# Presentation: 049417

## Proton Source Status and Plans

- Eric Prebys
- FNAL Accelerator Division

## Outline

- “Finley Report”
- Linac status
- Proton Demands
- Major Projects Since Last Review
- Booster Performance
- Near Term Priorities
- Major Work in the Next Year.
- The “Proton Plan”

## 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)”, FNAL Beams-doc-1036, 2001].
- This work will form the basis of “The Proton Plan”.

## General Comments

- The linac is not currently a performance bottleneck for the complex *when it is running stably.*
- There are ongoing longevity and reliability concerns in the linac
- General state of instrumentation is inadequate to characterize linac behavior
- The 7835 tubes from Burle continue to be a major concern, although the situation is better than it was a year ago.
- There are new worries about the klystrons, which we formerly believed were not an issue.
- There are some other longevity issues, if we expect the linac to last another ~10 years.

## 7835 Status

- Lots of interaction between the lab (Czarapata) and Burle to help them improve their reliability.
- They seem to remember how to make tubes again.
- Present inventory:

- + one ready to be tested

## Christmas Klystron Woes

- As of Dec. 1, we believed 800 MHz klystrons were not a worry.
- Very long lifetime (in socket!!)
- We had six spares
- A few days before Christmas, the klystron in station one failed.
- Three spares turned out to be bad
- Tracked down to vacuum problem (and a flaw in our measurement technique).
- Plan
- We’ve pulled one good spare from the MuCool project
- Ralph Pasquinelli put in charge of investigating and acting
- We think we understand the problem and will work with L3 to address it.
- Current stock
- Two good spares.
- One “gassy” tube, probably bad
- Three bad tubes at L3, one ready to be repaired (no good estimate)
- Two more bad tubes which will either be shipped or analyzed here.

## Klystron Status

## Other Linac Projects

- New quad supplies in LEL
- Discussed under proton plan
- Upgrade High Energy Linac Low Level RF (HEL LLRF)
- Under way
- Upgrade LEL digitization
- Under way
- Upgrade LEL LLRF
- Being discussed
- Upgrade LEL modulator switch
- Being discussed
- Beam notching at the source
- Pre-notching
- 37 MHz laser chopping
- R&D phase
- Improving beam diagnostics in 400 MeV line
- Loss monitors
- Bunch length monitor
- Automated emittance measurement
- Dealing with MTA
- Now: preparing to send 200 MHz and 800 MHz RF
- Future: sending beam

## 400 MeV Line Work

- A new Lambertson was installed during the shutdown to steer beam from the Linac to the Booster
- Although the field qualities of this magnet were vastly superior to the old one, it was a major effort to tune for it.
- This highlighted our lack of understanding of the “400 MeV Line”.
- A major effort has gone into studying and optimizing this line.
- Improved optical model
- Automated beam line tuning
- Optimizing optics

## 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!!!!*

## Proton Demand

- Can we do this???

## Projects in 2003 (a short list)

- 2003 Activities centered around preparation for the September shutdown:
- Linac water system upgrade
- New Linac Lambertson
- Better optics in 400 MeV line
- Booster two-stage collimation system
- In the works a long time
- Now in place.
- Major modifications at main extraction region
- Address “dogleg problem” caused by extraction chicane system.
- New, large aperture magnets in extraction line:
- Should reduce above-ground losses
- Major vacuum system upgrade.
- Lots of smaller jobs.

## New Collimator System

- Should dramatically reduce uncontrolled losses

- Basic Idea...

- A scraping foil deflects the orbit of halo particles...

- ...and they are absorbed by thick collimators in the next periods.

## Long 3 Dogleg Work

- Increase spacing between dogleg pairs from 18” to 40” to reduce lattice distortions at injection.

- New magnet to match extraction line

## How are We Doing?

- “Mysterious” Performance Problems

- Power loss (W)

- Protons (p/min)

- Energy Lost (W-min/p)

- Big Shutdown

- BooNE turn-on (Sept. 2002)

## Recent Running (Last 4 Weeks)

- Power loss (W)

- Protons (p/min)

- Energy Lost (W-min/p)

- Record Performance

- Several Unrelated Problems

## How far have we come?

- Time (s)

- Before MiniBooNE

- Now (same scale!!)

- Energy Lost

- Charge through Booster cycle

- Note less pronounced injection and transition losses

## 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:
- Estimate another month or so to bring into standard operation. (discussed shortly)
- Aperture Improvments:
- Alignment (discussed shortly)
- Orbit control
- Abandoning our original global plan in favor of local control at problem spots for the time being.
- 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.
- Multibatch timing: Beam cogging (discussed shortly)

## Collimator Studies

- Shown is the effect of putting in one of the secondary collimators as a percentage change in losses as a function of time around the ring.
- Studies are continuing.
- “Rapid response team” will be put on problem.
- At present, primary collimators are not optimized to energy loss profile
- Will replace in upcoming shutdown.

- location

- Collimator location

## Alignment in the Booster

- Long been known to be 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?  A task force.

## Alignment Results

- Effect of Booster tower shielding

- 1⁄4” Misalignment at Collimators!

## Alignment Plan

- Peter Kasper put in charge of coordinating alignment on our end.
- O’sheg made task manager on the AMG end.
- Andrew Feld (booster technician) will be trained as a liaison.
- Near term goals (ASAP as opportunities arise)
- Complete vertical as-found (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.

- DONE

## Priorities 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) improvements:
- Injection Bump (ORBUMP) Power Supply
- Existing supply a reliability worry.
- Limited to 7.5 Hz
- Building new supply, capable of 15 Hz.
- Aiming for summer shutdown (aggressive, but doable)
- 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.
- Aiming for summer shutdown (aggressive, but doable).

## 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

## Planning for the future

- In response to the “Finley Report”, the lab management has asked for a “Proton Plan” for the proton source over the next few years, analogous to the Run II plan, but much lower in scope.
- The plan is to do what we can reasonably do to maximize the throughput and reliability of the existing proton source (incl. MI), under the assumption that a Proton Driver will eventually be built.
- Beyond the things I have already mentions, the scope is largely determined by the budgetary guidance:
- FY04:  $0-2M
- FY05: $6M
- FY06: $5M
- FY07: $5M
- FY08: $2.5M

## Comment on the Budget

- This budget is more than enough to do the basic things that we must do to keep the proton source going, provided some of it appears this year!
- It *precludes* certain ideas that have been suggested:
- New Linac front end, or any significant 200 MHz upgrade.
- Decreasing the Main Injector ramp time
- Which means there will be very little to do with the Main Injector.
- There are some “big” (>$1M) projects that must be discussed.

## Large Projects Under Consideration

- Booster RF system:
- Commission a design for a new booster RF system
- Larger aperture, higher gradient cavities
- Solid state distributed amplifiers
- Goal to have design by January 2005.
- Two year timescale to build and install (perhaps solid-state DA’s can come sooner).
- Cost ~all of it.
- Adding two additional cavities
- Use university prototypes + spare parts
- Cost ~$500K
- 30 Hz harmonic to booster ramp.
- Effectively increases RF power
- Cost of order $1-2M
- New LEL quad power supplies.
- A significant reliability worry
- Cost of order $1M.

## Schedule for the Plan

- Will proceed with the vital projects for this year.
- Hope to have a skeleton of a plan by the end of this month.
- Will have a more detailed plan and major recommendations by this summer.