snowmass 2001
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
RHIC Interaction Regions:Diagnostics and Correction
Fulvia Pilat
Snowmass, July 18, 2001Joint T1-T5-T9
F.Pilat – RHIC Interaction Regions
OutlineRHIC OverviewIR correction systems: motivation, design (RHIC, LHC, VLHC)RHIC IR’s: layout and configurationIR correction methodsLinear: IR bumps, action-jumpNonlinear: action kick, IR bumps, frequency analysisIR bumps method application to LHCResults for Run 2000Linear: local IR skew correction and global coupling correctionNonlinear: operational determination of IR nonlinear termsRun 2001: plans for machine development/ beam studiesBeam experiments for future hadron colliders
F.Pilat – RHIC Interaction Regions
12:00 o’clock
2:00 o’clock
4:00 o’clock6:00 o’clock
8:00 o’clock
PHOBOS10:00 o’clock
BRAHMS
STARPHENIX
RHIC
AGS
LINACBOOSTER
TANDEMS
Pol. Proton Source
High Int. Proton Source 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
9 GeV/uQ = +79
1 MeV/uQ = +32
HEP/NP
g-2U-line
BAF (NASA)
RHIC Complex
F.Pilat – RHIC Interaction Regions
RHIC Run 2000 and 2001
Run 2000May –July: commissioningAugust-September: operation and beam studiesReached 10% of design luminosity
Run 2001Started in MayMay-July: start-up and commissioningof 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 systemsMotivation: local correction of linear errors (coupling, gradient)Local correction of nonlinear errors ( IR magnets field errors)Beta squeeze, crossing angleBeam control, luminosity
Design:Multi-layer corrector packages installed next to IR triplet quadrupolesTypically, dipole dodecapoleIndependently powered RHIC LHC VLHC
F.Pilat – RHIC Interaction Regions
LHC inner triplet - correctors
MQXA MQXB MQXB MQXA
MCBXA
MQSXA
MCBX
MCBX
BPM
BPM
LMQXB LMQXC LMQXA
LQXB LQXC LQXA
To IP
“Q3” “Q2” “Q1”
MCBX: b1 a1MCBX: b1 a1MQSXA: a2 a3 a4 b4 MCBXA: a1 b1 b3 b6Optimization process:Magnet design – correction system
F.Pilat – RHIC Interaction Regions
IR Correction – VLHC Stage 2
D1A D1B
Q1a
Q2a
D2
IP
20m
12.1m 6m 22m
5.5m2m
16T 12T
400T/m 600T/m
12T
Q1b
Q2b
600T/m 600T/m
12.4m 12.4m7.9m 7.9m
3m
3m
a0a1a2a3
b0b2b3b5
BPMIR correctorPackage (skew)
IR correctorPackage
3m
F.Pilat – RHIC Interaction Regions
RHIC IR’s - layout
6 o’clock IR8 o’clock IR:Dipole correctorsSkew quadrupolesNonlinear
Other IR’s:dipole correctorsSkew quadrupoles(nonlinear layersexist but no PSyet)
F.Pilat – RHIC Interaction Regions
Run 2000 – IR correction linear
IR bump method Action-jump method
Determine local IR skew quadrupole correction strenghts (Cardona, Ptitsyn, Pilat)
F.Pilat – RHIC Interaction Regions
RHIC Coupling correction
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 rollerror) is constant on the ramp, while globalcorrection changes on the ramp (orientationof vector varies ~10%)
Run2000
Run2001
F.Pilat – RHIC Interaction Regions
IR Correction - linearFrom 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)
Configuration 2001 (blue ring) Q(min)Uncorrected 0.009Local correction IR8, IR10,IR2 0.019Local correction in all IR’s 0.008Local correction + global correction
0.0005 (tune meter resolution)
F.Pilat – RHIC Interaction Regions
IR nonlinear correction methodsdead-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) sidebandsSUSSIX
F.Pilat – RHIC Interaction Regions
IR bumps method - principleClosed local orbit bump (triplet)Observable as function of bump amplitude:rms orbit outside the bumpz=(x,y) cn=(an,bn) zba=bump amplitude
dsRzc
BB
Qzcfrmsz nba
nzN
z
arczban 1)(
sin22),()(
The orbit perturbation depends in the plane of the bump (H,V)And the parity of the multipole order
tune shiftArises from normal gradients (DQ) or repelling effect of linear coupling (measured by c)
dsRz
cBBnzcgQ n
nba
nN
ban 1
2
41),(
dseRz
aBBnzchc yxi
n
nba
nyxN
ban)(
1
2
21),(
Selection of one or the other effect depends on the plane of the bump, whether the multipoleis skew or normal and on the parity of the multipole order
F.Pilat – RHIC Interaction Regions
IR bumps: simulation, performance
Use MAD to compute orbit and tune response to H and V orbit bumps in theLHC IP5, assuming:0.1% gradient error (/~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
Perturbation BPM resolutionroll 0.1 mrad 15 m rmsb3 = 7.6 10-4 8 m rmsb4 = 7.2 10-4 3.5 m rms
F.Pilat – RHIC Interaction Regions
Run 2000–IR correction nonlinear
RHIC IR bumps – beam experimentBump data at IR2, IR6, IR8, blue & yellowMostly H bumps, some V bumpsTune resolution run 2000: 0.001Bump amplitude typically to 6Orbit linear, sextupoleTune 5th order polynomial
Tune resolution 2001 (0.0002) decapole dodecapole? 2001: automatic bump set-up
triplet
b3 a3 b4 b5 a5 b6
YO5 0.94 -0.55 0.03 -0.08 0.11 -0.01YI6 -0.95 0.14 0.36 0.03 -0.06 -0.03YI7 1.01 -0.22 0.81 0.36 -0.17 -0.15YO8 3.81 -0.47 -1.85 0.06YO1 0.32 -0.14 0 0YO2 1.51 0.76 -0.75 -0.21
F.Pilat – RHIC Interaction Regions
Run 2001 – Machine Development
Plan for RUN 2001:Scheduled MD time every week: 12h - wednesdayWeekly meetings – friday – to discuss plan and resultsWeekly report to “time meetings” – tuesday
MD coordinator – F.PilatMD 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
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 studiesCollaborations during Run 2000:
IR studies: J-P. Koutchouk, CERN T.Sen, FNALNonlinear studies: F.Schmidt, CERNInstrumentation: H.Schmickler, CERNOperations: M.Lamont, CERN
During Run 2001 (and 2002)Continue existing collaborationsExperiment plan for future hadron colliders discussed at Snowmass:RHIC, FNAL, HERA,….LHC?Phase 1: included in machine development plansPhase 2: formally approved beam experiments with collaborating institutions
Beam experiments as a test bench for GAN ?
F.Pilat – RHIC Interaction Regions
SummaryUse of IR correction system started at RHIC during Run 2000Local IR decoupling has been demostrated
integrates with the global coupling correctionOperational identification of IR nonlinear errors is possible (IR bumps technique)Experiment work will continue during MD time in Run 2001Collaborative beam experiments are discussed to validate future hadron collider design and performance