Proton Source Improvement WorkshopCogging

W. PellicoDec 6&7 2010

Booster Gap Three consecutive high intensity pulses (un-notched) will exceed extraction loss limit!

– Booster creates a 3 gap notch– The gap is created using two pulsed kickers

• Notcher – High Voltage Kicker at Long 5• Nocker - Lower Voltage Kicker at Long 12

– Used to clean out Notched Beam– Required for Cogged Cycles

– Beam is kicked into collimator region and Long 13 – The gap trigger is created and synched by modules in

Booster Low Level room (several modules required)– Synchronization of gap can be done to Pre-Acc notching– Notch for non-cogged cycles occurs at 400 Mev– Cogged notch occurs at ~700 MeV

Gap Creation

Scope Trace – Three Bucket Notch

Uncogged Cycle – Notch Crated at Injection

Cogged Cycle – Notch Created Later

Cogging Motivation • Booster needs to

fire (5) kickers in a (3 bucket) gap to keep losses down at extraction

• Booster syncs the gap to a MI marker (‘OAA’)

• Booster will extract on OAA +/- 1 bucket

MI with circulatingbeam

MI = 7*84 Bunches3319 Meters

Cogging History• Around 1998 – the first cogging studies (Webber, Pellico)

– 2002: VXI board layout completed based upon early studies

– 2005: Added additional automatic Update Trip Plan – 2006: Added BES over-ride– Multibatch MI operations• High Intensity Cycles & Rates

– Slip Stacking for Pbar Production– Slip Stacking for Numi

– MI cycles used for Tevatron loading• Cogged but not Notched

Wait for BoosterTo MI Event ($14 $19..)

Was this the first event of

load cycle Yes

NoMake a

‘Trip Plan’Start

Cogging Process

End of cycle:Get ready for next

Cogged Cycle Trip Plan Cycle

Start Tracking of Booster ‘Gap’

Create Gap

Wait for ‘OAA’ Track gap through cycle

Calculate End of Cycle Gap Error

Store gap position vs turn as reference

Create Gap Send MI a reset pulse to sync BES

Calculate Gap Error Pre T cogging

Extract onBES - GAP

Post TransitionCogging

Extract on ‘OAA’

Early Days

Current Typical Timeline $14 $19 $19 $19 $19 $14 $19 $19 $19 $19 $1D $1D $1D

First Cycle For Trip Plan

Typical Plots Showing Cogging

Rpos Variations for several MI Cycles

Typically - Horizontal position will vary +/- 6mm (Depends upon gain setting )

There are two types of correction:Fixed and Proportional

10July 27, 2004 Robert ZwaskaBooster Cogging

Gap Position tracking Relative to Trip Plan Gap

~ 3 turns

Slippage of Gap vs ‘Trip Plan’• Slippage in a cycle varies by > 200 buckets

– About 3 circumferences• Notch is essentially at a random position w.r.t the beam

circulating in the Main Injector

Example of Booster system improvement to help cogging

Conclusion/Issues• Dynamic Aperture– Beam Emittances– Beam Losses

• Higher losses on Cogged Cycles– Notch at Higher Energy– Gap not as clean– Orbit Control/Scraping

• Lots of hardware to maintain

• Jitter – Extraction and Gap Kickers

• Ready for Upgrade

• It works – much better then I would ever have hopped….