Fast Cycling Synchrotron Research Articles

Study the closed orbit correction of a compact hadron driver for cancer therapy

A design of a compact hadron driver for future cancer therapies based on the induction synchrotron concept is given. In order to realize a slow extraction technique in a fast cycling synchrotron, which allows the energy sweep beam scanning, the zero momentum-dispersion D(s) region and high flat D(s) region are necessary. The present design meets both requirements. The lattice has the two-fold symmetry with a circumference of 52.8 m, 2 m-long dispersion-free straight section, and 3 m-long large flat dispersion straight section. Assuming a 1.5 T bending magnet, the ring can deliver heavy ions of 200 MeV/au at 10 Hz. Details of the lattice parameters and orbit correction approach and method are discussed.

Longitudinal beam splitting and coalescing using an off-momentum drifting barrier bucket

There has been much research on longitudinal bunch splitting and coalescing for accelerator performance improvements in rf synchrotrons. In this paper, we report a scheme with several induction cells that goes beyond the limitation in which the phase drift speed of beam buckets must be much lower than that of the maximum off-momentum particles to minimize longitudinal emittance blowup. In principle, additional pulse acceleration voltages can be applied to produce a momentum jump of the beam and save beam manipulation time, which is crucial for fast-cycling synchrotrons with limited injection and extraction times. This paper compares the new and conventional schemes with experimental results. Finally, the beam behaviors are discussed with macroparticle simulations.

An analytical approach of the chromaticity correction for compact hadron river

A design of a compact hadron driver for future cancer therapies based on the induction synchrotron concept is given. In order to realize a slow extraction technique in a fast cycling synchrotron, which allows the energy sweep beam scanning, the zero momentum-dispersion D(s) region and high flat D(s) region are necessary. The present design lattice which meets both requirements. In this study, details of the lattice parameters is introduced and an analytical solution for chromaticity correction are described and discussed.

ESCORT: Energy sweep compact rapid cycling hadron therapy

The Energy Sweep Compact Rapid Cycling Hadron driver for future cancer therapies based on the induction synchrotron concept is described. This fast cycling synchrotron that allows the energy sweep beam scanning. Assuming a 1.5 T bending magnet, the ring can deliver heavy ions of 430 MeV/u at 10 Hz. A beam fraction is dropped from the barrier bucket at the desired timing and the increasing negative momentum deviation of this beam fraction becomes enough large for the fraction to fall in the electrostatic septum extraction gap, which is placed at the large D(s) region. The programmed energy sweeping extraction makes spot scanning beam irradiation on a cancer area in depth possible.

Vacuum System of the NICA Project

This paper presents the progress of development of the NICA project vacuum system. The main vacuum requirements in the chain of accelerators and the current status of work are described. Special attention is paid to the problems of achieving ultra-high vacuum in the booster. The test bench for the study of most efficient pumping tools for the beam chamber of the superconducting fast cycling synchrotron has been designed and built for this purpose in cooperation with the VakuumPraha Company (Prague, Czech Republic). The vacuum distribution in the superconducting accelerators with “warm” chamber parts at room temperature was simulated using specialized software. The simulation showed that it is necessary to install additional pumping equipment along the booster perimeter. To solve this problem, the original design of a titanium sublimation pump operating at cryogenic temperatures is under development in collaboration with the Budker Institute of Nuclear Physics (Novosibirsk, Russia).

Compact hadron driver for cancer therapies using continuous energy sweep scanning

A design of a compact hadron driver for future cancer therapies based on the induction synchrotron concept is presented. To realize a slow extraction technique in a fast-cycling synchrotron, which allows energy sweep beam scanning, a zero momentum-dispersion $D(s)$ region and a high flat $D(s)$ region are necessary. The proposed design meets both requirements. The lattice has two-fold symmetry with a circumference of 52.8 m, a 2-m dispersion-free straight section, and a 3-m-long large flat dispersion straight section. Assuming a 1.5-T bending magnet, the ring can deliver heavy ions ($200\text{ }\text{ }\mathrm{MeV}/\mathrm{u}$) at 10 Hz. A beam fraction is dropped from the barrier bucket at the desired timing, and the increasing negative momentum deviation of this beam fraction becomes large enough for the fraction to fall in the electrostatic septum extraction gap, which is placed at the large $D(s)$ region. The programmed energy sweep extraction enables scanning beam irradiation on a cancer site in depth without an energy degrader, avoiding the production of secondary particles and the degradation of emittance. Details of the lattice parameters and computer simulations for slow extraction are discussed. An example extraction scenario is presented. Qualities of the spilled beam such as emittance and momentum spread are discussed, as well as necessary functions and parameters required for the extraction system.

Design and study of new cables for superconducting accelerator magnets: Synchrotron SIS 100 at GSI and NICA collider at JINR*

Recent data from the design of new optimized options of NbTi composite wires and hollow cables for fast cycling synchrotron SIS100 at GSI and NICA collider at JINR are presented. The SIS100 new cable is proposed to be used for manufacturing of single-layer coil for dipole magnet with maximal amplitude of pulsed magnetic field up to 2 T. The cable should provide continues pulsed operation at the current amplitude of I = 13 kA and magnetic field ramp rate of dB/dt = 4 T/s. The results of experimental study of energy losses in the new wire and cable samples for SIS100 magnets are presented. The design cable parameters for the NICA 4 T dipole magnet are fixed at the level of I = 17 kA and dB/dt = 1 T/s. The status of the work is presented and discussed.

Cable Insulation Scheme to Improve Heat Transfer to Superfluid Helium in Nb-Ti Accelerator Magnets

In superconducting magnets operating at high heat loads as the ones for interaction region of particle colliders or for fast cycling synchrotrons, the limited heat transfer capability of state-of-the-art electrical insulation may constitute a heavy limitation to performance. In the LHC main magnets, Nb-Ti epoxy-free insulation, composed of polyimide tapes, has proved to be permeable to superfluid helium, however the heat flux is rather limited. After a review of the standard insulation scheme for Nb-Ti and of the associated heat transfer mechanisms, we show the existence of a large margin available to improve insulation permeability. We propose a possible way to profit of such a margin in order to increase significantly the maximum heat flux drainable from an all polyimide insulated Nb-Ti coil, as it is used in modern accelerator magnets.

Calculation of magnetic field for 4 T fast cycling superconducting dipole magnet

The problem of optimization of the two-dimensional magnetic field distribution of a dipole magnet with a field of 4 T and aperture diameter of 100–110 mm for a fast cycling synchrotron is considered. A singlelayer winding with a small number of turns is made from a hollow NbTi superconducting cable with an operating current up to 30 kA. The mathematical method providing optimization of the higher harmonics amplitude of the magnetic field by varying the position of current windings is described. The results of calculation of two-dimensional magnetic fields of the superconducting magnet are given.

Some Aspects of Cable Design for Fast Cycling Superconducting Synchrotron Magnets

The world's experience in application and manufacturing of superconducting cables for fast cycling synchrotrons (operating frequency f = 1 Hz) is limited up to now to a hollow multifilament NbTi cable cooled with two-phase helium flow. The cable of 7 mm in diameter has critical current of 8400 A at B = 2.5 T and dB/dt = 4 T/s. The degradation of critical current does not exceed 10% up to dB/dt = 8 T/s. The cable was designed and has been used for the magnets of the Nuclotron superconducting synchrotron at JINR in Dubna. The recent R&D was motivated by the new project of a superconducting synchrotron SIS100 at GSI in Darmstadt. Besides the basic option, i.e., the present Nuclotron-type cable, other design options are proposed. Their suitability for application in the conditions specified for the SIS 100 are considered. The improved characteristics of the Nuclotron-type cable and the magnet coil parameters are also presented.

Design of new hollow superconducting NbTi cables for fast cycling synchrotron magnets

Two new options for a hollow NbTi superconducting cable were considered. The first one is based on keystoned wires wrapped around a copper-nickel tube 5 mm in diameter. The second one is a hollow cable of rectangular cross section. The data from cable short sample tests are presented. Some problems with the production technology are discussed. This work is part of the R&D for the Future Accelerator Facility, at GSI in Darmstadt.

Superferric model dipole magnet with the yoke at 80 K for the GSI future fast cycling synchrotron

Experimental data of a fast cycling (f=1 Hz) 2T dipole magnet based on a superconducting NbTi multi filament hollow cable cooled with forced two phase helium flow at T=4.5K and iron yoke at T=80 K are presented. A new magnet design is proposed. The magnet yoke made of laminated steel consists of two parts: the internal smaller part has close mechanical and thermal contact with the coil while the outer part is separated from the cold mass with a gap of 1 mm and cooled with liquid nitrogen.

Fast cycling superconducting magnets: new design for ion synchrotrons

A new option of a superconducting dipole magnet for a fast cycling ( f=1 Hz) synchrotron is presented. The magnet is based on cos θ-type geometry, but its cold mass ( T=4.5 K) consisting of SC-coil and a reinforcing shell is separated from the iron yoke ( T=50–80 K) by a small vacuum gap. The arc-type one layer SC-coil is made of a hollow NbTi composite cable.

Experimental study of a prototype dipole magnet with iron at T=80 K for the GSI fast cycling synchrotron

Two new prototype dipole magnets for the proposed new fast cycling (f=1 Hz) synchrotron at GSI in Darmstadt have been designed, fabricated and tested. The magnets are based on a window frame iron yoke cooled by liquid nitrogen and a superconducting winding made from a hollow NbTi composite superconductor cable cooled with forced two-phase helium flow at T=4.5 K. The cold mass of the magnet is separated from the yoke by a small vacuum gap of 0.75 mm to 2.5 mm. A decrease of ac power losses by a factor of 2.3 in comparison with a standard Nuclotron dipole is obtained. The design features of two prototype dipoles as well as the test results are presented.

Analysis of energy make-up requirements for resonant-type ring magnet power supplies

For fast-cycling synchrotrons, a resonant-type magnet power supply has been used to provide a DC-based AC excitation current for ring magnets. Simple LC resonant networks are formed with the ring magnets in order to provide the sinusoidally varying magnet current. The energy lost in the resonant network due to parasitic resistance is resupplied by energy make-up networks, and a constant AC excitation of the magnets is maintained. The author presents the analysis of energy make-up requirements for resonant-type ring magnet power supplies, in order to examine the voltage and current requirements of the energy make-up network. >

The TRIUMF KAON Factory

To accelerate the 100 ?A proton beam from TRIUMF to 30 GeV a chain of 5 fast-cycling synchrotrons and dc storage rings is proposed. 450 MeV H- ions from TRIUMF are injected by stripping into the Accumulator ring. A 50 Hz Booster synchrotron then accelerates the proton pulse to 3 GeV, where the frequency swing is almost complete. In the main tunnel (170 m radius) are the Collector ring, which collects 5 Booster pulse trains, the 10 Hz Driver synchrotron and the dc Extender ring, where beam is stored for slow resonant extraction. The rings use separated function lattices, designed for very high transition energy. Dual frequency magnet power supplies provide a 3:1 rise:fall ratio, reducing the peak rf voltage requirements to 600 kV for the Booster (46-61 MHz) and 2400 kV in the Driver (61-63 MHz). RF beam splitters will be used to program beam bunches between 4 proton lines and vary the pulse spacing from 16 ns to 64 ns.

Kaon Factory with TRIUMF as Injector

A kaon factory is defined as a proton accelerator in the energy range of 15-30 GeV and with the average current range of 10-100 ..mu..A so that it can produce kaons copiously. Cost considerations become prohibitive, at these energy and current ranges, for any candidate accelerator mode except the synchrotron. The required average beam current of 100 ..mu..A is just possible with a fast cycling synchrotron, say, pulsing at 30 Hz and having 2 X 10/sup 13/ protons per pulse. The design of such a synchrotron with a linac injector is straightforward. To obtain a long beam spill for experiments one needs a beam-spill stretcher ring which is a dc storage ring having the same radius and installed in the same tunnel as the synchrotron. Accelerated beam pulses from the synchrotron are injected and stored in the stretcher ring to be spilled out uniformly in time by a resonant slow extraction system. The stretcher ring is an ideal application for superconducting magnets. To use a CW accelerator, or a cyclotron such as TRIUMF as the injector, one needs an accumulator ring which is an injection energy dc storage ring, again having the same radius and installed in the same tunnel more » as the synchrotron. The CW beam from the injector is accumulated in the accumulator during one complete cycle of the synchrotron and is transferred to the synchrotron in one turn to be accelerated as one pulse. This paper covers details of the timing properties between the accumulator, the synchrotron and the stretcher and goes on to describe the TRIUMF beam packet, the accumulator and accumulation scheme, and the foil scattering technique of the proposed kaon factory. « less

Injection Dynamics and Multiturn Charge-Exchange Injection into the Fast Cycling Synchrotron for the SNS

The Spallation Neutron Source (SNS) under construction at the Rutherford Laboratory is based on a high intensity, 800 MeV proton synchrotron, cycling at 50 Hz. An injected proton intensity of 5 × 1013 protons/pulse is obtained by injecting approximately 250 turns of negative hydrogen ions through a stripping foil in a charge-exchange injection system. The injection system is described and the results of studies on the injection dynamics are presented. The multiturn phase space stacking of the beam and the resulting proton density distributions have been studied with an aim to minimising beam instability problems in the synchrotron. With multiple traversals of the stripping foil, it is shown that obtaining high stripping efficiency with minimum scattering in energy and angle, places a severe constraint on the foil thickness in a high intensity machine. The high mean foil temperature and the thermal cycling produced by the high mean and pulsed current require the foil to be of a refractory material and the results of investigations into suitable materials are presented.

Search for the "Abnormal Nuclear State" Heavy, A > 200, Ion Acceleration in the AGS

Recent theoretical work speculates on the existence of abnormal states of matter which could possibly be created as a result of collisions of superenergetic heavy nuclei. For this reason the possibility of acceleration of heavy ions with mass number A > 200 to kinetic energies of 1 < Tn < 10 GeV/nucleon has been studied and found to be feasible without modification of the AGS vacuum and rf systems by using a fast cycling synchrotron as a booster ring. This booster is required in order to obtain the fully stripped ion state, since partially stripped heavy ion acceleration in a slow rise time accelerator is impractical because of extreme vacuum requirements. The fast cycling feature of the booster is essential in reducing transmission losses associated with electron capture or loss during acceleration and beneficial in increasing the final beam intensity.

Corrugated-Bellows Vacuum Chamber for Fast-Cycling Synchrotrons

Corrugated metal bellows of several meters length are a satisfactory and very inexpensive vacuum chamber for new or existing fast-cycling synchrotrons.