Event & Minutes


The three step scenario

Bruno Autin, CERN-PS

The basic questions

1.    Where do we go?
2.    How can we reach the goal?

The ultimate goal is a large muon collider (LMC) in the TeV range. In order to assess its feasibility and to produce first class physics before LMC completion, it is proposed to investigate two other applications of cold muon beams: a muon storage ring as a source of neutrinos which could be operated within six years and, later on, after LHC and NLC first discoveries, a precision muon collider (PMC) that could operate as a Higgs factory or at top threshold.

Integrated resources in arbitrary units versus time (GIF file)
Integrated resources in arbitrary units versus time (EPS file)

Machine parameters

The comparison of the machine parameters shows that, indeed, a progressive implementation of the various components can lead to the LMC with intermediate stages adapted to up to date physics experiments.
Neutrinos PMC LMC
Primary beam
particle p (heavy ion? e? ...) id. id.
t [ns] 1 id. id.
E [GeV] >10 id. id.
f [Hz] available > 15 15
n available 5 1013 2.5 1013
N available 2 4
Target & capture
particle m+ m+, m- m+, m-
material C Pb, Ga alloys Pb, Ga alloys
Dr-Dq [mm .mrad] ~ 15000 id. id.
DE-Dt [eV.s] ~ 1 - 6 id. id.
(et/et0)2 7 10-2 ~ 10-4 ~ 10-4
el/el0 1 ~ 2.5 10-2 ~ 2.5 10-2
DE [GeV] 10 - 20 2*(50 - 200) 2*1500
Final ring 
type storage ring collider collider
b*-value [m] ~ 100 0.026 0.003
Dp/p [%] ~ +_10 0.003 - 0.14 0.16
Flux [n-nbar/s]  4 - 120 1012 - -
Luminosity [cm-2s-1] - 1031 - 1032 7 1034

How to start

1. Choose neutrinos
2. Select the best system: proton driver & target.
3. Evaluate the minimum interesting flux and decide
    a. which capture system to build,
    b. whether cooling is necessary and, if so, the number of transverse cooling stages.
4. Build accelerator and storage ring.
5. Start first physics experiments.
    Neutrino source (GIF file)
    Neutrino source (EPS file)

How to continue and conclude

6. Upgrade capture and cooling by adding more stages for transverse and momentum cooling.
7. Build a collider oriented proton driver and target system.
8. Build acceleration system for PMC.
9. Build PMC.
10. Build acceleration system for LMC.
11. Build LMC.

Studies, Research and Development

The various areas where the participants to this study can contribute are listed in the table here below. In the beam-matter column are regrouped  both particle interaction and technological aspects.
Beam - matter Optics Acceleration
Rapid cycling synchrotrons RF cavities (JHF type)
SC cavities Recirculators linac
Target & capture
Particle yield Solenoid Bunch rotator
Target Horns
Radiation problems Lithium lens
Plasma lens
Absorbers Low b lattice SC cavities
Cooling and heating processes Orbit dispersion
Solenoids and Lithium lenses
Dipoles and quadrupoles
SC magnets Compact isochronous lattice Short bunch
Background Very low b* Instabilities
v radiation Very low Dp/p RF quadrupoles
Optical stochastic cooling Polarization
Beam-beam passivation SC dipoles and quadrupoles

Generic aspects of research on m machines

It may turn out that the project is too ambitious and that one cannot build a muon collider. However, the R&D investment will not be lost because it can serve other applications.

High intensity proton driver

Japan Hadron Facility type of research.
Radio-active beams.
Neutron spallation.

High intensity m - beams

Rich physics program (next speakers).
m catalyzed fusion?

Fast acceleration

Linear accelerators.
Escape space charge problems in high intensity machines.


Very low b* insertions are mandatory for any collider.
High field dipoles and quadrupoles have also to be developed for a super-LHC.