Sources and Medium Energy Accelerators
Accel/Storage Rings 12: FFAGs and Cyclotrons

Paper	Title	Page
WEP231	TRIUMF Cyclotron Beam Quality Improvement	1921
	I.V. Bylinskii, R.A. Baartman, F.W. Bach, J.F. Cessford, G. Dutto, Y.-N. Rao, L.W. Root, R. Ruegg TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	TRIUMF cyclotron for decades operated at 500 MeV. Recently, the two primary beamlines 1A and 2A, have been reconfigured for running at 480 MeV. The objective was to reduce beam losses caused by the electromagnetic stripping by 30%. The radiation losses reduction was confirmed with both online measurements and residual activation field mapping after 8 month of beam production. In order to improve stability of both primary beams, one of the harmonic coils was configured in Bz-mode to compensate for the beam split ratio fluctuations. Br-mode of this coil and two outer radius trim coils was utilized to correct the beam vertical position at extraction. Moreover, to make the beam spot position on the target stable and insensitive to any uncontrolled movement of the stripper foil due to heat distortion, the beamline front end optics was tuned to compensate the cyclotron's inherent dispersion. Details of these developments and improvements are discussed in the paper.
WEP232	A Multi Megawatt Ring Cyclotron to Search for CP Violation in the Neutrino Sector	1924
	L. Calabretta, M.M. Maggiore, D. Rifuggiato INFN/LNS, Catania, Italy A. Calanna CSFNSM, Catania, Italy L.A.C. Piazza INFN/LNL, Legnaro (PD), Italy
	A new approach to search for CP violation in the neutrino sector* is proposed by the experiment called DAEδALUS (Decay At rest Experiment for cp At Laboratory for Underground Science). DAEδALUS needs three sources of neutrino fluxes, each one located at 1.5, 8 and 20 km from the underground detector. Each source has to be supplied with a proton beam with power higher than 1, 2 and 5 MW respectively. Here we present the study for a Superconducting Ring Cyclotron able to accelerate the H2+ molecules and to deliver proton beam with maximum energy of 800 MeV and the required power. Although the average power for the first 2 sites are 1 and 2 MW, the 20% duty cycle, required by the experiment, has the consequence that the peak power should stay in the range 5-10 MW and a peak current of about 4.5 mA of H2+ is necessary. We present the parameters of the superconducting magnetic sector simulated by the code TOSCA, the isochronous magnetic field produced and the magnetic forces acting on the coils. Some evaluation on the feasibility of the ring cyclotron, the advantages and problems relates with acceleration of the H2+ molecules will be also presented. * J. Alonso et al., “Expression of Interest for a Novel Search for CP Violation in the Neutrino Sector: DAEδALUS”, Jun 2010. e-Print: arXiv:1006.0260
WEP234	Longitudinal Dynamics in the EMMA ns-FFAG	1927
	J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom N. Bliss STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J.A. Clarke, N. Marks, B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the Science and Technology Facilities Council UK. Grant Number: ST/G004277/1 EMMA is the first non-scaling FFAG to be constructed, whose use of linear magnets means that the accelerating electron bunch rapidly crosses many resonances. We have modeled the capture and acceleration of bunches in the serpentine channel created by the radio-frequency cavities, and compare it to a proposed experiment in which induction cells allow slow acceleration. Two induction cores each providing ~20kV over 1.65 μs enable a number of resonance crossing experiments.
WEP237	The Oak Ridge Isochronous Cyclotron Refurbishment Project	1930
	A.J. Mendez, J.B. Ball, D. Dowling, S.W. Mosko, B.A. Tatum ORNL, Oak Ridge, Tennessee, USA
	Funding: Managed by UT-Battelle, LLC for the U.S. Department of Energy under contract DE-AC05-00OR22725. The Oak Ridge Isochronous Cyclotron (ORIC) has been in operation for nearly fifty years at the Oak Ridge National Laboratory (ORNL). Presently, it serves as the driver accelerator for the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), where beams are produced using the Isotope Separation Online (ISOL) technique for post-acceleration by the HRIBF 25URC tandem accelerator. Operability and reliability of ORIC are critical issues for the success of HRIBF and have presented increasingly difficult operational challenges for the facility in recent years. Earlier this year, a trim coil failure rendered ORIC inoperable for several months. This presented HRIBF with the opportunity to undertake various repairs and maintenance upgrades aimed at restoring the full functionality of ORIC and improving the reliability to a level better than what had been typical over the previous decade. In this paper, we present details of these efforts, including the replacement of the entire trim coil set and measurements of their radial field profile. Comparison of measurements and operating tune parameters with setup code predictions will also be presented.
THOCN6	Flux-coupled Cyclotron Stack: Optimization for Maximum Beam Power and Minimum Losses	2113
	P.M. McIntyre, A. Sattarov Texas A&M University, College Station, Texas, USA
	Funding: This work was supported in part by the U.S. Department of Energy under Grant DE-FG02-06ER41405 A flux-coupled stack of isochronous cyclotrons has been proposed as a driver for Accelerator-Driven Subcritical Systems (ADSS) for thorium-cycle fission power. The issues that limit beam current and phase space brightness are evaluated, including space charge tune shift, synchro-betatron coupling, orbit separation at injection and extraction, RF propagation within the accelerator envelope, RF parasitic modes, and stability of electrostatic septum operation. A design is presented that offers good optimization of these criteria.
	Slides THOCN6 [5.266 MB]
THOCN7	Isochronous (CW) High Intensity Non-scaling FFAG Proton Drivers	2116
	C. Johnstone Fermilab, Batavia, USA M. Berz, K. Makino MSU, East Lansing, Michigan, USA S.R. Koscielniak TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada P. Snopok IIT, Chicago, Illinois, USA
	Funding: Work supported in part under SBIR grant DE-FG02-08ER85222 and by Fermi Research Alliance, under contract DEAC02-07CH11359, both with the U.S. Dept. of Energy The drive for higher beam power, duty cycle, and reliable beams at reasonable cost has focused world interest on fixed field accelerators, notably FFAGs. High-intensity GeV proton drivers encounter duty cycle and space-charge limits in the synchrotron and machine size concerns in cyclotrons. A 10-20 MW proton driver is challenging, if even technically feasible, with conventional circular accelerators. Recently, the concept of isochronous orbits has been developed for nonscaling FFAGs using powerful new methodologies in FFAG accelerator design. Isochronous orbits enable the simplicity of fixed RF and, by tailoring the field profile, the FFAG can remain isochronous beyond the energy reach of cyclotrons. With isochronous orbits, the machine proposed here has the high average current advantage and duty cycle of the cyclotron in combination with the strong focusing, smaller losses that are more typical of the synchrotron. With the cyclotron as the current industrial and medical standard, a competing CW FFAG would impact facilities using medical accelerators, proton drivers for neutron production, and accelerator-driven nuclear reactors. This work reports on these new advances.
	Slides THOCN7 [2.429 MB]