1 / 24

PHYSICS WITH TAGGED FORWARD PROTONS AT RHIC

PHYSICS WITH TAGGED FORWARD PROTONS AT RHIC. Mainly : Introductions and Expectations First look at the data (2009 RHIC run). Kin Yip For STAR Collaboration Brookhaven National Lab. Aug. 31, 2009, Tatranská Štrba, Slovakia. RHIC-Spin Accelerator Complex. RHIC pC “CNI” polarimeters.

yardan
Download Presentation

PHYSICS WITH TAGGED FORWARD PROTONS AT RHIC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. PHYSICS WITH TAGGED FORWARD PROTONS AT RHIC • Mainly : • Introductions and Expectations • First look at the data (2009 RHIC run) Kin Yip For STAR Collaboration Brookhaven National Lab. Aug. 31, 2009, Tatranská Štrba, Slovakia

  2. RHIC-Spin Accelerator Complex RHIC pC “CNI” polarimeters absolute pH polarimeter Former location of pp2pp RHIC Siberian Snakes Siberian Snakes PHENIX STAR Spin Rotators * ~ 21 m for pp2pp/STAR in 2009 LINAC 5% Snake BOOSTER Pol. Proton Source AGS AGS quasi-elastic polarimeter AGS pC “CNI” polarimeter RF Dipoles 200 MeV polarimeter 15% Snake

  3. Relativistic Heavy Ion Collider (RHIC): THE QCD Factory QCD (theory of strong interaction): some of the current and future QCD measurements at RHIC • Confinement/phase of QCD - QGP • Distribution of spin in the nucleon - Spin sum rule • Parton splitting limit- Saturated gluon state (Color Glass Condensate…) • Gluonic degree of freedom in Hadrons – exotica (glueballs…) • Nature of diffractive processes –structure of Pomeron, Odderon…

  4. PHYSICS WITH TAGGED FORWARD PROTONS AND THE STAR DETECTOR p + p  p + X + p Double Pomeron Exchange (DPE) diffractive X= particles, glueballs Discovery Physics QCD color singlet exchange: C1, C1 p + p  p + p elastic Single Diffraction Dissociation (SDD)

  5. In the double Pomeron exchange process, each proton “emits” a Pomeron and the two Pomerons interact producing a massive system MX where MX =   gg(glueballs) , c(b), qq(jets), H(Higgs boson), The massive system could form resonances. We expect that because of the constraints provided by the double Pomeron interaction, glueballs, hybrids, and other states coupling preferentially to gluons, will be produced with much reduced backgrounds compared to standard hadronic production processes. CENTRAL PRODUCTION IN DPE For each proton vertex one has t four-momentum transfer p/p MX =invariant mass p p Mx RHIC

  6. Kinematic “filter” (dpT) for “gg” (F. Close et al./W102) • Coupling of the exchange particles to the final state mesons for gluon exchange (small dpT) and quark exchange (large dpT) • Spin-dependence of the coupling can be studied at RHIC “Large” ~ (≥ O(LQCD) q Large dPT PLB 397 339 (1997)

  7. Summary of the Existing Elastic Data( unpolarized ) 50 500 RHIC • Highest energy so far: • pp: 62 GeV (ISR) • p : 1.8 TeV (Tevatron) • RHIC energy range: • 50 GeV  s  500 GeV • Elastic measurements: Details on the nature of elastic scattering between the ISR and SPS energies NOT well understood: Unique measurements in wide t-range with polarized beams pp2pp 2003

  8. Can Odderon be identified at RHIC ? • Odderon is a counterpart of pomeron (C 1) with C 1: “RHIC is the machine to find it” (E. Leader, Odderon Workshop (2005)) by measuring • (pp – p ) ≠ 0 (~3mb) • d/dtpp ≠ d  /dtp • Shape of Asymmetries: ANN • Centrally produced C1 particle UA4      hard-scattering alone diffraction alone hep-ph/0210437 M. Islam et al.

  9. Implementation at RHIC  Detectors • TPC tracking in |y|<1 with TOF barrel and TPC PID (p/K separation up to~ 1.6 GeV/c) J.H. Lee • Roman Pots of pp2pp  STAR (existing equipment) • Need detectors (Roman Pots) to measure forward protons: small t (four-momentum transfer), (p/p) and MX (invariant mass) • Detector with good acceptance and particle ID (STAR) to measure centrallyproduced system

  10. RUN 2009 - PHASE I () • Important conditions: • Need to reachsmall t and values to measure small masses of interest  large *~21m (cf. ~0.7 m),special optics and beam collimation are needed. • Alignmentvery important  use elastic events; • Hence a dedicated five day run for pp2pp • Elastic scattering: • 100% acceptance for elastic scattering for 0.003  |t|  0.022; • With 20-40×106 elastic events, accurarices: • b=0.31 [cf. ~1.8] (GeV/c)2, Dr=0.01, • Dstot= 1-2 mb; • In four t subintervals we shall have 5×106 events in each resulting in corresponding errors dAN=0.0017[cf.  0.005], dANN=dASS=0.003 [cf. 0.017/0.008] .

  11. t-acceptance of Roman Pots • Phase I set-up focuses on low-t (installed) • Phase II covers higher-t range

  12. Acceptance & Expected yields in MX √s=500 GeV Phase II • Expected reconstructed phase-space including BR per 1M DPE events • Mx=1-3 GeV/c2 is kinematically well accessible in pion and kaon decay channels • High-Mx reconstruction is limited by PID (p/K separation up to ~ 1.6 GeV/c) • Expected Trigger rate for DPE: 80 Hz at L=1x1031cm-2s-1 • To collect 100K K+K- sample, needs only ~200 hr of running time Possible as NO special accelerator optics will be required

  13. TAGGING FORWARD PROTONS AT RHICTHE PP2PP ELASTIC SCATTERING EXPERIMENTAL SETUP Phys. Lett. B 579 (2004) 245-250, Phys. Lett. B 632 (2006) 167-172, Phys. Lett. B 647 (2007) 98-103

  14. Roman Pots moved to STAR • Vertical AND Horizontal RP setup for a complete f coverage

  15. Z-Vertex from the opposite PMT’s Online/QA (cm) Kin Yip Cluster position Y vs X in Roman Pots Online/QA (strip numbers)

  16. (ADC’s) of the clusters in silicons Online/QA Kin Yip in the unit of ADC’s

  17. Collinearity of candidate elastic events Mean ~ -0.12  ~ 0.15 Mean ~ -0.02  ~ 0.15 Online/QA (strip numbers)

  18. The Accounting Department … • ~33 M events elastic triggers • Selected “cleanest events” for later analysis which satisfy the following conditions: • Valid hit/strip with ADC  pedestal_per_channel + 5  • Cluster (≤5 valid consecutive hits) with total energy  20 • Treating 4 opposite roman pot pairs separately,  1 valid opposite pair “golden tracks” (with 1 cluster on each of the 4 planes in each Roman Pot)  ~78% (of elastic triggers) in a typical run • Required additional collinear conditions  ~74% (of elastic triggers) Kin Yip

  19. Candidate Central Production Event An STAR event triggered by the PMT’s in the Roman Pots

  20. Summary • We’ve had a great run - the setup and its integration with STAR worked very well (33M elastic triggers, 700k CP triggers) • We will focus now on data analysis: • Elastic scattering - spin dependence ANN, AN, ASS, AS, tot for the spin combinations. • Elastic scattering - spin averaged dN/dt => slope b, tot, , luminosity measurements. • Diffraction - Central Production, Single Diffraction Dissociation and its spin dependence. • Hope to have results in near future …. • There is more to do to fully explore physics potential and discovery possibilities at RHIC • Each proton run at RHIC allows to expand our research

  21. BACKUP SLIDES J.H. Lee

  22. ROMAN POTS (PHASE I) • Phase I: 8 Roman pots at ±55.5, ±58.5m from the IP • Require special beam tune :large b* (21m for √s=200 GeV) for minimal angular divergence • Ready to run in 2009: Will be focusing small-t processes (0.002<|t|<0.03 GeV2) J.H. Lee

  23. ROMAN POTS (PHASE II) • Phase II: 8(12) Roman Pots at ±13 and ±16m • Planed to be implemented in 2010-2011 • Doesn’t require special beam tune: main set-up for central DPE processes requiring wide-t coverage and high-luminosity • 2p coverage will be limited due to machine constraint J.H. Lee

  24. Roman Potsused (2002-2003) for pp2pp experiment at RHIC pp2pp set-up Roman Pot (above the beam) J.H. Lee to IR Roman Pot (below the beam)

More Related