# Presentation: 018136

## Plans and Limitations of the Fermilab Proton Source

*Eric Prebys*
- Proton Source/Accelerator Division
- FNAL

## Proton Team (“Finley Report”)

- Group formed in early 2003 to study proton demands and needs for the “near” future (through ~2012 or so), in the absence of a proton driver.
- Work culminated in a report to the director, available at www.fnal.gov/directorate/program_planning/studies/ProtonReport.pdf
- No big surprises [see P. Kasper “Getting Protons to NuMI (It’s a worry)”, 2001].
- This work will form the basis of “The Proton Plan”.

## Proton Demand

## What Limits Total Proton Intensity?

- Maximum number of Protons the Booster can stably accelerate: 5E12
- Maximum average Booster rep. Rate:  currently 7.5 Hz, may have to go to 10 Hz for NuMI+ *(full)* MiniBooNE
- (NUMI only) Maximum number of booster batches the Main Injector can hold: currently 6 *in principle*, possibly go to 11 with fancy loading schemes in the future
- (NUMI only) Minimum Main Injector ramp cycle time (NUMI only): 1.4s+loading time (at least 1/15s**nbatches*)
- Losses in the Booster:
- Above ground radiation
- Damage and/or activation of tunnel components

*Our biggest worry at the moment!!!!*

## How Have we been doing

- BooNE turn-on

- Power loss

-      Energy loss per proton (reduced by >3!)

- Total Protons

- Now

- Breaking records and contuning to improve!

## Formulating a Plan

- The lab has recognized that the proton demands of the experimental program are significant, if not daunting, and will require substantial efforts to meet.
- As the financial burden of Run II begins to ease, it’s envisioned that financial resources will be diverted to these efforts over the next few years.
- We are in the process of putting together a plan with the maximum likelihood of reaching these goals.
- Ultimate goal is to generate a project similar to Run II
- However, because the future (MiniBooNE) is already here, such a plan will necessarily have near and long term components.

## Near Term Priorities (Booster)

- Optimizing Booster for improved lattice:
- Tuning and characterizing 400 MeV line (Linac to Booster).
- Tuning Booster orbit to minimize losses.
- Commission Collimators:
- Over the shutdown, we installed a new collimator system, which we are starting to commission.
- Estimate about 2 months to bring into standard operation.
- Aperture Improvments:
- Alignment (discussed shortly)
- Orbit control
- Ramped orbit control program has been written.
- Will be commissioned soon (new personnel)
-  Important now that collimator is in place.
- Prototype RF Cavities
- Two large aperture prototype cavities have been built, thanks to the help of MiniBooNE and NuMI universities.
- We will install these as soon as they are ready to replace existing cavities which are highly activated.
- It’s hoped this work will allow us to reach the MiniBooNE baseline this year.

- Very Important!!

## Alignment in the Booster

- Always been recognized as a problem
- A little over a year ago, we started a vertical as-found of the entire Booster
- Level run
- 4 survey points on each magnet (some a bit complicated)
- (Mostly) completed during the shutdown.  Data now in hand.
- Some big problems!
- Historical difficulties
- Lack of priority!
- Lack of a coherent plan, both on our part and alignment.
- Inefficient use of downtime (response time issues).
- Solution?  What else – a task force.

## Big Alignment Problems!

## Alignment Plan

- Peter Kasper put in charge of coordinating alignment on our end.
- O’sheg made task manager on the AMG end.
- Andrew Feld will be trained as a liaison.
- Near term goals (ASAP as opportunities arise)
- Complete vertical network (5-10% to be done or redone)
- Develop a plan for vertical moves, including both “opportunities” and longer term requests.
- Align RF cavities and other key elements to optical center of straights.
- Longer term (aim to complete by next big shutdown)
- Produce a “beam sheet” based on Sasha’s MAD file
- Add non-magnetic elements
- Complete network, including horizontal.

## Issues over the Next Year

- Linac Characterization and Reliability
- Increase instrumentation of old linac to study instabilities.
- Develop set of performance parameters.
- Booster improvements.
- Prepare for modification of second extraction region
- New septum
- Modified dogleg magnets
- On track for next year’s shutdown.
- Injection Bump (ORBUMP) Power Supply
- Existing supply a reliability worry.
- Limited to 7.5 Hz
- Building new supply, capable of 15 Hz.
- Aiming for next year’s shutdown.
- Under consideration: New ORBUMP Magnets
- Existing magnets limited by heating to 7.5 Hz
- Working on a design for cooled versions.
- These, with a new power supply, will make the Booster capable of sustained 15 Hz operation.
- Biggest decision for the near future.

## Multibatch Timing

- In order to Reduce radiation, a “notch” is made in the beam early in the booster cycle.
- Currently, the extraction time is based on the counted number of revolutions (RF buckets) of the Booster. This ensures that the notch is in the right place.
- The actual time can vary by > 5 usec!
- This is not a problem if booster sets the timing, but it’s incompatible with multi-batch running (e.g. Slipstacking or NuMI)
- We must be able to fix this total time so we can synchronize to the M.I. orbit.
- This is called “beam cogging”.

## Active cogging

- Detect slippage of notch relative to nominal and adjust radius of beam to compensate.

- Allow to slip by integer turns, maintaining the same total time.

- Efforts in this area have been recently increased, with the help of a Minos graduate student (R. Zwaska).
- Aim to get working in the next few months

## Budget Guidance (courtesy S. Holmes)

- As Run II financial needs decrease, we can expect resources on the order of the following
- FY04 ~$2M (may or may not be there)
- FY05 ~$6M
- FY06 ~$5M
- Scale of $5M/yr after that
- For the purposes of planning, I am treating this as upper limit.
- This level of funding precludes the consideration of certain projects.

## Long Term, Big $$ Ideas Under Consideration

- New Booster RF system: (~$15M)
- Larger aperture cavities (two prototypes will be installed soon).
- New solid state preamps and modulators (would pay for itself in a few years).
- Possibly add two RF stations (increase reliability a capacity)?
- New Linac front end: (~$30M)
- Replace Preac and 200 MHz linac with RFQ feeding 400 MHz klystron-driven linac.
- Addresses 7835 Amplifier Tube Problem
- Possible part of proton driver?
- Reduce Main Injector ramp time: (??)
- Still needs time to load protons
- Needs to fit in with stacking.
- Necessary to get the kind of protons that off-axis is talking about.

## The 7835 Power Triode – A BIG Worry 

- Very complex technology
- RF, material science, vacuum, chemistry
- Similar to other tubes made by Burle
- 4617
- 7835 only used in the scientific community.
- One military user for 4617
- Quality varies from decade to decade
- Can we rely on these until proton driver?
- Might feed into linac decision.
- Current plan: “Keep Fingers Crossed”.

## Output Limitations of Present Source

- DISCLAIMER
- In the following slide, I make *extremely* optimistic assumptions, to set *upper* limits.
- Assumptions:
- 5E12 protons per batch out of Booster.
- All Booster loss problems solved.
- Booster can run continuously at 15 Hz.
- We can load 12 batches into the Main Injector with *NO* extra slipping/barrier time.
- NO extended shutdowns (2E7 seconds/year).

## Maximum Throughput vs MI Ramp Time

## Summary

- Within the budgetary guidance we have been given, we believe we can:
- Enable the booster to run safely up to 15Hz
- Reduce Booster losses significantly, possibly allowing us to reach the MiniBooNE goal and/or continue to run MiniBooNE in parallel with NuMI
- What NuMI might expect:
*Probably* 2-2.5E20 in the first year of running.
*Perhaps* 3-4E20 per year after a could of years of running. (This is NOT a promise)
- Anything beyond that requires money at a level that would significantly compete with other projects, particularly the proton driver.
- If you want more protons than this, you want a proton driver.