490 research outputs found
Absolute calibration of GafChromic film for very high flux laser driven ion beams.
We report on the calibration of GafChromic HD-v2 radiochromic film in the extremely high dose regime up to 100 kGy together with very high dose rates up to 7 × 1011 Gy/s. The absolute calibration was done with nanosecond ion bunches at the Neutralized Drift Compression Experiment II particle accelerator at Lawrence Berkeley National Laboratory (LBNL) and covers a broad dose dynamic range over three orders of magnitude. We then applied the resulting calibration curve to calibrate a laser driven ion experiment performed on the BELLA petawatt laser facility at LBNL. Here, we reconstructed the spatial and energy resolved distributions of the laser-accelerated proton beams. The resulting proton distribution is in fair agreement with the spectrum that was measured with a Thomson spectrometer in combination with a microchannel plate detector
Reaching the quantum limit of sensitivity in electron spin resonance
We report pulsed electron-spin resonance (ESR) measurements on an ensemble of
Bismuth donors in Silicon cooled at 10mK in a dilution refrigerator. Using a
Josephson parametric microwave amplifier combined with high-quality factor
superconducting micro-resonators cooled at millikelvin temperatures, we improve
the state-of-the-art sensitivity of inductive ESR detection by nearly 4 orders
of magnitude. We demonstrate the detection of 1700 bismuth donor spins in
silicon within a single Hahn echo with unit signal-to-noise (SNR) ratio,
reduced to just 150 spins by averaging a single Carr-Purcell-Meiboom-Gill
sequence. This unprecedented sensitivity reaches the limit set by quantum
fluctuations of the electromagnetic field instead of thermal or technical
noise, which constitutes a novel regime for magnetic resonance.Comment: Main text : 10 pages, 4 figures. Supplementary text : 16 pages, 8
figure
Assessable Learning Outcomes for the EU Education and Training Framework core and Function A specific modules: Report of an ETPLAS Working Group
Article 23(2) of the European Union Directive 2010/63/EU, which regulates welfare provisions for animals used for scientific purposes, requires that staff involved in the care and use of animals for scientific purposes be adequately educated and trained before they undertake any such work. However, the nature and extent of such training is not stipulated in the Directive. To facilitate Member States in fulfilling their education and training obligations, the European Commission developed a common Education and Training Framework, which was endorsed by the Member States Competent Authorities. An Education & Training Platform for Laboratory Animal Science (ETPLAS) Working Group was recently established to develop further guidance to the Learning Outcomes in the Framework, with the objective to clarify the levels of knowledge and understanding required by trainees, and to provide the criteria by which these Learning Outcomes should be assessed. Using the Framework document as a starting point, assessment criteria for the Learning Outcomes of the modules required for Function A persons (carrying out procedures on animals) for rats, mice and zebrafish were created with sufficient detail to enable trainees, providers and assessors to appreciate the level of knowledge, understanding and skills required to pass each module. Adoption and utilization of this document by training providers and accrediting or approving bodies will harmonize introductory education and training for those involved in the care and use of animals for scientific purposes within the European Union, promote mutual recognition of training within and between Member States and therefore free movement of personnel
Electrical activation and electron spin resonance measurements of implanted bismuth in isotopically enriched silicon-28
We have performed continuous wave and pulsed electron spin resonance
measurements of implanted bismuth donors in isotopically enriched silicon-28.
Donors are electrically activated via thermal annealing with minimal diffusion.
Damage from bismuth ion implantation is repaired during thermal annealing as
evidenced by narrow spin resonance linewidths (B_pp=12uT and long spin
coherence times T_2=0.7ms, at temperature T=8K). The results qualify ion
implanted bismuth as a promising candidate for spin qubit integration in
silicon.Comment: 4 pages, 4 figure
QFT on homothetic Killing twist deformed curved spacetimes
We study the quantum field theory (QFT) of a free, real, massless and
curvature coupled scalar field on self-similar symmetric spacetimes, which are
deformed by an abelian Drinfel'd twist constructed from a Killing and a
homothetic Killing vector field. In contrast to deformations solely by Killing
vector fields, such as the Moyal-Weyl Minkowski spacetime, the equation of
motion and Green's operators are deformed. We show that there is a *-algebra
isomorphism between the QFT on the deformed and the formal power series
extension of the QFT on the undeformed spacetime. We study the convergent
implementation of our deformations for toy-models. For these models it is found
that there is a *-isomorphism between the deformed Weyl algebra and a reduced
undeformed Weyl algebra, where certain strongly localized observables are
excluded. Thus, our models realize the intuitive physical picture that
noncommutative geometry prevents arbitrary localization in spacetime.Comment: 23 pages, no figures; v2: extended discussion of physical
consequences, compatible with version to be published in General Relativity
and Gravitatio
PSS44 USTEKINUMAB IMPROVES WORK PRODUCTIVITY AND DECREASES WORKDAYS MISSED DUE TO PSORIASIS IN PATIENTS WITH MODERATE TO SEVERE PSORIASIS
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Electronic sputtering and desorption effects in TOF-SIMS studies using slow highly charged ions like Au{sup 69+}
Secondary ion yields from highly oriented pyrolytic graphite (HOPG) and SiO{sub 2} (native oxide on float zone silicon) targets at impact of slow (v {approx} 0.3 v{sub bohr}) highly charged ions have been measured by Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS). A direct comparison of collisional and electronic effects in secondary ion production using a beam of charge state equilibrated 300 keV Xe{sup 1+} shows a secondary ion yield increase with incident ion charge of {>=}100
Beam power scale-up in MEMS based multi-beam ion accelerators
We report on the development of multi-beam RF linear ion accelerators that
are formed from stacks of low cost wafers and describe the status of beam power
scale-up using an array of 120 beams. The total argon ion current extracted
from the 120-beamlet extraction column was 0.5 mA. The measured energy gain in
each RF gap reached as high as 7.25 keV. We present a path of using this
technology to achieve ion currents >1 mA and ion energies >100 keV for
applications in materials processing
Coulomb Explosion and Thermal Spikes
A fast ion penetrating a solid creates a track of excitations. This can
produce displacements seen as an etched track, a process initially used to
detect energetic particles but now used to alter materials. From the seminal
papers by Fleischer et al. [Phys. Rev. 156, 353 (1967)] to the present [C.
Trautmann, S. Klaumunzer and H. Trinkaus, Phys. Rev. Lett. 85, 3648 (2000)],
`Coulomb explosion' and thermal spike models are treated as conflicting models
for describing ion track effects. Here molecular dynamics simulations of
electronic-sputtering, a surface manifestation of ion track formation, show
that `Coulomb explosion' produces a `heat' spike so that these are early and
late aspects of the same process. Therefore, differences in scaling are due to
the use of incomplete spike models.Comment: Submitted to PRL. 4 pages, 3 figures. For related movies see:
http://dirac.ms.virginia.edu/~emb3t/coulomb/coulomb.html PACS added in new
versio
Electron spin as a spectrometer of nuclear spin noise and other fluctuations
This chapter describes the relationship between low frequency noise and
coherence decay of localized spins in semiconductors. Section 2 establishes a
direct relationship between an arbitrary noise spectral function and spin
coherence as measured by a number of pulse spin resonance sequences. Section 3
describes the electron-nuclear spin Hamiltonian, including isotropic and
anisotropic hyperfine interactions, inter-nuclear dipolar interactions, and the
effective Hamiltonian for nuclear-nuclear coupling mediated by the electron
spin hyperfine interaction. Section 4 describes a microscopic calculation of
the nuclear spin noise spectrum arising due to nuclear spin dipolar flip-flops
with quasiparticle broadening included. Section 5 compares our explicit
numerical results to electron spin echo decay experiments for phosphorus doped
silicon in natural and nuclear spin enriched samples.Comment: Book chapter in "Electron spin resonance and related phenomena in low
dimensional structures", edited by Marco Fanciulli. To be published by
Springer-Verlag in the TAP series. 35 pages, 9 figure
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