55589649
Effect of the induced voltage on the bunch motion at the transition energy
The requirement of the two RF systems in the RHIC (Relativistic Heavy Ion Collider), 26.7 MHz for the particle acceleration and 160 MHz for storage collision mode, raises the difficult problem of the induced high-frequency RF voltage during the bunch acceleration through the transition energy. Analysis of the induced 160-MHz RF voltage on the bunch distribution indicates that the tolerable remnant 160-MHz RF voltage is V/sub 2/<25 kV at the transition energy region. The phase space growth is found to be proportional to V/sub 2//V/sub 1/, where V/sub 1/ is the accelerating voltage. These remnant fields are not important outside the transition energy region due to synchrotron mixing. Since the bunch length in the accelerating RF system is approximately 2 pi radians in the high-frequency RF phase, the error in the high-frequency RF stable phase plays little role in the phase space area growth.<<ETX>>
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>>
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}
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.
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.
120908048
Comment on “Quasiperiodic spin-orbit motion and spin tunes in storage rings”
117701762
Origin of Cosmic Acceleration with Large Scale Structure
The current accelerating universe can be explained by adding an exotic energy density with a negative pressure or modifying the gravity. Both the physical energy component and the modification of gravity can give rise to an effective dark energy equation of state which can characterize the expansion history of the universe. To distinguish the true origin of the cosmic acceleration, we need to know experiments giving both the expansion history of the universe and the growth rate of matter density fluctuations. Large scale structure surveys can satisfy this requirement. We investigate the Integrated Sachs Wolfe effect as one of possible methods to constrain the effective dark energy equation of state.
118870108
Global Photon Summary
Isolated high transverse energy (“prompt”) photons have a point-like coupling to the hard interaction, allowing for direct probes and precision tests of perturbative QCD (pQCD). The particular virtue of prompt photon processes is that the observed final state photon emerges directly from a QCD diagram without the subsequent hadronisation which complicates the study of high E T quarks and gluons. This avoid all the systematics associated with jet measurement.
122265337
A QCD Sum Rule Approach with an Explicit Di-quark Field
We introduce a phenomenological QCD sum rule with an explicit diquark field. We investigate certain configurations of hadrons are expected to have a good diquark structure. The parameters of the model are a diquark mass $${(m_\phi)}$$ and condensate $${(\langle \phi^2\rangle)}$$ . Assuming that Λ baryons can be represented by a diquark and a spectator quark configuration, we find the sum rule works well for Λ, Λc, and Λb. We also find a duality relation between the mass and the condensate for which the parameter sets give good Borel curves. To maintain good Borel curve, a smaller diquark condensate is needed for an increased diquark mass. Using these parameter sets, we test the diquark structure in some hadrons which contain both good and bad diquark configurations.
14407999
Lee Wick Dark Energy
We consider the cosmological application of Lee-Wick theory where a field has a higher derivative kinetic operators. The higher derivative term can be eliminated by introducing a set of auxiliary fields. We investigate the cosmological evolutions of these fields as a candidate of dark energy. This model has the same structure as so called ``quintom' model except the form of potentials and the sign of the slope of the potentials. This model can give the stable late time phantom dominated scaling solution ($\omega_{\DE} < -1$) or tracking attractors ($\omega_{\DE} = 0$) depending on the choice of the slopes of the potential. In order to be a viable dark energy candidate, the present energy density contrast of dark energy ($\Omega_{\DE}^{(0)}$) should be close to an observed value (0.73) at the same time. However, a simple toy model of the theory can not satisfy both $\omega_{\DE}^{(0)} \simeq -1$ and $\Omega_{\DE}^{(0)} = 0.73$. If we include the self interaction term of Lee Wick field, then we are able to produce the observed values of those quantities. However, in this case we are not be able to have the stable solutions and we need to suffer from the fine tuning of its mass.
7063414
Mass-Deformed Bagger-Lambert Theory and its BPS Objects
We find a 16-supersymmetric mass-deformed Bagger-Lambert theory with SO(4)xSO(4) global R symmetry. The R charge plays the role of the noncentral term in the superalgebra. This theory has one symmetric vacuum and two inequivalent broken sectors of vacua. Each sector of the broken symmetry has SO(4) geometry. We find the 1/2 BPS domain walls connecting the symmetric phase and any broken phase, and 1/4 BPS supertubelike objects, which may appear as anyonic q-balls in the symmetric phase or vortices in the broken phase. We also discuss mass deformations, which reduce the number of supersymmetries.