p. limon october 16, 2003 hadron collider workshop 2003 fermilab 1 outline a quick review of the...

October 16, 2003 Hadron Collider Workshop 2003 Fermilab

1P. Limon

Outline

A quick review of the VLHCo A short description

o Some important technical points

The VLHC in a global plan for HEPo How & why a VLHC fits into a global plan

Some remarks on planning for HEP

o Promoting huge accelerator projects in today’s political climate is very difficult. We make it more difficult by pursuing a flawed strategy. How can we make it better?


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Design Study for a Staged Very Large Hadron Collider

Fermilab-TM-2149June 11, 2001

www.vlhc.org


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The Staged VLHC Concept

Take advantage of the space and excellent geology near Fermilab.

o Build a BIG 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


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Conclusions (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. Low emittance is important!)

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.


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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 tunnel is possible in the Fermilab area. Managing such a large construction project will be a challenge.

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


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Conclusions (3)

The Stage 2 VLHC can reach 200 TeV and 2x1034 or possibly significantly more in the 233 km tunnel. o 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 There is the need for magnet and vacuum R&D to demonstrate feasibility and to reduce cost.

Result of work completed after the “Study.”

o For very high energy colliders, very high magnetic fields (B>12T) are not the best solution.


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VLHC 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

β* atcollis (ion m) 0.3 0.5

Fre e spa ce i n the interacti on regi (on m) ± 20 ± 30Interaction s per bunc h cross ing a t Lpeak 21 55Debri s powe r pe r IR ( )kW 6 94Synchrotr on radiatio n powe r ( /Wm/bea )m 0.03 5.7Avera ge powe r u (se M ) W for collide r ring 25 100


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Transmission Line Magnet

2-in-1 warm iron

Superferric: 2T bend field

100kA Transmission Line

alternating gradient (no quadrupoles needed)

65m Length

Self-contained including Cryogenic System and Electronics Cabling

Warm Vacuum System 30cm support tube/vacuum jacketcry pipes

100kA return bus

vacuum chamber

SC transmission line


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The First Stage-1 Magnet Yokes


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VLHC Tunnel Cross Section


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Underground Construction

Three orientations chosen to get representative geological samples of sites near Fermilab.

o South site samples many geologic strata and the Sandwich fault.

o One north site is flat and goes through many strata.

o Other north site is tipped to stay entirely within the Galena-Platteville dolomite, and is very deep.

These are not selected sites – merely representative.

o Cost of other sites can be built from data gained in these sites.


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EAST-WEST SECTION


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VLHC Cost Basis

Used the “European” cost base

o No detectors (2 halls included), no EDI, no indirects, no escalation, no contingency – a “European” base estimate.

Estimated the cost drivers using a standard cost-estimating format. This is done at a fairly high level.

o Underground construction (Estimates done by AE/CM firm)

o Above-ground construction (Estimates done by FNAL Facility Engineering Section)

o Arc magnets

o Corrector and special magnets (injection, extraction, etc)

o Refrigerators

o Other cryogenics

o Vacuum

o Interaction regions

Used today’s (2001) prices and today’s technology. No improvements in cost from R&D are assumed.


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VLHC Stage 1 Cost Drivers

Comparison: the SSC Collider Ring, escalated to 2001 is $3.79 billion

* Underground construction cost is the average of the costs of three orientations, and includes the cost of a AE/CM firm at 17.5% of construction costs.

In FY2001 K$ VLHC Estimate VLHC Fraction

Total 3,981,159 100.00%Civil Underground * 1,968,000 49.43%Civil Above Ground 310,000 7.79%Arc Magnets 791,767 19.89%Correctors & Special Magnets 112,234 2.82%Vacuum 153,623 3.86%Installation 232,397 5.84%Tunnel Cryogenics 22,343 0.56%Refrigerators 94,785 2.38%Interaction Regions 26,024 0.65%Other Accelerator Systems 269,986 6.78%


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Stage-2 Magnets

There are several magnet options for Stage 2. Presently Nb3Sn is the most promising superconducting material.

Stage-2 Dipole Single-layer common coil Stage-2 Dipole Warm-iron Cosine


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Stage-2 Cost & Performance

What are the general design ideas that exist for magnets for the Stage 2 VLHC?

We did not make a cost estimate of the Stage 2 VLHC, but we tried to understand major cost sensitivities.

o For example, how does the cost vary as a function of magnetic field?

After the “Study,” we did some work to help understand the limitations of Stage 2 performance.

o Does synchrotron radiation put limits on performance, or does it influence the choice of magnetic field?

Can detectors live in the radiation field?

These questions were studied to help guide future R&D.


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VLHC Cost based on SSC cost distribution


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Synchrotron 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


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Magnet aperture required for beam screen and photon stops

200 TeV; 30 km bend radius

14 m magnet length

Min. BS-beam clearance=4 mm

Diameter increases due to increased coolant flow requirements


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

VLHC Optimum Field


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Detector Radiation Dose

~ 50 kW (total) at IP


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Stage-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.

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.


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Next Steps

Most important, we must understand the science needs and the opportunities a VLHC presents.

o This workshop is a start!

If we ever want a VLHC, we have to keep at the R&D, particularly for high- and low-field magnets, tunneling and vacuum.

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


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The HEP Plan

We are on the verge of important discoveries

o There are many hints that great physics is just over the horizon — understanding EWSB, neutrino mass, dark energy, dark matter and more — an exciting time.

Possibilities for new HEP tools are excellent

o Run II is moving ahead (some problems, but getting better)

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 be started in 5 to 10 years)

Should we include a VLHC in this plan?


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VLHC 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 want a VLHC.

The timing and eventual existence of a VLHC will depend on decisions about all other multi-billion-dollar facilities including linear collider.

o The U.S. has the best combination of resources, infrastructure, space and geology for a VLHC. It is difficult to build it anywhere else.

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 soon after. This results in a long delay for VLHC.

o A significant energy upgrade of the LHC will be very costly and very risky, for very little gain.

Furthermore, more than VLHC is missing from the plan.

o What about underground labs, super neutrino beams, astrophysics experiments or R&D for the future? All these should be in the plan.


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The HEP Plan

We do not have a viable strategy for the survival of HEP. o A global scrap over a linear collider does not constitute a

strategy. There has been some recent progress in formulating a path to a linear

collider technology decision.

We do not even have a plan to make a plan.o In the U.S., for example, the HEPAP recommendation to create

a mechanism to formulate a coherent strategy has become the narrowly-focused P5.

HEP must change the way it does things if it is going to survive!


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The HEP Plan

Big HEP instruments require more than business as usual

o A global strategy derived from a large vision of scientific goals — the “Science Roadmap.” Sell the science, not the instruments.

o The inclusion of a range of scientific disciplines and government policy makers from the beginning.

o A fair and open mechanism to modify the roadmap and the plan as results dictate.

Why 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.


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A Word About R&D

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

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

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.


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Conclusions

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

Sell the science, not the instruments

o Learn from the NASA strategy, in which the goals are truly large and visionary, and the instruments are 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 very large facility, we need to have a vigorous R&D program now.

o The R&D is very challenging, and the penalty for failure will be severe.


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Last Slide

p. limon october 16, 2003 hadron collider workshop 2003 fermilab 1 outline a quick review of the...

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