32 research outputs found
A First Search for Cosmogenic Neutrinos with the ARIANNA Hexagonal Radio Array
The ARIANNA experiment seeks to observe the diffuse flux of neutrinos in the
10^8 - 10^10 GeV energy range using a grid of radio detectors at the surface of
the Ross Ice Shelf of Antarctica. The detector measures the coherent Cherenkov
radiation produced at radio frequencies, from about 100 MHz to 1 GHz, by
charged particle showers generated by neutrino interactions in the ice. The
ARIANNA Hexagonal Radio Array (HRA) is being constructed as a prototype for the
full array. During the 2013-14 austral summer, three HRA stations collected
radio data which was wirelessly transmitted off site in nearly real-time. The
performance of these stations is described and a simple analysis to search for
neutrino signals is presented. The analysis employs a set of three cuts that
reject background triggers while preserving 90% of simulated cosmogenic
neutrino triggers. No neutrino candidates are found in the data and a
model-independent 90% confidence level Neyman upper limit is placed on the all
flavor neutrino+antineutrino flux in a sliding decade-wide energy bin. The
limit reaches a minimum of 1.9x10^-23 GeV^-1 cm^-2 s^-1 sr^-1 in the 10^8.5 -
10^9.5 GeV energy bin. Simulations of the performance of the full detector are
also described. The sensitivity of the full ARIANNA experiment is presented and
compared with current neutrino flux models.Comment: 22 pages, 22 figures. Published in Astroparticle Physic
Building the impedance model of a real machine
A reliable impedance model of a particle accelerator can be built by combining the beam coupling impedances of all the components. This is a necessary step to be able to evaluate the machine performance limitations, identify the main contributors in case an impedance reduction is required, and study the interaction with other mechanisms such as optics nonlinearities, transverse damper, noise, space charge, electron cloud, beam-beam (in a collider).
The main phases to create a realistic impedance model, and verify it experimentally, will be reviewed, highlighting the main challenges. Some examples will be presented revealing the levels of precision of machine impedance models that have been achieved
LHC Impedance Model: Experience with High Intensity Operation in the LHC
The CERN Large Hadron Collider (LHC) is now in luminosity production mode and has been pushing its performance in the past months by increasing the proton beam brightness, the collision energy and the machine availability. As a consequence, collective effects have started to become more and more visible and have effectively slowed down the performance increase of the machine. Among these collective effects, the interaction of brighter LHC bunches with the longitudinal and transverse impedance of the machine has been observed to generate beam induced heating, as well as longitudinal and transverse instabilities since 2010. This contribution reviews the current LHC impedance model obtained from theory, simulations and bench measurements as well as a selection of measured effects with the LHC beam
Update on Beam Induced RF Heating in the LHC
Since June 2011 the rapid increase of the luminosity performance of the LHC has come at the expense of both increased temperature and pressure of specific, near-beam, LHC equipment. In some cases, this beam induced heating has caused delays while equipment cool-down, beam dumps and even degradation of some devices. This contribution gathers the observations of beam induced heating, attributed to longitudinal beam coupling impedance, their current level of understanding and possible actions planned to be implemented during the 1st LHC Long Shutdown (LS1) in 2013-2014
Nanoforum 2013:
This issue contains a selection of papers presented at NANOFORUM 2013 that reached its ninth
edition and confirmed itself as a first-rate meeting dedicated to nano and advanced technologies.
The aim of the event was, as tradition of this successful series of conferences, to present an
overview of recent topics being developed in many of the wide-ranging fields related to the
“nanoworld,” and to give a stimulating glimpse on future directions in nanotechnology.
NANOFORUM 2013 has provided the opportunity to meet specialized Italian and foreign operators
of companies and research center
Biomedical applications of nanodiamonds: An overview
Nanodiamonds are a novel class of nanomaterials which have raised much attention for application in biomedical field, as they combine the possibility of being produced on large scale using relatively inexpensive synthetic processes, of being fluorescent as a consequence of the presence of nitrogen vacancies, of having their surfaces functionalized, and of having good biocompatibility. Among other applications, we mainly focus on drug delivery, including cell interaction, targeting, cancer therapy, gene and protein delivery. In addition, nanodiamonds for bone and dental implants and for antibacterial use is discussed. Techniques for detection and imaging of nanodiamonds in biological tissues are also reviewed, including electron microscopy, fluorescence microscopy, Raman mapping, atomic force microscopy, thermal imaging, magnetic resonance imaging, and positron emission tomography, either in vitro, in vivo, or ex vivo. Toxicological aspects related to the use of nanodiamonds are also discussed. Finally, patents, preclinical and clinical trials based on the use of nanodiamonds for biomedical applications are reviewed