IHEP Beijing, Beijing
Funding: Work supported by National Natural Science Foundation of China contract 10725525
The upgraded project of the Beijing Electron-Positron Collider (BEPCII) can be operated not only for high energy physics experiments as a charm factory, but for synchrotron radiation users as a first generation light source. The design of the synchrotron radiation (SR) mode of the BEPCII storage ring keeps all the original beam lines of the BEPC. The lattice based on the layout of the collider can meet all the requirements of the SR users, and the emittance is minimized. Optimization of the SR mode focuses on reducing the effects from wigglers around the ring. Some results from the operations of the SR mode are also given.
JLAB, Newport News, Virginia
Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The conceptual design of a ring-ring electron-ion collider based on CEBAF has been continuously optimized to cover a wide center-of-mass energy region and to achieve high luminosity and polarization to support next generation nuclear science programs. Here, we summarize the recent design improvements and R&D progress on interaction region optics with chromatic aberration compensation, matching and tracking of electron polarization in the Figure-8 ring, beam-beam simulations and ion beam cooling studies.
JLAB, Newport News, Virginia
LBNL, Berkeley, California
Funding: (1) Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 (2) Supported by the U. S. Department of Energy under Contract no. DE-AC02-05CH11231.
The collective beam-beam effect can potentially cause a rapid growth of beam sizes and reduce the luminosity of a collider to an unacceptably low level. The ELIC, a proposed ultra high luminosity electron-ion collider based on CEBAF, employs high repetition rate crab crossing colliding beams with very small bunch transverse sizes and very short bunch lengths, and collides them at up to 4 interaction points with strong final focusing. All of these features can make the beam-beam effect challenging. In this paper, we present simulation studies of the beam-beam effect in ELIC using a self-consistent strong-strong beam-beam simulation code developed at Lawrence Berkeley National Laboratory. This simulation study is used for validating the ELIC design and for searching for an optimal parameter set.
ORNL, Oak Ridge, Tennessee
University of Tennessee, Knoxville, Tennessee
MIT Lincoln Laboratory, Boston MA
Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
Investigations of the rf properties of certain twisted waveguide structures show that they support favorable accelerating fields. This makes them potential candidates for accelerating cavities. Using the particle tracking code, ORBIT, We examine the beam - rf interaction in the twisted cavity structures to understand their beam transport and acceleration properties. The results will show the distinctive properties of these new structures for particle transport and acceleration, which have not been previously analyzed.
ORNL, Oak Ridge, Tennessee
Funding: *SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
The combined time required for diffusion release from target materials and effusive-flow of short-lived ion species must be minimized at ISOL based radioactive ion beam (RIB) facilities. Computational simulation studies with state-of-the-art codes offer cost effective means for designing targets with optimized diffusion release properties and vapor transport systems with short path lengths, as required for such applications. To demonstrate the power of the technique for designing optimum thickness targets, analytic solutions to the diffusion equation are compared with those obtained from a finite-difference code for radioactive particle release from simple geometries. The viability of the Monte Carlo technique as a practical means for optimally designing vapor transport systems is demonstrated by simulating the effusive-flow of neutral particles through several complex vapor transport systems. Important issues which affect the yield rates of short-lived species generated in high power ISOL targets are also discussed.
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
The Spallation Neutron Source (SNS) is a second generation pulsed-neutron source and designed to provide a 1-GeV, 1.44-MW proton beam to a mercury target for neutron production. Since the initial commissioning of accelerator complex in 2006, the SNS has begun neutron production operation and beam power ramp-up has been in progress toward the design goal. Since the design beam power is almost an order of magnitude higher compared to existing neutron facilities, all subsystems of the SNS were designed and developed for substantial improvements compared to existing accelerators and some subsystems are first of a kind. Many performance and reliability aspects were unknown and unpredictable, for which it takes time to understand the systems as a whole and/or needs additional performance improvements. A power ramp-up plan has been revised based on the operation experiences and understandings of limits and limiting conditions through extensive studies with an emphasis on machine availability. In this paper the operational experiences of SNS Superconducting Linac (SCL), the power ramp-up status and plans will be presented including related subsystem issues.
ORNL, Oak Ridge, Tennessee
Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
The Spallation Neutron Source (SNS) linac system is designed to deliver 1 GeV pulsed H- beams up to 1.56 MW for neutron production. As beam power was increased from 10 kW to 660 kW in less than three years, beam loss in the accelerator systems particularly in the superconducting linac (SCL), became more significant. In the previous studies, unexpected beam loss in the SCL was mainly attributed to longitudinal problems. However, our most recent simulations have focused on beam transverse effects. These include multipole components from magnet imperfections and dipole corrector windings of the linac quadrupoles. The effect of these multipoles coupled with other errors will be discussed.