BNL, Upton, Long Island, New York, USA
PU, Princeton, New Jersey, USA
BNL, Upton, Long Island, New York, USA
PU, Princeton, New Jersey, USA
Fermilab, Batavia, USA
LBNL, Berkeley, California, USA
BNL, Upton, Long Island, New York, USA
A future electron ion collider "QCD test facility" is designed in the present Relativistic Heavy Ion Collider (RHIC) tunnel. Electron acceleration and de-acceleration is preformed with energy recovery linac with multiple passes. We report on a combination of a multi-pass linac with the Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) arcs. A single NS-FFAG arc allow electrons to pass through the same structure with an energy range between 1.425 and 10 GeV. The NS-FFAG is placed in the existing RHIC tunnel. The 200 MeV injector bring the polarized electrons to the 1.225 GeV GeV superconducting linac. After one pass through the linac 1.425 GeV electrons enter NS-FFAG arc and after 7 passes reach the energy of 10 GeV. After collisions the beam is brought back by the NS-FFAG and decelerated to the initial energy and directed to the dump.
BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, USA
One option for acceleration Muons from 30 to 750 GeV is to use a rapid cycling synchrotrons with frequencies of 400-550 Hz. A lattice has been proposed which employs 8T, 4.2 m long superconducting dipole magnets which are interleaved with 1.8T, 7.5 m long normal conducting dipoles. The present design of the normal conducting dipoles for this lattice is based on grain oriented steel, which possesses good magnetic properties in the direction of the grains. Grain oriented steel however is highly anisotropic, which can potentially lead to field quality problems. In this paper we present an alternative design, which suggests lower losses, a higher peak field and better field quality.
BNL, Upton, Long Island, New York, USA
In muon accelerators, ionization cooling is the only viable option for reducing the muon beam emittance to values necessary for a muon collider. An ionization cooling lattice requires a large momentum acceptance, small beta functions, an extremely large dynamic aperture, and a modeset amount of dispersion to have good performance. The latter values are a function of beam momentum. One step in understanding the lattice performance is to determine these quantities for a lattice cell being studied. This is modestly more complex than usual since the lattice is generally highly coupled. We first review the general method for computing these quantities for a general lattice. Then we look at several lattices of interest, compute these quantities, and relate their values and momentum dependencies to the performance of the lattices.
BNL, Upton, Long Island, New York, USA
Muon Colliders require cooling in six dimensions (x, x', y, y', t, E). Several ionization 6D cooling lattices, using vacuum acceleration, are reviewed: RFOFO lattices, both curved* and rectilinear** cool one sign to low emittances; A Helical FOFO snake*** cools both signs, but not to low emittances. A Planar Snake**** lattice is proposed that cools both muon signs, and appears suitable for low emittances. The parameters and performance for an example suitable for the early stages of cooling is given.
*P. Snopok et al., IJMPA 24, p. 987 (2009).
**V. Balbekov, Proc. of PAC 2003, Portland, OR, p. 2017 (2003).
***Y. Alexahin, AIP Conf. Proc. 1222, p. 313 (2010).
****R.B. Palmer, “6D Cooling in Periodic Lattices”, June 6, 2013, http://www.cap.bnl.gov/AAG/GroupMeetings/
BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, USA
An ionization cooling channel is a tightly spaced lattice containing absorbers for reducing the momentum of the muon beam, rf cavities for restoring the longitudinal momentum and solenoids for focusing the beam. Such a lattice is an essential step for a Muon Collider. Here, we explore two different schemes for designing ionization cooling channels for muon related applications. The first is an upward helical lattice commonly known as the Guggenheim channel. The second is a novel linear channel with either wedge or block absorbers for cooling and tilted solenoids for emittance exchange. The latter scheme addresses several of the engineering challenges of a conventional Guggenheim channel. We incorporate both schemes into a new lattice design for a muon collider, and examine their performance numerically. We optimize the designs and compare the conductor current densities requirements for all of the simulated scenarios.
BNL, Upton, Long Island, New York, USA
LLNL, Livermore, California, USA
Muon Colliders use ionization cooling to reduce the emittance of the muon beam prior to acceleration. A Muon Collider requires the normalized longitudinal emittance to be less than 2 mm while the normalized transverse emittance is a few hundred μm. At the last stages of the cooling channel, the bunch has 4×1012 muons, an average momentum of 200 MeV/c, and an rms bunch of 2 cm. With this beam intensity and relatively low momentum, we expect space charge effects to have a significant impact on beam dynamics. Currently, codes that could study both space-charge and particle-matter-interaction are limited. Here, with the aid of the particle-in-cell code Warp, a model is developed to examine space-charge for muon cooling lattices and some recent results are presented. Space-charge compensation solutions are discussed and the minimum cooling emittance as a function of the beam charge is identified.