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Tevatron Collider Run II - Doing Shots

Elvin HarmsFermilab Antiproton SourceHarms@fnal.gov X4387

11 January 2001 CDF – Intro to Shots 2

fWhat’s a Shot?

• Transferring Antiprotons from the Accumulator to the Tevatron.

11 January 2001 CDF – Intro to Shots 3

fWhat’s Shot set up ?

• All of the preparatory steps needed to do shots.

11 January 2001 CDF – Intro to Shots 4

fAccelerator Complex Overview

Tevatron

Proton source

Main InjectorRecycler

Antiproton source

11 January 2001 CDF – Intro to Shots 5

fAccelerator Complex Overview

Tevatron

Proton source

Main InjectorRecycler

Antiproton sourceAP3

P2

P1

AP1

A1

MI-8

11 January 2001 CDF – Intro to Shots 6

fAccelerator Complex Overview

– Proton source• Cockroft-Walton preaccelerator 750 keV

11 January 2001 CDF – Intro to Shots 7

fAccelerator Complex Overview

– Proton source• Drift tube Linac

116 MeV

– Proton source• Side-coupled

cavity Linac 400 MeV

11 January 2001 CDF – Intro to Shots 8

fAccelerator Complex Overview

– Proton source• Rapid-cycling Booster synchrotron 8 GeV

11 January 2001 CDF – Intro to Shots 9

fAccelerator Complex Overview

• Main Injector/Recycler 8 to 150 GeV

11 January 2001 CDF – Intro to Shots 10

fAccelerator Complex Overview

• Antiproton source– Antiproton production target station 120 GeV– Debuncher 8 GeV– Accumulator 8 GeV

11 January 2001 CDF – Intro to Shots 11

fAccelerator Complex Overview

• Tevatron– Superconducting synchrotron 980

GeV

11 January 2001 CDF – Intro to Shots 12

fShot set-up – prerequisites

• Previous Store ended• Tevatron at 150 GeV• Desired number of antiprotons

accumulated

11 January 2001 CDF – Intro to Shots 13

fShot set-up – a 3-ring circus

Tevatron Main Injector Pbar sourceSet at 150 GeV Check/correct closed orbit Cool Pbars into core &

maintain stability

Verify/correct A150 line tune

Check/correct extraction positions

Accept reverse protons, maximize transmission

from MI, minimize injection oscillations

Load protons Provide protons for tuneup of beam lines

Redistribute core longitudinally for

unstacking

11 January 2001 CDF – Intro to Shots 14

fShot set-up - Tevatron

• Back to 150 GeV• Reverse injection to MI

11 January 2001 CDF – Intro to Shots 15

fShot set-up – Main Injector

• Orbit/tunes set• Reverse protons to Pbar• Protons to Tevatron

11 January 2001 CDF – Intro to Shots 16

fShot set-up – Antiproton source

• ‘cool’ the core• maintain stability

– tranverse emittances– longitudinally

• tools– Stochastic cooling– Stabilizing RF– dampers

11 January 2001 CDF – Intro to Shots 17

fShot set-up – Antiproton source

• Reverse Proton tune up

11 January 2001 CDF – Intro to Shots 18

fShot set-up – Antiproton source

• Minimize Accumulator Turn-by-Turn oscillations

11 January 2001 CDF – Intro to Shots 19

fShot set-up – ‘dry’ shots

• Test shots without beam– RF systems play except for unstacking amplitude– Verify phase lock– Verify timing– Verify kicker magnets are working

11 January 2001 CDF – Intro to Shots 20

fShot set-up – Antiproton source

• Squaring the core– Frequency-modulated 1.25 MHz RF– Unstack uniform intensity bunches

11 January 2001 CDF – Intro to Shots 21

fDoing Shots

• Load protons• Unstack from core• Pbars to MI• Accelerate to 150 GeV & Coalesce• Transfer to Tevatron/cog

11 January 2001 CDF – Intro to Shots 22

fDoing Shots

• Unstacking– ‘square’ core allows uniform intensity of pbar

bunches

11 January 2001 CDF – Intro to Shots 23

fDoing Shots

• Unstacking– 2.5 MHz (h=4) RF system– 4 bunches at a time– low initial voltage – increase voltage to

narrow bunches– lock to MI RF– bunch at 53 MHz (h=84)– extract– ~30 seconds per transfer

11 January 2001 CDF – Intro to Shots 24

fDoing Shots

• Unstacking & Extraction– Re-bunch at 53 MHz on extraction orbit– Shuttered fast kicker magnet (1.6s)

11 January 2001 CDF – Intro to Shots 25

fDoing Shots

• Transfer to MI• Acceleration to 150 GeV• coalescing• another talk

11 January 2001 CDF – Intro to Shots 26

fDoing Shots

• Coalescing– 4-53 MHz bunch trains into 4-2.5 MHz bunches

11 January 2001 CDF – Intro to Shots 27

fDoing Shots

• Transfer to the Tevatron– another talk

11 January 2001 CDF – Intro to Shots 28

fTevatron Loading scheme

• Antiprotons are loaded four bunches at a time for a total of 9 transfers from the Accumulator to MI to the Tevatron

• The 36 bunches of Pbars are equally spaced in 3 groups of 12 around the Tevatron

11 January 2001 CDF – Intro to Shots 29

fImportant Tools

• Sequencer• Time Line Generator (TLG)• Dedicated Applications• CDA/SDA

11 January 2001 CDF – Intro to Shots 30

fImportant Tools

• Sequencer– ACNET application– Automates much of the process– Flexible– Interactive

11 January 2001 CDF – Intro to Shots 31

fImportant Tools

• Time Line Generator (TLG)– central Beam switching system– who gets what beam when and how often– different Timelines for different modes

• Shot set up• Load protons• Load pbars

11 January 2001 CDF – Intro to Shots 32

fImportant Tools

• Dedicated Applications– Beam line tuning– Orbit display and control– RF and stochastic cooling systems– Diagnostic display– Parameter pages

11 January 2001 CDF – Intro to Shots 33

fImportant Tools

• CDA/SDA– Gather, display, and analyze data from shots– State-based– Java applications

11 January 2001 CDF – Intro to Shots 34

fArmchair Shooter

• How to watch?– Channel 13/Notify– Pbar TV channel 7 – AP1 wall current monitor– Pbar TV channel 15 – Accumulator Vector Signal Analyzer– Pbar TV channel 16 – Accumulator unstacking display– Pbar TV channel 18 – Accumulator Vector Signal Analyzer– Pbar TV channel 28 – Accumulator Stack (longitudinal)

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