100 research outputs found
Exchange energies in CoFeB/Ru/CoFeB Synthetic Antiferromagnets
The interlayer exchange coupling confers specific properties to Synthetic
Antiferromagnets that make them suitable for several applications of
spintronics. The efficient use of this magnetic configuration requires an
in-depth understanding of the magnetic properties and their correlation with
the material structure. Here we establish a reliable procedure to quantify the
interlayer exchange coupling and the intralayer exchange stiffness in synthetic
antiferromagnets; we apply it to the ultrasmooth and amorphous
CoFeB (5-40 nm)/Ru/ CoFeB material
platform. The complex interplay between the two exchange interactions results
in a gradient of the magnetization orientation across the thickness of the
stack which alters the hysteresis and the spin wave eigenmodes of the stack in
a non trivial way. We measured the field-dependence of the frequencies of the
first four spin waves confined within the thickness of the stack. We modeled
these frequencies and the corresponding thickness profiles of these spin waves
using micromagnetic simulations. The comparison with the experimental results
allows to deduce the magnetic parameters that best account for the sample
behavior. The exchange stiffness is established to be 16 2 pJ/m,
independently of the CoFeB thickness. The interlayer
exchange coupling starts from -1.7 mJ/m for the thinnest layers and it can
be maintained above -1.3 mJ/m for CoFeB layers as thick as 40 nm. The
comparison of our method with earlier characterizations using the sole
saturation fields argues for a need to revisit the tabulated values of
interlayer exchange coupling in thick synthetic antiferromagnets
Monitoring the Bragg peak location of 73 MeV/u carbon ions by means of prompt -ray measurements
By means of a time-of-flight technique, we measured the longitudinal profile
of prompt -rays emitted by 73 MeV/u C ions irradiating a PMMA
target. This technique allowed us to minimize the shielding against neutrons
and scattered -rays, and to correlate prompt gamma emission to the ion
path. This correlation, together with a high counting rate, paves the way
toward real-time monitoring of the longitudinal dose profile during ion therapy
treatments. Moreover, the time correlation between the prompt gamma detection
and the transverse position of the incident ions measured by a beam monitor can
provide real-time 3D control of the irradiation.Comment: to be published in Applied Physics Letter
Real time monitoring of the Bragg-peak position in ion therapy by means of single photon detection
For real-time monitoring of the longitudinal position of the Bragg-peak during an ion therapy treatment, a novel non-invasive technique has been recently proposed that exploits the detection of prompt -rays issued from nuclear fragmentation. Two series of experiments have been performed at the GANIL and GSI facilities with 95 MeV/u and 305 MeV/u 12C6+ ion beams stopped in PMMA and water phantoms. In both experiments a clear correlation was obtained between the carbon ion range and the prompt photon profile. Additionally, an extensive study has been performed to investigate whether a prompt neutron component may be correlated with the carbon ion range. No such correlation was found. The present paper demonstrates that a collimated set-up can be used to detect single photons by means of time-of-flight measurements, at those high energies typical for ion therapy. Moreover, the applicability of the technique both at cyclotron and synchrotron facilities is shown. It is concluded that the detected photon count rates provide sufficiently high statistics to allow real-time control of the longitudinal position of the Bragg-peak under clinical conditions
Development of a Compton camera for medical applications based on silicon strip and scintillation detectors
International audienceA Compton camera is being developed for the purpose of ion-range monitoring during hadrontherapy via the detection of prompt-gamma rays. The system consists of a scintillating fiber beam tagging hodoscope, a stack of double sided silicon strip detectors (90 Ă‚ 90 Ă‚ 2 mm 3 , 2 Ă‚ 64 strips) as scatter detectors, as well as bismuth germanate (BGO) scintillation detectors (38 Ă‚ 35 Ă‚ 30 mm 3 , 100 blocks) as absorbers. The individual components will be described, together with the status of their characterization
Nouvelles méthodes d'imagerie en ligne pour le contrôle de l'irradiation en hadronthérapie
International audienc
Real-Time Online Monitoring of the Ion Range by Means of Prompt Secondary Radiations
International audiencePrompt secondary radiations such as gamma rays and protons can be used for ion-range monitoring during ion therapy either on an energy-slice basis or on a pencil-beam basis. We present a review of the ongoing activities in terms of detector developments, imaging, experimental and theoretical physics issues concerning the correlation between the physical dose and hadronic processe
Intégration temporelle pour une détection robuste d\textquoterightobjets mobiles éloignés à partir d\textquoterightune caméra en mouvement
International audienc
Abattage et réfrigération des moutons
[Notes_IRSTEA]ann./bibl./tabl./pl.Les aspects techniques et économiques sont successivement passés en revue pour l'abattage et la préparation des carcasses de mouton, le traitement des principaux produits du cinquième quartier, et la réfrigération des produits
Real-time monitoring of ion ranges
International audienc
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