# Presentation: 512847

## Proton PlanProton Projections 

- Eric Prebys

## Outline

- Projection Procedure
- Accuracy to date
- Issues and Refinements
- Updated Projections
- Conclusions

## General Comments

- Accurate proton delivery projections are one of the most important facets of the proton plan
- Run II has shown that accuracy provides more long term satisfaction than wild optimism.
- Both MINOS and MINIBOONE were conceived under what are now understood to be unrealistic assumptions about proton delivery
- Putting things in perspective

## Reminder: Modes of Operation

- “2+5” Operation
- Two batches are slip stacked together for pBar production.
- 5 single batches are loaded for NuMI
- All are accelerated together
- This has been standard operation since shortly after NuMI turned on
- “2+9” Operation
- 5 single batches are loaded
- 6 batches are slipped together with these
- -> five double batches and one single batch
- At flat top, one double batch is extracted for pbar and the rest are extracted to NuMI

## Time Line

- “2+5”

- “2+9”

## Procedure for estimating Proton Delivery

- Assume traditional operational priority:
- Protons for pBar production
- Limited by ability to slip stack
- Limited by max cooling rate
- Protons for NuMI
- Limited by max Booster batch size
- Limited by max MI cycle rate
- Limited by max MI proton capacity
- (will be) limited by ability to slip stack NuMI protons in MI
- Protons for BNB (currently MiniBooNE)
- Determined by difference between Booster capacity and maximum MI loading.
- Currently limited by Booster lossesUltimately limited by Booster rep. rate.
*Extremely* sensitive to fluctuations in total Booster output

## Important Milestones

- 2006 Shutdown
- Maximum Booster rep. rate increases from 7.5Hz->9Hz
- Main Injector Improvements will allow studies of full 2+9 operation
- Assume beam loss in Main Injector limits us to 2+5 as standard operation.
- 2007 Shutdown
- Installation of half of Booster correctors will allow increased throughput
- Collimation and RF Improvements in the Main Injector will allow operational slip stacking (2+9) operation to NuMI
- 2008 Shutdown
- With the installation of last Booster correctors and improved gamma-t magnets, all Proton Plan projects complete.

## Evaluate Effect of Booster Improvements

- Calculate effect of various improvements based on increased acceptance:
- Use:

- Effective aperture reduction

## Additional Effects

- Increased transmission with Long 13 is removed
- 3%
- Probably conservative
- Effect of sparse sextupole correctors on emmittance
- ~10%
- Does not yet include significantly improved harmonic corrections
- Effect of Linac Low Level RF
- ~5% improvement on average beam intensity

## Estimating Booster Output

- History has shown that the lab tends to overestimate the benefits of particular improvements.
- Tuning and optimization take a long time
- Tend to asymptotically approach the goal, then get distracted by other things.
- So we...
- Evaluate the potential of particular improvements based on effective aperture increase or uncontrolled beam loss reduction:
- For example, if something reduces uncontrolled loss by 10%, it has the potential to allow us to send 10% more beam.
- Consider the following scenarios:
- “Design”: After *one year* of tuning, we realize *half* of the potential benefit.
- “Fallback”: After *one year* of tuning, we realize *one quarter* of the potential benefit.

## Peak Booster Intensities

- These are “peak” numbers
- An “average to peak” correction is applied to get average values
- These are the numbers from loss limits
- The real peak value will be limited by the 9Hz rep rate at about 1E17, depending on batch size.

## Design and Base

- NuMI
- Design
- Booster delivering nominal batch intensities
- Slip stacking implemented in a few months after the 2007 shutdown
- Base
- Booster batches slightly less
- No slip stacking
- MiniBooNE
- Design
- NuMI running at “design”
- Booster achieves nominal throughput
- Base
- NuMI running at “design”, BUT
- Booster throughput at fallback level
- NuMI continues to have priority
- Note, there are many other scenarios and operational options which are to numerous to explicitly consider

## Factors Considered in FY05, FY06 Projections

- Linear ramp-up to see benefit of improvements
- Slip stacking efficiency
- Done in a confusing way (more about this later)
- Annual shutdowns (assume 2 mo/yr)
- Uptimes: based on MiniBooNE 2004
- Peak to average corrections
- For BNB, based on MiniBooNE 2004
- For NuMI, used reasonable guess
- Effects of shot setup
- Implemented as VB routines in Excel spreadsheet
- Easy to modify

## How are we doing so far?

- Compare NuMI and MiniBooNE to FY05 and FY06 “blue and red” curves
*Approximately *equal to Proton Plan projections shown at last review
- General comments
- Booster peak intensities have not been quite as high as projected
- NuMI rate has been severely affected by unplanned down times
- MiniBooNE benefited significantly from these downtimes

## Total Protons Through Booster

- Turn on slower than expected

## Protons to NuMI

- Water in target

- Horn ground fault (loose foot)

- Tritium in water

- Special runs

- Resin beads in water system

- Note: without slip stacking, NuMI rate set by 5 booster batch limit, so no way to get back to curve by end of FY

- NuMI Beam delivery significantly impacted by unforseen down times

## BNB (MiniBooNE)

- Generally, NuMI’s problems have allowed MiniBooNE to stay on or close to the curve, although Booster throughput has not been quite what was projected

## Revisions to Long Term Projections

- Batch size
- Old scheme used one batch size with low “efficiency” for slip stacked batches
- Accurate but confusing
- New scheme has two explicit batch sizes
- Slip stacking to NuMI
- Originally believed we could start slip stacking after the 2006 shutdown.
- Now believe slip stacking losses will necessitate collimators, which will not be installed until 2007 shutdown
- Uptime
- Major factor in NuMI beam delivery
- Old scheme had only small variation between design and base (~81%)
- New scheme:
- NuMI “base” will be ~uptime from turn-on through shutdown (70%)
- BNB base will budget 1 unscheduled horn replacement every two years (78%)

## Revisions (cont’d)

- Post shutdown turn-on
- Historically tried to cover this by using a projection shutdown longer than actual shutdown
- Real shutdown always extended to same length
- Still looks bad
- New scheme:
- Post shutdown exponential ramp up with ( ~2 weeks)
- Cogging losses
- Old scheme did not account for the fact that cogged cycles (pbar and NuMI) lose more energy than uncogged cycles.
- Somewhat compensated by the old way we handled slip stacked batch sizes.
- Now include 20% increased energy loss for cogged cycles.

## Machine Loading

- Assumes model where slip stacking is implemented by going immediately to 2+9, but with reduced batch sizes to NuMI.
- Ultimate goal (44 week year)
- NuMI: 3.2E20 p/yr
- BNB: 1.8E20 p/yr

## Cumulative Totals

## Conclusions

- We have attempted to meet the proton delivery goals put in place at the beginning of the proton plan
- Have done pretty well with respect to BNB
- NuMI did well the first FY, but has fallen a bit short this FY
- Plagued by unplanned down times
- Overly optimistic turn on after shutdown.
- We are continuing to revise our projections for the future to provide experimenters with the most accurate information we possibly can.