• Ph.D., MIT, 1990.

Research Interest:

Our research objectives are to search for strangelets (E864 at AGS-BNL) and H-dibaryons (E896 at AGS-BNL) at the Alternating Gradient Synchrotron (AGS-BNL), and to search for Quark-Gluon Plasma (QGP) at the Relativistic Heavy Ion Collider (RHIC). AGS-BNL is an accelerator complex at the Brookhaven National Laboratory capable of accelerating Gold ions up to 11.7 GeV per nucleon. Nucleus-nucleus collisions at the AGS-BNL are characterized by the formation of high baryon densities and the high yield of strange quarks. A strangelet is a drop of quark matter with a large strange quark content. E864 is a spectrometer experiment with a sensitivity of the order of 10^-11 per collision for long lived strangelets. The H-dibaryon is a quark bag of uuddss quarks which could be formed through the coalescence of Lambda hyperons. E896 is a spectrometer experiment capable of measuring particles with the life time of weak decay.

The RHIC is currently under construction at the Brookhaven National Laboratory. Two colliding Gold ions of 100 GeV per nucleon at the RHIC will produce extremely high energy densities in the collision where Quark-Gluon Plasma (QGP) may be formed. The production of the QGP and the study of the phase transition from normal nuclear matter to QGP will have an important impact on the understanding of the early universe. The STAR (Solenoid Tracker At RHIC) system includes a solenoid magnet, a cylindrical Time-Projection Chamber (TPC), a Silicon Vertex detector (SVT), electromagnetic calorimeters (EMC), a time-of-flight counter and an external TPC. The physics emphasis of the STAR will be on global event-by-event analysis, strangeness and hyperons production, high Pt hadrons, jets and photons, and HBT correlation. The RHIC SPIN physics for spin structure function of the nucleons is also an important part of the STAR program. The UCLA group has been active in the TPC and the EMC projects. The STAR experiment is scheduled to run in the spring of 1999.

Selected Recent Publications:

1. E864 Collaboration, T.A. Armstrong et al., "Search for Neutral Strange Quark Matter in High Energy Heavy Ion Collisions" Phys. Rev. C59, 1829 (1999).
2. E864 Collaboration, T.A. Armstrong et al., "Anti-proton Production in 11.5GeV/c Au+Pb Nucleus-Nucleus Collisions" Phys. Rev. Lett.79, 3351 (1997).
3. E864 Collaboration, T.A. Armstrong et al., "Search for Charged Strange Quark Matter Produced in 11.5 GeV/c Au+Pb Collisions" Phys. Rev. Lett.79, 3612 (1997).
4. DLS Collaboration, H.Z. Huang et al., "Mass and Transverse Momentum Dependence of Dielectron Production in p+d and p+p Collisions at 4.9 GeV" Phys. Rev. C49, 314 (1994).
5. E802 Collaboration, T. Abbott et al., "Kaon and Pion Production in Central Si+Au Collisions at 14.6 AGeV/c" Phys. Rev. Lett.64 847 (1990).