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Goto, Yuji

Publications and source records attributed to Goto, Yuji.

Inclusive cross section and single transverse-spin asymmetry of very forward neutron production at PHENIX

The cross section and x{sub F} dependence of A{sub N} of very forward neutron production in polarized p + p collisions at √s = 200 GeV were measured in the PHENIX experiment at RHIC. The measured cross sections were consistent with the x{sub F} scaling claimed by the ISR experiment. Significant negative A{sub N} was observed in the forward region, and no significant backward A{sub N} was observed. We also measured √s and p{sub T} dependence of A{sub N} of very forward neutron production at √s from 62.4 to 500 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Proceedings of RIKEN BNL Research Center Workshop: The Physics of p ↑ +A Collisions at RHIC

The RIKEN BNL Research Center (RBRC) was established in April 1997 at Brookhaven National Laboratory. It is funded by the "Rikagaku Kenkyusho" (RIKEN, The Institute of Physical and Chemical Research) of Japan. The Memorandum of Understanding between RIKEN and BNL, initiated in 1997, has been renewed in 2002, 2007 and again in 2012. The Center is dedicated to the study of strong interactions, including spin physics, lattice QCD, and RHIC physics through the nurturing of a new generation of young physicists. The RBRC has both a theory and experimental component. The RBRC Theory Group and the RBRC Experimental Group consists of a total of 25-30 researchers. Positions include the following: full time RBRC Fellow, half-time RHIC Physics Fellow, and full-time postdoctoral Research Associate. The RHIC Physics Fellows hold joint appointments with RBRC and other institutions and have tenure track positions at their respective universities or BNL. To date, RBRC has over 95 graduates (Fellows and Post- docs) of which approximately 40 theorists and 20 experimenters have already attained tenure positions at major institutions worldwide. Beginning in 2001 a new RIKEN Spin Program (RSP) category was implemented at RBRC. These appointments are joint positions of RBRC and RIKEN and include the following positions in theory and experiment: RSP Researchers, RSP Research Associates, and Young Researchers, who are mentored by senior RBRC Scientists. A number of RIKEN Jr. Research Associates and Visiting Scientists also contribute to the physics program at the Center. RBRC has an active workshop program on strong interaction physics with each workshop focused on a specific physics problem. In most cases all the talks are made available on the RBRC website. In addition, highlights to each speaker’s presentation are collected to form proceedings which can therefore be made available within a short time after the workshop. To date there are over one hundred proceeding volumes available. A 10 teraflops RBRC QCDOC computer funded by RIKEN, Japan, was unveiled at a dedication ceremony at BNL on May 26, 2005. This supercomputer was designed and built by individuals from Columbia University, IBM, BNL, RBRC, and the University of Edinburgh, with the U.S. D.O.E. Office of Science providing infrastructure support at BNL. Physics results were reported at the RBRC QCDOC Symposium following the dedication. QCDSP, a 0.6 teraflops parallel processor, dedicated to lattice QCD, was begun at the Center on February 19, 1998, was completed on August 28, 1998, and was decommissioned in 2006. It was awarded the Gordon Bell Prize for price performance in 1998. QCDOC was decommissioned in May 2012. The next generation computer in this sequence, QCDCQ (600 Teraflops), is currently operational and is expected to produce many more interesting discoveries in the future.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Spin physics at RHIC

Polarized-proton collisions at a collision energy 200 GeV started in 2001 at RHIC in BNL. We have investigated a polarized structure of the proton to understand the origin of the nucleon spin 1/2 with polarized-proton collisions. The first goal of spin physics at RHIC is determination of the gluon-spin contribution to the proton spin. The PHENIX and STAR experiments have investigated the gluon-spin contribution by measuring longitudinal-spin asymmetries of neutral pion and jet produced in longitudinally-polarized proton collisions. Experimental results have shown that these asymmetries are small and strong constraints have been given for the gluon-spin contribution. From 2009, polarized-proton collisions at a collision energy 500 GeV started and we have investigated flavor-sorted contribution of the quark spin to the proton spin with weak-boson production. The final remaining piece of information to understand the proton spin is orbital-angular momenta of quarks and gluons. Multi-dimensional structure of the nucleon which includes information of the orbital-angular motion inside the nucleon has been investigated with transverse-spin asymmetry measurements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗