# Presentation: 468339

**The Relativistic Nuclear Collisions Program**
**at the Lawrence Berkeley Laboratory**
**An Overview**
**Presented by **
**Jim Thomas**
**5/17/2006**

## Who we are ...

**9 Scientists**
**2 Retirees**
**6 PostDocs **
**1 Engineer**
**2.5 Computing at PDSF**

**8 Students**
**1 Visiting PD**
**1 Administrator**
**and no place to sit down**

## What we do ...

**Create and study hot, dense, nuclear matter in order to search for the quark–gluon plasma and characterize its properties**
**Study the spin structure of the nucleon**

## How we do it ...

**STAR is a collider detector at RHIC**
**RHIC delivers a variety of heavy ion *****and*****  polarized proton beams   at energies up to 200 GeV / A**
**At its heart is the worlds largest Time Projection Chamber**
**Designed and built in Berkeley**
**STAR Upgrades progressing well**
**ALICE is a collider detector at the Large Hadron Collider**
**The LHC will deliver heavy ion beams, and protons, at energies up to 30x RHIC energies**
**The ALICE TPC will become the biggest in the world ... when it runs**
**Based on STAR technology**
**LBNL and ALICE/USA are providing the EM calorimeter**

## What we have learned so far ...

- Nuclear Matter produced in Au-Au collisions is 30x denser than normal nuclear matter
- The quarks and gluons that are liberated  in a collision are not free streaming particles.  They “flow” and “scale” as if engulfed in a dense partonic liquid.
- Au-Au collisions are not a superposition   of p-p collisions.   The away side jet, in a back to back jet, is suppressed when it passes through the nuclear collision zone.
- Flow, quark scaling, and the high rate of energy loss for jets is a surprise.  It suggests a new kind of partonic matter ... perhaps a new state of matter at RHIC.
- These discoveries will be explored in more detail: with the STAR upgrades, at low energies in the baryon rich regime at RHIC & GSI, and at high energies with ALICE.

## Two Views of a Relativistic HI Collision

**Side View**

**End View**

**Two Views of a Relativistic HI Collision**

- The angular distribution in momentum space is not isotropic

- It is a strongly coupled system and the energy lost by a parton in the medium is large  – unlike in a p-p collision

- Angular distributions are very revealing

## High Pt Jets Probe the Medium

**The angular distribution of particles, triggered on a jet, shows  a clear back-to-back structure in p-p and d-Au collisions**
**But the away side jet is suppressed in Au-Au collisions**

- Surface emission

- While the backward going jet gets lost in the bulk of the medium

- For the new frontiers ... see the talk by Marco van Leeuwen

## The v2 Parameter Measures Flow

**A free streaming system of particles does not flow**
**v****2**** is large at RHIC **
**v****2**** persists to high p****t**

- PRL _86_, 402 (2001) & nucl-ex/0107003

**The mass dependence is reproduced by hydrodynamic models**
**Hydro assumes local thermal equilibrium **
**At early times**
**Followed by hydrodynamic expansion**
**v****2**** at high p****t**** shows meson/baryon differences**

## Quark Number Scaling

- The flow pattern in v2(pT) for hadrons
- is predicted to be simple _if_ flow is developed at the quark level
**p****T**** → p****T ****/n **
**v****2**** → v****2**** / n ,**
- n = (2, 3) for (meson, baryon)

- For the frontiers in energy loss and flow, see the talk by Lijuan Ruan

## Nucleon Spin Structure

**Nucleon Spin Structure**

- time

- 1933

- ~1970

- Frisch and Stern:
*The proton has substructure*

- ~1985

- Polarized deep-inelastic scattering:
*Quark spins carry only a small fraction*
*of the nucleon spin.*

- ?

- Electron-proton deep-inelastic scattering:
*Quarks are spin-1/2*

- ~2002

- RHIC: first polarized proton-proton collider

- For the frontiers in Spin Physics see the talk by E. Sichtermann

## UPC - Ultra Peripheral Collisions

**The Lorentz contracted nuclei act as sources of  E&M  fields. The interaction is between the exchange particles of the fields.**
**	****Electromagnetic Fields****	****– ****	****photons**
**	****Strong-Force Fields    ****	****– ****	****gluons(mesons/Pomerons)**
**	****A+A ******** A+A+X**
**For coherent interactions,  the maximum momentum transfer is determined by the nuclear form  factor / nuclear size:**
**	**
**	****max(Q)  ********  1/R**
**This has two important consequences:**
**	**
**	****1) The final state will have a low p****T****, p****T**** ******** 1/R**
**	****2) The maximum photon energy is  ********  ******** (1/R)**
**Heavy-Ions are advantageous because L******** ******** Z****4****   **
**	**
**	****Z****4**** = 4 · 10****7**** for Au**** **

## UPC - 200 GeV 0 analysis

**Coherent: p****T**** < h/R****A**
**Entire nucleus is target**
**dN/dt ~ exp(-bt)**
**b ~ R****A****2**
**Incoherent – individual nucleon is target**
**Can study ********0**** absorption, etc.**
**dN/dt ~ exp(-bt)**
**b ~ R****p****2**

** ******** ****mass spectra show ********0****, interference with direct pp production**
**Accompanied by mutual Coulomb excitation (MCE) **

- 0

- Interference
- Term

## Top Ten STAR Papers

**Top Ten STAR Papers**

**Top Cite 250+**
**“****Elliptic flow in Au + Au collisions at (S(NN))**(1/2) = 130 GeV”**
**	****PRL 86 (2001) 402.****   ****	****	**_**Poskanzer**_**, **_**Snellings**_**, Voloshin**
**“****Disappearance of Back to Back High Pt Hadron Correlations ...”**
**	****PRL 90 (2003) 082302.****   ****	**_**Hardtke**_**, Miller, Harris**
**Top Cite 100+**
**“****Evidence from d+Au Measurements for Final State Suppression ...” **
**	****PRL 91 (2003) 072304.****   ****	**_**Hardtke**_**, **_**Jacobs**_**, **_**Klay**_**, **_**Putschke**_**, Dunlop, ...**
**“****Transverse Momentum and Collision Energy Dependence ...”**
**	****PRL 91 (2003) 172302.****   ****	**_**Jacobs**_**, **_**Klay**_**, Dunlop, Gagliardi, Gans**
**“****Centrality Dependence of High Pt Hadron Suppression ...”**
**	****PRL 89 (2002) 202301.   ****	**_**Filimonov**_**, **_**Jacobs**_**, **_**Klay**_**, **_**Choi**_**, **_**Kunde**_**, ...**
**“****Identified Particle Elliptic Flow in Au+Au Collisions ...”**
**	****PRL 87 (2001) 182301.****   ****	**_**Poskanzer**_**, **_**Snellings**_**, **_**Tang**_**, Voloshin**
**“****Pion Interferometry of s(NN)**(1/2) = 130-GeV Au+Au Collisions at RHIC”**
**	****PRL 87 (2001) 082301.****	**_**Hardtke**_**, Cramer, Lisa, ...**
**“****Particle Type Dependence of Azimuthal Anisotropy and Nuclear Modification ...”**
**	****PRL 92 (2004) 052302.****	**_**Sorensen**_**, **_**Xu**_**, Fu, Huang, Lamont, Long**
**“****Azimuthal Anisotropy and Correlations in the Hard Scattering Regime at RHIC”**
**	****PRL 90 (2004) 032301.****	**_**Filimonov**_**, **_**Hardtke**_**, **_**Jacobs**_**, **_**Poskanzer**_**, **_**Snellings**_**, ...**
**“****Elliptic Flow From Two and Four Particle Correlations in Au+Au Collisions ...”**
**	****PRC 66 (2002) 034904.****	**_**Poskanzer**_**, **_**Snellings**_**,**_**Tang**_**, Keane, Voloshin**

## Theory and Experiment

**Working Together to do Great Science at RHIC**

## STAR Management Roles from within RNC

**STAR Deputy Spokesperson**
**Hans Georg Ritter**
**STAR Junior Council Members**
**Sarah Blyth, Lijuan Ruan**
**STAR Advisory Board**
**Jim Thomas, Nu Xu **
**Co-convenors for UPC, High p****T****, and Forward Tracking Working Groups**
**Spencer Klein, Marco van Leeuwen, Ernst Sichtermann**
**Trigger Board Members**
**Marco van Leeuwen, Ernst Sichtermann**
**STAR Upgrades Committee**
**Howard Wieman, Peter Jacobs, Hans Georg Ritter**
**STAR Council Member **
**Nu Xu**

## PDSF at LBNL

**PDSF  -  Parallel Distributed Systems Facility**
**Originally acquired from SSC surplus equipment pool**
**1.8 M$ in FY00-FY03 from NSD equipment funds and from DOE**
**Upgraded and improved each year**
**LDRD funds provide specific intellectual investments such as manpower for GRID development **
**Operated by NERSC for STAR and other HE & NP activities**
**MOU between LBNL, STAR, and DOE to cover STAR simulations, embedding*, and analysis activities**
**500 CPUs, 100 TB of disk, 1000 TB available in HPSS**
**Operating funds**
**RNC - ****2.5 FTEs**** **
**ATLAS/Physics - ****0.5 FTE**
**NERSC - ****2 FTE**
**Yearly mass storage (HPSS) **
**	****allocation to STAR ~ 1 M$**

- One half to one third of all STAR computing

**Looking to the future**

## The STAR Heavy Flavor Tracker

**The STAR Heavy Flavor Tracker**

**A new detector**
**30 ********m silicon pixels**
**Direct Topological reconstruction of open Charm hadrons**
**Detect charm decays with small c********, including D****0**** ******** K ******
**New physics**
**Charm collectivity and flow to test thermalization at RHIC**
**Charm Energy Loss to test pQCD in a hot and dense medium at RHIC**
**Proposal undergoing review by BNL & STAR**
**Prototype `08, complete `10**

- For a full discussion of the HFT see the talks by H. Wieman and Nu Xu

## Baryon Rich Physics at RHIC and FAIR

**Mapping the QCD phase diagram**
**Search for the boundary between hadronic and partonic worlds**
**Search for the critical point**
**Needs theory and experimental collaboration**

- 2.1   FAIR     8.1 GeV

- 4.6                        RHIC                     20.     GeV

- For the frontiers in Baryon Rich Physics, see the talk by Nu Xu

**ALICE EMC Management from within RNC**

**J. Symons (Division Director)**

## The ALICE  EMCal  ...  a major US Contribution

**Jet Quenching at the LHC**
**Pb + Pb at 5.5 TeV**
**EMCal+ALICE tracking+PID:**
**Full study of jets over huge kinematic range; unique and important probes of QCD matter**
**Lead-scintillator sampling calorimeter**
**|********| < 0.7 ,  ******** = 110******** ,  13,000 towers**
**Shashlik geometry**
**Major Milestones in FY06**
**Fermilab test beam: complete modules tested with final CERN electronics**
**CDR complete: in preparation for CD1**
**Mechanical support structure to be installed summer ‘06**
**Proposed funding assuming an eight super-module scope of work**

| 06 | 07 | 08 | 09 | 10 |  11 |
| --- | --- | --- | --- | --- | --- |
| 822K | 1 M | 2.4 M | 3 M | 3 M | 1.2 M |
| R&D | Const | Const | Const | Const | Const |

- For a full description of the ALICE program, see the talk by Peter Jacobs

## Honors and Service to the NP Community

**Humbolt Foundation Fellow**
**Hans Georg Ritter**
**APS Fellows**
**Peter Jacobs**
**jt**
**DNP Nominating Committee**
**jt**

**GSI/Fair PAC**
**Hans Georg Ritter**
**RHIC PAC**
**Peter Jacobs**
**PDSF**
**Organization of Meetings**
**Too numerous to list**

## Recent Alumni

**Glenn Cooper, 2000 **
**UC Berkeley, Industry**
**Milton Toy, 2001 **
**UCLA, Industry**
**Jinghua Fu, 2002 **
**Wuhan U, Faculty Tsinghua U**
**Ian Johnson, 2003 **
**UC Davis, PD CERN**
**Bum Choi, 2003 **
**UT Austin, Industry**
**Chris Kunz, 2003 **
**Carnegie-Mellon, Industry**
**Vladimir Morozov, 2003 **
**UC Berkeley, Industry**
**Xin Dong, 2005 **
**USTC, PD USTC**
**Heather Gray, 2005 **
**Univ. Cape Town, Caltech**
**Johanne Gonzalez, 2006**
**UCLA, Industry**
**Alexander Wetzler, 2006 **
**Frankfurt, Industry**

**Joakim Nystrand, 2001 **
**Faculty U Bergen**
**Fuqiang Wang, 2001**
**Faculty Purdue **
**Raimond Snellings, 2002**
**NIKEF**
**Masashi Kaneta, 2002**
**Riken BNL**
**Aihong Tang, 2002**
**BNL/NIKEF**
**David Hardtke, 2003**
**UC Berkeley**
**Falk Meissner, 2004**
**Industry**
**Jennifer Klay, 2004**
**LLNL & Cal Poly**
**Javier Castillo, 2004**
**Orsay**
**Fabrice Retiere, 2004**
**TRIUMF**
**Kirill Filimonov, 2005**
**UC Berkeley**

**Eugene Yamamoto, 2005**
**Industry**
**Kai Schweda, 2005**
**Helmholtz Fellow, Heidelberg**
**Paul Sorensen, 2005**
**Goldhaber Fellow, BNL**
**Markus Oldenburg, 2006**
**CERN Fellow**
**Jay Marx, 2006**
**Ligo ED, Caltech**

## Summary

**A vigorous program of research in Heavy Ion Physics at RHIC**
**PID studies of soft hadronic probes including flow **
**Detailed studies of Jet quenching and energy loss**
**We are upgrading STAR to enable new physics opportunities****	**
**The direct topological reconstruction of open charm with the HFT **
**	****to probe light quark thermalization and heavy flavor energy loss**
**A robust program of Spin measurements with STAR**
**Focus on the gluon contribution to the spin of the nucleon**
**Pursue the individual quark contributions in the future with upgrades**
**Exploring new opportunities to study baryon rich matter **
**	****at RHIC and Fair**
**Locate the phase boundary between hadronic matter and deconfined quarks and gluons**
**Also establishing a HI research program at ALICE**
**Building the EM Calorimeter and leading the physics program**
**A strong group of young people **
**Training the next generation**
**Doing world class physics**

**The end**

## STAR Publications Summary

**54 ****	****	****publications in the refereed literature  ****(31 PRL, 17 PRC, 5 PLB, 1 NPA)**
**  ****6 ****	****	****submitted to journals**
**  ****5 ****	****	****under final review by the collaboration**
_**10 **__**	**__**	**__**in preparation by editorial committees**_
**75 ****	****	****publications in preparation or published**
**60%  of all STAR publications have primary authors from the RNC group**
**70%  of all STAR PRLs have primary authors from the RNC group**
**45%  of all RHIC citations are from STAR papers  ****(PRL, PRC, PLB, NPA, JPG)**
**30%  of all RHIC citations have primary authors from the RNC group**

**Average of 103 Citations per PRL from a total of ~3500 citations, to date**