July 17, 2003 EPS 2003 Aachen 1P. Limon

HADRON COLLIDERSOutline

The Tevatrono What are the issues?o What is the plan for the immediate future?

The LHC and its upgradeso What upgrades are possible?o When do we start, and what is happening now?

What are the steps beyond that?o What are the possibilities for hadron colliders at higher energy?o How do they compare in utility and cost?

Is there a sensible plan for HEP that includes hadron colliders?o How can we improve the planning process?

July 17, 2003 EPS 2003 Aachen 2P. Limon

HADRON COLLIDERSMotivation

Hadron colliders are the discovery machines of high- energy physics.o Tevatrono LHC & LHC Upgradeso VLHC

These colliders have much in common, but the ultimate performance of each is determined by different phenomena.o Tevatron: Ability to produce, cool and deliver anti-protonso VLHC: Synchrotron radiation & IR debris powero LHC: In between - synch. rad., beam-beam interaction, ?

Careful analysis of these differences will help us construct the right plan.

July 17, 2003 EPS 2003 Aachen 3P. Limon

HADRON COLLIDERS TevatronPerformance

Run II has not yet reached its expected luminosity performance

o The luminosity is determined by proton & antiproton intensities at collision

there are indications of beam-beam limitations

– Lifetimes and emittance growth in presence of other beam

o The efficiency for delivering both proton and pbar beams to collision is not yet reliable

There is now a plan to fix some of those problems.

o Improved instrumentation to help understand the issues

o Improved “housekeeping” to make operation of the whole complex more robust

o Improved antiproton production and cooling

o Improved transfer efficiencies and reduced emittance blowup

July 17, 2003 EPS 2003 Aachen 4P. Limon

HADRON COLLIDERS TevatronRun II Peak Luminosity

July 17, 2003 EPS 2003 Aachen 5P. Limon

HADRON COLLIDERS TevatronLuminosity vs. Pbars at Low Beta

Runs 631-2375

0

10

20

30

40

50

0 200 400 600 800 1000 1200 1400

Pbars at Low Beta (x109)

Luminosity (x10

30)

July 17, 2003 EPS 2003 Aachen 6P. Limon

HADRON COLLIDERSTevatron

Pbar Efficiency, Stack to Low Beta

0

10

20

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0 200 400 600 800 1000 1200 1400

Pbars at Low Beta (x109)

Luminosity (x10

30)

July 17, 2003 EPS 2003 Aachen 7P. Limon

HADRON COLLIDERSTevatron

What’s the Plan to Do Better?

The Run II Luminosity Upgrade plan concentrates first on things that will improve efficiency http://www.fnal.gov/pub/now/upgradeplan/o Beam position monitor and other instrumentation upgradeso Dampers in MIo Re-alignment of Tevatron and Pbar sourceo Reduce MI cycle time for Pbar production

Completed in 2004o Slip stacking of protons in MI and pbar target sweepingo Initial pbar acceptance improvements and Debuncher cooling upgrade

Completed in 2005o Recycler Ring with electron cooling integrated into operationo Rapid transfer of pbars from Accumulator to Recyclero Accumulator stacktail cooling upgrade

Completed in 2007o Pbar production acceptance upgrade with higher-gradient lithium lenso Increased helical beam separationo Introduction of active beam-beam compensation

July 17, 2003 EPS 2003 Aachen 8P. Limon

HADRON COLLIDERS TevatronProjected Integrated Luminosity

July 17, 2003 EPS 2003 Aachen 9P. Limon

HADRON COLLIDERSLHC

Luminosity Upgrade - Why & When

July 17, 2003 EPS 2003 Aachen 10P. Limon

HADRON COLLIDERS LHC Luminosity UpgradeWork has started

HEPAP put R&D for a luminosity upgrade in its highest priority category:

o “The science of extending exploration of the energy frontier with the LHC accelerator and detector luminosity upgrades is absolutely central. The R&D phase for these will need to start soon if the upgrades are to be finished by the present target date of 2014.”

From the High-Energy Physics Facilities of the DOE Office of Science Twenty-Year Road Map, HEPAP report to the Director of the Office of Science, 17 March 2003.

Technical work has begun in the U.S. within the LHC Accelerator Research Program (LARP) collaboration of DOE national labs - BNL, Fermilab & LBNL

o Received a favorable recommendation from a DOE review in June, 2003

o Working on projects to help bring on the LHC quickly and efficiently Participate strongly in commissioning and in some instrumentation

o Working on magnet R&D and accelerator design to provide fully integrated interaction regions suitable for ultra-high-luminosity operation

July 17, 2003 EPS 2003 Aachen 11P. Limon

HADRON COLLIDERS

Quads 1st Dipoles 1st

Quads between Twin Quads 1stTwin Dipole 1st

LHC Luminosity UpgradeSome Possible Upgraded LHC IRs

July 17, 2003 EPS 2003 Aachen 12P. Limon

HADRON COLLIDERSLHC Energy Upgrade

What about an LHC energy upgrade?

o Whereas a luminosity upgrade is relatively cheap, quick and non-disruptive, an energy upgrade is not an upgrade — it is an entirely new collider — and, it will probably need a new injector, too

o The best performance from Nb3Sn magnets will result in only a 70% increase in energy

o The R&D to develop robust and cost-effective magnets at the highest field will take a long time and be very costly.

o It will be expensive and risky for little return

A staged VLHC is a better path.

o Higher energy per $ or €, even in its initial stage

o Upgradeable to > 200 TeV (cm)

The freedom to make tradeoffs between tunnels and technical components is a powerful tool to reduce cost and improve performance.

July 17, 2003 EPS 2003 Aachen 13P. Limon

HADRON COLLIDERS

Design Study for a Staged Very Large Hadron Collider

Fermilab-TM-2149June 11, 2001

www.vlhc.org

July 17, 2003 EPS 2003 Aachen 14P. Limon

HADRON COLLIDERS VLHCConclusions (1)

A staged VLHC starting with 40 TeV and upgrading to 200 TeV in the same tunnel is, technically, completely feasible.

There are no serious technical obstacles to the Stage-1 VLHC at 40 TeV and 1034 luminosity.

o The existing Fermilab accelerator complex is an adequate injector for the Stage-1 VLHC, but lower emittance would be better. (We should take this into account if Fermilab builds a high-power injector)

o VLHC operating cost is moderate, using only 20 MW of refrigeration power, comparable to the Tevatron.

o Improvements and cost savings can be gained through a vigorous R&D program in magnets and underground construction.

July 17, 2003 EPS 2003 Aachen 15P. Limon

HADRON COLLIDERSVLHC

Conclusions (2)

The construction cost of the first stage of a VLHC is comparable to that of a linear electron collider, ~ $4 billion using “European” accounting.o From this and previous studies, we note that the cost of a collider

of energy near 40 TeV is almost independent of magnetic field.

o A total construction time of 10 years for Stage-1 is feasible, but the logistics will be complex.

o Making a large-circumference tunnel is possible. A number of different possibilities in the Fermilab area were studied. Managing such a large construction project will be a challenge. The political issues associated with a large tunnel must be

handled with care.

o Building the VLHC at an existing hadron accelerator lab saves significant money and time.

July 17, 2003 EPS 2003 Aachen 16P. Limon

HADRON COLLIDERSThe Staged VLHC Concept

The Vision

o Build a BIG-circumference tunnel.o Fill it with a “cheap” 40 TeV collider.o Later, upgrade to a 200 TeV collider in the same

tunnel. Spreads the cost Produces exciting energy-frontier physics sooner & cheaper Allows time to develop cost-reducing technologies for Stage 2 Creates a high-energy full-circumference injector for Stage 2 A large-circumference tunnel is necessary for a synchrotron

radiation-dominated collider. This is a time-tested formula for success

Main Ring Tevatron LEP LHC

July 17, 2003 EPS 2003 Aachen 17P. Limon

HADRON COLLIDERSVLHC Parameters

Stage 1 Stage 2

Total Circumference (km) 233 233

Center-of-Mass Energy (TeV) 40 200

Number of interaction regions 2 2

Peak luminosity (cm-2s-1) 1 x 1034 2.0 x 1034

Dipole field at collision energy (T) 2 11.2

Average arc bend radius (km) 35.0 35.0

Initial Number of Protons per Bunch 2.6 x 1010 5.4 x 109

Bunch Spacing (ns) 18.8 18.8

b* at collision (m) 0.3 0.5

Free space in the interaction region (m) ± 20 ± 30

Interactions per bunch crossing at Lpeak 21 55

Debris power per IR (kW) 6 94

Synchrotron radiation power (W/m/beam) 0.03 5.7

Average power use (MW) for collider ring 25 100

July 17, 2003 EPS 2003 Aachen 18P. Limon

HADRON COLLIDERSVLHC Tunnel Cross Section

July 17, 2003 EPS 2003 Aachen 19P. Limon

HADRON COLLIDERS VLHCSynchrotron radiation

Synchrotron radiation masks look promising. They decrease refrigerator power and permit higher energy and luminosity. They are practical only in a large-circumference tunnel.

A “standard” beam screen will work up to 200 TeV and 2x1034. Beyond that, the coolant channels take too much space.

A synchrotron radiation “mask” will allow even higher energy and luminosity.

BEAM SCREEN

SLOT

GAP

PHOTON-STOP

Coolant

July 17, 2003 EPS 2003 Aachen 20P. Limon

HADRON COLLIDERS

PSR<10 W/m/beam peak tL > 2 tsr Int/cross < 60 L units 1034 cm-2s-1

VLHCOptimum Field

July 17, 2003 EPS 2003 Aachen 21P. Limon

HADRON COLLIDERS VLHC Total collider cost

based on SSC cost distribution

July 17, 2003 EPS 2003 Aachen 22P. Limon

HADRON COLLIDERSStage-2 VLHC Conclusions

The Stage 2 VLHC can reach 200 TeV and 2x1034 or more in the 233 km tunnel.

A large-circumference ring is a great advantage for the high-energy Stage-2 collider. A small-circumference high-energy VLHC may not be realistic.

o The optimum magnetic field for a 100-200 TeV collider is less than the highest field strength attainable because of synchrotron radiation, total collider cost and technical risk.

10 T < B < 12 T appears optimum for 100 TeV < Ecm < 200 TeV

The minimum aperture of the magnet is determined by beam stability and synchrotron radiation, not by field quality.

There is the need for magnet and vacuum R&D to demonstrate feasibility and to reduce cost. o This R&D will not be easy, will not be quick, and will not be cheap.

July 17, 2003 EPS 2003 Aachen 23P. Limon

HADRON COLLIDERSVLHC Next Steps

There will be a VLHC Physics Workshop this year.

o Date: October 16 - 18, 2003 at Fermilabo Organizers:

Uli Baur SUNY-Buffalo

Contact: baur@ubhex.physics.buffalo.edu

Chip Brock Michigan State University Chris Hill Fermilab Gian Giudice CERN Paris Sphicas CERN

http://conferences.fnal.gov/hadroncollider/

July 17, 2003 EPS 2003 Aachen 24P. Limon

HADRON COLLIDERSThe HEP Plan

We are on the verge of important discoverieso There are many hints that great physics is just over the horizon —

understanding EWSB, neutrino mass, dark energy, dark matter and more.

o An exciting time.

The possibilities for new HEP tools are excellento Run II is progressing (with some difficulty)

o LHC is being built (with the usual problems)

o A renaissance in neutrino physics (New stuff)

o A linear collider is being considered (and might start in 5 to 10 years)

Should we include a VLHC in this plan?

July 17, 2003 EPS 2003 Aachen 25P. Limon

HADRON COLLIDERSVLHC in the HEP Plan

Why do we need to include the VLHC in the HEP plan?o If we believe that we may eventually want higher-energy collisions at

high luminosity, we will almost certainly need a VLHC.

The timing and eventual existence of a VLHC will depend on decisions about all other multi-billion-dollar facilities including a linear collider.o If a linear collider is built in the U.S. for billions of $, the U.S. is unlikely

to spend billions on a VLHC until many years later. o The U.S. has the best combination of resources, infrastructure, space

and geology for a VLHC. It is difficult to builda VLHCt anywhere else.o A significant energy upgrade of the LHC will be very costly and very

risky, for very little gain.

o Result: A long delay to higher energy

July 17, 2003 EPS 2003 Aachen 26P. Limon

HADRON COLLIDERSThe HEP Planning Process

We need to reexamine our strategy for progress, planning and politics, not only for the VLHC, but for all large facilities.

Big HEP instruments require more than business as usual

o We need a global strategy derived from a large vision of scientific goals — the “Science Roadmap.”

Sell the science, not the instruments.

o Think of the facilities as missions along the way to the science goals.

o We need a fair and open mechanism to modify the roadmap and the plan as results dictate.

o We will be competing with other large science facilities, or even non-scientific projects for government support.

o We must include a range of scientific disciplines and high-level government policy makers from the beginning of planning.

July 17, 2003 EPS 2003 Aachen 27P. Limon

HADRON COLLIDERSA Global HEP Strategy

Why do we need a global strategy?

o Big HEP instruments are too costly to be planned, built and operated nationally or regionally.

o HEP instruments are complex and take a long time to design and build. Everyone must be involved; everyone must help.

o International collaboration has many political, human and scientific benefits beyond cost-sharing.

While we’re planning, important instruments are missing from the existing plans.

o What about underground labs, super neutrino beams, astrophysics experiments or R&D for the future? All these should be in the plan, and all should be part of a Global Strategy.

July 17, 2003 EPS 2003 Aachen 28P. Limon

HADRON COLLIDERSA Word About R&D

The machines and facilities we are talking about are costly and complex.

o Mistakes and delays are potentially very damaging financially, politically and scientifically.

o Political and financial recovery is difficult and time-consuming.

o It takes longer than you think to develop the components of a cutting-edge collider.

The R&D investment for future HEP instruments will be much greater than we are accustomed to.

July 17, 2003 EPS 2003 Aachen 29P. Limon

HADRON COLLIDERSConclusions

The most important requirement for the survival of HEP is worldwide cooperation resulting in a global strategy based on a visionary science roadmap.

o Sell the science, not the instruments

o The goals should be truly large and visionary, and the instruments missions along the way.

The parameters and schedule for a VLHC will depend on the timing and location of all other large facilities. The global plan should recognize these couplings.

If we ever want to build a VLHC, or any other large facility, we need to have a vigorous R&D program now.

o The technology is very challenging, and the penalty for failure will be severe.

July 17, 2003 EPS 2003 Aachen 30P. Limon

HADRON COLLIDERSLast Slide