A double-hyperfragment event has been found in a hybrid-emulsion experiment. It is identified uniquely as the sequential decay of ( 6)(LambdaLambda)He emitted from a Xi(-) hyperon nuclear capture at rest. The mass of ( 6)(LambdaLambda)He and the Lambda-Lambda interaction energy DeltaB(LambdaLambda) have been measured for the first time devoid of the ambiguities due to the possibilities of excited states. The value of DeltaB(LambdaLambda) is 1.01+/-0.20(+0.18)(-0.11) MeV. This demonstrates that the Lambda-Lambda interaction is weakly attractive.

The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. Disciplines Engineering Physics | Physics Comments This is a manuscript of an article from Nuclear Instruments and Methods in Physics Research

In Fig. 3 and its inset the vertical scales should be reduced by a factor of 4. This plotting error affects only the figure. All relevant quantities in the text and in the table are correct as published. We regret the oversight.The corrected version of Fig. 3 is reproduced here. This correction does not affect any results or conclusions of the published paper.FIG. 3. Inclusive ÿ ; K spectrum on Si at K 6 2 . The curves are the calculated spectra for the repulsive (solid) and shallow (dashed) -nucleus potentials, fitted to the measured spectrum. A value of the scaling factor and 2 per degree of freedom are shown for each fitting.

We have measured invariant mass spectra of electron-positron pairs in the target rapidity region of 12GeV p+A reactions. We have observed a significant difference in the mass spectra below the ω meson between p+C and p+Cu interactions. The difference is interpreted as a signature of the ρ/ω * Present Address: Center for Nuclear Study, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan, email: ozawa@cns.s.u-tokyo.ac.jp † Present Address: ICEPP, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan ‡ Present Address: Physics Department, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan § Present Address: Fujitsu Corporation, 4-1-1, Kamikodanaka, Nakahara, Kawasaki, Kanagawa 211-8588, Japan * * Present Address: RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan † † Present Address: Xaxon Corporation,1-3-19, Tanimachi, Chu-ou, Osaka, Japan ‡ ‡ Present Address: Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 , Japan 1 modification at normal nuclear-matter density. 24.85.+p,25.30.-c Typeset using REVT E X 2 Recently, chiral property of QCD in hot(T = 0) or dense(ρ = 0) matter attracts wide interests in the field of hadron physics. The dynamical breaking of chiral symmetry in the QCD vacuum induces an effective mass of quarks, known as constituent quark mass. In hot and/or dense matter this broken symmetry is subject to restore partially or completely, and hence the properties of hadrons can be modified. To observe such an effect, measurements of in-medium decay of vector mesons, especially in the lepton-pair channel, are highly desirable to obtain directly the meson properties in matter [1].Although many heavy-ion experiments were carried out in CERN-SPS and BNL-AGS to study hot and dense matter, there was only an experiment which could address the mass modification of vector mesons. The CERES/NA45 collaboration measured low-mass electron pair productions in Pb-Au collisions at 158 A GeV [2], and observed an enhancement of e + e − pair yield in the mass range 0.3 < m ee < 0.7 GeV/c 2 over the expected yield from the known hadronic sources in pp collisions. This striking effect could be understood as a consequence of the mass modification of the ρ and ω meson in hot matter.In QCD the mass of vector mesons, mainly determined by the effective mass of quarks, is closely related toqq condensates ( qq ) which is an order parameter of the chiral symmetry of the QCD vacuum. In this framework a significant decrease of qq is expected not only at high temperature but also at normal nuclear density [3]. Using the QCD sum rule, Hatsuda and Lee theoretically predicted in-medium modification of the vector mesons [4]. According to this model, mass decrease at normal nuclear density is 120 ∼ 180 MeV/c 2 for the ω and ρ mesons and 20 ∼ 40 MeV/c 2 for the φ meson. Thus the measurements of such mesons, which are produced and decayed in a nucleus, are of great interest. The present experiment is one of the several experimental efforts [1...

Cascade hypernuclei have been studied in the (K Ϫ ,K ϩ) reaction on a scintillating fiber target. The experimental result is compared with a theoretical calculation in order to extract information concerning the ⌶ Ϫ nucleus potential. ͓S0556-2813͑98͒01108-X͔