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Snowmass 2001. RHIC Interaction Regions: Diagnostics and Correction. Fulvia Pilat. Snowmass, July 18, 2001 Joint T1-T5-T9. Outline. RHIC Overview IR correction systems : motivation, design (RHIC, LHC, VLHC) RHIC IR’s : layout and configuration IR correction methods

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Snowmass

2001

RHIC Interaction Regions:

Diagnostics and Correction

Fulvia Pilat

Snowmass, July 18, 2001

Joint T1-T5-T9


Outline
Outline

  • RHIC Overview

  • IR correction systems: motivation, design (RHIC, LHC, VLHC)

  • RHIC IR’s: layout and configuration

  • IR correction methods

    Linear: IR bumps, action-jump

    Nonlinear: action kick, IR bumps, frequency analysis

    IR bumps method  application to LHC

  • Results for Run 2000

    Linear: local IR skew correction and global coupling correction

    Nonlinear: operational determination of IR nonlinear terms

  • Run 2001: plans for machine development/ beam studies

  • Beam experiments for future hadron colliders

F.Pilat – RHIC Interaction Regions


RHIC Complex

12:00 o’clock

PHOBOS

BRAHMS

2:00 o’clock

10:00 o’clock

RHIC

PHENIX

8:00 o’clock

4:00 o’clock

STAR

6:00 o’clock

9 GeV/u

Q = +79

U-line

BAF (NASA)

Design Parameters:

Beam Energy = 100 GeV/u

No. Bunches = 57

No. Ions /Bunch = 1  109

Tstore = 10 hours

Lave = 2  1026 cm-2 sec-1

m g-2

High Int. Proton Source

LINAC

BOOSTER

Pol. Proton Source

HEP/NP

AGS

1 MeV/u

Q = +32

TANDEMS

F.Pilat – RHIC Interaction Regions


Rhic run 2000 and 2001
RHIC Run 2000 and 2001

  • Run 2000

  • May –July: commissioning

  • August-September: operation and

  • beam studies

  • Reached 10% of design luminosity

  • Run 2001

  • Started in May

  • May-July: start-up and commissioning

  • of new systems (PS, transition, PLL, etc.)

  • End July-September: operations with Au-Au and machine development (MD)

  • October-November : polarized p commissioning and operation (MD ?)

  • December-January: Au-Au operations and MD program

    Goal: design luminosity

F.Pilat – RHIC Interaction Regions


Ir correction systems
IR Correction systems

  • Motivation:

  • local correction of linear errors (coupling, gradient)

  • Local correction of nonlinear errors ( IR magnets field errors)

  • Beta squeeze, crossing angle

  • Beam control, luminosity

    Design:

  • Multi-layer corrector packages installed next to IR triplet

    quadrupoles

  • Typically, dipole  dodecapole

  • Independently powered

    RHIC  LHC  VLHC

F.Pilat – RHIC Interaction Regions


Lhc inner triplet correctors
LHC inner triplet - correctors

MCBX: b1 a1

MCBX: b1 a1

MQSXA: a2 a3 a4 b4

MCBXA: a1 b1 b3 b6

Optimization process:

Magnet design – correction system

F.Pilat – RHIC Interaction Regions


Ir correction vlhc stage 2
IR Correction – VLHC Stage 2

IR corrector

Package (skew)

a0

a1

a2

a3

BPM

600T/m

600T/m

Q2a

Q2b

12T

IP

12.1m

6m

22m

3m

12.4m

12.4m

D1A

D1B

D2

3m

Q1a

Q1b

7.9m

7.9m

20m

16T

12T

2m

5.5m

b0

b2

b3

b5

3m

400T/m

600T/m

IR corrector

Package

F.Pilat – RHIC Interaction Regions


Rhic ir s layout
RHIC IR’s - layout

  • 6 o’clock IR

  • 8 o’clock IR:

  • Dipole correctors

  • Skew quadrupoles

  • Nonlinear

  • Other IR’s:

  • dipole correctors

  • Skew quadrupoles

    (nonlinear layers

    exist but no PS

    yet)

F.Pilat – RHIC Interaction Regions


Run 2000 ir correction linear
Run 2000 – IR correction linear

Determine local IR skew quadrupole correction strenghts (Cardona, Ptitsyn, Pilat)

IR bump method

Action-jump method

F.Pilat – RHIC Interaction Regions


Rhic coupling correction
RHIC Coupling correction

Run

2000

Run

2001

Global coupling correction: 3 families

Combine 2 to get 2 orthogonal knobs

(RHIC can be decoupled only with the families)

Local correction of IR effects (alignment roll

error) is constant on the ramp, while global

correction changes on the ramp (orientation

of vector varies ~10%)

F.Pilat – RHIC Interaction Regions


Ir correction linear
IR Correction - linear

  • From Run 2000 IR bump data and action jump data, we have predictions

    for the 12 IR skew quad correctors in each ring

  • The results from the 2 methods agree (5-10%)

  • The predicted values from the 2000 data analysis agree with the

    corrector settings found operationally in 2001

  • The residual coupling in the machine (not arising from the IR triplets)

    is corrected with skew quadrupole families by correcting the coupling

    resonance (minimum tune separation)

F.Pilat – RHIC Interaction Regions


Ir nonlinear correction methods
IR nonlinear correction methods

dead-reckoning: action-kick minimization(Wei)

order-by-order prescription, assumes field errors known

(off-line code – “IR filter”- to set corrector strengths)

operational: beam based + off-line analysis

IR bumps: measure and fit observables vs. bump amplitude:

(Koutchouk)rms orbit (BPM’s, linear, sextupole)

(Ptitsyn, Pilat)tunes (Tune Meter, up to dodecapole)

(tune spread) (Schottky, octupole, dodecapole?)

frequency analysis: “better FFT” detect and correct nonlinear

(Schmidt) sidebands

SUSSIX

F.Pilat – RHIC Interaction Regions


Ir bumps method principle
IR bumps method - principle

Closed local orbit bump (triplet)

Observable as function of bump amplitude:

rms orbit outside the bump

z=(x,y) cn=(an,bn) zba=bump amplitude

The orbit perturbation depends in the plane of the bump (H,V)

And the parity of the multipole order

tune shift

Arises from normal gradients (DQ) or repelling effect of linear coupling (measured by c)

Selection of one or the other effect depends on the plane of the bump, whether the multipole

is skew or normal and on the parity of the multipole order

F.Pilat – RHIC Interaction Regions


Ir bumps simulation performance
IR bumps: simulation, performance

Use MAD to compute orbit and tune response to H and V orbit bumps in the

LHC IP5, assuming:

0.1% gradient error (Db/b~20%), 1 mrad roll (c~0.04)

Multipoles set to 10 units in Q2B.

Orbit response:

(assuming 20 data points)

Tune response:

Assuming 20 measurements and tune resolutionof 2 10-4

 resolve multipoles up to b6 (dodecapole)

DC offset of BPM can be eliminated by subtracting 2 orbits

Accuracy can be improved by increasing the number of measurements

F.Pilat – RHIC Interaction Regions


Run 2000 ir correction nonlinear
Run 2000–IR correction nonlinear

  • RHIC IR bumps – beam experiment

  • Bump data at IR2, IR6, IR8, blue & yellow

  • Mostly H bumps, some V bumps

  • Tune resolution run 2000: 0.001

  • Bump amplitude typically to 6s

  • Orbit linear, sextupole

  • Tune 5th order polynomial

Tune resolution 2001 (0.0002) decapole

dodecapole? 2001: automatic bump set-up

F.Pilat – RHIC Interaction Regions


Run 2001 machine development
Run 2001 – Machine Development

Plan for RUN 2001:

  • Scheduled MD time every week: 12h - wednesday

  • Weekly meetings – friday – to discuss plan and results

  • Weekly report to “time meetings” – tuesday

    MD coordinator – F.Pilat

  • MD starts when RHIC in operation mode – end July

    (first collisions at 100 GeV/u Monday this week! )

  • Program to continue till end of the run ~end January

F.Pilat – RHIC Interaction Regions


Md program 2001
MD Program 2001

  • IR studies (V.Ptitsyn)

  • IBS, Nonlinear, Beam-Beam (W.Fischer)

  • Background, Collimation, Luminosity (A.Drees)

  • Optics, AC Dipole (M.Bai)

  • Impedance (S-Y Zhang)

  • Longitudinal/RF studies (M.Brennan)

  • Transition studies (J.Kewisch)

  • Deuterons in AGS/RHIC (K.Gardner)

    www.agsrhichome.bnl.gov/AP/RHIC2001/BeamStudies/index.html

F.Pilat – RHIC Interaction Regions


Collaborative beam studies
Collaborative beam studies

Collaborations during Run 2000:

  • IR studies: J-P. Koutchouk, CERN T.Sen, FNAL

  • Nonlinear studies: F.Schmidt, CERN

  • Instrumentation: H.Schmickler, CERN

  • Operations: M.Lamont, CERN

    During Run 2001 (and 2002)

  • Continue existing collaborations

  • Experiment plan for future hadron colliders discussed at Snowmass:

    RHIC, FNAL, HERA,….LHC?

    Phase 1: included in machine development plans

    Phase 2: formally approved beam experiments with collaborating institutions

    Beam experiments as a test bench for GAN ?

F.Pilat – RHIC Interaction Regions


Summary
Summary

  • Use of IR correction system started at RHIC during Run 2000

  • Local IR decoupling has been demostrated

    integrates with the global coupling correction

  • Operational identification of IR nonlinear errors is possible (IR bumps technique)

  • Experiment work will continue during MD time in Run2001

  • Collaborative beam experiments are discussed to validate future hadron collider design and performance

F.Pilat – RHIC Interaction Regions


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