Texas A&M UniversityAccelerator Physics &Technology

Enabling the Future of HEP

Peter McIntyreAccelerator Research Laboratory

Texas A&M University

p-mcintyre@physics.tamu.edu

mcinturff@phyacc.tamu.edu

HEP discoveries rely upon ever-better technology and accelerator physics

• Technology Technology Discovery Whendevelopment

• 1972-1990 e+e- - SPEAR, LEP c, τ, g, ΓZ 1975-1990• 1970-1980 NbTi magnets b, ν osc. 1980-• 1976-80 colliders W±, Z, t 1982-• 1965-2000 superconducting RFCESR,JL,ILC1990-• 1990-95 asymmetric e+e- b osc, CKM 1995-• 1985-2000 high-field NbTi H, SUSY 2007-It takes a decade to develop a new technology,

more years to implement it into a facility to feed discovery.Those are the essential roles of long-lead R&D. Many of the original ideas and developments for each of these

technologies started at universities.

pp

Harvard

Wisconsin

Harvard, TAMU

Cornell

Berkeley

Berkeley

Why devise ever-better accelerator technology? Consider the LHC:

• Extend the mass reach for colliding beams - an instrument of discovery:

• Higgs sector• Supersymmetry / Supergravity• New gauge couplings

The Higgs boson and the spectrum of sparticles should be discovered at LHC, unless…

The flood of precise data from astrophysics suggests that the gauge fields of nature may be far more complex than the picture of the Standard Model + Supergravity

Can we extend the energy reach for direct discovery of new gauge fields?

Evolution of the gluon spectrum

Dutta 2004Triple the energy – double the mass reach

Assumptions:

•Luminosity grows x3 with adiabatic damping

•Luminosity needed to produce a given number of particles of mass m (assuming gauge couplings constant) scales with m2

•So twice the mass scale requires 4/3 the luminosity.

Discovery of sparticles• Ellis et al have calculated the masses of the lightest 2 visible sparticles in

minimum supersymmetric extension of the Standard Model (MSSM), constrained by the new results from astrophysics and cosmology.

0

500

1000

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0 500 1000 1500

mN

LVS

P (

GeV

)

mLVSP (GeV)

CMSSM, µ>0

= observable in WIMP searches (σ> 10-8 pb)

X = observable at LHC

= only observableat LHC Tripler

Texas A&M Accelerator R&D is building a future for high energy research

• Superconducting magnet technology– Tame Nb3Sn, extend performance to 16 T ↑– Introduce Bi-2212 inner windings, extend to 25 T

• Hadron collider physics & technology– Kill electron cloud effect (threatens LHC luminosity)– Innovations for separation dipole, low-β quads for IR– Photon stops to remove heat from synchrotron light

• Superconducting cavity technology– New structure enables use of optimized Nb foil, no welds– Kill HOMs within cavity structure, suppress instabilities

The Texas A&M AARD groupa resource for HEP discovery

• Leaders: Peter McIntyre & Al McInturff– The perfect team of idea man and master builder.

• Calculations of fields, stress, beam dynamics: Dior Sattarov– master of finite elements, particle-in-cell, and neutron transport.

• Building at the edge:– Raymond Blackburn: excellent in taking projects from design

through fabrication– Nick Diazenko: master tool & die maker, makes structures that others

would consider impossible.– Tim Elliott: 20 years expertise in precision fab, vacuum

technology, EDM machining. electronics, industrial processes– Bill Henchel: 25 years experience in cryogenics, superconducting

magnet fab. accelerator operations, electronics– Drew Jaisle: 15 years as machinist, versed in lead technologies,

magnet fab technician, builds and operatex complex assemblies.

Graduate Students

• Patrick Noyes– thesis building and testing TAMU2

• Joong Byeon– Bi-2212 winding technology for hybrid dipole.

• Don Smith– materials science of metal matrix composites

• Nate Pogue– Electrode assembly to kill electron cloud effect in LHC

• Mili Datta– Superconducting materials development

A crack team developing new technology and having fun

1. Nb3Sn Dipoles to 16 Tesla

TAMU4: 14.1 T, 4 x 3 cm2 aperture28 cm2 superconductorCollider-quality field, suppress p.c. multipoles

Microbore: 12 T, 3 x2 cm2 aperture8 cm2 Nb3Sn superconductorMinimum superconductor of any design

Stress management

Steel flux plate redistributes flux, suppresses multipoles from

persistent currents0.5 T 12 T

Nb3Sn dipole technology at Texas A&M:stress management, flux plate, bladder preload

Large Hadron Collider

123410 14

beamscollidingproton -proton

−−=ℑ

=

scmTeVs

27 km circumference tunnel at CERN

ATLAS detector

CMS detector

2. Hybrid Dipoles: Bi-2212 with Nb3SnTriple the energy of LHC

24 Tesla → 40 TeV

challenges for materials science, magnetics, cryogenics

Higher field requires new superconductor, handling immense stress loads

NbTi Nb3Sn Bi-2212

Bi-2212

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1000

0 20 40 60 80 100 120 140 160 180

Stress (MPa)

Crit

ical

Cur

rent

(A) Face Loading

Unload

4 T, 4.2 K

Nb3Sn

Cost today: NbTi $100/kgNb3Sn $1,000/kgBi-2212 $2,000/kg

Magnets are getting more efficient!

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0 5 10 15 20 25field strength (T)

coil

area

(cm

2 )

quadratic B dependence

RHIC (7 cm)

Tevatron (5 cm)

Pipe (2 cm)

SSC (5 cm)

LHC (7 cm)

microbore (3x2 cm)

TAMU4 (3 cm)

LHC Tripler(6x4 cm)

NbTi

Nb3Sn

Bi-2212

3. Optimizing the Intersection Region of LHC with new magnet technology

The IR is analogous to the objective of a microscope

• It brings the beams into collision and focuses them to minimum spot size → maximum luminosity

• Need to minimize focal length f, minimize chromatic aberrations df/dE, harmonic distortion df/dr

• Minimize chromaticity and distortion by bringing the objective as close to the object as possible. Inquire with experiments how close to go ~12 m from crossing, ~30 cm radius clear.

• Maximize gradient to minimize focal length• Develop designs for quadrupoles, dipoles that can tolerate

high radiation, high heat

Optimize LHC Interaction Region

Comparison to baseline IR:

Reduce β* to 15 cm

Reduce # of subsidiary bunch crossings by half

Reduce sensitivity to error fields and placements by factor 3

Open space for another doublet to fully match IR to arc lattice.

IP 50 m 100 m

Optimized IR design

Baseline IR design

New technology for low-β quads and separation dipoles

First quad must take big heat, particle load.

Separation dipole must take huge particle load to sides.

350 T/mironless quad

9 Tlevitated dipole

Structured cable for Bi-2212 and for Nb3Sn in high heat load,

radiation damage

6-on-1 cabling of round strand around thin-wall Inconel X750 spring tube

Draw within a thicker Inconel 718 jacket

Interior is not impregnated – only region between cables in winding

Volumetric cooling to handle volumetric heating from particle losses.

Bi-2212

0.8 mm φ strands

300 A/strand

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-5

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ultip

oles

x10

4

b2 @ 24T

b2 @ 3 T

Photon Stop• Photoemission yields

vanish for E > 100 eV

0.0001

0.001

0.01

0.1

1

0.1 1 10 100 1000 10000photon enegy (eV)

dP/d

E

LHC

Tripler

Vertical penetration through flux return (coils have clearance)

Effect on <b3> ~10-5 cm-2

4. Kill electron cloud effect in LHC arcs

•Suppress electron multipactingby locating an electrode on bottom of beam screen.

•Bias +100 V, suppress all secondary electrons, kills ECE

shadow of D dipole liner in F dipole

shadow of D dipole liner in middle dipole

beam screen

cryopumping slots

1 mm

dipole bore tube

5. New cavity structure for ILC

•The state of the art in superconducting cavities: Solid Nb cavities @ 1.8 K → 25 MV/m @ 1.3 GHz•Fabrication: circumferencial

electron beam welds

Polyhedral cavity structure

normal joints

zr

r-z sheet currentsφ sheet currents

Construction of the polyhedral cavity

a) flat s.c. strip

b) copper bar drilled with cooling channels

f) weld seams, HIP to bond

g) EDM cut to30o wedge

d) EDM cut contour

c) bend to contour

e) fit s.c. foil to Cu

weld seams on outside

cooling channels

Accelerator Physics and Technology: Solving important practical problems

• MeV electron accelerators for environment, food safety– Destroy toxic organic impurities, remove heavy metals in water– Precipitate submicron carbon from power plant exhausts– Kill bacteria in food– Drive gas →liquid conversion of natural gas

• Thorium cycle fission to power the world’s energy needs– Subcritical operation – cannot explode– Lead moderator & heat transfer – cannot melt down– Eats its own long-lived isotopes – no high-level waste to bury– Does not make bomb-capable isotopes – non-proliferation– Enough Th fuel to power the Earth for a thousand years.

6. Electron beams for clean water, food irradiation

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1 MeV beam energy, 100 kW beam power, 70% efficient, $1 million

7. Thorium cycle fission powerMake fission power from 232Th→233Th→233Pa→233U driven by fast neutrons from spallation of 800 MeV protons.

Two key problems have prevented it from being feasible until now:

How to generate 15 MW of 800 MeV proton beam in an efficient, compact device?

How to drive the spallation–transmutation sequence uniformly throughout the core?

Seven accelerators in one:Power, Reliability, Neutronics

Proton beam

Spallation zone

Fuel cells

Molten lead moderator/heat exchange

4 m

8. Metal Matrix CompositesSuper-strong materials

The goal: ultimate-strength materials – fibers (e.g. SiC) reinforce metals (e.g. steel) – same idea as reinforced concrete, fiberglass

The challenge: reinforcement requires interface bonding between fiber and metal matrix – lots of difficulties from incompatible phase chemistry, thermal mismatch, diffusion during processing

The solution: develop bonding strategy at interface that can adapt ‘any’ fiber to ‘any’ matrix