# Presentation: 922166

## Day-One Physics: PHOBOS Mark BakerGeorge Stephans 

- Ready for full physics program on Day 1.
- Expect many physics results in Year 1.
- Very simple run plan in Year 1.
- Minimal impact on RHIC scheduling.

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997

## PHOBOS  Full Day 1 Configuration

- Full PHOBOS detector
- 2 spectrometer arms
- multiplicity/vertex detector
- 2 TOF-wall segments
- NO planned Additional Equipment
- READY for full physics program

- Day 1 = 01-OCT-1999

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997

## Minimum-bias AuAu @ full energy
Goal: Collect the maximum # of events with as little trigger bias as possible.
70% centrality cut & -20 cm<ZVTX<15 cm
sample very loose interaction triggers
sample beam crossing events

- Goal: Collect the maximum # of events with as little trigger bias as possible.
- 70% centrality cut & -20 cm<ZVTX<15 cm
- sample very loose interaction triggers
- sample beam crossing events

*PHOBOS*  Year 1 *AuAu* Physics Program

- Year 1 = FY2000 (until summer shutdown)

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997

##  PHOBOS  Physics Goals

- Typical physics topics:
- Look for Excess Entropy
- Multiplicity distributions and fluctuations
- Source Size & Lifetime (HBT)
- Look for collective phenomena (over large V)
- Identified spectra at low pT
- Look for unusual medium effects
- Phi mass and width

- Study QCD confinement and vacuum

- Yes

- Yes

- Yes

- 1st  look

_**Year 1**_

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997

## Measurement & centrality dependence of:
Event-by-event charged multiplicity
N, dN/d, d2N/dddistributions
dN/d, d2N/ddcorrelations & fluctuations
Identified particle correlations  
e.g. Bose-Einstein (HBT)
Inclusive identified spectra, stressing low pT
d2N/dy dmT distributions

- Event-by-event charged multiplicity
- N, dN/d, d2N/dddistributions
- dN/d, d2N/ddcorrelations & fluctuations
- Identified particle correlations
- e.g. Bose-Einstein (HBT)
- Inclusive identified spectra, stressing low pT
- d2N/dy dmT distributions

*PHOBOS*  Year 1 *AuAu* Physics Program

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997

## First look at:
Analysis of  mass and width
emphasis on low pT
Decaying particle spectra, such as s
emphasis on low pT

- Analysis of  mass and width
- emphasis on low pT
- Decaying particle spectra, such as s
- emphasis on low pT

*PHOBOS*  Year 1 *AuAu* Physics Program

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997

## Majority of running with full energy Au-Au
As much variety as early as possible:
A-A (lighter species)
p-p at same E/A as the Au beam
p-Au (Au moving clockwise from above)
Au-p (Au moving counter-clockwise)
Au-Au at lower energy

- As much variety as early as possible:
***A-A ***(lighter species)
***p-p*** at same E/A as the ***Au*** beam
***p-Au*** (***Au*** moving clockwise from above)
***Au-p*** (***Au*** moving counter-clockwise)
***Au-Au*** at lower energy

*PHOBOS*  Year 1 Beam Request

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997

## Accesses are quick and easy
No (or minimal) shielding work needed.
No PHOBOS-specific planned access needed 
Almost all accesses should coincide with planned down time for RHIC or other detector.
Request: When possible, long beam-down times should be scheduled well in advance.

- No (or minimal) shielding work needed.
- No PHOBOS-specific planned access needed
- Almost all accesses should coincide with planned down time for RHIC or other detector.
_**Request:**_ When possible, long beam-down times should be scheduled well in advance.

*PHOBOS*  Year 1 Access Request

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997

## Conclusions

- PHOBOS plans to be ready on Day 1.
- PHOBOS expects lots of physics in year 1.
- Simple run plan for year 1:
- Run RHIC and PHOBOS as much as possible
- Take as many events as possible
- Request beam variety during first two years.

- RHIC Endgame                                           Baker/Stephans

- SEPT. 1997