar spine, femoral neck, and forearm. BMD was adjusted for height (HAZ) in children (age ≤20 years). Low BMD was defined as a BMD Z-score and HAZ ≤-2 in adults and children, respectively, in addition to patients currently on bisphosphonate therapy.ResultsNine of thirty-five adults (26%) and eleven of forty children (27%) had low BMD. Adults with FA had significantly lower BMD Z-scores than those with other diagnoses; however, HAZ did not vary significantly in children by diagnosis. Risk factors included hypogonadism, iron overload, and glucocorticoid use.ConclusionsAdults and children with IBMFS have high prevalence of low BMD. Prompt recognition of risk factors and management are essential to optimize bone health
Accelerator performance analysis of the Fermilab Muon Campus
Fermilab is dedicated to hosting world-class experiments in search of new
physics that will operate in the coming years. The Muon g-2 Experiment is one
such experiment that will determine with unprecedented precision the muon
anomalous magnetic moment, which offers an important test of the Standard
Model. We describe in this study the accelerator facility that will deliver a
muon beam to this experiment. We first present the lattice design that allows
for efficient capture, transport, and delivery of polarized muon beams. We then
numerically examine its performance by simulating pion production in the
target, muon collection by the downstream beam line optics, as well as
transport of muon polarization. We finally establish the conditions required
for the safe removal of unwanted secondary particles that minimizes
contamination of the final beam.Comment: 10 p
THE CO.TR.I.S SYSTEM: TOWARDS A SMARTER COASTAL TRANSPORT NETWORK FOR SMART ISLANDS
The Coastal Transport Information System (Co.Tr.I.S) is a multifunction information system that is developed for the effective design of coastal transportation lines. The system incorporates several subsystems which include the models, tools, and techniques that support the design of improved coastal networks. Co.Tr.I.S main aim is to support any decision making process of the involved players (Ministry, Maritime companies, Local Authorities, Travel Agencies, Passengers, etc) regarding the improvement & the optimal use of a coastal transport network. Co.Tr.I.S data retrieval, analysis, visualization, network design & decision support can accelerate the very slow (currently annual in Aegean) rate of coastal transport network update/upgrade procedures, and, create smarter network implementations that may adapt online on the various demand or requirement changes or updates. Connections, transportation, mobility, as well as port automation are some of the key factors for the “smartification” of entire islands especially in an archipelago like the Aegean Sea. In this work, we present the network design optimization functionality of Co.Tr.I.S, the various optimization stages, the Genetic Algorithm (GA) implementations and its potential to propose a better network design based on each user preferences. A sample case study is given to show its smartness & adaptability to each user needs and, finally, a discussion follows on how it could be complemented by emerging smart technologies for smarter islands
Dynamics of ripple formation on silicon surfaces by ultrashort laser pulses in sub-ablation conditions
An investigation of ultrashort pulsed laser induced surface modification due
to conditions that result in a superheated melted liquid layer and material
evaporation are considered. To describe the surface modification occurring
after cooling and resolidification of the melted layer and understand the
underlying physical fundamental mechanisms, a unified model is presented to
account for crater and subwavelength ripple formation based on a synergy of
electron excitation and capillary waves solidification. The proposed
theoretical framework aims to address the laser-material interaction in
sub-ablation conditions and thus minimal mass removal in combination with a
hydrodynamics-based scenario of the crater creation and ripple formation
following surface irradiation with single and multiple pulses, respectively.
The development of the periodic structures is attributed to the interference of
the incident wave with a surface plasmon wave. Details of the surface
morphology attained are elaborated as a function of the imposed conditions and
results are tested against experimental data
Making silicon hydrophobic: wettability control by two-lengthscale simultaneous patterning with femtosecond laser irradiation
We report on the wettability properties of silicon surfaces, simultaneously structured on the
micrometre-scale and the nanometre-scale by femtosecond (fs) laser irradiation to render
silicon hydrophobic. By varying the laser fluence, it was possible to control the wetting
properties of a silicon surface through a systematic and reproducible variation of the
surface roughness. In particular, the silicon–water contact angle could be increased from
66° to more
than 130°. Such behaviour is described by incomplete liquid penetration within the silicon features,
still leaving partially trapped air inside. We also show how controllable design and
tailoring of the surface microstructures by wettability gradients can drive the
motion of the drop's centre of mass towards a desired direction (even upwards)
Investigation of femtosecond laser induced ripple formation on copper for varying incident angle
The hydrodynamic mechanisms associated with the formation of femtosecond laser induced ripples on copper for two angles of incidence are reported. Laser pulse length used for this work is 35 fs. A revised two-temperature model is presented that comprises transient changes of optical characteristics during the irradiation with femtosecond pulses to model relaxation processes and thermal response in bulk copper. The theoretical model takes into account the fluid flow dynamics that result in ripple periods shorter than the wavelength of the surface plasmon polaritons. Theoretical and experimental results are reported for incident angles of 0°and 45° relative to the surface normal. There is agreement between the experimentally measured and the theoretically predicted ripple periodicity for 50 pulses at 0° incidence. By contrast, for 100 pulses at 0° incidence, and 50 and 100 pulses at 45° incidence, the experimentally measured ripples have a larger period than the one predicted by the model while the trends in period with increased incident angle, and increased fluence are in agreement between the experimental and the theoretical results
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