Alan G. Gara

A 0.5 teraflops machine optimized for lattice QCD

Abstract We describe plans for a parallel computer composed of 16K nodes interconnected in a 16 3 × 4 mesh. Each node is made up of a Texas Instruments TMS320C31 digital signal processor, 0.5M words of error-corrected memory and a gate array providing memory management and inter-node communication. The machine will have a peak speed of 0.8Tflops and is estimated to sustain ≈ 0.5Tflops for lattices as small as 32 3 × 8. We plan to complete the machine within two years for a cost of

High rate drift chambers

3M.

Status of the 0.8 teraflops supercomputer at Columbia

Fermilab experiment 690, a study of target dissociation reactions pp + pX using an 800 GeVlc proton beam and a liquid hydrogen target, collected data in late 1991. The incident beam and 600-800 GeV/c scattered protons were measured using a system of six 6” x 4” and two 15” x 8” pressurized drift chambers spaced over 260 meters. These chambers provided precise measurements at rates above 10 MHz (2 MHz per centimeter of sense wire). The measurement resolution of the smaller chambers was 90 urn, and the resolution of the larger chambers was 125 pm. Construction details and performance results, including radiation damage, are presented.

Status of the QCDSP project

The first stage in the construction of the 0.8 Teraflops Supercomputer at Columbia, a working, two node parallel computer, has been successfully completed. The next stage, a 512 node, 26 Gigaflops prototype, is in its final construction phase. A general description and current status of the hardware and software is presented.

QCDSP — A status report

Abstract We describe the completed 8,192-node, 0.4Tflops machine at Columbia as well as the 12,288-node, 0.6Tflops machine assembled at the RIKEN Brookhaven Research Center. Present performance as well as our experience in commissioning these large machines is presented. We outline our on-going physics program and explain how the configuration of the machine is varied to support a wide range of lattice QCD problems, requiring a variety of machine sizes. Finally a brief discussion is given of future prospects for large-scale lattice QCD machines.

The QCDSP project —a status report

Abstract The QCDSP machine at Columbia University has grown to 2,048 nodes achieving a peak speed of 100 Gigaflops. Software for quenched and Hybrid Monte Carlo (HMC) evolution scheme has been developed for staggered fermions, with support for Wilson and clover fermions under development. We provide an overview of the runtime environment, the current status of the QCDSP construction program and preliminary results not presented elsewhere in these proceedings.

QCD on the BlueGene/L Supercomputer

We give a brief overview of the massively parallel computer project underway for nearly the past four years, centered at Columbia University. A 6 Gflops and a 50 Gflops machine are presently being debugged for installation at OSU and SCRI respectively, while a 0.4 Tflops machine is under construction for Columbia and a 0.6 Tflops machine is planned for the new RIKEN Brookhaven Research Center.

Preliminary results of the analysis of the centrally produced φφ system

In June 2004 QCD was simulated for the first time at sustained speed exceeding 1 TeraFlops in the BlueGene/L supercomputer at the IBM T.J. Watson Research Lab. The implementation and performance of QCD in the BlueGene/L is presented.

Λ0 Polarization in Exclusive pp Reactions From the FNAL e690 Experiment

We present preliminary results of the analysis of the centrally produced φφ system at 800 GeV/c in the reaction pp → pslow(φφ)pfast. A partial wave analysis of the data up to 2.6 GeV/c2 shows that three waves with JPCLS = 2++02 and with different Jz and reflectivity are needed to describe the data. A fit to the wave amplitudes using Jost functions gives two resonances, one above and one below the φφ threshold. The resonance above threshold has a Breit‐Wigner structure with MR = 2.243 ± 0.015(stat) ± 0.010(syst) GeV and ΓR = 0.368 ± 0.033(stat) ± 0.030(syst) GeV.

FNAL‐E690: Charm, Light Meson, and Baryon Polarization Studies

It is an experimental evidence that all baryons are created polarized from unpolarized p—nucleus collisions. So far, the origin of this polarization remains unexplained in spite of the experimental evidences accumulated in the past thirty years. Up to these days, Λ0 is the most studied baryon for polarization, for it is copiously produced in p—nucleus collisions at the energies of the principal high energy physics accelerators of the world. This paper is an overview of the experimental evidences accumulated on the polarization of Λ0 from unpolarized exclusive pp collisions as function of xF, PT, and M(Λ0K+) in the past fifteen years inside Fermilab e690 experiment, in the particular reactions pp→pΛ0K0π+, pp→ppΛ0Λ−0, pp→pΛ0K+, produced at 800 GeV.