# Presentation: 396662

## Hadron Spectra from

**Hadron Spectra ****from**

**Gábor I. Veres / MIT**

**for the**

**PHOBOS Collaboration**

##                 Collaboration

- Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Russell Betts, Abigail Bickley,
- Richard Bindel, Wit Busza (Spokesperson), Alan Carroll, Zhengwei Chai, Patrick Decowski,
- Edmundo García, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Stephen Gushue,
- Clive Halliwell, Joshua Hamblen, Adam Harrington, Conor Henderson, David Hofman, Richard Hollis,
- Roman Hołyński, Burt Holzman, Aneta Iordanova, Erik Johnson, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Michael Ricci,
- Christof Roland, Gunther Roland, Joe Sagerer, Iouri Sedykh, Wojtek Skulski, Chadd Smith,
- Peter Steinberg, George Stephans, Andrei Sukhanov, Marguerite Belt Tonjes, Adam Trzupek,
- Carla Vale, Siarhei Vaurynovich, Robin Verdier, Gábor Veres, Edward Wenger, Frank Wolfs,
- Barbara Wosiek, Krzysztof Woźniak, Alan Wuosmaa, Bolek Wysłouch, Jinlong Zhang
- 	ARGONNE NATIONAL LABORATORY	BROOKHAVEN NATIONAL LABORATORY
- 	INSTITUTE OF NUCLEAR PHYSICS, KRAKOW	MASSACHUSETTS INSTITUTE OF TECHNOLOGY
- 	NATIONAL CENTRAL UNIVERSITY, TAIWAN	UNIVERSITY OF ILLINOIS AT CHICAGO
- 	UNIVERSITY OF MARYLAND	UNIVERSITY OF ROCHESTER

## PHOBOS Detector System

** ****New trigger system**
**for d+Au PID spectra**

**TOF**

**TOF**

**SpecTrig**

**See poster by C. Henderson and G.V.**

## PHOBOS PID Capabilities

**p****T ****(GeV/c)**

**0.05**

**0.5**

**5.0**

**Stopping**
**particles**

**dE/dx**

**TOF**

**E****loss**** ****(MeV)**

**dE/dx**

**  ****Subm. to PRL**
**nucl-ex/0401006**

**1/v (ps/cm)**

## Acceptance for PID Analyses

**dE/dx**

**TOF**

- 

**K**

**p**

**p****T**** (GeV/c)**

**p****T**** (GeV/c)**

**p****T**** (GeV/c)**

## Particle Ratios Using dE/dx PID

**PHOBOS 200 GeV**

## ...p/p Compared to Models

**200 GeV**

**PHOBOS Preliminary**

## Particle Ratios Using dE/dx PID

**PHOBOS 200 GeV**

## Particle/Antiparticle Ratios using the TOF

**d+Au**

**T**

## Identified pT -spectra in d+Au

- Identified pT -spectra in d+Au

- Not feed-down corrected

- Scale uncertainty: 15%

## Particle Composition in d+Au

- Not feed-down corrected

## Identified mT-spectra in d+Au

- Identified mT-spectra in d+Au

- Scale uncertainty: 15%

- Not feed-down corrected

## Identified mT-spectra at 200 GeV

- Identified mT-spectra at 200 GeV

**Subm. to PRL**
**nucl-ex/0401006**

**d+Au**

- Scale uncertainty: 15%

- Not feed-down corrected

**Au+Au**

**  ****Spectra **
**normalized**
** ****at 2 GeV/c**

**200 GeV**

- 

## Comparison: Low Energy d+Au

**Cronin, PRD 11, 3105, 1975**

**y**

**0.2<   <1.2**

**   ********lab****=3.26**

- Not feed-down corrected

##    d+Au

-  **  ****d+Au**
**200 GeV**

## Centrality dependence

**Centrality dependence**

**peripheral 40-70%**

**central 0-20%**

-  **  ****d+Au**
**200 GeV**

**medium 20-40%**

## Cronin Effect in d+Au vs. Centrality

**  ****6% most**
**central Au+Au**

**PRL 91, 072302 (2003)**

**peripheral**

**central**

## PRL 91, 072302 (2003)

**PRL 91, 072302 (2003)**

## Cronin Effect as a Function of (d+Au)

## Cronin Effect as a Function of (d+Au)

- Cronin Effect as a Function of (d+Au)

##  Evolution of RdAu with   

-  Evolution of RdAu with 

**See poster by J.L. Kane**

## Summary

**More coming soon...**

**Phobos has PID coverage from 0.05 to 3.5 GeV/c in p****T**
- 				First PID ratios and spectra from PHOBOS TOF
- 				Surprisingly small centrality dependence of p/p ratios
- 				Approximate mT scaling in d+Au as opposed to Au+Au
- 				Particle composition in d+Au: similar pT-dependence to
-  				lower energy data (but different overall proton fraction)
**Study of**** ********-dependence**
- 				Exciting new -dependent RdAu values measured
- 				RdAu continuously decreases with 