2nd Muon Collider Design workshop, JLab, Newport News VA December 8-12, 2008

Summary on the Muon Collider Lattice and Interaction Region Design

Y.Alexahin

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MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

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 2nd MCD workshop, JLab, December 12, 2008

Basic parameters

Oide (modified) “Dipole first”

Beam energy, GeV 750 750

Number of IPs 1 2

Circumference, km 4.9 3.1

*, cm 1 1

_max, km 275 32

Momentum compaction 1.8e-4 5.5e-5

800MHz RF voltage*, GV 1.56 0.31

Momentum acceptance, % 0.75 0.63

Tunes 30.55/30.45 42.1/41.1

DA, for =25m >5 ~3

-------------------------------------------------------------------------------

*) for energy spread E=0.2% and bunch length s=1cm

2

s

E

RFcRF f

cERV

- one more reason to reduce circumference!

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

IR Optics

x y

Dx DDx/50

Wx

Wy

“Dipole first” modified Oide

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

Momentum Acceptance

c

p

p

Qy

Qx

“Dipole first” modified Oide

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

Nonlinear Detuning and Dynamic Aperture

0 50 100 150 200 2500

50

100

150

200

250

CSIx [m]

CSIy [m]

Normalized anharmonicities:

dQ1/dE1 = 0.25242152E+08

dQ1/dE2 = 0.19616977E+08

dQ2/dE2 = 0.18515914E+08

“Dipole first” modified Oide

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

Status of the lattice design

x

yx,

“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 2nd MCD workshop, JLab, December 12, 2008

Detector Protection (S.Kahn)

Detector schematics

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

Bethe-Heitler Muon Trajectories for the 2×2 TeV Collider

Muon pair production at beam pipe for exampleNNeNeN (electrons are more likely to hit beam pipe).

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

IP Configuration Parameters

6.5 m8 m7 mDistance to First Quad

0.5 cm0.8 cmRiris

1.1 m1.1 m80 cmMin Aperture Point

3 cm3 cm6 cmOpen Space to IP

20º20º20ºShield Angle

2×2 TeV250×250 GeV50×50 GeVParameter

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

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 2nd MCD workshop, JLab, December 12, 2008

Low-beta Region Muon Collider Detector (Mary Anne Cummings)

Last serious design effort was Snowmass 1996Lack 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 physicso Top production in forward regions as CoM energy goes upo Asymmetries are more pronounced in forward regionso Z’ => ttbaro Final states with many fermions (like ordinary SM tt-events) are hardly ever

contained in the central detectorAdvances in detector technologies have made extending the forward

reach possible – minimizing a competitive disadvantage with linear colliders

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

Forward Calorimetry

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

NIU Calorimeter R & D: Calorimeter Tiles

(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.

Candidate for “instrumented shielding” that will comprise a forward region muon collider detector, addressing the challenges of viability and particle ID requirements

a) b)

MC Lattice & IR Design - Y. Alexahin 2nd MCD workshop, JLab, December 12, 2008

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 2nd MCD workshop, JLab, December 12, 2008

Summary

With the present level of understanding it seems possible:

=1cm

c ~ 10-5 -10-4

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.