K.Y. Ng

Design of the muon collider isochronous storage ring lattice

The muon collider would ex-tend limitations of the e{sup +} e- colliders and provide new physics potentials with a possible discovery of the heavy Higgs bosons. At the maximum energy of 2 TeV the projected luminosity is of the order of 10{sup 35} cm{sup {minus}2}s{sup {minus}1}. The colliding {mu}{sup +} {mu}{sup {minus}} bunches have to be focused to a very small transverse size of few tenths of {mu}m which is accomplished by the betatron functions at the crossing point of {beta}* = 3mm. This requires the longitudinal space of the same length 3 mm. These very short bunches at 2 TeV could circulate only in a quasi-isochronous storage ring where the momentum compaction is very dose to zero. We report on a design of the muon collider isochronous lattice. The momentum compaction is brought to zero by having the average value of the dispersion function through dipoles equal to zero. This has been accomplished by a combination of the FODO cells together with a low beta insertion. The dispersion function oscillates between negative and positive values.

A lattice for the muon collider demonstration ring in the RHIC tunnel

The future /spl mu//sup +//spl mu//sup -/ muon collider should have a luminosity of the order of 10/sup 35/ cm/sup -2/ s/sup -1/, an the energy of 2/spl times/2 TeV. We present here a demonstration machine at a lower energy to test the feasibility of all components involved, which could be placed inside the existing Relativistic Heavy Ion Collider (RHIC) tunnel. The maximum energy of the muons in the RHIC tunnel depends on the maximum attainable field in the dipoles. The maximum energy in the existing RHIC rings for protons is 250 GeV, where the strength of the magnetic field in the dipoles is 3.5 T. A design of the storage ring lattice for a 50 GeV muon demonstration machine is also presented.

A transitionless lattice for the Fermilab Main Injector

Medium energy (1 to 30 GeV) accelerators are often confronted with transition crossing during acceleration. A lattice without transition, which is a design for the Fermilab Main Injector, is presented. The main properties of this lattice are that the gamma /sub t/ is an imaginary number, the maxima of the dispersion function are small, and it has two long-straight sections with zero dispersion.<<ETX>>

An AGS experiment to test bunching for the proton driver of the muon collider.

The proton driver for the muon collider must produce short pulses of protons in order to facilitate muon cooling and operation with polarized beams. In order to test methods of producing these bunches they have operated the AGS near transition and studied procedures which involved moving the transition energy {gamma} to the beam energy. They were able to produce stable bunches with RMS widths of {sigma} = 2.2-2.7 ns for longitudinal bunch areas of {minus}1.5 V-s, in addition to making measurements of the lowest two orders of the momentum compaction factor.

Emittance measurement and modeling for the fermilab booster

We systematically measured the emittance evolution of a fast cycling proton accelerator on a turn-by-turn basis under various beam intensities via an ionization profile monitor (IPM). The vertical emittance growth rate was derived and phenomenologically analyzed. The transverse and longitudinal components in the horizontal beam size were separated by making use of their different evolution behaviors. The quadrupole mode beam size oscillation after transition crossing is also studied and explained. We found a considerable space-charge-induced emittance growth rate component in the vertical plane but not as much for the horizontal plane. We carried out multiparticle simulations to understand the mechanism of space-charge-induced emittance growth. The major sources of emittance growth were found to be the random skew-quadrupole and dipole field errors in the presence of large space-charge tune spread.

Examination of the stability of the advanced imaginary gamma /sub t/ lattice

An advanced imaginary- gamma /sub t/ lattice for the Fermilab Main Injector is examined for its response to quadrupole field errors, quadrupole misalignment errors, as well as its dynamical aperture. It is found that the lattice is tunable except near an integer tune. The misalignment sensitivity factors are acceptable and can be lowered if the low-beta triplet quadrupoles are specially aligned. The dynamical aperture is very large provided that a family of harmonic sextupoles is installed.<<ETX>>

Fast beam stacking using RF barriers

Two barrier RF systems were fabricated, tested and installed in the Fermilab Main Injector. Each can provide 8 kV rectangular pulses (the RF barriers) at 90 kHz. When a stationary barrier is combined with a moving barrier, injected beams from the Booster can be continuously deflected, folded and stacked in the Main Injector, which leads to doubling of the beam intensity. This paper gives a report on the beam experiment using this novel technology.