41299039
Observation of higher-order snake resonances in polarized proton acceleration in RHIC.
Higher-order and coupled snake resonances were observed during the 2002 polarized proton run in RHIC. Strong depolarization was observed when the fractional part of the vertical betatron tune approached 1/4, and when the fractional part of the horizontal tune approached 3/14. Because of the closed orbit error, each snake resonance splits into two. From the width of the observed snake resonances, we can derive the strength of the imperfection spin resonance. Our results appear consistent with the measured closed orbit error.
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}
121911294
The RHIC design overview
The salient performance objectives for the Relativistic Heavy Ion Collider (RHIC) are presented and the rationale for the design choices of the major collider systems is conveyed. RHIC provides collisions of heavy ions covering the entire mass range from protons to gold. For the prototypical case of Au-on-Au, one obtains energies up to 100 GeV/n per beam and luminosities of B2 � 10 26 cm � 2 s � 1 , averaged over a 10-h storage time. Operation with polarized protons is also possible. The overall accelerator complex used for gold ions consists of the Tandem Van de Graaff, the Booster, the AGS, and the Collider itself, and the scenario for the beam transfer between machines is described. The two separate collider rings cross at six interaction points, where the lattice design provides low-beta insertions for maximum luminosity. The interaction diamond length of o20 cm rms is achieved by bunched beam operation and holding the 56 bunches in a 197 MHz radio-frequency (RF) system after their acceleration in a 28 MHz RF system. The rings are constructed with superconducting magnets, which have a cold bore aperture of 6.9 cm in the arcs. The RHIC specific design challenges posed by intrabeam scattering of heavy ions, passage through transition energy with slow-ramping superconducting magnets, and control of magnetic errors in the low-beta triplet quadrupoles are addressed. r 2002 Elsevier Science B.V. All rights reserved.
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>>
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.
116942523
Microwave instability near transition energy
Monte Carlo simulation for the microwave instability agrees with analytic calculation solving the Vlasov equation, provided that bunch shape distortion due to coupling is taken into account. 9 refs., 2 figs.
122040769
Vector mesons in nuclear matter
In this talk, I will summarize the progress in understanding the changes the vector meson spectral density in nuclear medium using the constraint equations obtained from the Borel transformed dispersion relation and QCD Operator Product Expansion. We will discuss the results for the scalar mass shift and dispersion effects (three momentum dependence) for the light quark system (ρ,ω), the strange quark system (φ) and the heavy quark system (J/ψ) in nuclear medium. For the light quark systems, a nontrivial change in the mass and/or width are expected, while the dispersion effects are found to be small. Existing model calculations for the dispersion effects are compared to the constraint equation in detail. Very small, but accurate mass shift is obtained for the heavy quark system.
8052456
COUPLED QUINTESSENCE AND CMB
We revise the stability of the tracking solutions and briefly review the potentials of quintessence models. We discuss the evolution of linear perturbations for $V(\phi) = V_{0} \exp(\lambda \phi^2/2)$ potential in which the scalar field is non-minimally coupled to cold dark matter. We consider the effects of this coupling on both cosmic microwave background temperature anisotropies and matter perturbations. We find that the phenomenology of this model is consistent with current observations up to the coupling power $n_{c} \leq 0.01$ while adopting the current parameters measured by WMAP, $\Omega_{\phi}^{(0)}=0.76$, $\Omega_{cdm}^{(0)}=0.191$, $\Omega_{b}^{(0)}=0.049$, and $h=0.70$. Upcoming cosmic microwave background observations continuing to focus on resolving the higher peaks may put strong constraints on the strength of the coupling.
16534140
Constraints on the coupled quintessence from cosmic microwave background anisotropy and matter power spectrum
We discuss the evolution of linear perturbations in a quintessence model in which the scalar field is nonminimally coupled to cold dark matter. We consider the effects of this coupling on both cosmic microwave background temperature anisotropies and matter perturbations. Because of the modification of the scale of cold dark matter as {rho}{sub c}={rho}{sub c}{sup (0)}a{sup -3+{xi}}, we can shift the turnover in the matter power spectrum even without changing the present energy densities of matter and radiation. This can be used to constrain the strength of the coupling. We find that the phenomenology of this model is consistent with current observations up to the coupling power n{sub c}{<=}0.01 while adopting the current parameters measured by the Wilkinson Microwave Anisotropy Probe. Upcoming cosmic microwave background observations continuing to focus on resolving the higher peaks may put strong constraints on the strength of the coupling.
121501735
Nucleon magnetic form factors in the cloudy bag model
Abstract The nucleon magnetic moments and magnetic form factors have been calculated in the cloudy bag model. The π NN, π N Δ , γπ form factors and the CM corrections have been taken into account. We obtained very good results for these quantities.
118595202
Lagrangian perturbation theory: Third-order solution for general dark energy models
We investigate the Lagrangian perturbation theory of a general dark energy models with a constant equation of state, \omega, and derive the fitting form of the fastest growing mode solutions up to the third order. These fitting forms are less than few % errors compared to the numerical calculation. We also correct the solutions of Einstein-de Sitter and the open universe with the proper initial conditions and the correct consideration for the growing mode solutions in order to compare with the general dark energy models. Even though these fitting forms are limited to the constant equation of state models, one can apply these to the time-varying \omega by interpolating between models with the constant \omega. These fitting forms can be used for the correct prediction for the two point correlation function and can give the proper predictions for the different dark energy models.