1,892 research outputs found
European research activities on charge state breeding related to radioactive ion beam facilities
International audienceEuropean effort on charge breeders is mainly dedicated to present and future Radioactive Ion Beam facilities. The main projects are High Intensity and Energy-ISOLDE at CERN, SPIRAL2 at GANIL and EURISOL. Most of the experimental developments are funded by the European programmes EURONS (EUROpean Nuclear Structure) and EURISOL (European Isotope Separation On-Line Radioactive Ion Beam Facility). Two ion source types (EBIS and ECRIS) have been adapted to accept the injection and the capture of an ion beam, in order to increase its charge with the highest efficiency within the shortest time. Both charge breeders are advantages and disadvantages with regard to their use in a Radioactive Ion Beam facility. The most important parameters studied are acceptance (in emittance and intensity) of the charge breeder, efficiency and charge breeding time of a specific n+ charge state, emittance of the extracted n+ beam. The charge breeder parameters are studied with different 1+ ion sources dedicated to 1+ radioactive ion beam production and the tuning procedure of the charge breeder as a beam line section of a specific accelerator is established and measured too
First plasma of the A-PHOENIX electron cyclotron resonance ion source
International audienceA-PHOENIX is a new compact hybrid electron cyclotron resonance ion source (ECRIS) using a large permanent magnet hexapole (1.92 Tesla at the magnet surface) and High Temperature Superconducting Solenoids (3 Tesla) to make min-|B| structure suitable for 28 GHz CW operation. The final assembly of the source was achieved at the end of june 2007. The first plasma of A-PHOENIX at 18 GHz was done on August the 16th 2007. The technological specificities of A-PHOENIX are presented. The large hexapole builded is presented and experimental magnetic measurements show that it is nominal with respect to simulation. A fake plasma chamber prototype including thin iron inserts showed that the predicted radial magnetic confinement can be fulfilled up to 2.15 Tesla at the plasma chamber wall. Planning of experiments scheduled until end 2008 is presented
Normal subgroups in the Cremona group (long version)
Let k be an algebraically closed field. We show that the Cremona group of all
birational transformations of the projective plane P^2 over k is not a simple
group. The strategy makes use of hyperbolic geometry, geometric group theory,
and algebraic geometry to produce elements in the Cremona group that generate
non trivial normal subgroups.Comment: With an appendix by Yves de Cornulier. Numerous but minors
corrections were made, regarding proofs, references and terminology. This
long version contains detailled proofs of several technical lemmas about
hyperbolic space
Full-Course Oral Levofloxacin for Treatment of Hospitalized Patients with Community-Acquired Pneumonia
Most guidelines for the management of hospitalized patients with community-acquired pneumonia (CAP) recommend commencing therapy with intravenous antibiotics, primarily because of concern about absorption of oral antibiotics in acutely ill patients. However, patients who respond are rapidly switched to oral therapy, which has been shown to reduce costs and to shorten the length of stay. The aim of the present study was to determine whether a full course of oral antibiotics is as efficacious and as safe as intravenous-to-oral sequential antibiotic therapy for the treatment of hospitalized, non-ICU patients with CAP. In an open-labelled, controlled study, 129 hospitalized patients with CAP were randomly assigned in a 2:1 ratio to receive either a full course of oral levofloxacin (500mg q12h) or an intravenous-to-oral sequential therapy consisting of intravenous ceftriaxone (2g q24h) with or without clarithromycin (500mg q12h) followed by an oral antibiotic (a beta-lactam agent in the majority of patients). The primary study endpoint was the resolution of CAP; secondary endpoints included length of stay and overall mortality. CAP resolved in 72 of 79 (91.1%) patients in the levofloxacin group and in 34 of 37 (91.9%) patients in the intravenous-to-oral sequential therapy group (difference, −0.8%, 95%CI, −11.6-10.0). Median length of stay was 8 days (range, 2-74 days) in the levofloxacin group and 10 days (range, 3-29 days) in the intravenous-to-oral sequential therapy group (P=0.28). Day 30 mortality rates were 1.3% (1 of 79) and 8.1% (3 of 37), respectively (difference, −6.8%, 95%CI, −16.0-2.3). Full-course oral levofloxacin is as efficacious and as safe as standard intravenous-to-oral sequential antibiotic therapy for the treatment of hospitalized patients with CA
The Dust Trail of Comet 67P/Churyumov-Gerasimenko
We report the detection of comet 67P/Churyumov-Gerasimenko's dust trail and
nucleus in 24 micron Spitzer Space Telescope images taken February 2004. The
dust trail is not found in optical Palomar images taken June 2003. Both the
optical and infrared images show a distinct neck-line tail structure, offset
from the projected orbit of the comet. We compare our observations to simulated
images using a Monte Carlo approach and a dynamical model for comet dust. We
estimate the trail to be at least one orbit old (6.6 years) and consist of
particles of size >~100 micron. The neck-line is composed of similar sized
particles, particles of size but younger in age. Together, our observations and
simulations suggest grains 100 micron and larger in size dominate the total
mass ejected from the comet. The radiometric effective radius of the nucleus is
1.87 +/- 0.08 km, derived from the Spitzer observation. The Rosetta spacecraft
is expected to arrive at and orbit this comet in 2014. Assuming the trail is
comprised solely of 1 mm radius grains, we compute a low probability (~10^-3)
of a trail grain impacting with Rosetta during approach and orbit insertion.Comment: Accepted for publication in Icaru
Spitzer observations of the asteroid-comet transition object and potential spacecraft target 107P (4015) Wilson-Harrington
Context. Near-Earth asteroid-comet transition object 107P/ (4015)
Wilson-Harrington is a possible target of the joint European Space Agency (ESA)
and Japanese Aerospace Exploration Agency (JAXA) Marco Polo sample return
mission. Physical studies of this object are relevant to this mission, and also
to understanding its asteroidal or cometary nature. Aims. Our aim is to obtain
significant new constraints on the surface thermal properties of this object.
Methods. We present mid-infrared photometry in two filters (16 and 22 microns)
obtained with NASA's Spitzer Space Telescope on February 12, 2007, and results
from the application of the Near Earth Asteroid Thermal Model (NEATM).We
obtained high S/N in two mid-IR bands allowing accurate measurements of its
thermal emission. Results. We obtain a well constrained beaming parameter (eta
= 1.39 +/- 0.26) and obtain a diameter and geometric albedo of D = 3.46 +/-
0.32 km, and pV = 0.059 +/- 0.011. We also obtain similar results when we apply
this best-fitting thermal model to single-band mid-IR photometry reported by
Campins et al. (1995), Kraemer et al. (2005) and Reach et al. (2007).
Conclusions. The albedo of 4015 Wilson-Harrington is low, consistent with those
of comet nuclei and primitive C-, P-, D-type asteorids. We establish a rough
lower limit for the thermal inertia of W-H of 60 Jm^-2s^(-0.5)K^-1 when it is
at r=1AU, which is slightly over the limit of 30 Jm^-2s^(-0.5)K-1 derived by
Groussin et al. (2009) for the thermal inertia of the nucleus of comet
22P/Kopff.Comment: 4 pages, 1 figure and 3 tables. Paper accepted for publicatio
Quenching factor measurement in low pressure gas detector for directional dark matter search
There is considerable experimental effort dedicated to the directional
detection of particle dark matter. Gaseous mu-TPC detectors present the
privileged features of being able to reconstruct the track and the energy of
the recoil nucleus following the interaction. A precise measurement of the
recoil energy is a key point for the directional search strategy. Quenching has
to be taken into account, i.e. only a certain fraction of the recoil energy is
deposited in the ionization channel. Measurements of the ionization quenching
factor for different gas mixture at room temperature have been made with a
dedicated ion beam facility at the LPSC of Grenoble.Comment: Proceedings of the 3rd International conference on Directional
Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10 June 201
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