RIKEN Nishina Center for Accelerator-Based Science Experimental Group

Group Leader: Robert Tribble (Ph.D.)

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Research Summary

We study the strong interaction (QCD) using the heavy-ion collider RHIC. In the polarized p+p experiment at RHIC, we have shown for the first time that the spin of the gluon in the proton is polarized in the same direction as the proton spin. The spin polarization of the anti-quark in the proton was also measured.
In the heavy-ion experiment at RHIC, we found that the ultrahigh-temperature matterl QGP was formed there. From measurements of thermal photons emitted from the hot QGP, we showed that the initial temperature of the QGP at RHIC is about 4 trillion degrees.
Recently, we built a silicon tracking detector INTT for the new sPHENIX experiment. sPHENIX has started experiments in 2024.

Main Research Fields

Mathematical & Physical Sciences

Keywords

Quark
High temperature and high density matter
Nucleon structure
Spin

Selected Publications

1. PHENIX Collaboration (U. Acharya et al.):
"Measurement of Direct-Photon Cross section and Double-Helicity Asymmetry at √(S)=510 GeV in p+p collisions"
Phys. Rev. Lett. 130, 251901 (2023)
2. PHENIX Collaboration (C. Aidala et al.):
"Creation of quark-gluon plasma droplets with three distinct geometries"
Nature Physics 15, 214 (2019)
3. PHENIX Collaboration (A. Adare et al.):
"Cross Section and Parity-Violating Spin Asymmetries of W Boson Production in polarized p+p Collisions at √(S)=500 GeV"
Phys. Rev. Lett. 106, 062001 (2011)
4. PHENIX Collaboration (A. Adare et al.):
"Enhanced Production of Direct Photons in Au+Au Collisions at √(S_NN) =200 GeV and Implications for the Initial Temperature"
Phys. Rev. Lett. 104, 132301 (2010)
5. PHENIX Collaboration (Stephen Scott Adler et al.):
"Measurement of direct photon production in p + p collisions at √(S)= 200-GeV."
Phys.Rev.Lett.98:012002 (2007)
6. PHENIX Collaboration (A. Adare et al.):
"J/psi Production vs Centrality, Transverse Momentum, and Rapidity in Au+Au Collisions at √(S_NN) = 200-GeV."
Phys.Rev.Lett.98:232301 (2007)
7. PHENIX Collaboration (A. Adare et al.):
"Energy Loss and Flow of Heavy Quarks in Au+Au Collisions at √(S_NN) = 200-GeV"
Phys.Rev.Lett.98:172301 (2007)
8. PHENIX Collaboration (Adcox, K. et al.):
"Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration"
Nucl.Phys., A757, 184-283 (2005).
9. PHENIX Collaboration (Adler, S.S.et al.):
"Midrapidity Neutral Pion Production in Proton-Proton Collisions at √(S)=200 GeV"
Phys.Rev.Lett., 91, 241803 (2003)
10. PHENIX Collaboration (Adcox, K. et al.):
"Suppression of hadrons with large transverse momentum in central Au+Au collisions at √(S_NN) = 130-GeV"
Phys.Rev.Lett., 88, 022301 (2002).

Recent Research Results

Oct. 30, 2023
Investigating how gluons help protons get their spin

Lab Members

Principal investigator

Robert Tribble: Group Leader

Core members

Rachid Nouicer: Senior Visiting Scientist
Takao Sakaguchi: Visiting Scientist

Contact Information

2-1 Hirosawa,
Wako, Saitama
351-0198, Japan
Email: robert.tribble@riken.jp