170077348
Report from Working Group T 5 : Beam Dynamics
During the last several decades there have been tremendous advances in the power and the techniques of particle accelerators. In parallel, there have been remarkable advances in the understanding of how charged particle beams interact with themselves and with external environments. The current status of beam dynamics is such that some of the mathematical tools for the collective instabilities, phase-space dilutions and beam cooling methods, nonlinear phenomenon, etc. have become practical design tools for currently operating accelerators. As we contemplate the next generation of large-scale accelerator projects, there are more challenges ahead, both in improving the predictive power of the current calculations as well as in developing new topics. This report is a summary of the discussions of the Beam Dynamics (T5) Working Group at Snowmass on the progress and challenges for the beam dynamics of future accelerators.
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.
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>>
120908048
Comment on “Quasiperiodic spin-orbit motion and spin tunes in storage rings”
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.
118835651
New physics searches with photons in CDF
A brief review of searches for physics beyond the Standard Model with photons using the CDF detector at the Tevatron is given here. These include searches for supersymmetry, extra dimensions, excited electrons and W/Z+{gamma} production, as well as anomalous photon production. Recent results from CDF Run II experiment are presented, but some results from Run I are also reviewed.
119196758
Klebanov-Witten flows in M-theory
A bstractWe study renormalization group flows among three dimensional superconformal gauge theories which closely resemble the renowned Klebanov-Witten flow in four dimensions. In the large N limit, each theory appearing in the flow is holographically dual to M-theory on AdS4 times a toric Sasaki-Einstein seven-manifold. The theories are obtained through the so-called flavoring method, which adds some fundamental matter fields to the dimensionally reduced Klebanov-Witten theories. We reconfirm the matching between the gauge theories and the dual geometries by comparing the chiral ring structure. As a more refined test of the flows, we compute the three-sphere partition function of the gauge theories. The square of the free energy, inversely proportional to the volume of the seven-manifold, decreases by a universal ratio 16/27 for all flows considered in this paper.
37603515
Light Gravitinos at Colliders and Implications for Cosmology
Light gravitinos, with mass in the eV to MeV range, are well motivated in particle physics, but their status as dark-matter candidates is muddled by early-Universe uncertainties. We investigate how upcoming data from colliders may clarify this picture. Light gravitinos are produced primarily in the decays of the next-to-lightest supersymmetric particle, resulting in spectacular signals, including di-photons, delayed and nonpointing photons, kinked charged tracks, and heavy metastable charged particles. We find that the Tevatron with 20  fb^(-1) and the 7 TeV LHC with 1  fb^(-1) may both see evidence for hundreds of light-gravitino events. Remarkably, this collider data is also well suited to distinguish between currently viable light-gravitino scenarios, with striking implications for structure formation, inflation, and other early-Universe cosmology.
118471394
Palatini f(R) Cosmology
We investigate the modified gravity theories in terms of the effective dark energy models. We compare the cosmic expansion history and the linear growth in different models. We also study the evolution of linear cosmological perturbations in modified theories of gravity assuming the Palatini formalism. We find the stability of the superhorizon metric evolution depends on models. We also study the matter density fluctuation in the general gauge and show the differential equations in super and sub-horizon scales.
10444896
Active cooling control of the CLEO detector using a hydrocarbon coolant farm
Abstract We describe a novel approach to particle-detector cooling in which a modular farm of active coolant-control platforms provides independent and regulated heat removal from four recently upgraded subsystems of the CLEO detector: the ring-imaging Cherenkov detector, the drift chamber, the silicon vertex detector, and the beryllium beam pipe. We report on several aspects of the system: the suitability of using the aliphatic-hydrocarbon solvent PF TM -200IG as a heat-transfer fluid, the sensor elements and the mechanical design of the farm platforms, a control system that is founded upon a commercial programmable logic controller employed in industrial process-control applications, and a diagnostic system based on virtual instrumentation. We summarize the system's performance and point out the potential application of the design to future high-energy physics apparatus.