114,461 research outputs found
Terahertz-driven linear electron acceleration
The cost, size and availability of electron accelerators is dominated by the
achievable accelerating gradient. Conventional high-brightness radio-frequency
(RF) accelerating structures operate with 30-50 MeV/m gradients. Electron
accelerators driven with optical or infrared sources have demonstrated
accelerating gradients orders of magnitude above that achievable with
conventional RF structures. However, laser-driven wakefield accelerators
require intense femtosecond sources and direct laser-driven accelerators and
suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing
requirements due to the short wavelength of operation. Here, we demonstrate the
first linear acceleration of electrons with keV energy gain using
optically-generated terahertz (THz) pulses. THz-driven accelerating structures
enable high-gradient electron or proton accelerators with simple accelerating
structures, high repetition rates and significant charge per bunch. Increasing
the operational frequency of accelerators into the THz band allows for greatly
increased accelerating gradients due to reduced complications with respect to
breakdown and pulsed heating. Electric fields in the GV/m range have been
achieved in the THz frequency band using all optical methods. With recent
advances in the generation of THz pulses via optical rectification of slightly
sub-picosecond pulses, in particular improvements in conversion efficiency and
multi-cycle pulses, increasing accelerating gradients by two orders of
magnitude over conventional linear accelerators (LINACs) has become a
possibility. These ultra-compact THz accelerators with extremely short electron
bunches hold great potential to have a transformative impact for free electron
lasers, future linear particle colliders, ultra-fast electron diffraction,
x-ray science, and medical therapy with x-rays and electron beams
Can we apply accelerator-cores to control-intensive programs?
There is a trend towards using accelerators to increase performance and energy efficiency of general-purpose processors. So far, most accelerators have been build with HPC-applications in mind. A question that arises is how well can other applications benefit from these accelerators?
In this paper, we discuss the acceleration of three benchmarks
using the SPUs of a Cell-BE. We analyze the potential speedup given the inherent parallelism in the applications. While the potential speedup is significant in all benchmarks, the obtained speedup lags behind due to a mismatch between micro-architectural properties of the accelerators and the benchmark properties
Future Accelerators (?)
I describe the future accelerator facilities that are currently foreseen for
electroweak scale physics, neutrino physics, and nuclear structure. I will
explore the physics justification for these machines, and suggest how the case
for future accelerators can be made.Comment: Presented at the Conference on the Intersections of Particle and
Nuclear Physics (CIPANP 2003), New York City, May 200
Gravitomagnetic Accelerators
We study a simple class of time-dependent rotating Ricci-flat cylindrically
symmetric spacetime manifolds whose geodesics admit gravitomagnetic jets. The
helical paths of free test particles in these jets up and down parallel to the
rotation axis are analogous to those of charged particles in a magnetic field.
The jets are attractors. The jet speed asymptotically approaches the speed of
light. In effect, such source-free spacetime regions act as "gravitomagnetic
accelerators".Comment: 4 pages, 2 figures; v2: reference added; v3: slightly expanded
version accepted for publication in Phys. Lett.
Linear accelerators
Radio-frequency linear accelerators are used as injectors for synchrotrons
and as stand-alone accelerators for the production of intense particle beams,
thanks to their ability to accelerate high beam currents at high repetition
rates. This lecture introduces their main features, reviewing the different
types of accelerating structures used in linacs and presenting the main
characteristics of linac beam dynamics. Building on these bases, the
architecture of modern proton linear accelerators is presented with a
particular emphasis on high-energy and high-beam-power applications.Comment: 25 pages, contribution to the CAS - CERN Accelerator School: Course
on High Power Hadron Machines; 24 May - 2 Jun 2011, Bilbao, Spai
- …