CERN p+Nucleus Workshop -- Accelerator

1. CERN p+Nucleus Workshop -- Accelerator • p+A at the LHC is still officially an accelerator upgrade. It is not yet officially approved. • First year that LHC might run p+Pb: 2010 • Probable “target” luminosity: 1029/(cm2s) • 1030 may be possible if they get lucky • Can’t use the “constant frequency” solution that worked well at RHIC  injection/ramping will be more difficult, and • Nucleon-nucleon CM is not at lab rapidity = 0 • Δy = 0.46, √sNN = 8.8 TeV for p+Pb • Δy = 0.12, √sNN = 6.2 TeV for d+Pb

2. CERN p+Nucleus Workshop – Experiments • ALICE, ATLAS, CMS all thinking about p+Pb • People also thinking about Pb+p as a high-energy γ+ p surrogate • “Company line”: no need for p+p reference. Will come from interpolation between Tevatron and 14 TeV • Probably okay for “really hard” processes • May be problematic for measurements focused on small-x saturation effects • If the accelerator turn-on goes well, even getting the 14 TeV reference data may be difficult

3. Questions Regarding RHIC Expectations Hi Thomas: I'm doing some preparation for the RHIC II pA/Forward working group meeting on Wednesday morning, and I have a few questions about asymmetric collisions.  The spreadsheet that was sent around in March quoted luminosities/week of:         d+Au, achieved:  4.5 nb^-1         d+Au, RHIC II:   62 nb^-1         p+Au, RHIC II:   83 nb^-1 My questions are: (1)  What luminosities might we expect during the next ~5 years (e.g., prior to electron cooling)? (2)  Theoretically and experimentally, there would be some advantages in running p+Au.  In the past it's been stated p+Au collisions require that the DX magnets be moved.  Given the improved understanding of the accelerator over the past few years, is this still true? (3)  If (2) is still true, is there a rough estimate of how long the magnet moves would take?  [The bottom line is that we need to understand if p+nucleus operation would require a full RHIC running year to be dedicated solely to p+nucleus measurements.] Thanks for your help! Carl Gagliardi

5. Gluon saturation at small x & shadowing in nuclei Also important for AA initial state RHIC allows study of transition. LHC always saturated (except very high pT and y<-3) • Models: • gluon saturation, CGC • leading twist shadowing (coherence) • mass renorm. (Vitev) • Sudakov suppr. (Kopeliovich) • limiting fragmentation Especially for LHC where always saturated at midrapidity LHC only 1-month/yr shared between pp, pA and AA – earliest pA 2010? • How to distinguish?? • correlations • energy,rapidity dependence • universality polarized and diffractive pA are useful - need theoretical calculations. need hard processes sensitive to gluons • Forward hadrons • need forw. π0 → STAR FMS • hadron PID for |y|>1 compare open & closed Heavy-quarks (c,b) & bound states Direct photons for |y|>1 → PHENIX NCC need cleaner way to get open-c, -b wide kinematic range to understand physics & differentiate models vertex detectors! • Onia – rare processes • PHENIX onia • Need STAR forward J/ψ → ee • separating D & B in single-lepton spectra? • use B → J/ψ X measurement • very high statistics could allow seeing 2 c’s D → Kπ nice but difficult! High Luminosities needed!