Muon Collider Ring Magnet Progress

SC Magnetsat Fermilab

Muon Collider Ring Magnet Progress

Alexander Zlobin

Technical Division Fermilab


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

Muon Collider Parameters 10

s (TeV) 1.5 3

Av. Luminosity / IP (1034/cm2/s) 0.8* 3.4

Max. bending field (T) 9.2** 14

Av. bending field in arcs (T) 7.7 12

Circumference (km) 2.6 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 60 700

+ in collision / 8GeV proton 0.008 0.007

8 GeV proton beam power (MW) 4.8 4.3

-----------------------------------------------------------------------*) With reduction by beam-beam effect**) Not 10T just by mistake

hC

Pfh

Nnf rep

b

~2

1

4

2

0L

P – average muon beam power (~ )

4

Nr

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”

MC Ring Magnet Parameters

All Experimenters’ Meeting, 2/15/2010 2Muon Collider Ring Magnet Progress


3

MC IR Magnet Parameters

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

Final Focus Quads 9

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 82

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

Quench @ 1.9K 308 228 160 160

Margin @ 4.5K 1.13 1.12 1.12

Margin @ 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

All Experimenters’ Meeting, 2/15/2010 Muon Collider Ring Magnet Progress

MAP Proposal: “Work on collider lattices must go hand-in-hand with

the magnet, superconducting rf, and detector studies”.

“The proper design of this ring is a prerequisite for the success of the whole project”.


Magnet Design Study Issues

Superconductor choice to provide the required Gnom (Bnom) in MC Ring magnets (Q and D) with the required apertures

Magnet operation temperature and margins Field quality Lorentz forces and stress management Magnet radiation heat load, lifetime,

protection Coil cooling and heat removal Magnet quench protection (magnet

inductances and stored energy) etc.



Baseline conductor – Nb3Sno Best combination of properties (Jc, Tc, Bc2, stress sensitivity)o Commercially available strands in long lengtho Good progress in Nb3Sn accelerator magnet technologies

Superconductor Choice


From P. Lee


Practical 2-layer designs, Bnom~11-12 T, Bmax~13-14 T Operation margin ~10% @ 4.5K (~20% @ 1.9K)

o Operation at 4.5K more preferable o 10% is OK for Nb3Sn magnets based on LARP studies

Good field quality aperture (<1 unit) ~2/3 coil ID Quench protection looks OK (short magnets) Max stress in Q2, Q3 >150 MPa => Nb3Sn conductor

degradation (OK based on recent LARP results) Nb3Sn IR quads with aperture 90-120 mm are modeled by LARP

Large-aperture IR Quadrupoles


SC Magnetsat Fermilab Traditional 2-layer design

o Bmax(4.5/1.9 K) ~12.5/13.5 T o Margin ~55% @4.5K (~70% @1.9K)o Good field quality inside R<55 mmo Coil shielding in the midplane

shorter magnet, inner absorber, low-Z material in coil midplane,

Open midplaneo New design concepto Bmax(4.5/1.9 K)~9/10 T o Margin ~10% @4.5K (~20%@1.9K) o Field quality is limited

Large stored energy => factor of 5-8 larger than in present LHC IRQ

Design studies: margin, field quality, stress management, quench protection.

Modeling: can we make such magnets!?

8T IR Dipole



Radiation studies have been started (V. Alexakhin, N. Mokhov)

3 designs with masks: Standard optics, 5-sigma internal absorbers, shifted Q

Muons and Neutrons, Gamma and Electrons

Power distribution, heat load, radiation dose, etc.

Preliminary results are quite encouraging

Issues: o high heat load in masks, o sagitta in 6m long dipole

Study will continue

First Radiation Studies



High heat deposition (0.5-1kW/m) in magnet midplane => large power consumption => open midplane magnet design

Coil design options: shell-type vs. block-type Coil support => mechanical stricture Coil cooling => indirect cooling scheme is needed

10T Ring Dipole


Aperture – 60mmBop~10T with ~10% margin at 4.5K.

Midplane gap: ~10 mm

New challenging design => model magnet R&D.FNAL plans (HFM program):•FY10 : coil, structure, tooling design and procurement•Practice coil, inner coil fabrication and test•FY11: outer coil fabrication, 1st model test •FY11-13: design and performance optimization


Conclusions

The level of efforts on MC ring and IR studies (including magnets) has been significantly increased

Collaboration of accelerator, magnet and detector groups has been established

Significant progress has been made in 2009: MC lattice and IR optics, magnets, radiation studies, dynamic aperture… The work will continue.

Present MC Ring magnet parameters are at the limits of Nb3Sn technology

To achieve these parameters magnet design studies and experimental R&D program are neededo Large aperture quadrupole - input from LARPo Collider and IR Dipoles – to be demonstrated!


Documents

Muon Collider Ring Magnet Progress