BNL, Upton, Long Island, New York, USA
Head-on beam-beam compensation is adopted to compensate the large beam-beam tune spread from the proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC). Two e-lenses are being built and to be in stalled near IP10 in the end of 2011. In this article we perform numeric simulation to investigate the effect of the electron beam parameters on the proton dynamics. The electron beam parameters include its transverse profile, size, current, offset and random errors in them.
JLAB, Newport News, Virginia, USA
Muons, Inc, Batavia, USA
BNL, Upton, Long Island, New York, USA
Recirculating Linear Accelerators (RLA) are an efficient way of accelerating short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. To reduce the number of required return arcs, we employ a Non-Scaling Fixed-Field Alternating-Gradient (NS-FFAG) arc lattice design. We present a complete linear optics design of a muon RLA with two-pass linear NS-FFAG droplet return arcs. The arcs are composed of symmetric cells with each cell designed using combined function magnets with dipole and quadrupole magnetic field components so that the cell is achromatic and has zero initial and final periodic orbit offsets for both passes’ energies. Matching to the linac is accomplished by adjusting linac quadrupole strengths so that the linac optics on each pass is matched to the arc optics. We adjust the difference of the path lengths and therefore of the times of flight of the two momenta in each arc to ensure proper synchronization with the linac. We investigate the dynamic aperture and momentum acceptance of the arcs.
IUCEEM, Bloomington, Indiana, USA
IUCF, Bloomington, Indiana, USA
LBNL, Berkeley, California, USA
BNL, Upton, Long Island, New York, USA
To increase luminosity in the Relativistic Heavy Ion Collider’s (RHIC’s) polarized proton 250 GeV operations, we are considering reducing beta* to 0.65 m at the interaction points (IPs), and increasing bunch intensity. The new working point near the 2/3 integer will used on the ramp to preserve polarization. In addition, we plan to adjust the betatron-phase advances between IP6 and IP8 to (k+1/2)*PI so to lower the dynamic beta-beat from the beam-beam interaction. The effects of all these changes will impact the dynamic aperture, and hence, it must be evaluated carefully. In this article, we present the results of tracking the dynamic aperture with the proposed lattices.
ANL, Argonne, USA
Recently there was a situation at the APS when one sextupole power supply failed during top-up operation (all magnets at the APS have separate power supplies). The beam was not lost but the lifetime decreased significantly to the point where it was hard for the injectors to provide enough charge for top-up injections. Luckily, the power supply was able to reset quickly, and the operation was not compromised. One can anticipate similar failures in the future when it would not be possible to reset the power supply. In such a case, the APS would need to operate with lower lifetime until the next intervention period. Here we present an optimization of the sextupole distribution in the vicinity of the failed sextupole that allows us to partially recover the lifetime. A genetic optimization algorithm that involves simultaneous optimization of the dynamic and energy apertures was used*. Experimental tests are also presented.
* M. Borland et al., "Application of Direct Methods of Optimizing Storage Ring Dynamic and Momentum Apertures," Proc. ICAP2009, to be published.
BNL, Upton, Long Island, New York, USA
Dynamic aperture (DA) optimization with direct particle tracking is a straight forward approach when the computing power is permitted. It can have various realistic errors included and is more close than theoretical estimations. In this approach, a fast and parallel tracking code could be very helpful. In this presentation, we describe an implementation of storage ring particle tracking code TESLA for beam dynamics optimization. It supports MPI based parallel computing and is robust as DA calculation engine. This code has been used in the NSLS-II dynamics optimizations and obtained promising performance.
LBNL, Berkeley, California, USA
This is a feasibility study of using a modern Graphics Processing Unit (GPU) to parallelize the accelerator particle tracking code. To demonstrate the massive parallelization features provided by GPU computing, a simplified TracyGPU program is developed for dynamic aperture calculation. Performances, issues, and challenges from introducing GPU are also discussed.
Fermilab, Batavia, USA
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
BNL, Upton, Long Island, New York, USA
In this article we perform simulation studies to investigate the effects of betatron phase advances between the beam-beam interaction points on half-integer resonance driving terms, second order chromaticity and dynamic aperture in RHIC. The betatron phase advances are adjusted with artificial matrices inserted in the middle of arcs. The lattices for 2011 polarized proton (p-p) run and 2010 RHIC Au-Au runs are used in this study. We also scan the betatron phase advances between IP8 and the electron lens for the proposed Blue ring lattice with head-on beam-beam compensation.
ANL, Argonne, USA
The Advanced Photon Source (APS) is a 7-GeV storage ring light source that has been in operation for over a decade. In the near future, the ring may be upgraded, including changes to the lattice such as provision of several long straight sections (LSSs). Use of deflecting cavities for generation of short x-ray pulses is also considered. Because APS beamlines are nearly fully built out, we have limited freedom to place LSSs in a symmetric fashion. Arbitrarily placed LSSs will drastically reduce the symmetry of the optics and would typically be considered unworkable. We apply a recently developed multi-objective direct optimization technique that relies on particle tracking to compute the dynamic aperture and Touschek lifetime. We show that this technique is able to tune sextupole strengths and select the working point in such a way as to recover the dynamic and momentum acceptances. We also show the results of experimental tests of lattices developed using these techniques.
BNL, Upton, New York, USA
The NSLS-II storage ring lattice is comprised of 30 DBA cells arranged in 15 superperiods. There are 15 long straight sections (9.3m) for injection, RF and insertion devices and 15 shorter straights (6.6m) for insertion devices. In the baseline lattice, the short straights have small horizontal and vertical beta functions but the long straights have large horizontal beta function optimized for injection. In this note, we explore the possibility of maintaining three long straights with large horizontal beta function while providing the other 12 long straights with smaller horizontal beta function to optimize the brightness of insertion devices. Our study considers the possible linear lattice solutions as well as characterizing the nonlinear dynamics. Results are reported on optimizations of dynamic aperture required for good injection efficiency and adequate Touschek lifetime.