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Status of the Muon Collider Ring Design. Y. Alexahin (Fermilab APC). Baseline design (1.5TeV c.o.m.) Task list Recent progress - effect of IR dipole multipole errors (A.Netepenko) - fringe field of IR quads (V.Kapin) - collimation scheme - 3TeV c.o.m Lattice (Eliana)

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slide1
Status of the Muon Collider Ring Design

Y. Alexahin (Fermilab APC)

  • Baseline design (1.5TeV c.o.m.)
  • Task list
  • Recent progress

- effect of IR dipole multipole errors (A.Netepenko)

- fringe field of IR quads (V.Kapin)

- collimation scheme

- 3TeV c.o.m Lattice (Eliana)

  • Plans

Muon Accelerator Program Winter Meeting, Jefferson Lab, 02/28-03/04/2011

slide2
2

1.5 TeV c.o.m. MC IR Layout

y

x

Dx

Rendition by A. Netepenko

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide3
3

Coil aperture

mm

160

Gap

mm

55

Nominal field

T

8

Nominal current

kA

17.85

Quench field @ 4.5 K

T

9.82

Rref=40mm

b1=10000

b3=-5.875

b5=-18.320

b7=-17.105

IR Dipole

IR dipole coil cross-section and good field region

Calculated multipole components

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide4
4

Task List - I

  • Lattice Design
    • fringe field & systematic multipole correction
    • *-tuning sections
    • collimation scheme
    • closed orbit & optics correction scheme
    • injection & abort
    • monochromatization scheme (?)
  • RF system
    • accelerating structure design
    • high-order mode analysis
    • impedance & wakefield calculations
    • longitudinal dynamics simulations

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide5
5

Task List - II

  • Beam-Beam & Collective Effects
    • incoherent beam-beam simulations
    • transverse impedance & wakefield calculations
    • coherent beam-beam modes stability
    • plasma beam-beam compensation (?)
  • Designs for Different Energies/Species
    • IR for 3 TeV c.o.m. collider
    • Higgs / Top Factory (?)
    • -p collider (?)
    • Highlighted items must be done by the end of 2011,
    • others by the end of 2012

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide6
6

Effect on Chromatic Functions

Wy

Wy

Dx

Wx

Wx

Dipoles cut in short pieces with thin multipoles added

Effect is strong but positive: Wy reduced by ~25%, easy to correct (just reduce strength of the 1st sext)

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide7
7

Effect on Dynamic Aperture

1024 turns DA, no beam-beam, reference emittance 10 mm mrad

Strong effect on DA is baffling, explained by change in detuning coefficient

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide8
8

Sextupole Correction

y

Dx

Quadratic effect dominates not allowing to reduce dQy/dEy

x

Corr. sext.

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide9
9

Octupole Correction of Detuning

Octupoles (placed at the same locations) allow to reduce dQy/dEy and restore DA.

Effects of higher order multipoles in IR dipoles are yet to be studied

1024 turns DA, no beam-beam, reference emittance 10 mm mrad

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide10
10

Fringe Field of IR quads (V.Kapin)

y0

y0

x0

x0

1024 turns DA (MAD-X PTC) in units of initial coordinates atIP without (left) and with(right) quadrupole fringe field in hard-edge approximation. No beam-beam,

Compare with the beam size of 6m at IP.

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide11
11

Fringe Field of IR quads (cont’d)

Ey

Ey

Ex

Ex

DA in the plane of Courant-Snyder invariants. Compare with r.m.s. emittance of 3.5 nm.

Fringe-field effect is strong but not forbidding (we know that from K.Oide).

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide12
12

* Tuning Section (Eliana)

Dx

y

x

Goal: vary * in a wide range w/o any change in Dx

6 conditions (on ,  and  in x, y) require 6 quads in a dispersion-free straight

Is it possible to use this straight for halo removal?

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide13
13

Halo Removal Idea (Mokhov et al., 1998)

Electrostatic deflector is too weak for TeV energies, is ~100 kV ~5 ns pulsed deflector feasible?

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide14
14

Induction Column (G.Caporaso et al.)

Laser

Optical fiber distribution system

Proton source

Focusing

HGI

SiC photoconductive switches

Stack of Blumleins loaded on a central electrode (instead of a beam of particles) as a pulse source?

Stack of “Blumleins”

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide15
15

Plans

  • Lattice design:

- complete 1.5TeV design with tuning & collimation sections

- develop 3TeV design

  • Fringe fields & Multipoles:

- include realistic long. profile (Enge function) in MAD-X (F.Schmidt, CERN) or borrow from COSY-Infinity (V.Kapin)

- nonlinear corrector arrangement for fringe field and multipole error correction (V.Kapin, F.Schmidt)

  • Strong-Strong Beam-Beam Simulations:

- K.Ohmi (KEK) is willing to join with MAP

- A.Valishev and E.Stern (FNAL) also promised to look

  • Self-Consistent Longitudinal Dynamics:

- V.Balbekov & L.Vorobiev (FNAL GS) can address it (using ORBIT?)

MC Design Status- Y. Alexahin MAP meeting 03/02/2011

slide16
Final Focus Quads

11

Requirements adopted for this design:

 full aperture 2A = 10sigma_max + 2cm (Sasha Zlobin wants + 1cm more)

 maximum tip field in quads = 10T (G=200T/m for 2A=10cm)

 bending field 8T in large-aperture open-midplane magnets, 10T in the arcs

 IR quad length < 2m (split in parts if necessary!)

a (cm)

5y

5x

z (m)

Gradient (T/m) 250 187 -131 -131 -89 82

Quench @ 4.5K 282 209 146 146 (with inner radius 5mm larger)

Quench @ 1.9K 308 228 160 160

Margin @ 4.5K 1.13 1.12 1.12

Margin @ 1.9K 1.23 1.22 1.22

 Is the margin sufficient? If not lower beam energy or increase * to allow for smaller aperture

 We don’t need 5sigma+ half-aperture, 3sigma+ is enough: can accommodate N=50 m!

 No dipole field from 6 to 16.5m, is it worthwhile to create ~2T by displacing the quads?

MC Lattie Design - Y.Alexahin FNAL, November 11, 2009

MC Lattie Design - Y.Alexahin 3rd MCDW BNL December 3, 2009

slide17
One More Innovation: the Arc Cell

5

Dx (m)

SY

SA

SY

SX

DDx/5

SX

x

y

 Central quad and sextupole SA control the momentum compaction factor and its derivative (via Dx and DDx) w/o significant effect on chromaticity

 Large  -functions ratios at SX and SY sextupole locations simplify chromaticity correction

 Phase advance 300/ cell  spherical aberrations cancelled in groups of 6 cells

 Large dipole packing factor  small circumference (C=2.6 km with 9.2T dipole field)

Now C=2.5 km with B=10T

MC Lattice Update - Y. Alexahin NFMCC Meeting Oxford, MS, January 14, 2010

slide18
Momentum Acceptance

6

x*

Qx

Qy

y*

p

p

p

c

Fractional parts of the tunes

With 2 IPs the central tunes are 18.56, 16.58

- good (!) for beam-beam effect

- good for the orbit stability and DA

 Static momentum acceptance = 1.2%, while the baseline scheme calls for only 0.3%

 Central value of themomentum compaction factor = -1.4510-5, can be made even smaller

MC Lattice Update - Y. Alexahin NFMCC Meeting Oxford, MS, January 14, 2010

slide19
Muon Collider Parameters

9

h

z / 

“Hour-glass factor”

s (TeV) 1.5 3

Av. Luminosity / IP (1034/cm2/s) 1.25* 5

Max. bending field (T) 10 14

Av. bending field in arcs (T) 8.3 12

Circumference (km) 2.5 4

No. of IPs 2 2

Repetition Rate (Hz) 15 12

Beam-beam parameter / IP 0.087 0.087

* (cm) 1 0.5

Bunch length (cm) 1 0.5

No. bunches / beam 1 1

No. muons/bunch (1012) 2 2

Norm. Trans. Emit. (m) 25 25

Energy spread (%) 0.1 0.1

Norm. long. Emit. (m) 0.07 0.07

Total RF voltage (MV) at 800MHz 20230

+ in collision / 8GeV proton 0.008 0.007

8 GeV proton beam power (MW) 4.8 4.3

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

*) With increase by the beam-beam effect

P – average muon beam power (~  )

– beam-beam parameter

  • C – collider circumference (~  if B=const)
  • – muon lifetime (~ )
  • * – beta-function at IP

MC Lattice Update - Y. Alexahin NFMCC Meeting Oxford, MS, January 14, 2010

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