| Paper |
Title |
Page |
| WEPLS016 |
Studies of a Gas-filled Helical Muon Beam Cooling Channel
|
2424 |
| |
- R.P. Johnson, K. Paul, T.J. Roberts
Muons, Inc, Batavia
- Y.S. Derbenev
Jefferson Lab, Newport News, Virginia
- K. Yonehara
Fermilab, Batavia, Illinois
|
|
| |
A helical cooling channel (HCC) can quickly reduce the six dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of solenoidal, helical dipole, and helical quadrupole magnetic fields to provide the focusing and dispersion needed for emittance exchange as the beam follows an equilibrium helical orbit through a continuous homogeneous absorber. We consider liquid helium and liquid hydrogen absorbers in HCC segments that alternate with RF accelerating sections and we also consider gaseous hydrogen absorber in pressurized RF cavities imbedded in HCC segments. In the case of liquid absorber, the possibility of using superconducting RF in low magnetic field regions between the HCC segments may provide a cost effective solution to the high repetition rate needed for an intense neutrino factory or high average luminosity muon collider. In the gaseous hydrogen absorber case, the pressurized RF cavities can be operated at low temperature to improve their efficiency for higher repetition rates. Numerical simulations are used to optimize and compare the liquid and gaseous HCC techniques.
|
|
| WEPLS018 |
Optics for Phase Ionization Cooling of Muon Beams
|
2430 |
| |
- R.P. Johnson
Muons, Inc, Batavia
- S.A. Bogacz, Y.S. Derbenev
Jefferson Lab, Newport News, Virginia
|
|
| |
The realization of a muon collider requires a reduction of the 6D normalized emittance of an initially generated muon beam by a factor of more than 106. Analytical and simulation studies of 6D muon beam ionization cooling in a helical channel filled with pressurized gas or liquid hydrogen absorber indicate that a factor of 106 is possible. Further reduction of the normalized 4D transverse emittance by an additional two orders of magnitude is envisioned using Parametric-resonance Ionization Cooling (PIC). To realize the phase shrinkage effect in the parametric resonance method, one needs to design a focusing channel free of chromatic and spherical aberrations. We report results of our study of a concept of an aberration-free wiggler transport line with an alternating dispersion function. Resonant beam focusing at thin beryllium wedge absorber plates positioned near zero dispersion points then provides the predicted PIC effect.
|
|
| WEPLS019 |
Parameters for Absorber-based Reverse Emittance Exchange of Muon Beams
|
2433 |
| |
- R.P. Johnson
Muons, Inc, Batavia
- Y.S. Derbenev
Jefferson Lab, Newport News, Virginia
|
|
| |
The normalized longitudinal emittance of a muon beam after six-dimensional ionization cooling appears very small compared to the value that could be utilized or maintained after acceleration to muon collider energy. This circumstance offers the possibility for further reduction of the transverse emittance by introducing absorber-based reverse emittance exchange (REMEX) between longitudinal and transverse degrees of freedom before acceleration to high energy. REMEX follows Parametric-resonance Ionization Cooling and is accomplished in two stages. In the first stage the beam is stretched to fill the RF bucket at the initial cooling energy. In the second stage the beam is accelerated to about 2.5 GeV, where energy straggling begins to limit the absorber technique, and stretched again. The potential transverse emittance reduction and the intrinsic limitations of the REMEX technique have been analyzed earlier. In this report, we describe the required beam transport and RF parameters needed to achieve the maximum REMEX effect.
|
|