1. Summary on the Muon Collider Lattice and Interaction Region Designf
Summary on the Muon Collider Lattice and Interaction Region Design
Y.Alexahin
2nd Muon Collider Design workshop, JLab, Newport News VA December 8-12, 2008

2. INTERACTION REGION Chair, Al Garren
The session
INTERACTION REGION Chair, Al Garren
Update on the 'Dipole first' Muon Collider optics (Yuri Alexahin)
Studies for a Muon Collider Optics with non-interleaved sextupole scheme (Eliana Gianfelice-Wendt )
Considerations on Optimized IR Design (Yaroslav Derbenev)
Beam Induced Detector Backgrounds for a Muon Collider (Steve Kahn)
Low-beta Region Muon Collider Detector (Mary Anne Cummings)
The first two talks gave an update on the existing MC designs,
Yaroslav formulated principles on which a new design will be based (“bend everything!”)
Steve reviewed previous work and plans on detector shielding from secondaries
Mary Anne outlined new ideas in the detector design
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

3. Basic parameters
Oide (modified) “Dipole first”
Beam energy, GeV
Number of IPs 1 2
Circumference, km
*, cm
_max, km
Momentum compaction 1.8e e-5
800MHz RF voltage*, GV
Momentum acceptance, %
Tunes / /41.1
DA,  for =25m >5 ~3
*) for energy spread E=0.2% and bunch length s=1cm
- one more reason to reduce circumference!
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

4. IR Optics
“Dipole first” modified Oide
x y Dx
DDx/50 Wx Wy
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

5. Momentum Acceptance
“Dipole first” modified Oide p Qy Qx c p
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

6. Nonlinear Detuning and Dynamic Aperture
“Dipole first” modified Oide
Normalized anharmonicities:
dQ1/dE1 = E+08
dQ1/dE2 = E+08
dQ2/dE2 = E+08
 CSIx [m]
 CSIy [m]
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

7. Status of the lattice design
“Dipole first” optics provides necessary DA for the medium-emittance option, but only marginal for HE
Modified Oide lattice has sufficient DA for the high-emittance option, but the circumference is too large.
Next step - to combine the best of the two:
There is still no design suitable for the low emittance option, hopefully the approach outlined by Yaroslav will lead to one.
But it must include crossing angle and all the complications associated with it!
“Dipole first” lattice has the first 7.5T dipole 2.5m from the IP.
Will it complicate or help to protect the detector by sweeping the secondaries?
How the dipole fringe field will affect the detector performance?
Programs outlined by Steve and Mary Anne will provide the guidance
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

8. Detector Protection (S.Kahn)
Detector schematics
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

9. Bethe-Heitler Muon Trajectories for the 2×2 TeV Collider
Muon pair production at beam pipe
for example
NN
eNeN
(electrons are more likely to hit beam pipe).
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

10. IP Configuration Parameters
Distance to First Quad
0.5 cm
0.8 cm
Riris
1.1 m
80 cm
Min Aperture Point
3 cm
6 cm
Open Space to IP
20º
Shield Angle
2×2 TeV
250×250 GeV
50×50 GeV
Parameter
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

11. Future Plans
We need to start to examine beam related backgrounds produced by currently in vogue IP designs.
This is expected to take a fair amount of work.
We would have to optimize the current IP design as previously done to reduce backgrounds.
Compare to previous designs.
We need to reexamine the forward/backward shielding.
Can we reduce the 20º blind cone angle by instrumenting the cone to identify electromagnetic punch-through background so that it can be ignored.
Can we instrument the core to identify muons. This would help enormously in identifying multi-lepton channels produced by SUSY.
Can we instrument the low beta forward-backward regions.
Mary Anne will tell us more about that.
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

12. Low-beta Region Muon Collider Detector (Mary Anne Cummings)
Last serious design effort was Snowmass 1996
Lack of coverage in the forward/backward angular region:
Shielding is necessary against electrons from muon decays
The area < 20 degrees for/back was inert material (tungsten),
but possibility down to < 9 degrees considered
Serious limitation to possible physics
Top production in forward regions as CoM energy goes up
Asymmetries are more pronounced in forward regions
Z’ => ttbar
Final states with many fermions (like ordinary SM tt-events) are hardly ever contained in the central detector
Advances in detector technologies have made extending the forward reach possible – minimizing a competitive disadvantage with linear colliders
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

13. Forward Calorimetry
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

14. NIU Calorimeter R & D: Calorimeter Tiles
Candidate for “instrumented shielding” that will comprise a forward region muon collider detector, addressing the challenges of viability and particle ID requirements a) b)
(a): Examples of plastic scintillator tiles for use in calorimeters; (b): Array of scintillating tiles arranged on 1m x 1m plate of a prototype CALICE hadron calorimeter, built by the NIU group.
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

15. Major Issues for Phase I SBIR
Scope of Muons, Inc. SBIR Phase I: establish the viability of
“instrumented shielding” to extend the physics coverage of a Muon Collider Detector by studying the
The limits of detector performance (e.g., cell occupancy, efficiency) in the forward interaction region as a function of muon collider bunch intensity and luminosity.
The shielding requirements for all detectors, especially those that might be affected by the instrumentation of the tungsten cone.
The optimization of the collider parameters and low beta insertion designs to minimize the beam-related backgrounds that get into the detector.
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008

16. Summary With the present level of understanding it seems possible:
 =1cm
 c ~
 momentum acceptance ±1%
 Dynamic aperture ~ 5 for N=25 m (HE option)
 Circumference ~3km
(all at the same time)
To proceed further to a realistic design a close collaboration between lattice designers and detector, energy deposition and magnet technology groups is a must.
I hope we’ll establish such collaboration with MuonsInc people.
MC Lattice & IR Design - Y. Alexahin nd MCD workshop, JLab, December 12, 2008