Robert B. Palmer

An ionization cooling channel for muon beams based on alternating solenoids

The muon collider requires intense, cooled muon bunches to reach the required luminosity. Due to the limited lifetime of the muon, the cooling process must take place very rapidly. Ionization cooling seems to be our only option, given the large emittances of the muon beam from pion decay. However, this ionization cooling method has been found quite difficult to implement in practice. We describe a scheme based on the use of liquid hydrogen absorbers followed by RF cavities (pillbox or open iris type), embedded in a transport lattice based on high field solenoids. These solenoidal fields are reversed periodically in order to suppress the growth of the canonical angular momentum. This channel has been simulated in detail with independent codes, featuring conventional tracking in e.m. fields and detailed simulation of multiple scattering and straggling in the the absorbers and windows. These calculations show that the 15 Tesla lattice cools in 6D phase space by a factor /spl ap/2 over a distance of 20 m.

A practical high-energy high-luminosity mu+ mu- collider

We present a candidate design for a high-energy high-luminosity {mu}{sup +}-{mu}{sup -} collider, with {ital E}{sub cm}=4 TeV, {ital L}=3{times}10{sup 34} cm{sup -2}s{sup -1}, using only existing technology. The design uses a rapid-cycling medium-energy proton synchrotron, which produces proton beam pulses which are focused onto two {pi}-producing targets, with two {pi}-decay transport lines producing {mu}{sup +}{close_quote}s and {mu}{sup -}{close_quote}s. The {mu}{close_quote}s are collected, rf-rotated, cooled and compressed into a recirculating linac for acceleration, and then transferred into a storage ring collider. The keys to high luminosity are maximal {mu} collection and cooling; innovations with these goals are presented, and future plans for collider development are discussed. This example demonstrates a novel high-energy collider type, which will permit exploration of elementary particle physics at energy frontiers beyond the reach of currently existing and proposed electron and hadron colliders. {copyright} 1995 {ital American Institute of Physics}.

Coherent paier creation as a positron source for linear colliders

We propose a positron source for future linear colliders which uses the mechanism of coherent pair creation process from the collision of a high energy electron beam and a monochromatic photon beam. We show that there is a sharp spike in the pair‐produced positron energy spectrum at an energy much lower than the primary beam energy. Thr transverse emittance is ‘‘damped,’’ yielding final positrons with lower normalized emittance than the initial electrons. Numerical examples invoking conventional lasers and Free Electron Lasers (FEL) for the photon beams are considered.

Phase rotation at the front end of a neutrino factory

The muon collection scheme for a muon-storage-ring-based neutrino factory consists of a target irradiated with a 1 MW proton beam followed by a 30-m decay channel and then a 300-m long induction linac phase rotation. The purpose of the induction-linac section is to reduce the /spl delta/E/E spread of the collected muons to a value which is manageable for the subsequent buncher and cooling sections. We describe in this paper the overall design concept of the phase-rotation system and give key parameters for the induction linacs.

Design of the muon collider lattice: Present status

The last component of a muon collider facility, as presently envisioned, is a colliding-beam storage ring. Design studies on various problems for this ring have been in progress over the past year. In this paper we discuss the current status of the design. The projected muon currents require very low beta values at the IP, {beta}* = 3 mm, in order to achieve the design luminosity of L = 10{sup 35} cm{sup -2} s{sup -1}. The beta values in the final-focus quadrupoles are roughly 400 km. To cancel the corresponding chromaticities, sextupole schemes for local correction have been included in the optics of the experimental insertion. The hour-glass effect constraints the bunch length to be comparable too. To obtain such short bunches with reasonable rf voltage requires a very small value of the momentum compaction a, which can be obtained by using flexible momentum compaction (FMC) modules in the arcs. A preliminary design of a complete collider ring has now been made; it uses an experimental insertion and arc modules as well as a utility insertion. The layout of this ring is shown schematically, and its parameters are summarized. Though some engineering features are unrealistic, and the beam performance needsmorexa0» some improvement, we believe that this study can serve as the basis for a workable collider design. The remaining sections of the paper will describe the lattice, show beam behaviour, and discuss future design studies.«xa0less

Final focus system for a muon collider: A test model

The present scenario for a high luminosity 4 TeV on center of mass muon collider required a beta function {beta}* {approx} 3mm at the interaction point. We discuss a test model of a basic layout which satisfies the requirements although it is not fully realistic.

Superconducting accelerator magnets: A review of their design and training

This paper reviews the basic mechanical designs of most of the superconducting magnets developed for high energy hadron accelerators. The training performance of these magnets is compared with an instability factor defined by the square of the current density in the stabilizing copper divided by the surface‐to‐volume ratio of the strands. A good correlation is observed.

Higher Luminosity eRHIC Ring-Ring Options and Upgrade

Lower risk ring-ring alternatives to the BNL linac-ling [1] eRHIC electron ion collider (EIC) are discussed. The baseline from the Ring-Ring Working Group [2] has a peak proton-electron luminosity of ≈ 1.2 × 10 cm s. An option has final focus quadrupoles starting immediately after the detector at 4.5 m, instead of at 32 m in the baseline. This allows the use of lower βs. It also uses more, 720, lower intensity, bunches, giving reduced IBS emittance growth and requiring only low energy pre-cooling. It has a peak luminosity of ≈ 7 × 10 cm s. An upgrade of this option, requiring magnetic, or coherent, electron cooling, has 1440 bunches and peak luminosity of ≈ 15 × 10 cm s.

Progress toward a high‐energy, high‐luminosity μ+‐μ− collider

In the past two years, considerable progress has been made in development of the μ+‐μ− collider concept. This collider concept could permit exploration of elementary particle physics at energy frontiers beyond the reach of currently existing and proposed electron and hadron colliders. As a bench‐mark prototype, we present a candidate design for a high‐energy high‐luminosity μ+‐μ− collider, with Ecm=4 TeV, L=3×1034 cm−2s−1, based on existing technical capabilities. The design uses a rapid‐cycling medium‐energy proton synchrotron, producing proton beam pulses which are focused onto two π‐producing targets, with two π‐decay transport lines producing μ+’s and μ−’s. The μ’s are collected, rf‐rotated, cooled and compressed into a recirculating linac for acceleration, and then transferred into a storage ring collider. The keys to high luminosity are maximal μ collection and cooling, and innovations with these goals are presented. Possible variations and improvements are discussed. Recent progress in collider con...