# Presentation: 391219

## RHICatBrookhaven National LabGene Van BurenBNL Technicians – May 1, 2002

- http://www.bnl.gov/rhic
- http://www.star.bnl.gov/

## Outline

- What is the science we’re trying to do here?
- How do we go about doing it?
- The lab experiment (RHIC)
- The detectors (STAR, Phenix, Phobos, Brahms)
- Interpretation of the data...

## The current picture of Matter...

- confinement

## Some Motivation

- 	In order to study the question of ‘vacuum’, we must turn to a different direction; we should investigate some ‘bulk’ phenomena by distributing high energy over a relatively large volume.”
- T.D. Lee (Nobel Laureate)
- Rev. Mod. Phys. 47 (1975) 267.

*Some Motivation*

## Phase Transitions & Atoms

***ICE***

***WATER***

***STEAM***

***Add heat***

***Add heat***

**These are the phases of matter we see in our****normal lives, but there are more!  Keep adding heat!**

***SOLID***

***LIQUID***

***GAS***

## Phase Diagrams

*Phase Diagrams*

**Water**

**Nuclear Matter**

## Lattice QCD predictions 

- TC ~ 160 MeV, stable
- Baryon free,  early universe condition
- F. Karsch, hep-lat/0106019

**Energy Density**

**Temperature**

## A Silly Analogy

- Suppose...
- You lived in a frozen world where water existed only as ice
- and ice comes in only quantized sizes ~ ice cubes
- and theoretical friends tell you there should be a liquid phase
- and your only way to heat the ice is by colliding two ice cubes
- So you form a “bunch” containing a billion ice cubes
- which you collide with another such bunch
- 10 million times per second
- which produces about 1000 IceCube-IceCube collisions per second
- which you observe from the vicinity of Mars
- Change the length scale by a factor of ~1013
- You’re doing physics at RHIC!

- Bill Zajc, QM2001

**Notes:**
Call a cube ~ a few cm  scale change is 10^13, so 1 meter bunch long bunch becomes 10^10 km 

## A phase transition seen from CERN

**- the skier can move **
**further ... **
**a  new phase develops**

**- A skier (quark) is**
**confined inside snow**
**patches (hadrons)**

**- the skier (quark ?)**
**can move freely**
**over long distances ...**

- Luciano Maiani, February 2000

**T**

## How do we see these other phases?

- Get a BIG microscope

- Our microscope, RHIC, can see things much, much smaller!
- ...but what we are looking at isn’t sitting still...

*RHIC*

## RHIC @ Brookhaven National Laboratory 

*RHIC @ Brookhaven National Laboratory *

**h**

**Long Island**

**R**elativistic
**H**eavy
**I**on
**C**ollider

-  2 concentric rings of superconducting magnets
-  3.8 km circumference
-  counter-rotating beams of ions from *p* to Au

**STAR**

**PHENIX**

**PHOBOS**

**BRAHMS**

## Nuclear Physics

- Low energy nuclear physics is dominated by potential interactions and mutual excitations

**The UrQMD Collaboration**

## Nuclear Physics

- Low energy nuclear physics is dominated by potential interactions and mutual excitations

**The UrQMD Collaboration**

## Nuclear Physics

**The UrQMD Collaboration**

- Ultra-relativistic energies probe the fundamental interactions of the constituent particles

## Nuclear Physics

**The UrQMD Collaboration**

- Ultra-relativistic energies probe the fundamental interactions of the constituent particles

## The Two “Large” Detectors at RHIC

**Coils**

**Forward Time Projection Chamber**

**Electronics Platforms**

_**STAR**_
** ****Solenoidal field**
** ****Large-******** Tracking**
**TPC’s, Si-Vertex Tracking**
**RICH, EM Cal, TOF**
**~420 Participants**

**  ****Measurements of Hadronic Observables **
**   ****using a Large Acceptance**
**  ****Event-by-Event Analyses of Hadrons and **
**   ****Jets**

*The Two “Large” Detectors at RHIC*

## The Two “Small” Detectors at RHIC

_**BRAHMS**_
-      **2 “Conventional” Spectrometers**
**     ****Magnets, Tracking Chambers, TOF, RICH**
**~40 Participants**

** ****Inclusive Particle Production Over Large **
**  ****Rapidity Range**

_**PHOBOS**_
**     “****Table-top” 2 Arm Spectrometer**
**     ****Magnet, Si ********-Strips, Si Multiplicity Rings, TOF**
**     ****~80 Participants**

** ****Charged Hadrons in Select Solid Angle**
** ****Multiplicity in 4******
** ****Particle Correlations**

- Ring Counters

- Paddle Trigger Counter

- Spectrometer

- TOF

- Octagon+Vertex

*The Two “Small” Detectors at RHIC*

## The STAR Collaboration

## STAR Collaborators      /Institutions

**Brazil:****	****    **
**	****Universidade de Sao Paolo**
**China:****	****    **
**	****IHEP - Beijing,  IPP - Wuhan**
**England:****  **
**	****University of Birmingham**
**France:****     **
**	****Institut de Recherches Subatomiques Strasbourg,   SUBATECH - Nantes**
**Germany:****  **
**	****Max Planck Institute  Munich, University of Frankfurt**
**India:**
**        ****Institute of Physics - Bhubaneswar, VECC Calcutta, Panjab University - Chandrigrarh, Unveristy of Rajasthan - Jaipur, Jammu University, IIT -Bombay**
**Poland:****  **
**	****Warsaw University, Warsaw University of Technology**
**Russia:****  **
**	****MEPHI – Moscow,  LPP/LHE JINR – Dubna,  IHEP - Protvino**

**U.S. Universities:****    **
**            ****Arkansas,  UC Berkeley,  UC Davis,  UCLA,  **
**           ****Carnegie Mellon, Creighton,  Indiana,  ****Kent**
**            ****State****,  MSU,  CCNY,  Ohio State,   Penn State,**
**            ****Purdue,  Rice,  Texas A&M,  UT Austin, **
**            ****Washington,  Wayne State,  Yale**

**U.S. Labs:****   ****	**
**            ****Argonne,   Berkeley,  and Brookhaven**
**            ****National Labs **

- 42

- ~400

## TPC Cylinder

## Central Membrane

*Central Membrane*

## Membrane Installed

*Membrane Installed*

## Inside the TPC

## TPC Transport

## TPC Transport

## STAR Experiment Halls

*STAR Experiment Halls*

## Assembly 1

## Assembly 2

## Assembly 3

## Assembly 4

## Assembly 5

## Assembly 6

## Lots of skilled labor!

## What is STAR?

## What is STAR?

## TPC Operation Simulation

## PHENIX Simulation

## Au on Au Event at CM Energy   130 GeV*A

*Au on Au Event at CM Energy   130 GeV*A*

- Data Taken June 25, 2000

## Au on Au Event at CM Energy   130 GeV*A

*Au on Au Event at CM Energy   130 GeV*A*

- Pictures from Level 3 online display.   Data Taken June 25, 2000

## Centrality Selection at RHIC

## <Nch> = 4200  470

- Central Rapidity Region:
- Charged Multiplicity in Au+Au at sNN = 130 GeV

- Corrected for decay feeddown: HIJING1.35
- Multiplicity Sys Error:  6%
- 5% most central via ZDC cut
- Shape dominated by nuclear geometry

- dNh-/d|=0   = 280120
- dNch/d|=0   = 567 138
- Relative flat in 
- 38% up compared to pp
- 52% up compared to SPS

*nucl-ex/0106004*

- 5% most central

_**PHOBOS: 3% most central collisions**_
**<N****ch****> = 4200 ******** 470**

## PHENIX Measurement of the Energy Density 

*PHENIX **Measurement of the Energy Density** *

-      ~30 times normal nuclear density     ~_1.5 to 2 times higher_ than         any previous experiments

**Notes:**
Na49 enhanced their value of energy density by 1.1 for “head on collisions”. Phenix removed that in making the comparison.  NA49 got 3.2 GeV/fm**3

## ...and that’s just the beginning...

- RHIC works!
- All four experiments have successfully gathered and begun to analyze data.
- The physics interpretations of these data are often difficult and may take a while.
- Plenty of exciting physics to come, and plenty of work ahead!