Snowmass 2001

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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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