RHIC Interaction Regions: Diagnostics and correction

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Snowmass 2001
RHIC Interaction Regions Diagnostics and
Correction
Fulvia Pilat
Snowmass, July 18, 2001 Joint T1-T5-T9
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Outline

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

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RHIC Complex
1200 oclock
PHOBOS
BRAHMS
200 oclock
1000 oclock
RHIC
PHENIX
800 oclock
400 oclock
STAR
600 oclock
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
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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

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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

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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
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IR Correction VLHC Stage 2
a0 a1 a2 a3
IR corrector Package (skew)
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
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RHIC IRs - layout

• 6 oclock IR
• 8 oclock IR
• Dipole correctors
• Skew quadrupoles
• Nonlinear
• Other IRs
• dipole correctors
• Skew quadrupoles
• (nonlinear layers
• exist but no PS
• yet)

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Run 2000 IR correction linear
Determine local IR skew quadrupole correction
strenghts (Cardona, Ptitsyn, Pilat)
IR bump method
Action-jump method
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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)
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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)

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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) rm
s orbit (BPMs, linear, sextupole) (Ptitsyn,
Pilat) tunes (Tune Meter, up to
dodecapole) (tune spread) (Schottky, octupole,
dodecapole?)   frequency analysis better
FFT detect and correct nonlinear (Schmidt) sideb
ands SUSSIX
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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) zbabump 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
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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/b20), 1 mrad roll
(c0.04) 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
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Run 2000IR 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
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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

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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/in
  dex.html

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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 ?

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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
  Run 2001
• Collaborative beam experiments are discussed to
  validate future hadron collider design and
  performance