muon accelerator program winter meeting, jefferson lab, 02/28-03/04/2011

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

Status of the Muon Collider Ring Design

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

Y. Alexahin (Fermilab APC)

1.5 TeV c.o.m. MC IR Layout

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

2

Rendition by A. Netepenko

x Dx

y

IR Dipole


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

1

1

4 i)i(10),(i),(n

n

refnnrefxy r

yxabByxByxB

IR dipole coil cross-section and good field region

Calculated multipole components

Task List - I


4

• 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

Task List - II


5

• 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

Effect on Chromatic Functions


6

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)

Wy

Wx WxDx

Wy

Effect on Dynamic Aperture


7

y

x

y

x

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

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

Sextupole Correction


8

5

4

5

102.1

104.9

105.1

x

x

y

x

y

y

dEdQ

dEdQ

dEdQ

5

5

6

102.1

102.3

109.1

x

x

y

x

y

y

dEdQ

dEdQ

dEdQ

Dx

y

x

Corr. sext.

cKbKadEdQ

y

y 222

Quadratic effect dominates not allowing to reduce dQy/dEy

Octupole Correction of Detuning


9

5

5

4

1031.1

1085.1

1052.6

x

x

y

x

y

y

dEdQ

dEdQ

dEdQ

5

5

6

102.1

102.3

109.1

x

x

y

x

y

y

dEdQ

dEdQ

dEdQ

y

x1024 turns DA, no beam-beam, reference emittance 10 mm mrad

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

Fringe Field of IR quads (V.Kapin)


10

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 6m at IP.

x0

y0 y0

x0

Fringe Field of IR quads (cont’d)


11

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).

Ex

Ey Ey

Ex

* Tuning Section (Eliana)


12

x

y

Goal: vary * in a wide range w/o any change in Dx6 conditions (on , and in x, y) require 6 quads in a dispersion-free straightIs it possible to use this straight for halo removal?

Dx

Halo Removal Idea (Mokhov et al., 1998)


13

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

Induction Column (G.Caporaso et al.)


14

Optical fiber distribution

system

Proton source HGI

Stack of “Blumleins”

SiC photoconductive

switches

Focusing

Laser

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

Plans


15

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

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!)

Gradient (T/m) 250 187 -131 -131 -89 82Quench @ 4.5K 282 209 146 146 (with inner radius 5mm larger)Quench @ 1.9K 308 228 160 160Margin @ 4.5K 1.13 1.12 1.12Margin @ 1.9K 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?

a (cm)

z (m)

5y

5x

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

One More Innovation: the Arc Cell 5

SY

DDx/5

Dx (m)

SX SX

SASY

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)

dsDDDCd

d

dsDC

C

xx

p

c

Cx

c

0

2

0

)(211

,1

Now C=2.5 km with B=10T

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

Momentum Acceptance 6

Fractional parts of the tunes

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

Central value of the momentum compaction factor = -1.4510-5, can be made even smaller

With 2 IPs the central tunes are 18.56, 16.58

- good (!) for beam-beam effect - good for the orbit stability and DA

p

c

x*

y*

p

Qx Qy

p


Muon Collider Parameters 9

s (TeV) 1.5 3Av. Luminosity / IP (1034/cm2/s) 1.25* 5Max. bending field (T) 10 14Av. bending field in arcs (T) 8.3 12Circumference (km) 2.5 4No. of IPs 2 2Repetition Rate (Hz) 15 12Beam-beam parameter / IP 0.087 0.087* (cm) 1 0.5Bunch length (cm) 1 0.5No. bunches / beam 1 1No. muons/bunch (1012) 2 2Norm. Trans. Emit. (m) 25 25Energy spread (%) 0.1 0.1Norm. long. Emit. (m) 0.07 0.07Total RF voltage (MV) at 800MHz 20 230+ in collision / 8GeV proton 0.008 0.0078 GeV proton beam power (MW)4.8 4.3----------------------------------------------------------------------- *) With increase by the beam-beam effect

hCP

fhNn

f repb

~21

4

2

0L

P – average muon beam power (~ )

4Nr

C – collider circumference (~ if B=const)

– muon lifetime (~ )

* – beta-function at IP

– beam-beam parameter

0.5 1 1.5 2

0.6

0.7

0.8

0.9

h

z /

“Hour-glass factor”


muon accelerator program winter meeting, jefferson lab, 02/28-03/04/2011

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