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E864: Exotic Nuclei and Rare Probes

E864: Exotic Nuclei and Rare Probes. James Nagle Columbia University for the E864 Collaboration. E864 Collaboration. Graduate Students. University of Bari/INFN Brookhaven National Laboratory University of California, Los Angeles University of California, Riverside

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E864: Exotic Nuclei and Rare Probes

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  1. E864:Exotic Nuclei and Rare Probes James Nagle Columbia University for the E864 Collaboration

  2. E864 Collaboration Graduate Students University of Bari/INFN Brookhaven National Laboratory University of California, Los Angeles University of California, Riverside Columbia University Iowa State University Massachusetts Institute of Technology United States Military Academy Pennsylvania State University Purdue University Vanderbilt University Wayne State University Yale University Ken Barish Sotiria Batsouli Scott Coe Rob Davies Patricia Fachini Brett Fadem Evan Finch Nigel George Robert Hoversten Hazim Jaradat John Lajoie Tim Miller Marcello Munhoz James NagleAndrew Rose Gene Van Buren Zhangbu Xu

  3. Nucleosynthesis Shortly after the Big Bang, the universe cooled such that light nuclei such as deuterium, helium and lithium were formed. • Relativistic Heavy Ion Collisions - “Little Bang” Nucleosynthesis • Source dimension and flow information • Strange baryons available to form HyperNuclei • Antibaryons for AntiNuclei • Exotic Particle Formation (Strange Quark Matter)

  4. Experiment Experiment E864 at the BNL-AGS Au + Pt collisions at 11.6 GeV/nucleon High rate, magnetic spectrometer designed to measure massive states near midrapidity and low transverse momentum

  5. Transverse Expansion Slopes show strong mass dependence Heavier states are more sensitive to density profile and flow parameters Box profile Gaussian profile A. Polleri et al., nucl-th/9711011

  6. Source Dimensions Nuclei yields contain source information at thermal freeze-out, just like HBT. B3 = 3He/p3 NA44 results Pb+Pb S +Pb W.J.Llope, S.E.Pratt et al., Phys. Rev.C.

  7. “Heavy” Light Nuclei Penalty per nucleon: Small Deviations from scaling observed…..

  8. Binding Energy Correct for spin factor (2J+1) and isospin difference (n/p ~ 1.2). More tightly bound objects have higher yield…. Exp( BE / 5.8 MeV ) Not the freeze-out temperature. p n p n n deuteron alpha p p

  9. A = 5 Unstable States 5Li  4He + p (ct ~100 fm/c) Preliminary Close to scaling relation….

  10. AntiDeuterons Preliminary Coalescence rate lower for AntiNuclei than Nuclei? Predicted if surface emission of antibaryons due to annihilation…..

  11. Antideuteron formation p n Not possible p L p However… Strange AntiBaryons E864 measurement indicates Y / p = 3.5  1.2 Preliminary Once p corrected, the coalescence rates agree within errors.

  12. Strange Nucleosynthesis Calculations for hypernuclei and H-dibaryon assume same transition probability as for normal nuclei ! L n deuteron H-dibaryon L p Testing this assumption to understanding E896, E910, E888, E864…..which assume H coalescence is critical A.J. Baltz, C. Dover et al., Phys. Lett. B325, 7 (1994). B.A. Cole, M. Moulson, W.A. Zajc, Phys. Lett. B350, 147 (1995).

  13. HyperNuclei Mass Distribution Sampled 9.5 billion central Au+Pt interactions Preliminary analysis of 2/3 of data sample shown here Branching Fraction 25% Signal observed at the 1.8 sigma level…. 3LH  3He + p - 3LH  3He + p - Invariant Mass (GeV)

  14. Lower Transition Rate ? Check transition rate by measuring ingredients and resulting states. Compare: In same region in phase space. Preliminary = 0.162  0.088 E864 E891

  15. Strange Quark Matter SQM = many quarks in a color-singlet configuration E886 E878 s d d u u u s s d u d d u s Null Result…. 10-8 to 10-9 For SQM t > 50 ns E864 (PRL) E864 Final T.A. Armstrong et al., Phys. Rev. Lett. 79, 3612 (1997). T.A. Armstrong et al., Nucl. Phys. A 625, 494 (1997). T.A. Armstrong et al., Phys. Rev. C, R1829 (1999).

  16. SQM Implications Plasma Distillation Many predictions ruled out, but calculations are not precise. Coalescence Predictions Strange Coalescence Sensitive to: A = 6-7 and |S| = 2-3 However, must consider hypernuclei measurement……. Plasma Predictions E864 Final Limits Z = +2

  17. Conclusions • Measurements over 10 orders of magnitude in yield • Light Nuclei Scaling and Deviations • Strange Antibaryon Enhancement and AntiNuclei Yields • Penalty for HyperNuclei • Strange Quark Matter< 10-9

  18. Binding Energy in Thermal Model Fit results to a thermal temperature on the order of 50 MeV which is quite low; however flow has not been accounted for at this point and measurements are at low pt.

  19. Strange AntiBaryons Target Incoming Au beam L p p

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