586 research outputs found
Results for the response function determination of the Compact Neutron Spectrometer
The Compact Neutron Spectrometer (CNS) is a Joint European Torus (JET)
Enhancement Project, designed for fusion diagnostics in different plasma
scenarios. The CNS is based on a liquid scintillator (BC501A) which allows good
discrimination between neutron and gamma radiation. Neutron spectrometry with a
BC501A spectrometer requires the use of a reliable, fully characterized
detector. The determination of the response matrix was carried out at the Ion
Accelerator Facility (PIAF) of the Physikalisch-Technische Bundesanstalt (PTB).
This facility provides several monoenergetic beams (2.5, 8, 10, 12 and 14 MeV)
and a 'white field'(Emax ~17 MeV), which allows for a full characterization of
the spectrometer in the region of interest (from ~1.5 MeV to ~17 MeV. The
energy of the incoming neutrons was determined by the time of flight method
(TOF), with time resolution in the order of 1 ns. To check the response matrix,
the measured pulse height spectra were unfolded with the code MAXED and the
resulting energy distributions were compared with those obtained from TOF. The
CNS project required modification of the PTB BC501A spectrometer design, to
replace an analog data acquisition system (NIM modules) with a digital system
developed by the 'Ente per le Nuove tecnologie, l'Energia e l'Ambiente' (ENEA).
Results for the new digital system were evaluated using new software developed
specifically for this project.Comment: Proceedings of FNDA 201
Atomic oxygen studies on polymers
The purpose was to study the effects of atomic oxygen on the erosion of polymer based materials. The development of an atomic oxygen neutral beam facility using a SURFATRON surface wave launcher that can produce beam energies between 2 and 3 eV at flux levels as high as approx. 10 to the 17th power atoms/cm (2)-sec is described. Thin film dielectric materials were studied to determine recession rates and and reaction efficiencies as a function of incident beam energy and fluence. Accelerated testing was also accomplished and the values of reaction efficiency compared to available space flight data. Electron microscope photomicrographs of the samples' surface morphology were compared to flight test specimens
Neutron to proton ratios of quasiprojectile and midrapidity emission in the Zn + Zn reaction at 45 MeV/nucleon
Simultaneous measurement of both neutrons and charged particles emitted in
the reaction Zn + Zn at 45 MeV/nucleon allows comparison of the
neutron to proton ratio at midrapidity with that at projectile rapidity. The
evolution of N/Z in both rapidity regimes with increasing centrality is
examined. For the completely re-constructed midrapidity material one finds that
the neutron-to-proton ratio is above that of the overall Zn + Zn
system. In contrast, the re-constructed ratio for the quasiprojectile is below
that of the overall system. This difference provides the most complete evidence
to date of neutron enrichment of midrapidity nuclear matter at the expense of
the quasiprojectile
Tuning a Schottky barrier in a photoexcited topological insulator with transient Dirac cone electron-hole asymmetry
The advent of Dirac materials has made it possible to realize two dimensional
gases of relativistic fermions with unprecedented transport properties in
condensed matter. Their photoconductive control with ultrafast light pulses is
opening new perspectives for the transmission of current and information. Here
we show that the interplay of surface and bulk transient carrier dynamics in a
photoexcited topological insulator can control an essential parameter for
photoconductivity - the balance between excess electrons and holes in the Dirac
cone. This can result in a strongly out of equilibrium gas of hot relativistic
fermions, characterized by a surprisingly long lifetime of more than 50 ps, and
a simultaneous transient shift of chemical potential by as much as 100 meV. The
unique properties of this transient Dirac cone make it possible to tune with
ultrafast light pulses a relativistic nanoscale Schottky barrier, in a way that
is impossible with conventional optoelectronic materials.Comment: Nature Communications, in press (12 pages, 6 figures
Influence of Neutron Enrichment on Disintegration Modes of Compound Nuclei
Cross sections, kinetic energy and angular distributions of fragments with
charge 6Z28 emitted in 78,82Kr+40C at 5.5 MeV/A reactions were
measured at the GANIL facility using the INDRA apparatus. This experiment aims
to investigate the influence of the neutron enrichment on the decay mechanism
of excited nuclei. Data are discussed in comparison with predictions of
transition state and Hauser-Feshbach models.Comment: 8 pages, 1 figure, paper presented at the First Workshop on "State of
the Art in Nuclear Cluster Physics" 13-16 May, 2008, at Strasbourg, France
(SOTANCP2008) and accepted for publication at International Journal of Modern
Physics E (Special Issue), Proceedings of SOTANCP2008 (to be published
Atmospheric pressure plasma analysis by modulated molecular beam mass spectrometry
Fractional no. d. measurements for a radiofrequency plasma needle operating at atm. pressure were obtained using a mol. beam mass spectrometer (MBMS) system designed for diagnostics of atm. plasmas. The MBMS system comprises three differentially pumped stages and a mass/energy analyzer and includes an automated beam-to-background measurement facility as a software-controlled chopper mechanism. The automation of the beam modulation allows the neutral components in the plasma to be rapidly and accurately measured using the mass spectrometer by threshold ionization techniques. Data are reported for plasma generated by a needle plasma source operated using a He/air mixt. In particular, data for the conversion of atm. O and N into nitric oxide are discussed with ref. to its significance for medical applications such as disinfecting wounds and dental cavities and for microsurgery. [on SciFinder (R)
Prescription Drug Labeling Medication Errors: A Big Deal for Pharmacists
Today, in the health care profession, all types of medication errors including missed dose, wrong dosage forms, wrong time interval, wrong route, etc., are a big deal for better patient care. Today, problems related to medications are common in the healthcare profession, and are responsible for significant morbidity, mortality, and cost. Several recent studies have demonstrated that patients frequently have difficulty in reading and understanding medication labels. According to the Institute of Medicine report, “Preventing Medication Errors”, cited poor labeling as a central cause for medication errors in the USA. Evidence suggests that specific content and format of prescription drug labels facilitate communication with and comprehension by patients. Efforts to improve the labels should be guided by such evidence, although an additional study assessing the influence of label design on medication-taking behavior and health outcomes is needed. Several policy options exist to require minimal standards to optimize medical therapy, particularly in light of the new Medicare prescription drug benefit
Photosynthetic responses in Phaeocystis antarctica towards varying light and iron conditions
The effects of iron limitation on photoacclimation to a dynamic light regime were studied in Phaeocystis antarctica. Batch cultures were grown under a sinusoidal light regime, mimicking vertical mixing, under both iron-sufficient and -limiting conditions. Iron-replete cells responded to changes in light intensity by rapid xanthophyll cycling. Maximum irradiance coincided with maximum ratios of diatoxanthin/diadinoxanthin (dt/dd). The maximum quantum yield of photosynthesis (F-v /F-m) was negatively related to both irradiance and dt/dd. Full recovery of F-v /F-m by the end of the light period suggested successful photoacclimation. Iron-limited cells displayed characteristics of high light acclimation. The ratio of xanthophyll pigments to chlorophyll a was three times higher compared to iron-replete cells. Down-regulation of photosynthetic activity was moderated. It is argued that under iron limitation cells maintain a permanent state of high energy quenching to avoid photoinhibition during exposure to high irradiance. Iron-limited cells could maintain a high growth potential due to an increased absorption capacity as recorded by in vivo absorption, which balanced a decrease in F-v/F-m . The increase in the chlorophyll a-specific absorption cross section was related to an increase in carotenoid pigments and a reduction in the package effect. These experiments show that P. antarctica can acclimate successfully to conditions as they prevail in the Antarctic ocean, which may explain the success of this species
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