54963187
Diffusion mechanism of particle beams in the presence of phase modulation in double RF systems
The particle diffusion mechanism due to phase modulation on one of the RF cavities in a double RF system is studied. We find that the Einstein relation is satisfied if there is a global chaos in the phase space. On the other hand, the existence of dominant parametric resonances forces the particles streaming along the separatrix, which may result in an anomalous diffusion process. The particle tracking simulations based on the Hamiltonian for the double RF system is employed to reveal the essential diffusion mechanism. Also for the first time, a coherent octupole mode has been observed in the bunch beam excitation. The phase space evolution of the octupole mode is displayed.
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.
120908048
Comment on “Quasiperiodic spin-orbit motion and spin tunes in storage rings”
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.
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.
119383752
Prompt photon processes in photoproduction at HERA
Abstract We present results for the photoproduction of inclusive prompt photons and for prompt photons accompanied by jets, measured with the ZEUS detector at HERA. Cross sections as a function of pseudorapidity and transverse energy are presented for 5 E T γ E T jet > 5 GeV in the centre of mass energy range 120–270 GeV. Comparisons are made with predictions from leading logarithm parton shower Monte Carlos and next-to-leading order QCD calculations using currently available models of the photon structure. NLO QCD calculations describe the shape and magnitude of the measurements reasonably well.
41568305
Lagrangian perturbation theory: exact one-loop power spectrum in general dark energy models
Recently, we found that the correction for the Einstein–de Sitter (EdS) assumption on the one-loop matter power spectrum for general dark energy models using the standard perturbation theory is not negligible (Lee et al., arXiv:1407.7325, 2014). Thus, we investigate the same problem by obtaining the exact displacement vector and kernels up to the third order for the general dark energy models in the Lagrangian perturbation theory (LPT). Using these exact solutions, we investigate the present one-loop matter power spectrum in the $$\Lambda $$ΛCDM model with $$\Omega _{m0} = 0.25 (0.3)$$Ωm0=0.25(0.3) to obtain a $$0.2 (0.18)$$0.2(0.18) % error correction compared to that obtained from the EdS assumption for the $$k = 0.1\,\mathrm{h\, Mpc}^{-1}$$k=0.1hMpc-1 mode. If we consider the total matter power spectrum, the correction is only $$0.05 (0.03)$$0.05(0.03) % for the same mode. It means that the EdS assumption is a good approximation for the $$\Lambda $$ΛCDM model in LPT theory. However, one can use this method for general models where the EdS assumption is improper.
17171580
Emergence of classicality in quantum phase transitions
We show that classicality emerges during quantum phase transitions due to parametric interactions without coupling to environments. The Wigner functions are explicitly calculated for the Gaussian vacuum, number, and thermal states of a free scalar field that describes the spinodal instability regime. The Wigner functions are sharply peaked around their classical trajectories during the phase transition and exhibit classical correlation only for unstable long wavelength modes but retain quantum coherence for short wavelength modes. Thus classicality emerges from the quantum evolution of phase transitions without a classical order parameter. We define a quantal ordering parameter that is linear in the field variable and satisfies the classical field equation.
119519436
A dual gravity study of the (2+1)D compact U(1) gauge theory coupled with strongly interacting matter fields
Abstract We consider the D2-brane probe action in the gravity background dual to N coincident D p -branes by treating the separation between the D2- and D p -branes as a non-dynamical parameter for p = 2 , 4 , 6 . The gauge coupling, the core size of a non-BPS instanton and the mass gap of the compact U ( 1 ) gauge theory in the D2-brane are determined as a function of the separation in the type IIA gravity region. The results are interpreted in terms of the ( 2 + 1 ) D U ( 1 ) gauge theory coupled with the matter fields which are also strongly coupled with the ( p + 1 ) D SU ( N ) gauge field. It is shown that strong coupling of the matter fields to the SU ( N ) gauge field can drastically modify their screening of the U ( 1 ) gauge field. The non-perturbative dependence of the U ( 1 ) gauge coupling on the energy scale is obtained.