1. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 1 BRAHMS@RHIC Nuclear Modification factors in Cu-Cu and Au-Au collisions Truls Martin Larsen Niels Bohr Institute for the BRAHMS Collaboration

2. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 2 What is the system size and energy dependence of high p T suppression? The BRAHMS experiment What we measure: R cp and R AA Experimental results: Au-Au collisions at Cu-Cu collisions at Comparing Au and Cu Summary

3. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 3 BRAHMS detector

4. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 4 BRAHMS p T and  coverage [MRS: Mid Rapidity Spectrometer] [FS: Forward Spectrometer] Pseudo rapidity coverage: MRS: -0.1 <  < 1.2 FFS: 2.0 <  < 3.7

5. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 5 Central to peripheral ratio and the nuclear modification factor Central to peripheral ratio: Nuclear Modification factor: [H. Weber, UrQMD]

6. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 6 R AA in AuAu at Unidentified hadrons (published): Strong suppression at mid- and forward rapidity in central collisions. (Systematic error shown as blue squares) [Phys. Rev. Lett. 91, 072305 (2003)]

7. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 7 R AA in AuAu at Suppression at all  ! R AA at  = 3.2 is only negative hadrons Only statistical errors shown Preliminary [Poster (4) by Catalin Ristea (session 1)] R AA

8. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 8 R AA in AuAu at Unidentified hadrons: R AA shows no suppression at midrapidity in central collisions Cronin enhancement in peripheral Only statistical errors shown pp reference is based on ISR data Preliminary

9. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 9 R cp in CuCu at Unidentified hadrons at  = 0  = 0.9  = 2.5  = 3.0 Only statistical errors shown Preliminary

10. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 10 R cp in CuCu at Negative and positive hadrons Only statistical errors shown Preliminary

11. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 11 R AA in CuCu at Unidentified hadrons at  = 0 and 1 Cronin enhancement at all centralities Only statistical errors shown Preliminary

12. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 12 AuAu and CuCu at Preliminary

13. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 13 System comparison R AuCu AuAu collisions shows suppression relative to CuCu collisions Only statistical error shown Preliminary

14. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 14 Summary Central collisions: AuAu @ 200 GeV: Suppression No rapidity dependence AuAu @ 62.4 GeV: No suppression   = 0 ~ 1 CuCu @ 62.4 GeV: Cronin Enhancement Semi peripheral collisions: AuAu @ 200 GeV: No suppression No rapidity dependence AuAu @ 62.4 GeV: Cronin Enhancement CuCu @ 62.4 GeV: Cronin enhancement R AuAu similar to R CuCu with the same

15. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 15 BRAHMS Collaboration I.Arsene 12, I.G. Bearden 7, D. Beavis 1, S.Bekele 11, C. Besliu 10, B. Budick 6, H. Bøggild 7, C. Chasman 1, C. H. Christensen 7, P. Christiansen 7, R.Clarke 10, R.Debbe 1, J. J. Gaardhøje 7, K. Hagel 8, H. Ito 1, A. Jipa 10, J. I. Jordre 10, F. Jundt 2, E.B.Johnson 11, J.I.Jordre 9, C.Jørgensen 7, R. Karabowicz 3, E. J. Kim 11, T.M.Larsen 7, J. H. Lee 1, Y. K.Lee 5, S.Lindal 12, G. Løvhøjden 2, Z. Majka 3, M. Murray 11, J. Natowitz 8, B.S.Nielsen 7, D.Ouerdane 7, R.Planeta 3, F. Rami 2, C.Ristea 7, O.Ristea 10, D. Röhrich 9, B. H. Samset 12, S. J. Sanders 11, R.A.Sheetz 1, P. Staszel 3, T.S. Tveter 12, F.Videbæk 1, R. Wada 8, H.Yang 9, Z. Yin 9, and I. S. Zgura 10 1 Brookhaven National Laboratory, USA, 2 IReS and Université Louis Pasteur, Strasbourg, France 3 Jagiellonian University, Kracow, Poland 5 Johns Hopkins University, Baltimore, USA, 6 New York University, USA 7 Niels Bohr Institute, University of Copenhagen, Denmark 8 Texas A&M University, College Station. USA, 9 University of Bergen, Norway 10 University of Bucharest, Romania, 11 University of Kansas, Lawrence,USA 12 University of Oslo Norway 48 physicists from 12 institutions

16. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 16 N bin collisions AuAu at 200GeV: (0-10%) = 887± 39 (10-20%) = 534± 46 (20-40%) = 244± 23 (40-60%) = 71.2± 7.3 AuAu at 62.4 GeV: (0-10%) = 754± 40 (10-20%) = 459± 55 (20-40%) = 217± 26 (40-60%) = 70.0± 8.9 CuCu at 62.4 GeV: (0-10%) = 142 ± 5.1 (10-20%) = 98.5± 9.5 (20-40%) = 51.6± 4.7 (40-60%) = 18.6± 1.9

17. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 17 Cu Cu positive hadrons

18. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 18 Cu Cu negative hadrons

19. Truls Martin Larsen, BRAHMS Collaboration, QM05 3.-9. Aug 19 pp reference yields p-p yields only available at midrapidity: eta=0 and eta=1 Fit to ISR data