1,009 research outputs found
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
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
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
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
Luminosity, Energy and Polarization Studies for the Linear Collider: Comparing e+e- and e-e- for NLC and TESLA
We present results from luminosity, energy and polarization studies at a
future Linear Collider. We compare e+e- and e-e- modes of operation and
consider both NLC and TESLA beam parameter specifications at a center-of-mass
energy of 500 GeV. Realistic colliding beam distributions are used, which
include dynamic effects of the beam transport from the Damping Rings to the
Interaction Point. Beam-beam deflections scans and their impact for beam-based
feedbacks are considered. A transverse kink instability is studied, including
its impact on determining the luminosity-weighted center-of-mass energy.
Polarimetry in the extraction line from the IP is presented, including results
on beam distributions at the Compton IP and at the Compton detector.Comment: 17 pages, 12 figures. Presented at 5th International Workshop on
Electron-Electron Interactions at TeV Energies, December 12-14, 2003, Santa
Cruz, C
Calculation of the Coherent Synchrotron Radiation Impedance from a Wiggler
Most studies of Coherent Synchrotron Radiation (CSR) have only considered the
radiation from independent dipole magnets. However, in the damping rings of
future linear colliders, a large fraction of the radiation power will be
emitted in damping wigglers. In this paper, the longitudinal wakefield and
impedance due to CSR in a wiggler are derived in the limit of a large wiggler
parameter . After an appropriate scaling, the results can be expressed in
terms of universal functions, which are independent of . Analytical
asymptotic results are obtained for the wakefield in the limit of large and
small distances, and for the impedance in the limit of small and high
frequencies.Comment: 10 pages, 8 figure
Limits on Pulsar Parameters for Pulsed detections with H.E.S.S
The non-detection of pulsed sub-TeV gamma-rays from EGRET pulsars proves that
the EGRET pulsed spectra of all gamma-ray pulsars should terminate at energies
below a few hundred GeV. The spectrum of a typical integrated pulse profile
predicted by the polar cap model resemble typically a hard component, followed
by a super exponential cutoff between 1 MeV (PSR B1509-58) and tens of GeV
(e.g. Crab, PSR B1951+32 etc). Using a topological trigger for the H.E.S.S.
Telescope System in the non-imaging mode, we show that H.E.S.S. should be able
to detect pulsed emission from PSR B1706-44 within a few hours if the cutoff
energy is above 30 GeV as suggested by EGRET observations. The recently
detected radio pulsar PSR J1837-0604 (pulsar period: 96 ms) associated with the
unidentified EGRET source GeV J1837-06010 should also be detectable within a
few hours if the source is pulsed and if its cutoff is similar to that of PSR
B1706-44. H.E.S.S. should even be able to image middle-aged, low-multiplicity
pulsars for which the mean photon energy is expected to be well above 10 GeV.
Such observations should provide important constraints on the final
evolutionary status of gamma-ray pulsars and millisecond pulsars in general.Comment: 4 pages, 2 figures, in Proc. 27th ICRC, Hamburg, 07-15 August 2001,
OG16
Prospects of observing pulsed radiation from gamma-ray pulsars with H.E.S.S
Observations and theoretical studies have demonstrated that the pulsed
spectra of all gamma-ray pulsars terminate at energies below a few hundred GeV.
In most cases we expect this cutoff energy E_o to be around 10 GeV. Only with
next generation ground-based gamma-ray telescopes, which are expected to have
non-zero trigger probabilities near 10 GeV, can we expect to detect pulsations.
The large gamma-ray fluxes below E_o, together with the associated sharp pulse
profiles, compensate for the lack of imaging capability near threshold. For
H.E.S.S. we find that the pulsed component of PSR B1706-44 should be detectable
near threshold, whereas the unidentified GeV EGRET sources should be detectable
if the superexponential cutoff energy is larger that approximately 30 GeV for
relatively hard pulsar photon spectra (~E^-1.5).Comment: 4 pages, 2 figures, Proceedings of the Heidelberg International
Symposium on High Energy Gamma-Ray Astronom
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