How the Tevatron became the Fermilab pbar-p collider

25th Anniversary of pbar-p collisions in the Tevatron

John Peoples

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Discovering the W and Z with very high energy pbar-p colliders

• In 1976 Rubbia, Kline and McIntyre proposed that the CERN SPS and the Fermilab Main Ring could produce W’s and Z’s if they could be operated as two beam single ring colliders at a luminosity ~ 10 29 cm-2s-1 .

• Their scheme was conceptually feasible if one could build a pbar source that could produce a few 10 11 usable pbars per day.

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The elements of a successful 500 GeV CM pbar-p collider facility

• A high energy storage ring that could store and collide counter rotating beams p’s and pbar’s, with an energy >250 GeV. Three proton bunches of 10 11 p’s/bunch and three Pbar bunches of ~ 10 10 /bunch could produce the desired luminosity of ~ 10 29 cm-2s-1 .

• A Pbar producer: A ~50 GeV proton synchrotron that could produce a usable beam of 10 7 ~5 GeV pbars every few seconds. (> 10 11 /day).

• A Pbar source: A ~5 GeV storage ring that could accept and “cool” a few 10 11 pbars/day to a beam size that the ~50 GeV synchrotron could accept efficiently.

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CERN and the elements

• CERN: One plan– High energy storage ring: SPS at 270 GeV– Pbar producer: PS at 25 GeV– Pbar source: AA at 3.5 GeV (S-cool, new)

• CERN approved the plan in early 1978– First collisions in the SPS at 540 GeV in 1982– First W’s and Z’s seen in 1983 and 1984

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Fermilab and the elements

• Fermilab Scheme 1:–High energy storage ring: Main Ring at 125

GeV/ beam (250 GeV CM)– Pbar producer: Main Ring at 80 GeV–Pbar source: Cooling Ring (200 MeV, e-cool)

• Fermilab Scheme 1: It was dropped because it was complicated and marginal and diverted effort from the Doubler.

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The Outcome of the Armistice Day Shootout of November 1978

• Leon set Fermilab’s Priorities for the future:– Pbar-p Colliding beams will be in the Doubler. – The completion of the Energy/Saver Doubler is the top

priority. The Doubler Section is created.– The Colliding Beams Department in the Research

Division is responsible for building CDF.– The Accelerator Division is responsible for developing

the technology and the design for an antiproton source .

• Efforts on all quick and dirty colliding beam schemes were stopped.

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The origin of the Tevatron I Project

• In mid 1979 Leon got a phone call from Washington. “If Fermilab submits a proposal for colliding beams it is likely that it will be approved.”

• Fermilab submits a proposal for Tevatron I. Cost $41.5 million. It appears in the FY81 budget.

• The Tevatron I Section is established to design and manage the project.

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Fermilab and the elements(again)

• Fermilab Scheme 2 (as submitted to DOE):– high energy storage ring: Tevatron at 900 GeV– pbar producer: Main Ring at 80 GeV– Pbar source: Two rings (one new and R&D) • Ring 1: Stochastic cooling and deceleration to 200 MeV• Ring 2 200 MeV e-cooling Ring ( the R&D project)

• Fermilab Scheme 2 could have worked but it could not win the race for the W.

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Director’s Review of TeV I in June 1981

• The Committee’s response:– “The design appears to be adequate to meet the goals for Pbar

production and accumulation listed in the design report. However those goals are too modest. “

– “We recommend that the Laboratory re-examine the goals and develop a feasibility design commensurate with the full potential of the Main Ring-Booster combination to produce pbars.”

• The Director’s direction: – Develop an alternate design which rests on the considerations of

technical feasibility (& not cost).– Provide a progress report in 40 days.

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The Tevatron I Project

• The 1982 scheme: the source we built– High energy storage ring: Tevatron at 900 GeV– Pbar producer: Main Ring at 120 GeV– Pbar source: Two rings (both Booster size ) • Ring 1: The Debuncher (8 GeV, S-cool)• Ring 2: The Accumulator (8 GeV, S-cool)

• The new TeV I project had room to grow in capability and match the ultimate capability of the Tevatron. It cost a lot more: $82.5 M.

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TeV I Antiproton Source

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12/20/83

1988-89 Collider Run Results

Design Goal Achieved 1988-89

Number of bunches/beam 3 6

Number of p’s/bunch 6 x 1010 5.5 x 1010

Number of ’s/bunch 6 x 1010 2.5 x 1010

Β* at BØ [cm] 100 cm 55 cm

Єv, ЄH protons [mm-mr] 24 24

Єv, ЄH antiprotons [mm-mr] 24 18

Energy [GeV] 900 900

Peak Luminosity [cm-2 sec-1] 1030 2 x 1030

Initial Luminosity Lifetime [hr] 12 12

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Additional Slides

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9/15/97

Tevatron I Complex (1987-1989)

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