1,173 research outputs found
Simulation Studies of the NLC with Improved Ground Motion Models
The performance of various systems of the Next Linear Collider (NLC) have
been studied in terms of ground motion using recently developed models. In
particular, the performance of the beam delivery system is discussed. Plans to
evaluate the operation of the main linac beam-based alignment and feedback
systems are also outlined.Comment: Submitted to XX International Linac Conferenc
NLC Luminosity as a Function of Beam Parameters
Realistic calculation of NLC luminosity has been performed using particle
tracking in DIMAD and beam-beam simulations in GUINEA-PIG code for various
values of beam emittance, energy and beta functions at the Interaction Point
(IP). Results of the simulations are compared with analytic luminosity
calculations. The optimum range of IP beta functions for high luminosity was
identified.Comment: 4 pages, 7 figure
Beam-based Feedback Simulations for the NLC Linac
Extensive beam-based feedback systems are planned as an integral part of the
Next Linear Collider (NLC) control system. Wakefield effects are a significant
influence on the feedback design, imposing both architectural and algorithmic
constraints. Studies are in progress to assure the optimal selection of devices
and to refine and confirm the algorithms for the system design. We show the
results of initial simulations, along with evaluations of system response for
various conditions of ground motion and other operational disturbances.Comment: 3 pages. Linac2000 conferenc
Tuning Knobs for the NLC Final Focus
Compensation of optics errors at the Interaction Point (IP) is essential for
maintaining maximum luminosity at the NLC. Several correction systems (knobs)
using the Final Focus sextupoles have been designed to provide orthogonal
compensation of linear and the second order optics aberrations at IP. Tuning
effects of these knobs on the 250 GeV beam were verified using tracking
simulations.Comment: 4 pages, 3 figure
Corrigendum
Identification of grape cultivars from Liguria (north-western Italy)Vitis 48 (4),175-183 (2009
Identification of grape cultivars from Liguria (north-western Italy)
In order to identify grape varieties from Liguria (north-western Italy), 51 accessions (major, minor and neglected cultivars) were compared to those present in the grape collections of the neighbouring regions. Synonyms were confirmed by SSR markers (9 loci). Only 36 unique genetic profiles were found within grapes from Liguria, demonstrating the occurrence of synonyms with cultivars either from the same region or from other grape growing areas. Six evident misnames were found as well as homonyms. Four unexpected synonyms provided an opportunity to trace the likely origin and/or the movement of ancient cultivars, including ‘Vernaccia di San Gimignano’.
Feedback Systems for Linear Colliders
Feedback systems are essential for stable operation of a linear collider,
providing a cost-effective method for relaxing tight tolerances. In the
Stanford Linear Collider (SLC), feedback controls beam parameters such as
trajectory, energy, and intensity throughout the accelerator. A novel dithering
optimization system which adjusts final focus parameters to maximize luminosity
contributed to achieving record performance in the 1997-98 run. Performance
limitations of the steering feedback have been investigated, and improvements
have been made. For the Next Linear Collider (NLC), extensive feedback systems
are planned as an intregal part of the design. Feedback requiremetns for JLC
(the Japanese Linear Collider) are essentially identical to NLC; some of the
TESLA requirements are similar but there are significant differences. For NLC,
algorithms which incorporate improvements upon the SLC implementation are being
prototyped. Specialized systems for the damping rings, rf and interaction point
will operate at high bandwidth and fast response. To correct for the motion of
individual bunches within a train, both feedforward and feedback systems are
planned. SLC experience has shown that feedback systems are an invaluable
operational tool for decoupling systems, allowing precision tuning, and
providing pulse-to-pulse diagnostics. Feedback systems for the NLC will
incorporate the key SLC features and the benefits of advancing technologies.Comment: Invited talk presented at IEEE Particle Accelerator Conference
(PAC99
Status of KLOE-2
In a few months the KLOE-2 detector is expected to start data taking at the
upgraded DANE -factory of INFN Laboratori Nazionali di
Frascati. It aims to collect 25 fb at the peak, and about 5
fb in the energy region between 1 and 2.5 GeV. We review the status and
physics program of the projectComment: 6 pages, 5 figures, to appear in the Proceedings of the PHIPSI09
Workshop, Oct 13-16, 2009, Beijing, Chin
Novel Double Triple Bend Achromat (DTBA) lattice design for a next generation 3 GeV Synchrotron Light Source
The Double Triple Bend Achromat (DTBA) lattice~\cite{DTBAipac16} is a novel
lattice design for a next generation 3 GeV Synchrotron Light Source. Starting
from a modification of the Hybrid Multi Bend Achromat (HMBA)
lattice~\cite{ESRF} developed at ESRF and inspired by the Double-Double Bend
Achromat (DDBA) lattice~\cite{Diamond1, Diamond2} developed at Diamond, DTBA
combines the advantages of both cells. The typical MBA lattice cells have one
straight section dedicated to an insertion device, whereas this new cell layout
has two such drifts, thus increasing the fraction of available space for the
installation of insertion devices. The DTBA lattice achieves an emittance of
, a dynamic aperture of
(calculated at the injection point), an injection efficiency of
and a lifetime of with
errors. The characteristics of DTBA, the methodology and results of the linear
and non-linear optics optimisations, with and without the presence of errors,
are presented in detail
Time-dependent Gutzwiller approximation for the Hubbard model
We develop a time-dependent Gutzwiller approximation (GA) for the Hubbard
model analogous to the time-dependent Hartree-Fock (HF) method. The formalism
incorporates ground state correlations of the random phase approximation (RPA)
type beyond the GA. Static quantities like ground state energy and double
occupancy are in excellent agreement with exact results in one dimension up to
moderate coupling and in two dimensions for all couplings. We find a
substantial improvement over traditional GA and HF+RPA treatments. Dynamical
correlation functions can be easily computed and are also substantially better
than HF+RPA ones and obey well behaved sum rules.Comment: 4 pages, 2 figure
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