# Presentation: 004587

## New Corrector System for the Fermilab Booster

- E.J. Prebys, C.C. Drennan, D.J. Harding, V. Kashikhin, J.R. Lackey, A. Makarov, W.A. Pellico*Fermilab, Batavia, IL  60510*

- MiniBooNE-neutrinos from 8 GeV Booster proton beam (L/E~1): absolutely confirm or refute the LSND result: Running since fall 2002.  To date has taken >8E20 protons: *more protons than all other experiments in the 35 year history of the lab combined!*

- NuMI/Minos – neutrinos from 120 GeV Main Injector proton beam (L/E~100):precision measurement  of  oscillations as seen in atmospheric neutrinos.  Began running in March, 2005.  Will ultimately use numbers of protons similar to MiniBooNE

- The Fermilab Booster

- The Booster takes the 400 MeV Linac beam and accelerates it to  8 GeV.
- Runs at an instantaneous 15 Hz repetition rate
-  From the Booster, beam can be directed to the Fermilab Main Injector or directly to an 8 GeV beam line currently servicing the MiniBooNE Experiment

- 400 Mev Beam from Linac

-  8GeV Beam to Main Injector and MiniBooNE

- 472m in circumference
- 24-fold periodic lattice
-  Each period contains 4 combined function magnets.
-  Magnets cycle in a 15 Hz offset resonant circuit.

- LATTICE

- Increasing Proton Demand

- NEUTRINO PROGRAM

- ANTIPROTON PRODUCTION

-   8E12 protons sent to the Main Injector every 2.2 seconds, to be accelerated to 120 GeV and delivered to the antiproton production trarget
-  ~1E16 protons per hour
-  Small compared to...

***ABSTRACT***
- We present an ambitious ongoing project to build and install a new corrector system in the Fermilab 8 GeV Booster. The system consists of 48 corrector packages, each containing horizontal and vertical dipoles, normal and skew quadrupoles, and normal and skew sextupoles. Space limitations in the machine have motivated a unique design, which utilizes custom wound coils around a 12 pole laminated core. Each of the 288 discrete multipole elements in the system will have a dedicated power supply, the output current of which is controlled by an individual programmable ramp.  This poster describes the physics considerations which drove the design, as well as issues in the control of the system.

- Nova – Same beam line as Minos, but detector built off axis.  Would like 2-4 times the protons of Minos.

- Existing Corrector System

- Corrector Packages (x48):

- Corrector Package

- BPM

- Horizontal chromaticity

- Vertical chromaticity

- 3rd order resonance correction

- Shortcomings of Existing System

- Orbit motion:

- Tune variation:

- Orbits shown relative to injection at 5 ms intervals

- Predicted and measured tunes

- New Corrector System

- Motivations:
- Dipoles
- Must produce ± 1cm of beam motion at all momenta
- Sufficient slew rate to correct for observed beam motion
- Quadrupoles
- Maintain tunes arbitrarily close to upper integer resonance throughout cycle to mitigate space charge tune shift
- Capable of slewing anywhere from half integer to integer resonance in 1 ms at transition
- Sextupoles
- Same integrated strength as existing system.
- Capable of slewing between extrema in 1 ms at transition

- Magnetic specifications

- Unique design    - laminated core    - 12 poles    - wound for 6 discrete multipoles

- Fabrications details    - water cooled    - all coils potted in place    - alignment keyways for BPM

- Sextupole System
- Horizontal chromaticity controlled by sextupoles at all odd short straights
- Vertical chromaticity controlled by sextupoles at long straights in 4, 10, and 18
- Third order corrections controlled by skew and normal sextupoles at long straights in periods 4,5,6,7

- Dipoles
- Ramped in high-beta periods
- DC control in low-beta periods

- Quadrupoles:
- Ramped in groups: long normal, long skew, short normal, short skew
- Individual DC correction for harmonic control

- Features of New System:
- Increased strength of dipole and quadrupole elements
- Normal and skew sextupoles at all 48 sub-periods
- Individual, ramped current control of all 6x48=228 elements
- Emulation of existing hardware
- Dramatically improved alignment

- Fabrication and installation:
- First 24 magnets being fabricated now
- These will be installed in the long straight (vertical high-beta) regions in August and September, 2007
- Remaining correctors will be fabricated and installed in 2008

- Total proton output limited by beam loss (radiation in Booster) -> *Must improve efficiency!*

## Control of Corrector System

- Time Dependent Dipole Control

- Initial System (identical to present)

- Closed Orbit Correction

- Orbit deviations:

- Corrections to magnet currents:

- Harmonic Correction

- Correct with normal sextuples

- Correct with skew sextuples

- New sextupole system can correct for all potential third order resonances

- Corrected with existing system

- Time dependent dipole control:
- Used for existing system
-  Dipoles only have time-dependent current ramps at high beta regions
- Verticals at long straights, horizontals at short straights
- Straightforward to modify for new correctors
- Will now have control of all dipoles

- Closed orbit control:
- Finds optimum magnet currents to reproduce desired orbit
-  Can select from a variety of algorithms
- Commissioning with existing corrector system
-  Insufficient strength to control position throughout cycle
- Being modified to accommodate new correctors

- Tune Control

- Correctors grouped by type
-  Long normal, long skew, short normal, short skew
- Ramps superimposed on harmonic (DC) terms
- New system will be strong enough to allow tune control feedback
-  In development

- Related Posters

- “Design and Fabrication of a Multi-element Corrector Magnet for the Fermilab Booster”
- D. Harding, et al
- MOPAS006, Monday June 25, 2-4PM, Southwest Hall
- Describes details of the magnet design and fabrication
- “Using a Slowly Rotating Coil System for AC Field Measurements of Fermilab Booster Correctors”
- G. Velev, *et al*
- MOPAS021, Monday June 25, 2-4PM, Southwest Hall
- Describes the system used to qualify the magnet design and test the production units.
- “System Overview for the Multi-Element Corrector Magnets and Controls for the Fermilab Booster”
- C.C. Drennan, et al
- MOPAS005, Monday June 25, 2-4PM, Southwest Hall
- Details of the hardware implementation of the corrector system

- Work supported under DOE contract DE-AC02-76CH03000

- Corrections calculated according to the algorithm:

- Plans

- Initial operation will focus on establishing acceptable performance for the ongoing laboratory physics program as quickly as possible
- Will run new system in a mode which will emulate existing system, even if this means limiting some of the capability of the new system.
- The new corrector system will allow a great deal more versatility in the control of the accelerator
- Individual ramped control of every channel
- Among other things, this will allow for time dependent harmonic corrections.
- Fully exploiting the capabilities of the new system will represent challenges to both accelerator physics and application development for some time.