45815179
Analytic closed orbit analysis for RHIC insertion
Analytic closed-orbit analysis is performed to evaluate the tolerance of quadrupole misalignment and dipole errors (b/sub 0/, a/sub 0/) in the RHIC insertion. Sensitivity coefficients of these errors are tabulated for different beta * values. Using these sensitivity tables, it is found that the power supplies ripple of 10/sup -4/ can cause closed orbit motion of 0.05 mm at the IP, in comparison with the RMS beam size of 0.3 mm. It is desirable to have the power supply ripple less than 10/sup -5/.<<ETX>>
120908048
Comment on “Quasiperiodic spin-orbit motion and spin tunes in storage rings”
117036088
Comparison of multipole expansion and exact form of the eddy current field of the AGS Booster
Studies are made on magnetic field representation using a multipole expansion as well as the exact form to calculate the magnetic field produced by eddy currents in the vacuum chamber of the AGS Booster as well as the field produced by three turn correction coils attached to the top and bottom of the vacuum chamber. The multiple representation of the chamber field does not converge to the next field when X > 30mm and limits the particle motion. When the exact form of the chamber field is used, initial amplitudes in the horizontal plane (measured at QF) can be nearly as large as the chamber half aperture. Use of three turn correction coils to compensate the eddy current fields seems to reduce rather than increase the acceptance. 6 figs., 3 tabs.
124338422
FIRST OBSERVATION OF A SNAKE DEPOLARIZING RESONANCE
Using a 104MeV stored polarized proton beam and a full Siberian snake, we recently found evidence for a so-called {open_quotes}snake{close_quotes} depolarizing resonance. A full Siberian snake forces the spin tune {nu}{sub s} to be a half integer. Thus, if the vertical betatron tune {nu}{sub y} is set near a quarter integer, then the {nu}{sub s}=n{plus_minus}2{nu}{sub y} second-order snake resonance can depolarize the beam. Indeed, with a full Siberian snake, we found a deep depolarization dip when {nu}{sub y} was equal to 4.756; moreover, when {nu}{sub y} was changed to 4.781, the deep dip disappeared and the polarization was preserved. {copyright} {ital 1997} {ital The American Physical Society}
120417645
Snakes and spin rotators for high energy accelerators
Abstract A modification to the continuous family of snake and spin rotators, discovered by Steffen, is discussed. A compact snake configuration is found to have the advantages of requiring a smaller total integrated dipole magnet strength and a smaller transverse displacement for circulating particles. A split snake configuration has the advantage of allowing an entire experimental insertion region to be located between the two halves of the snake. Such configurations could serve as both a snake and a 90° spin rotator for experiments requiring different helicity states. General properties of these snake configurations are discussed.
96454816
Design and fabrication of a multi-purpose Panofsky magnet
A fast, flexible magnet system, consisting of a Panofsky style ferrite picture-frame magnet and pulsed power supply, has been developed. Magnet specifications are: 8 cm /spl times/8 cm aperture, 23 cm length, 500 A pulsed/l60 A DC, and 1 /spl mu/s risetime. Designed for general accelerator physics studies, the magnet may be quickly converted from dipole to quadrupole or sextupole and higher multipole configurations by easily changing winding end terminations. In the quadrupole configuration a field gradient of 0.5 T/m is achieved at 500 A. This magnet has become an important tool for nonlinear beam dynamics experiments at the IUCF Cooler Ring.<<ETX>>
12243872
Toric AdS4/CFT3 duals and M-theory crystals
We study the recently proposed crystal model for three dimensional superconformal field theories arising from M2-branes probing toric Calabi-Yau four-fold singularities. We explain the algorithms mapping a toric Calabi-Yau to a crystal and vice versa, and show how the spectrum of BPS meson states fits into the crystal model.
119235210
Template overlap method for massive jets
We introduce a new class of infrared safe jet observables, which we refer to as template overlaps, designed to filter targeted highly boosted particle decays from QCD jets and other background. Template overlaps are functional measures that quantify how well the energy flow of a physical jet matches the flow of a boosted partonic decay. Any region of the partonic phase space for the boosted decays defines a template. We will refer to the maximum functional overlap found this way as the template overlap. To illustrate the method, we test lowest-order templates designed to distinguish highly-boosted top and Higgs decays from backgrounds produced by event generators. For the functional overlap, we find good results with a simple construction based on a Gaussian in energy differences within angular regions surrounding the template partons. Although different event generators give different averages for our template overlaps, we find in each case excellent rejection power, especially when combined with cuts based on jet shapes. The template overlaps are capable of systematic improvement by including higher order corrections in the template phase space.
18287866
Properties of the exact analytic solution of the growth factor and its applications
There have been the approximate analytic solution [V. Silveira and I. Waga, Phys. Rev. D 50, 4890 (1994).] and several approximate analytic forms [W. J. Percival, Astron. Astrophys. 443, 819 (2005).][S. M. Carroll, W. H. Press, and E. L. Turner, Annu. Rev. Astron. Astrophys. 30, 499 (1992).][S. Basilakos, Astrophys. J. 590, 636 (2003).] of the growth factor ${D}_{g}$ for the general dark energy models with the constant values of its equation of state ${\ensuremath{\omega}}_{\mathrm{de}}$ after Heath found the exact integral form of the solution of ${D}_{g}$ for the Universe including the cosmological constant or the curvature term. Recently, we obtained the exact analytic solutions of the growth factor for both ${\ensuremath{\omega}}_{\mathrm{de}}=\ensuremath{-}1$ or $\ensuremath{-}\frac{1}{3}$ [S. Lee and K.-W. Ng, arXiv:0905.1522.] and the general dark energy models with the constant equation of state ${\ensuremath{\omega}}_{\mathrm{de}}$ [S. Lee and K.-W. Ng, Phys. Lett. B 688, 1 (2010).] independently. We compare the exact analytic solution of ${D}_{g}$ with the other well known approximate solutions. We also prove that the analytic solutions for ${\ensuremath{\omega}}_{\mathrm{de}}=\ensuremath{-}1$ or $\ensuremath{-}\frac{1}{3}$ in [S. Lee and K.-W. Ng, arXiv:0905.1522.] are the specific solutions of the exact solutions of the growth factor for general ${\ensuremath{\omega}}_{\mathrm{de}}$ models in [S. Lee and K.-W. Ng, Phys. Lett. B 688, 1 (2010).] even though they look quite different. Comparison with the numerical solution obtained from the public code is done. We also investigate the possible extensions of the exact solution of ${D}_{g}$ to the time-varying ${\ensuremath{\omega}}_{\mathrm{de}}$ for the comparison with observations.
116349147
Cluster number counts in quintessence models
Abstract Even though the abundance and evolution of clusters have been used to study the cosmologicalparameters includingthe propertiesof darkenergy owing to their puredependenceon the geometryof the Universe and the power spectrum, it is necessary to pay particular attention to the eﬀectsof dark energy on the analysis. We obtain the explicit dark energy dependent rms linear massﬂuctuation σ 8 which is consistent with the CMB normalization with less than 2 % errors for generalconstant dark energy equation of state, ω Q . Thus, we do not have any degeneracy between σ 8 and the matter energy density contrast Ω 0m . When we use the correct value of the critical densitythreshold δ c = 1.58 obtained recently [30, 31] into the cluster number density n calculation in thePress-Schechter (PS) formalism, n increases as compared to the one obtained by using δ c = 1.69by about 60, 80, and 110 % at z = 0, 0.5, and 1, respectively. Thus, PS formalism predictsthe cluster number consistent with both simulation and observed data at the high mass region.We also introduce the improved coeﬃcients of Sheth-Tormen (ST) formalism, which is consistentwith the recently suggested mass function [36]. We found that changing ω
120358635
CLUSTER PHYSICS WITH DARK ENERGY
Dark energy affects the abundance and evolution of clusters owing to their dependence on the geometry of the Universe and the power spectrum. Usually, there exits the degeneracy between σ8 and the matter energy density contrast . We avoid this by using the explicit dark energy dependent rms linear mass fluctuation σ8 which is consistent with the CMB normalization for general constant dark energy equation of state, ωQ. When we use the correct value of the critical density threshold δc = 1.58 into the cluster number density n calculation in the Press–Schechter (PS) formalism, PS formalism predicts the cluster number consistent with both simulation and observed data at the high mass region. The improved coefficients of Sheth–Tormen (ST) formalism by using the correct δc is also obtained. We found that changing ωQ by ΔωQ = -0.1 from ωQ = -1.0 causes the changing of the comoving numbers of high mass clusters of M = 1016h-1M⊙ by about 20 and 40% at z = 0 and 1, respectively.