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News from PHOBOS

News from PHOBOS. a first look at d+Au p T spectra. Gunther Roland/MIT. 2003 Conference on Intersections of Particle and Nuclear Physics. Collaboration (May 2003). Birger Back, Mark Baker, Maarten Ballintijn, Donald Barton, Bruce Becker, Russell Betts,

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News from PHOBOS

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  1. News from PHOBOS a first look at d+Au pT spectra Gunther Roland/MIT 2003 Conference on Intersections of Particle and Nuclear Physics

  2. Collaboration (May 2003) Birger Back,Mark Baker, Maarten Ballintijn, Donald Barton, Bruce Becker, Russell Betts, Abigail Bickley, Richard Bindel, Andrzej Budzanowski, Wit Busza (Spokesperson), Alan Carroll, Patrick Decowski, Edmundo Garcia, Tomasz Gburek, Nigel George, Kristjan Gulbrandsen, Stephen Gushue, Clive Halliwell, Joshua Hamblen,Adam Harrington,Conor Henderson, David Hofman, Richard Hollis, Roman Holynski, Burt Holzman, Aneta Iordanova,Erik Johnson, Jay Kane, Nazim Khan, Piotr Kulinich, Chia Ming Kuo,Jang Woo Lee, Willis Lin, Steven Manly, Alice Mignerey, Gerrit van Nieuwenhuizen, Aaron Noell, Rachid Nouicer, Andrzej Olszewski, Robert Pak, Inkyu Park, Heinz Pernegger, Corey Reed, Louis Remsberg, Christof Roland, Gunther Roland, Joe Sagerer, Pradeep Sarin, Pawel Sawicki, Iouri Sedykh, Wojtek Skulski, Chadd Smith, Peter Steinberg, George Stephans, Andrei Sukhanov, Ray Teng, Marguerite Belt Tonjes, Adam Trzupek, Carla Vale, Robin Verdier, Gábor Veres, Bernard Wadsworth, Frank Wolfs, Barbara Wosiek, Krzysztof Wozniak, Alan Wuosmaa, Bolek Wyslouch, 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

  3. PHOBOS Detector in 2002 Spectrometer Ring Counters Octagon Triggering ZDC 1m ZDC

  4. pT Distribution of Charged Particles Phobos Preliminary Systematic Errors not shown

  5. pT Spectra for Au+Au @ 200 GeV Centrality Npart 45-50% 65 ± 4 35-45% 93 ± 5 25-35% 138 ± 6 15-25% 200 ± 8 6-15% 276 ± 9 0-6% 344 ± 12 Centrality range: <b> from 10 to 3 fm <> from 3 to 6 0.2<yp<1.4 nucl-ex/0302015 Submitted to Phys Lett B

  6. Ratio of Au+Au and pp spectra at 200 GeV • Strong modification of spectral shape relative to pp • already in mid-peripheral events • Strong violation of expected Ncoll scaling • Jet quenching? • Initial state Gluon Saturation? mid-peripheral Npart = 65 ± 4 central Npart = 344 ± 12

  7. ok, so let’s look at d+Au….

  8. This Year: PHOBOS Detector 2003 T0 T0 mini-pCal SPECTRIG  Moved TOF walls back ~ 5 m from interaction point  Installed new spectrometer trigger detector that selects on high pT tracks pCal  Installed new “time-zero” (T0) Cerenkov detectors to provide triggering and on-line vertexing as well as a start time for our TOF walls.  Proton calorimeter on Gold and Deuteron “going” sides for dA run

  9. Spectrometer Trigger accepted ToF walls (45o and 90o) rejected Scintillator hodoscopes (45o and 90o) • Select events with particle hitting ToF wall • Enhance high-pT (straight) tracks: “online” tracking • Decision made in 50 ns

  10. b b Peripheral Central Reminder: Centrality in Au+Au Data Paddle: Multiplicity in 3 < |h| < 4.5 • HIJING +GEANT • Glauber calculation • Model of paddle trigger Paddle signal Data+MC

  11. dN/dh/<Npart> (h~0) Pseudorapdity “Truth” <Npart> Centrality determination in d+Au HIJING d+Au MC Centrality in d+Au: Handle with care!

  12. Centrality cuts (4 bins) 0 – 20% 0.2<h<1.4 20 – 40% 40 – 70% 3.0<|h|<5.4 70 – 100% PHOBOS d+Aupreliminary Counts Centrality Npart 70-100% 3.3 ± 1 ADC Signal Sum (arb. units ) 40-70% 6.8 ± 2 20-40% 11 ± 1.5 0-20% 16 ± 2.5 Preliminary Results from d+Au

  13. PHOBOSpreliminary PHOBOS preliminary Yield/<Npart/2>/p+p fit Yield/<Npart/2>/p+p fit RdAu RdAu PHOBOS preliminary PHOBOS preliminary Preliminary Results from d+Au

  14. Reminder: Au+Au/pp at 200 GeV mid-peripheral Npart = 65 ± 4 central Npart = 344 ± 12

  15. PHOBOSpreliminary PHOBOS preliminary Yield/<Npart/2>/p+p fit Yield/<Npart/2>/p+p fit RdAu RdAu PHOBOS preliminary PHOBOS preliminary Preliminary Results from d+Au

  16. Summary • Successful run of upgraded Detector • Forward Proton calorimeter • Spectrometer Trigger • Online vertex Trigger. • First Look: Centrality dependence of d+Au pT spectra • Resemble p+A fixed target data • Very different from Au+Au • Much more to come • 4-p dN/dh • PID spectra, ratios • ?

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