998 research outputs found
Control Infrastructure for a Pulsed Ion Accelerator
We report on updates to the accelerator controls for the Neutralized Drift
Compression Experiment II, a pulsed induction-type accelerator for heavy ions.
The control infrastructure is built around a LabVIEW interface combined with an
Apache Cassandra backend for data archiving. Recent upgrades added the storing
and retrieving of device settings into the database, as well as ZeroMQ as a
message broker that replaces LabVIEW's shared variables. Converting to ZeroMQ
also allows easy access via other programming languages, such as Python
Laser cooling of new atomic and molecular species with ultrafast pulses
We propose a new laser cooling method for atomic species whose level
structure makes traditional laser cooling difficult. For instance, laser
cooling of hydrogen requires single-frequency vacuum-ultraviolet light, while
multielectron atoms need single-frequency light at many widely separated
frequencies. These restrictions can be eased by laser cooling on two-photon
transitions with ultrafast pulse trains. Laser cooling of hydrogen,
antihydrogen, and many other species appears feasible, and extension of the
technique to molecules may be possible.Comment: revision of quant-ph/0306099, submitted to PR
Electrical activation and electron spin coherence of ultra low dose antimony implants in silicon
We implanted ultra low doses (2x10^11 cm-2) of 121Sb ions into isotopically
enriched 28Si and find high degrees of electrical activation and low levels of
dopant diffusion after rapid thermal annealing. Pulsed Electron Spin Resonance
shows that spin echo decay is sensitive to the dopant depths, and the interface
quality. At 5.2 K, a spin decoherence time, T2, of 0.3 ms is found for profiles
peaking 50 nm below a Si/SiO2 interface, increasing to 0.75 ms when the surface
is passivated with hydrogen. These measurements provide benchmark data for the
development of devices in which quantum information is encoded in donor
electron spins
Transport of multiply and highly charged ions through nanoscale apertures in silicon nitride membranes
Irradiation of Materials with Short, Intense Ion pulses at NDCX-II
We present an overview of the performance of the Neutralized Drift
Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and report on
recent target experiments on beam driven melting and transmission ion energy
loss measurements with nanosecond and millimeter-scale ion beam pulses and thin
tin foils. Bunches with around 10^11 ions, 1-mm radius, and 2-30 ns FWHM
duration have been created with corresponding fluences in the range of 0.1 to
0.7 J/cm^2. To achieve these short pulse durations and mm-scale focal spot
radii, the 1.1 MeV He+ ion beam is neutralized in a drift compression section,
which removes the space charge defocusing effect during final compression and
focusing. The beam space charge and drift compression techniques resemble
necessary beam conditions and manipulations in heavy ion inertial fusion
accelerators. Quantitative comparison of detailed particle-in-cell simulations
with the experiment play an important role in optimizing accelerator
performance.Comment: 15 pages, 7 figures. revised manuscript submitted to Laser and
Particle Beam
Global mental health and climate change: A geo-psychiatry perspectiv
Climate changes affect planet ecosystems, living beings, humans, including their lives, rights, economy, housing, migration, and both physical and mental health. Geo-psychiatry is a new discipline within the field of psychiatry studying the interface between various geo-political factors including geographical, political, economic, commercial and cultural determinants which affect society and psychiatry: it provides a holistic overview on global issues such as climate changes, poverty, public health and accessibility to health care. It identifies geopolitical factors and their effects at the international and national levels, as well as considers the politics of climate changes and poverty within this context. This paper then introduces the Compassion, Assertive Action, Pragmatism, and Evidence Vulnerability Index (CAPE-VI) as a global foreign policy index: CAPE-VI calculates how foreign aid should be prioritised for countries that are at risk or already considered to be fragile. These countries are characterised by various forms of conflict, disadvantaged by extremes of climate change, poverty, human rights abuses, and suffering from internal warfare or terrorism
Male Contraceptives: A New Frontier in Contraception Medicine
In the field of contraceptive studies, discussions primarily focus on the practice of womenâs health and contraception. While it is true that unintended pregnancies and sexually transmitted diseases/infections (STI) pose major challenges in global public health, historically the burden of preventing these has largely fallen on women. Assuming that sexual intercourse requires an equal contribution between two partners, we hold that contraception and STI prevention should be a shared responsibility. Additionally, the ideal contraceptive method should prevent both unplanned pregnancies and STIs simultaneously. While abstinence remains the only 100% proven method of achieving such goals, it is not always practical or achievable in sexually active consenting or nonconsenting individuals. Because pregnancy occurs in a womanâs body, contraception has been regarded as a womenâs health issue and not a general health issue. This dynamic is shifting. There is currently a paucity of male contraceptives and STI prevention methods on the market, but current trends in research and clinical practice promise to equally enable both women and men when making contraception choices. This paper aims to provide a comprehensive review of the male contraceptive methods currently available, as well as to highlight some of the most recently published work in the area of male contraceptive research
Report from the First EPIICAL (Early-treated Perinatally HIV-infected Individuals: Improving Children's Actual Life with Novel Immunotherapeutic Strategies) General Assembly meeting, 9-11 November 2017, Rome, Italy
Three-Dimensional Basin and Fault Structure From a Detailed Seismic Velocity Model of Coachella Valley, Southern California
The Coachella Valley in the northern Salton Trough is known to produce destructive earthquakes, making it a high seismic hazard area. Knowledge of the seismic velocity structure and geometry of the sedimentary basins and fault zones is required to improve earthquake hazard estimates in this region. We simultaneously inverted first P wave travel times from the Southern California Seismic Network (39,998 local earthquakes) and explosions (251 land/sea shots) from the 2011 Salton Seismic Imaging Project to obtain a 3âD seismic velocity model. Earthquakes with focal depths â€10 km were selected to focus on the upper crustal structure. Strong lateral velocity contrasts in the top ~3 km correlate well with the surface geology, including the lowâvelocity (<5 km/s) sedimentary basin and the highâvelocity crystalline basement rocks outside the valley. Sediment thickness is ~4 km in the southeastern valley near the Salton Sea and decreases to <2 km at the northwestern end of the valley. Eastward thickening of sediments toward the San Andreas fault within the valley defines Coachella Valley basin asymmetry. In the Peninsular Ranges, zones of relatively high seismic velocities (~6.4 km/s) between 2â and 4âkm depth may be related to Late Cretaceous mylonite rocks or older inherited basement structures. Other highâvelocity domains exist in the model down to 9âkm depth and help define crustal heterogeneity. We identify a potential fault zone in Lost Horse Valley unassociated with mapped faults in Southern California from the combined interpretation of surface geology, seismicity, and lateral velocity changes in the model
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