Abstract

The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides continued work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (CoM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay ($\pi \to \mu \nu_{\mu}$) channel, muon cooling, acceleration, storage in a collider ring and the collider detector. We also present theoretical and experimental R & D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the R & D since the Feasibility Study of Muon Colliders presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A. Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics (Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].

Highlights

  • The standard model of electroweak and strong interactions has passed precision experimental tests at the highest energy scale accessible today

  • The driver lattice is derived from the lattice of the Japan Hadron Facility (JHF) driver using 90± FODO cells with missing dipoles in every third FODO cell, allowing a transition energy that is higher than the maximum energy or, perhaps, imaginary

  • The measurements that are needed to demonstrate the cooling capability and optimize the design of the alternating solenoid, wedge, and lithium lens cooling stages will require the construction and operation of an ionization cooling test facility. This facility will need (i) a muon beam with a central momentum that can be chosen in the range 100 300 MeVc, (ii) an experimental area that can accommodate a cooling and instrumentation setup of initially ϳ30 m in length, and eventually up to ϳ50 m in length, and (iii) instrumentation to precisely measure the positions of the incoming and outgoing particles in 6D phase space and confirm that they are muons

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Summary

INTRODUCTION

The standard model of electroweak and strong interactions has passed precision experimental tests at the highest energy scale accessible today. With careful design of the collider ring and shielding, it appears possible to reduce to acceptable levels the backgrounds within the detector that arise from the very large flux of electrons produced in muon decays These realizations led to an intense activity, which resulted in the muon collider feasibility study report [43,44] prepared for the 1996 DPF/DPB Summer Study on High-Energy Physics (the Snowmass ’96 Workshop). We reiterate that ionization cooling is uniquely suited to muons because of the absence of strong nuclear interactions and electromagnetic shower production for these particles at energies around 200 MeVc. Rapid acceleration to the collider beam energy is needed to avoid excessive particle loss from decay.

Brief overview
Higgs boson physics
Light particles in technicolor models
Exotic narrow resonance possibilities
Z factory
Threshold measurements at a muon collider
Heavy particles of supersymmetry
Strong scattering of weak bosons
Rare muon decays
Neutrino flux
Neutrino oscillations
Specifications
Possible options
A generic design
FNAL study
AGS upgrade
Progress and open issues
Pion production
Target
Phase rotation linac
Use of both signs
Solenoids and rf
Polarized muon production
Polarization preservation
Introduction
Cooling theory
Cooling system
Bent solenoid emittance exchange example
The liquid lithium lens
ACCELERATION
Accelerator options
Scenario examples
Acceleration for Higgs collider
Acceleration for 3 TeV collider
Recirculating linac accelerator lattice issues
Pulsed magnet systems
Superconducting linacs
Simulations
Acceleration research needed
Scraping
Scraping for high energy collider
Scraping for low energy collider
Beam-beam tune shift
Bending magnet design
Alternative cos theta Nb3Sn dipole
Study of C-magnet dipole
Energy scale calibration
Conventional radiation
Neutrino induced radiation
Muon decay background
Halo background
Pair production
Bethe-Heitler muons
DETECTOR SCENARIOS
Silicon vertex detector schemes
Outer tracking schemes
Electromagnetic calorimeter schemes
Hadronic calorimeter schemes
Muon detector schemes
Background
Findings
CONCLUSIONS
Full Text
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