Research Frontiers in Nuclear Physics

1. Research Frontiers in Nuclear Physics Central truths of nuclear physics driving research for more than one century • We are nothing (c. 1900) • We are dust (c. 1950) • We don’t matter (c. 2000)

2. Atom Nucleus (“ion” when alone) Proton Neutron Quarks Held together by gluons (not shown) We are nothing ! Most of “us” is (nearly) empty space • 99.9% of the mass of atoms is contained in the nucleus • The nucleus is about 10-12 of the size of the atom • Nuclear density 1014 times larger than density of water birth of nuclear physics Axel Drees

3. protons p n 100 82 50 126 50 20 82 50 8 20 2 neutrons 50 100 8 2 Nuclear Zoology and the Nuclear Chart • Categorize properties of nuclei and present in nuclear chart Fermi gas model Coulomb repulsion of protons valley of stability near Z = N No stable nuclei beyond 208 Pb limited range of nuclear force Magic Z and N numbers with many stable nuclei Indication of shell structure Axel Drees

4. 114 184 Going to the Extremes of Nuclear Structure • The many body problem • Nucleus is complex system of many strongly interacting particles • Needs to be treated microscopically • Remains one of the major theoretical challenges • Search for super heavy nuclei • Island of stability near next shell closer • The ultimate test of shell models • Element 112 discovered at GSI “Ununbiium” • Nuclei with extreme angular momentum • Sensitive test of shell models • Actively pursued by Prof. Fossan and Starosta at Stony Brook NSL and other facilities Axel Drees

5. ~ 100 s after Big Bang Nucleon Synthesis strong force binds protons and neutrons bind into light nuclei He to Li We are dust ! Most elements create in stellar catastrophes long after big bang Elements up to Fe fussed in Stars Heavy elements created in super nova explosions We are mostly stardust ! Axel Drees

6. Nuclei far from Stability • Explore “Terra Incognita” to proton and neutron drip line • Important for creation of heavy elements in Supernovae • Proton rich created with stable beams • Neutron rich require radio active beams • Neutron rich nuclei only created with radioactive beams • Interesting Atomic physics • ongoing experiments in NSL (Prof. Sprouse & Orozco) • Rare Isotope Accelerator new $800M US project Axel Drees

7. We don’t matter ! • More accurately: We’re not matter • Nearly all the mass of each atom is concentrated in the nucleus: • Each nucleus consists of neutrons and protons • Each neutron and proton consists of 3 quarks • Each quark has the mass of 5-7 MeV/c2 ~ 1% of a proton or neutron(!) • The rest of the mass of protons and neutrons (and hence our mass) is “frozen energy” from the Big Bang Axel Drees

8. ~ 10 ms after Big Bang Hadron Synthesis strong force binds quarks and gluons in massive objects: protons, neutrons mass ~ 1 GeV/c2 ~ 100 s after Big Bang Nucleon Synthesis strong force binds protons and neutrons bind in nuclei The Big Freeze Axel Drees

9. Fundamental Puzzles of Hadrons nuclear matter p, n • Confinement • Quarks do not exist as free particles • Large hadron masses • Free quark mass ~ 5-7 MeV • Quarks become “fat” in hadrons constituent mass ~ 330 MeV • Complex structure of hadrons • Sea quarks and anti quarks • Gluons • “spin crisis” Spin of protons not carried by quarks! Go back in time to big bang Feasible in heavy ion collisions Measurement with polarized proton beams at high energy All addressed at RHIC Axel Drees

10. “Travel” Back in Time • QGP in Astrophysics • early universe after ~ 10 ms • possibly in neutron stars • Relativistic • Heavy • Ion • Collider at BNL • Quest of heavy ion collisions • create QGP as transient state in heavy ion collisions • verify existence of QGP • Study properties of QGP • study QCD confinement and how hadrons get their masses Axel Drees

11. vacuum QGP Detecting the QGP “matter box” • “ideal” experiment • Rutherford experiment a atom discovery of nucleus SLAC electron scattering e  proton discovery of quarks • Experiments with QGP not quite that simple • QGP created in nucleus-nucleus collisions can not be put in “box” • Thousands of particles produced during collision penetrating beam absorption or scattering pattern Axel Drees

12. Au-Au Event in STAR summer 2001 Axel Drees

13. A Silly Analogy • Suppose… • You lived in a frozen world where there’s only as ice • and the ice is quantized in ice cubes • Some weird physicists tell you there should be water • and suggest to heat the ice 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 about 10 trillion • You’re doing physics at RHIC! Axel Drees

14. BRAHMS PHOBOS STAR PHENIX Relativistic Heavy Ion Collider RHIC Axel Drees

15. 11 nations • 51 institutions Stony Book: Prof. Averbeck, Drees, Jacak, Hemmick Axel Drees

16. PHENIX at RHIC • 2 central spectrometers West • 2 forward spectrometers South East • 3 global detectors North Axel Drees

17. PHENIX Central East Carriage Ring Imaging Cerenkov Drift Chamber Central Magnet West Carriage Axel Drees

18. p L e p K p jet J/Y g Freeze-out Hadronization QGP Thermaliztion Hard Scattering Au Au Space-time Evolution of Collisions f time g e  Expansion  space Axel Drees

19. J/ Suppression in QGP • Hard scattering creates also heavy “charm” quark pairs cc • Small fraction of charm pairs bind to J/ • Traveling through QGP c and c are screened by “color” charges • J/ states destroyed • In experiment measure J/   • Suppression of J/ in Pb-Pb observed at CERN • First data from RHIC, results coming soon ? Axel Drees

20. schematic view of jet production jet production in quark matter jet production in quark matter hadrons hadrons hadrons leading particle leading particle leading particle q q q q q q hadrons hadrons leading particle leading particle Positron Emission Tomography of the Brain Jets: New Penetrating Probe at RHIC • jets contribute ~30% of particle production at RHIC energies • hard to observe directly in A-A collisions • indirect measurements through • high pT leading particles • azimuthal correlation • in colored “quark matter” partons expected to lose significant energy via gluon bremsstrahlung • suppression of high pT particles “jet quenching” • suppression of angular correlation • pT dependent modification of particle ratios jet tomography of quark matter Axel Drees

21. PHENIX RHIC result on the suppression of high transverse momentum particles in high-energy gold-gold collisions is featured on the cover of next week’sPhysical Review Letters (14 January 2002) and in the 12/21/01 Physics Focus article on the web: http://focus.aps.org/v8/st34.html Brookhaven Science AssociatesU.S. Department of Energy Axel Drees

22. q q Near angle leading particle Back angle New Au-Au data taken in 2001 • Compare the yield per trigger for f ~0 and f ~p • (Au+Au – flow) / p+p per trigger. • Near angle ~ 1, pT>4 GeV/c dominantly from jet. • Back angle decrease with centrality Disappearance of away side jet. Now (2003) taking data with d-Au and p-p to complete picture Axel Drees

23. Frontiers of Nuclear Physics • Extremes of Nuclear structure • Super heavy elements • High spin state nuclei • Radio active beams • Nuclei far from stability • Hadron structure • Spin structure of proton • Confinement • Hadron masses • Quark Gluon Plasma • Study phase diagram of QCD future RIA Nuclear Structure Lab ongoing RHIC Future upgrades e RHIC Axel Drees