E.C. Aschenauer Varenna, July Large scientific instruments that produce and accelerate subatomic particles and ‘smashes them’  Fixed target  Collider Particles: electrons, positrons, protons, anti-protons, ions….. (atoms stripped of electrons: nuclei) Nuclei  protons + neutrons  quarks + gluons

E.C. Aschenauer Varenna, July RHIC NSRL LINAC Booster AGS Tandems STAR 6:00 o’clock PHENIX 8:00 o’clock Jet/C-Polarimeters 12:00 o’clock RF 4:00 o’clock EBIS ERL Test Facility A N DY 2:00 o’clock What do we collide ? p Polarized light ions He GeV/u Light ions (d,Si,Cu) Heavy ions (Au,U) GeV/u Polarized protons GeV 1 st Collisions: 13/06/2000

STAR PHENIX AGS LINAC BOOSTER Pol. Proton Source 500  A, 300  s Spin Rotators Partial Siberian Snake Siberian Snakes 200 MeV Polarimeter AGS Internal Polarimeter Rf Dipoles RHIC pC Polarimeters Absolute Polarimeter (H jet) AGS pC Polarimeters Strong AGS Snake MP6 MP7 Tandem Van der Graaf Stripping Au 77+ to MeV/u GeV/u GeV/u 79+ E.C. Aschenauer Varenna, July A N DY

Booster Ring AGS Switchyard RHIC Tandem Van de Graaff E.C. Aschenauer Varenna, July Blue Ring Yellow Ring

E.C. Aschenauer Varenna, July RHIC accelerates gold nuclei in two beams to about 100 GeV/nucleon each (i.e., to kinetic energies that are over 100 times their rest mass-energy) and brings these beams into a 200 GeV/nucleon collision. RHIC accelerates polarized protons up to 250 GeV and brings them into up to 500 GeV collision Three experiments, STAR,PHENIX, and A N DY study these collisions.

E.C. Aschenauer Varenna, July  1989RHIC design  1991construction starts  1996commissioning AtR injection lines  1997sextant test (1/6 of the ring)  1999RHIC engineering/test run  2000first collisions  Au-Au run, polarized p run  2003deuteron-Au run, pp  2004Au-Au physics run and 5 weeks pp development  2005 ….. RHIC is also a giant engineering challenge: magnets (3000+ industry and lab built superconducting magnets) cryogenics (2 weeks to cool down to 4.2K),instrumentation, etc.

The operation of RHIC and its injectors is a rather challenging endeavor…. RHIC operates for ~5-6 months/year – 24h/day 7 days/week RHIC Shutdown 6-7 months, for machine improvements (other programs are run by the injectors, Tandem delivering ions for industrial R&D, Booster delivering ions for NASA experiments, etc.)  CONTROL ROOM : remote access to instrumentations and controls  Accelerator physicists, shift leaders (machine initial set-up, new developments, beam experiments)  Operations group: operation coordinator, operators (“routine’ operations, shifts 1 OC + 2 operators)  Technical support (engineers and technicians on call and/or site for system diagnosis and trouble-shooting) E.C. Aschenauer Varenna, July 20118

Beam intensities Pilot bunch injection acceleration preparation collisions Set-up Store (collisions) time Start acceleration transition Beta* squeeze cogging re-bucketing collimation steering collisions E.C. Aschenauer Varenna, July 20119

E.C. Aschenauer Varenna, July

design luminosity Week 9 Feb to 17 Feb [66% of calendar time in store] enhanced luminosity 60x10 9 Au intensity Beam experiments E.C. Aschenauer Varenna, July

E.C. Aschenauer Varenna, July Polarized proton runs Operated modes (beam energies): Au–Au 3.8/4.6/5.8/10/14/32/65/100 GeV/n d–Au* 100 GeV/n Cu–Cu11/31/100 GeV/n p  –p  11/31/100, 250 GeV Planned or possible future modes: Au – Au2.5 GeV/n (~ SPS cm energy) U – U100 GeV/n p  – Au*100 GeV/n Cu – Au*100 GeV/n (*asymmetric rigidity) Achieved peak luminosities (100 GeV, nucl.-pair): Au–Au 195  cm -2 s -1 p  –p  60  cm -2 s -1 Other large hadron colliders (scaled to 100 GeV): Tevatron (p – pbar) 43  cm -2 s -1 LHC (p – p) 37  cm -2 s -1

E.C. Aschenauer Varenna, July 2011  Beam envelope function  * = 3.0 m at IP2  Reduced IP2 crossing angle from initially 2.0 mrad to zero  Added 3 rd collision with following criteria (last instruction): 1. N b ≤ 1.5x Beam loss rate <15%/h in both beams 3.Not before first polarization measurement 3h into store PHENIX STAR AnDY small impact visible impact, few percent loss to STAR/PHENIX loss rates  /IP =  /IP =

14 ~2mr crossing angle ~1.6mr crossing angle ~0mr crossing angle systematically increased thresholds for IP2 collisions A N DY got ~ 6.5/pb in run11 with  *=3m E.C. Aschenauer Varenna, July 2011

E.C. Aschenauer Varenna, July 2011  Can reduce  * at IP2 have run with  * = 2.0 m previously for BRAHMS  * = 1.5 m probably ok, needs to be tested  Longer stores 10h instead of 8h in Run-11 (depends on luminosity lifetime and store-to-store time)  Collide earlier in store when conditions are met needs coordination with polarization measurement, PHENIX and STAR  Electron lenses (see later) if A n DY runs beyond Run-13 increases max beam-beam tune spread, currently  Q max,bb ≈ can be used for to increase  ~N b /  and/or number of collisions Run-11 luminosity at A n DY: max ~0.5 pb -1 /store With improvements: ~3x increase, ~10 pb -1 /week (max) 15 pp in Run-4 (100 GeV)

E.C. Aschenauer Varenna, July

 revolve quickly and repeatedly around one's own axis, "The dervishes whirl around and around without getting dizzy”  twist and turn so as to give an intended interpretation, "The President's spokesmen had to spin the story to make it less embarrassing”  a distinctive interpretation (especially as used by politicians to sway public opinion), "the campaign put a favorable spin on the story" E.C. Aschenauer 17Varenna, July 2011

 Classical definition  the body rotation around its own axis  Particle spin:  an intrinsic property, like mass and charge  a quantum degree freedom associated with the intrinsic magnetic moment. G: anomalous gyromagnetic factor, describes the particle internal structure. For particles: point-like: G=0 electron: G= muon: G= proton: G= m: particle mass q: electrical charge of particle E.C. Aschenauer 18Varenna, July 2011

 Spin: single particle  pure spin state aligned along a quantization axis  Spin vector S: a collection of particles  the average of each particles spin expectation value along a given direction S N  Spin orbit interaction N  I S E.C. Aschenauer 19Varenna, July 2011

 Luminosity:  number of particles per unit area per unit time. The higher the luminosity, the higher the collision rates  beam polarization  Statistical average of all the spin vectors.  zero polarization: spin vectors point to all directions.  100% polarization: beam is fully polarized if all spin vectors point to the same directions. Transverse beam size # of particles in one bunch # of bunches E.C. Aschenauer 20Varenna, July 2011

 bending dipole  Constant magnetic field  Keeps particles circulating around the ring  quadrupole  Magnetic field proportional to the distance from the center of the magnet.  Keeps particles focused  radio frequency cavities  Electric field for acceleration and keeping beam bunched longitudinally E.C. Aschenauer 21Varenna, July 2011

Closed orbit in a machine with dipole errors Closed orbit in a perfect machine: center of quadrupoles Closed orbit: particle comes back to the same position after one orbital revolution E.C. Aschenauer 22Varenna, July 2011

Beta function Betatron tune: number of oscillations in one orbital revolution E.C. Aschenauer 23Varenna, July 2011

 In a perfect accelerator, spin vector precesses around the bending dipole field direction: vertical  Spin tune Qs: number of precessions in one orbital revolution. In general, Spin vector in particle’s rest frame B beam E.C. Aschenauer 24Varenna, July 2011

 Depolarization (polarization loss) mechanism  Come from the horizontal magnetic field which kicks the spin vector away from its vertical direction  Spin depolarizing resonance : coherent build-up of perturbations on the spin vector when the spin vector gets kicked at the same frequency as its precession frequency x y z beam Initial x y z beam 1 st full betatron Oscillation period x y z beam 2 nd full betatron Oscillation period E.C. Aschenauer 25Varenna, July 2011

 Imperfection resonance  Source: dipole errors, quadrupole mis- alignments  Resonance location: G  = k k is an integer  Intrinsic resonance  Source: horizontal focusing field from betatron oscillation  Resonance location: G  = kP±Qy P is the periodicity of the accelerator, Qy is the vertical betatron tune E.C. Aschenauer 26Varenna, July 2011

Intrinsic spin resonance Q x =28.73, Q y =29.72, emit= 10 E.C. Aschenauer Varenna, July  For protons, imperfection spin resonances are spaced by 523 MeV  the higher energy, the stronger the depolarizing resonance

 First invented by Derbenev and Kondratenko from Novosibirsk in 1970s  A group of dipole magnets with alternating horizontal and vertical dipole fields  rotates spin vector by 180 o E.C. Aschenauer 28Varenna, July 2011

E.C. Aschenauer 29Varenna, July 2011

 Use one or a group of snakes to make the spin tune to be 1/2 y z beam y z  Break the coherent build-up of the perturbations on the spin vector E.C. Aschenauer 30Varenna, July 2011

E.C. Aschenauer Varenna, July

E.C. Aschenauer 32Varenna, July 2011 A N DY(p)

 Energy: 23.8 GeV ~ 250 GeV (maximum store energy) A total of 146 imperfection resonances and about 10 strong intrinsic resonances from injection to 100 GeV.  Two full Siberian snakes E.C. Aschenauer 33Varenna, July 2011

E.C. Aschenauer Varenna, July

Simple example: spin-1/2 particles (proton, electron) Can have only two spin states relative to certain axis Z: S z =+1/2 and S z =-1/2 |P|<1 E.C. Aschenauer 35Varenna, July 2011

There are several established physics processes sensitive to the spin direction of the transversely polarized protons Scattering to the right Scattering to the left A N – the Analyzing Power (|A N |<1) (left-right asymmetry for 100% polarized protons) Once A N is known: E.C. Aschenauer 36Varenna, July 2011

A N depends on the process and kinematic range of the measurements pC elastic scattering Precision of the measurements N=N Left +N Right For  (P)=0.01 and A N ~0.01  N~10 8 ! Requirements: Large A N or/and high rate (N) Good control of kinematic range -t=2M C  E kin E.C. Aschenauer 37Varenna, July 2011

38 E.C. Aschenauer Varenna, July 2011 STAR (p) PHENIX (p) AGS LINAC BOOSTER Pol. Proton Source 500  A, 400  s Spin Rotators Solenoid Snake Siberian Snakes 200 MeV Polarimeter AGS pC CNI Polarimeter AC Dipole RHIC pC Polarimeters Absolute Polarimeter (H jet) RHIC Siberian Snakes Cold Snake Warm Snake A N DY (p)

Polarized hydrogen Jet Polarimeter (HJet) Source of absolute polarization (normalization to other polarimeters) Slow (low rates  needs lo-o-ong time to get precise measurements) Proton-Carbon Polarimeter (pC) Very fast  main polarization monitoring tool Measures polarization profile (polarization is higher in beam center) Needs to be normalized to HJet Local Polarimeters (in PHENIX and STAR experiments) Defines spin direction in experimental area Needs to be normalized to HJet All of these systems are necessary for the proton beam polarization measurements and monitoring E.C. Aschenauer 39Varenna, July 2011

Beam and target are both protons 40 RHIC proton beam Forward scattered proton H-jet target recoil proton P target is provided by Breit Rabi Polarimeter Left-right asymmetry in elastic scattering due to spin-orbit interaction: interaction between (electric or strong) field of one proton and magnetic moment associated with the spin of the other proton E.C. Aschenauer Varenna, July 2011

RHIC proton beam Recoil proton Height: 3.5 m Weight: 3000 kg Entire system moves along x-axis  10 ~ +10 mm to adjust collision point with RHIC beam. IP12 target E.C. Aschenauer 41Varenna, July 2011

RF transitions (WFT or SFT) |1> |2> |3> |4> Separating Magnet (Sextuples) H 2 desociater Holding magnet 2 nd RF- transitions for calibration P + OR P  H = p + + e  Atomic Beam Source Scattering chamber Breit-Rabi Polarimeter Separating magnet Ion gauge |1> |3> |2> |4> |1> |2> Ion gauge Hyperfine structure 42 E.C. Aschenauer Varenna, July 2011

43 proton beam Forward scattered proton proton target recoil proton BLUE mode YELLOW mode Energy vs Channel # ToF vs Energy E.C. Aschenauer Varenna, July 2011 Array of Si detectors measures T R & ToF of recoil proton. Channel # corresponds to recoil angle  R. Correlations (T R & ToF ) and (T R &  R )  the elastic process

1 day Breit-Rabi Polarimeter: Separation of particles with different spin states in the inhomogeneous magnetic field (ala Stern-Gerlach experiment) Nuclear polarization Very stable for entire run period ! Polarization cycle (+/ 0/  ) = (500/50/500) s Source of normalization for polarization measurements at RHIC Nuclear polarization of the atoms: 95.8%  0.1% After background correction: P target = 92.4%  1.8% E.C. Aschenauer 44Varenna, July 2011

Provides statistical precision  (P)/P ~ 0.10 in a store (6-8 hours) Example from Run-2006 ε beam ε target t=-2M p  E kin Use the same statistics (with exactly the same experimental cuts) to measure  beam and  target (selecting proper spin states either for beam or for target)  Many systematic effects cancel out in the ratio E kin (MeV) HJet Provides very clean and stable polarization measurements but with limited stat. precision  Need faster polarimeter! E.C. Aschenauer 45Varenna, July 2011

Ultra thin Carbon ribbon Target (5  g/cm 2 ) Si strip detectors (TOF, E C ) 18cm Polarized proton Recoil carbon Carbon target Left-right asymmetry in elastic scattering due to spin-orbit interaction: interaction between (electric or strong) field of Carbon and magnetic moment associated with the spin of the proton Target Scan mode (20-30 sec per measurement) Stat. precision 2-3% Polarization profile, both vertical and horizontal Normalized to H-Jet measurements over many fills (with precision <3%) E.C. Aschenauer 46Varenna, July 2011

zero hadronic spin-flip With hadronic spin-flip (E950) Phys.Rev.Lett.,89,052302(2002) pC Analyzing Power E beam = 21.7GeV E beam = 100 GeV unpublished Run04 Elastic scattering: interference between electromagnetic and hadronic amplitudes in the Coulomb-Nuclear Interference (CNI) region E.C. Aschenauer 47Varenna, July 2011

H-Jet ~1 mm 6-7 mm pC Collider Experiments P 1,2 (x,y) – polarization profile, I 1,2 (x,y) – intensity profile, for beam #1 and #2 x=x0x=x0 If polarization changes across the beam, the average polarization seen by Polarimeters and Experiments (in beam collision) is different E.C. Aschenauer 48Varenna, July 2011

Carbon Scan C target across the beam In both X and Y directions Target Position Intensity Polarization II PP Run-2009: E beam =100 GeV: R~0.1  5% correction E beam =250 GeV: R~0.35  15% correction Ideal case: flat pol. profile (  P =   R=0) E.C. Aschenauer 49Varenna, July 2011

Run-2009 results (E beam =100 GeV) Normalized to HJet Corrected for polarization profile (by pC)  P/P < 5% Dominant sources of syst. uncertainties: ~3% - HJet background ~3% - pC stability (rate dependencies, gain drift) ~2% - Pol. profile “Yellow” beam “Blue” beam E.C. Aschenauer 50Varenna, July 2011

E.C. Aschenauer 51Varenna, July 2011 A N DY(p) STAR (p) PHENIX (p) AGS LINAC BOOSTER Pol. Proton Source 500  A, 400  s Spin Rotators Solenoid Snake Siberian Snakes 200 MeV Polarimeter AGS pC CNI Polarimeter AC Dipole RHIC pC Polarimeters Absolute Polarimeter (H jet) RHIC Siberian Snakes Cold Snake Warm Snake Spin Rotators around experiments may change spin direction in experimental areas  Need to monitor spin direction in experimental areas

Utilizes spin dependence of very forward neutron production discovered in RHIC Run-2002 (PLB650, 325) neutron charged particles Zero Degree Calorimeter Quite unexpected asymmetry Theory can not yet explain it But already can be used for polarimetry! E.C. Aschenauer 52Varenna, July 2011

Vertical   ~ ±  /2 Radial   ~ 0 Longitudinal  no asymmetry Measures transverse polarization P T, Separately P X and P Y Longitudinal component: P – from CNI polarimeters Vertical Radial Longitudinal -  /2 0  /2 Asymmetry vs  E.C. Aschenauer 53Varenna, July 2011

3.3<|  |< 5.0 (small tiles only) Utilizes spin dependence of hadron production at high x F : Bunch-by-bunch (relative) polarization E.C. Aschenauer 54Varenna, July 2011 Monitors spin direction in STAR collision region Capable to precisely monitor polarization vs time in a fill, and bunch-by-bunch

E.C. Aschenauer Varenna, July

E.C. Aschenauer Varenna, July

ParameterUnitp-p relativistic , injection …25.9 relativistic , store …266.5 no of bunches, n b …112 ions per bunch, N b emittance e N x,y 95% mm-mrad20 average luminosity cm -2 s polarization,store%70 E.C. Aschenauer 57Varenna, July 2011

Separation of spin states in the inhomogeneous magnetic field E.C. Aschenauer 58Varenna, July 2011

 Polarimetry is a crucial tool in RHIC Spin Program Provides precise RHIC beam polarization measurements and monitoring Provides crucial information for RHIC pol. beam setup, tune and development  RHIC Polarimetry consists of several independent subsystems, each of them playing their own crucial role (and based on different physics processes) HJet: Absolute polarization measurements pC: Polarization monitoring vs bunch and vs time in a fill Polarization profile PHENIX and STAR Local Polarimeters: Monitor spin direction (through trans. spin component) at collision E.C. Aschenauer 59Varenna, July 2011