945 research outputs found
An original image slicer designed for Integral Field Spectroscopy with NIRSpec/JSWT
Integral Field Spectroscopy (IFS) provides a spectrum simultaneously for each
spatial sample of an extended, two-dimensional field. It consists of an
Integral Field Unit (IFU) which slices and re-arranges the initial field along
the entrance slit of a spectrograph. This article presents an original design
of IFU based on the advanced image slicer concept. To reduce optical
aberrations, pupil and slit mirrors are disposed in a fan-shaped configuration
that means that angles between incident and reflected beams on each elements
are minimized. The fan-shaped image slicer improves image quality in terms of
wavefront error by a factor 2 comparing with classical image slicer and,
furthermore it guaranties a negligible level of differential aberration in the
field. As an exemple, we are presenting the design LAM used for its proposal at
the NIRSPEC/IFU invitation of tender.Comment: Submitted to Optical Engineerin
Time Calibration of TileCal Modules with Cosmic Muons
A method to synchronize TileCal readout in time using cosmic muons has been developed. It is based on the comparison between the expected time of flight of muons crossing TileCal cells and the measured time. The method has been applied to cosmic data from September and October of 2007, when different sub-detectors of ATLAS were integrated during the Milestone Weeks. The resolution reached with this method is better than 0.7 ns when the statistical error is not the main contribution to the uncertainty
Total Prompt Energy Release in the Neutron-Induced Fission of 235-U, 238-U, and 239-Pu
This study addresses, for the first time, the total prompt energy release and
its components for the fission of 235-U, 238-U, and 239-Pu as a function of the
kinetic energy of the neutron inducing the fission. The components are
extracted from experimental measurements, where they exist, together with
model-dependent calculation, interpolation, and extrapolation. While the
components display clear dependencies upon the incident neutron energy, their
sums display only weak, yet definite, energy dependencies. Also addressed is
the total prompt energy deposition in fission for the same three systems.
Results are presented in equation form. New measurements are recommended as a
consequence of this study.Comment: Accepted for publication in Nuclear Physics
Modeling a Slicer Mirror Using Zemax User-Defined Surface
A slicer mirror is a complex surface composed by many tilted and decentered
mirrors sub-surfaces. The major difficulty to model such a complex surface is
the large number of parameters used to define it. The Zemax's
multi-configuration mode is usually used to specify each parameters (tilts,
curvatures, decenters) for each mirror sub-surface which are then considered
independently. Otherwise making use of the User-Defined Surface (UDS-DLL) Zemax
capability, we are able to consider the set of sub-surfaces as a whole surface.
In this paper, we present such a UDS-DLL tool comparing its performance with
those of the classical multi-configuration mode. In particular, we explore the
use of UDS-DLL to investigate the cross-talk due to the diffraction on the
slicer array mirrors which has been a burden task when using
multi-configuration mode.Comment: Submitted to the proceedings of the Durham Integral Field
Spectroscopy Workshop July 4th-8th 200
An original image slicer designed for Integral Field Spectroscopy with NIRSpec/JSWT
Submitted to Optical Engineering.Integral Field Spectroscopy (IFS) provides a spectrum simultaneously for each spatial sample of an extended, two-dimensional field. It consists of an Integral Field Unit (IFU) which slices and re-arranges the initial field along the entrance slit of a spectrograph. This article presents an original design of IFU based on the advanced image slicer concept. To reduce optical aberrations, pupil and slit mirrors are disposed in a fan-shaped configuration that means that angles between incident and reflected beams on each elements are minimized. The fan-shaped image slicer improves image quality in terms of wavefront error by a factor 2 comparing with classical image slicer and, furthermore it guaranties a negligible level of differential aberration in the field. As an exemple, we are presenting the design LAM used for its proposal at the NIRSPEC/IFU invitation of tender
Peptides in Receptor-Mediated Radiotherapy: From Design to the Clinical Application in Cancers
Short peptides can show high affinity for specific receptors overexpressed on tumor cells. Some of these are already used in cancerology as diagnostic tools and others are in clinical trials for therapeutic applications. Therefore, peptides exhibit great potential as a diagnostic tool but also as an alternative or an additional antitumoral approach upon the covalent attachment of a therapeutic moiety such as a radionuclide or a cytotoxic drug. The chemistry offers flexibility to graft onto the targeting-peptide either fluorine or iodine directly, or metallic radionuclides through appropriate chelating agent. Since short peptides are straightforward to synthesize, there is an opportunity to further improve existing peptides or to design new ones for clinical applications. However, several considerations have to be taken into account to optimize the recognition properties of the targeting-peptide to its receptor, to improve its stability in the biological fluids and its residence in the body, or to increase its overall therapeutic effect. In this review, we highlight the different aspects which need to be considered for the development of an efficient peptide receptor-mediated radionuclide therapy in different neoplasms
Conductive and convective heat transfer in fluid flows between differentially heated and rotating cylinders
The flow of fluid confined between a heated rotating cylinder and a cooled
stationary cylinder is a canonical experiment for the study of heat transfer in
engineering. The theoretical treatment of this system is greatly simplified if
the cylinders are assumed to be of infinite length or periodic in the axial
direction, in which cases heat transfer occurs only through conduction as in a
solid. We here investigate numerically heat transfer and the onset of
turbulence in such flows by using both periodic and no-slip boundary conditions
in the axial direction. We obtain a simple linear criterion that determines
whether the infinite-cylinder assumption can be employed. The curvature of the
cylinders enters this linear relationship through the slope and additive
constant. For a given length-to-gap aspect ratio there is a critical Rayleigh
number beyond which the laminar flow in the finite system is convective and so
the behaviour is entirely different from the periodic case. The criterion does
not depend on the Prandtl number and appears quite robust with respect to the
Reynolds number. In particular, it continues to work reasonably in the
turbulent regime.Comment: 25 pages, 9 figure
Spallation Residues in the Reaction 56Fe + p at 0.3, 0.5, 0.75, 1.0 and 1.5 A GeV
The spallation residues produced in the bombardment of 56}Fe at 1.5, 1.0,
0.75, 0.5 and 0.3 A GeV on a liquid-hydrogen target have been measured using
the reverse kinematics technique and the Fragment Separator at GSI (Darmstadt).
This technique has permitted the full identification in charge and mass of all
isotopes produced with cross-sections larger than 10^{-2} mb down to Z=8. Their
individual production cross-sections and recoil velocities at the five energies
are presented. Production cross-sections are compared to previously existing
data and to empirical parametric formulas, often used in cosmic-ray
astrophysics. The experimental data are also extensively compared to different
combinations of intra-nuclear cascade and de-excitation models. It is shown
that the yields of the lightest isotopes cannot be accounted for by standard
evaporation models. The GEMINI model, which includes an asymmetric fission
decay mode, gives an overall good agreement with the data. These experimental
data can be directly used for the estimation of composition modifications and
damages in materials containing iron in spallation sources. They are also
useful for improving high precision cosmic-ray measurements.Comment: Submited to Phys. Rev. C (10/2006
'Whatever it takes' to change beliefs: Evidence from Twitter
Resumen de la comunicación[EN] The sovereign debt literature emphasizes the possibility of avoiding a selffulfilling
default crisis if markets anticipate the central bank to act as the
lender of last resort. Motivated by the events of summer 2012 in the
eurozone, this paper investigates the extent to which changes in beliefs about
an intervention of the European Central Bank (ECB) explain the sudden
reduction of government bond yields for the so-called PIIGS countries. To
proxy beliefs, we study Twitter data from July to September 2012 and extract
beliefs using machine learning techniques. Our results are consistent with the
theoretical prediction that a central bank, which credibly commits to an
intervention, can restore the fundamental "good" equilibrium.Stiefel, M.; Vivès, R. (2018). 'Whatever it takes' to change beliefs: Evidence from Twitter. En 2nd International Conference on Advanced Reserach Methods and Analytics (CARMA 2018). Editorial Universitat Politècnica de València. 254-254. https://doi.org/10.4995/CARMA2018.2018.8328OCS25425
Measurement of residual nucleus cross sections and recoil energies in p + Fe collisions at 300, 500, 750, 1000 and 1500 MeV
The production of residual nuclei in p + Fe collisions has been measured at GSI on the FRS facility by means of the reverse kinematic techniques at 300, 500, 750, 1000 and 1500 MeV/A. The cross-sections larger than 0.01 mb of all isotopes with Z larger than 8 have been obtained. Velocity distributions were also measured. Comparisons to models describing spallation reactions and some empirical formulae often used in astrophysics are presented. These data are directly used to calculate impurety production and DPAs in a thin window as foreseen in spallation sources or accelerator-driven systems
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