Considerations on Interaction Region design for Muon Collider
WIN'05, June 7 2005A. Klier - Muon Collider Physics1 Physics at a Future Muon Collider Amit Klier...
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Transcript of WIN'05, June 7 2005A. Klier - Muon Collider Physics1 Physics at a Future Muon Collider Amit Klier...
WIN'05, June 7 2005 A. Klier - Muon Collider Physics 1
Physics at a FutureMuon Collider
Amit Klier
University of California, Riverside
WIN’05 – Delphi, Greece – June 2005
WIN'05, June 7 2005 A. Klier - Muon Collider Physics 2
OUTLINE
Why muon colliders?– Advantages– Problems
Some physics– Light Higgs Factory– Heavy Higgs
Toward a muon collider– Recent advances in 6-D Cooling R&D
WIN'05, June 7 2005 A. Klier - Muon Collider Physics 3
Why Muons?
As fundamental as electrons…– Unlike p, p, all the collision energy is useful
…and 200 times as heavySync. radiation energy loss is 2 billion times less:
– Compact storage rings up to a few TeV– Very good energy resolution
Coupling to the Higgs boson is 40,000 times greater:
– Produce Higgs Bosons via the s-channel
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Muon Colliders, Other Machines
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The Problem with Muons
They DECAY: muon lifetime = 2.2 sEverything has to be fast, specifically:– Cooling (ionization)– Acceleration (RLA, FFAG)
Muon Collider detectors need shielding against ’s from decay electrons
Decay neutrinos can be harmful at E≳4 TeV(they can be useful for a Neutrino Factory, but that’s for another talk)
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Some Physics
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Light Higgs Boson
Precision EW data seem to favor light SM Higgs Boson
So does SUSY
(from theory)
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SM (or SM-like) Higgs Factory
Higgs Boson width – few MeV for mhSM
<160 GeV Fine scan for E ≲hSM
Use spin precession for in situ energy determination to ~1 ppm
Luminosity is compromised by resolution, e.g. R=0.003% Lyear~ 0.1 fb-1
R=0.01% Lyear~ 0.22 fb-1
R=0.1% Lyear~ 1.0 fb-1
( R≡2E/E )
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Precision Measurements
For a SM-like ~110-GeV Higgs Boson, a muon collider Higgs Factory can measure the mass to an uncertainty of ~10-6 with L=0.2 fb-1 (compared to ~10-4 at a 500 GeV, 500 fb-1 LC and ~10-3 at the LHC)
Only in the s-channel h can be measured directly (otherwise need accurate WW* rate measurement, difficult at mh<120 GeV)
Precise measurement of the cross section of +-h0bb – independent of mb
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Heavy Higgs Bosons
SUSY H0 and A0 may be observed at the LHC Light h0 indicate high tan, which implies
greater H0-A0 mass degeneracy Muon g-2 results also favor high tan values
(≳8), with similar consequences An “intermediate energy” (few hundred GeV)
muon collider can be used to scan the the heavy Higgs mass range & separate the two
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Separating the Heavy Higgses
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Another Scenario
For some values of tan (~8-10) and mA (≳250 GeV) LHC/LC may not be able to observe H0 or A0
A muon collider may be needed to discover the heavy Higgs in this region
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CP Violation in the Higgs Sector
Polarized muon beams can be used to measure CP violation in the Higgs sector
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R&D Advances
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Toward a Muon Collider
The physics part of this talk is mostly based on Snowmass 2001 (and earlier) results. That’s “old news”
Muon Collaboration attention has shifted to the (seemingly more feasible, and probably as important) neutrino factory
This shouldn’t have affected the Muon Collider R&D effort…
Indeed, impressive advances were made, especially in simulating 6-D cooling
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How To Build a Muon Collider
p ± ±
targetproton driver(a few MW)
proton linac
pion decay
muon cooling
muon acceleration(up to 0.1 - 3 TeV) detectorstorage
ring
+
-
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How Much Cooling is Needed
Beam reduction of about 100 needed in each transverse and in the longitudinal direction (~106 6-D cooling) compared with muons from pion decay
Light Higgs Factory
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Ionization cooling:Fast, but cools only intransverse directions
(sufficient for factory) 6-D cooling via emittance exchange:
Repeated cooling/emittance exchangecools beam in all sixphase-space dimensions
6-D Coolingabsorber
RF RF
absorber
largeangularspread
smallangularspread
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Ring Coolers
First suggested by V.Balbekov in 2001
6-D cooling – about 50
However: Problems trying to
introduce realistic magnetic fields
Injection/extraction very difficult and affects performance badly
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The RFOFO Ring
Suggested by R.Palmer in 2002
6-D cooling ~ 300 Simulations work with
realistic magnetic field Injection/extraction still
a problem, but performance is less affected (still cools by about 200)
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Gas-Filled Cooling Ring
The idea: use the dipole volume itself as a “wedge absorber” by filling it with high-pressure H2 gas
Small Dipole Ring – suggested by A.Garren, H.Kirk in 2004
Can be used to demonstrate 6D cooling experimentally: moderate performance, but low cost (no SC…)
1.6 m
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Further Cooling – Lithium Lens
Recently simulated transverse cooling down to ~0.3 mm
But longitudinal emittance blows up
Latest development use bent Lithium Lenses (“ Li ring”)
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Helical Cooling Channel
Suggested by Y.Derbenev/Muons Inc.
High-pressure-H2-filled helical dipole & RF cavities in a solenoid
Simulated cooling: 300 Advantage: no need for
injection/kicker Challenges: high dipole
fields, rather complicated
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Parametric Resonance Cooling
Suggested by Y.Derbenev & Muons Inc.
Potential cooling 10 after the HCC/ Ring Cooler
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Reversed Emittance Exchange
For TeV-scale muon colliders, longitudinal cooling is sufficient, but more transverse cooling is needed
Reverse the emittance exchange process
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Conclusions
Muon colliders can contribute to Higgs physics in unique ways, complement LHC/LC
Being compact, muon colliders may eventually cost less than the “conventional” ones (LHC/LC), but are extremely challenging
A lot of progress in 6-D cooling simulations Greater effort is needed to put everything
together, demonstrate 6-D cooling in real life