First results from a second generation galactic axion experiment

We report first results from a large scale search for dark matter axions. The experiment probes axion masses of 1.3-13 micro-eV at a sensitivity which is about 50 times higher than previous pilot experiments. We have already scanned part of this mass range at a sensitivity better than required to see at least one generic axion model, the KSVZ axion. Data taking at full sensitivity commenced in February 1996 and scanning the proposed mass range will require three years

High precision branching ratio measurement for the superallowed β decay of [Formula Presented] A prerequisite for exacting tests of the standard model

Nonanalog Fermi and Gamow-Teller branches in the superallowed β decay of [Formula Presented] have been investigated using γ-ray and conversion-electron spectroscopy. Nine observed transitions, in conjunction with a recent shell model calculation, determine the branching ratio of the analog transition to be 99.5(1)%. The experimental upper limits for the Fermi decay to the [Formula Presented] and [Formula Presented] levels are in agreement with recent theoretical predictions. The [Formula Presented] value for the [Formula Presented] β decay is predicted to be 10405(9) keV. © 2003 The American Physical Society

Multiplicity distribution and spectra of negatively charged hadrons in Au+Au collisions at sqrt(s_nn) = 130 GeV

The minimum bias multiplicity distribution and the transverse momentum and pseudorapidity distributions for central collisions have been measured for negative hadrons (h-) in Au+Au interactions at sqrt(s_nn) = 130 GeV. The multiplicity density at midrapidity for the 5% most central interactions is dNh-/deta|_{eta = 0} = 280 +- 1(stat)+- 20(syst), an increase per participant of 38% relative to ppbar collisions at the same energy. The mean transverse momentum is 0.508 +- 0.012 GeV/c and is larger than in central Pb+Pb collisions at lower energies. The scaling of the h- yield per participant is a strong function of pt. The pseudorapidity distribution is almost constant within |eta|<1.Comment: 6 pages, 3 figure

Fine structure of the Gamow-Teller resonance revealed in the decay of Ho-150 2(-) isomer

The γ rays following the 72s 150Ho 2- Gamow-Teller β decay have been investigated with the CLUSTER CUBE setup, an array of six EUROBALL CLUSTER Ge detectors in close cubic geometry, providing a γ ray detection sensitivity of 2×10-5 per β-parent decay for γ-ray energies up to 5 MeV. The fine structure of the Gamow-Teller resonance at 4.4-MeV excitation in 150Dy has been studied. The resolved levels are compared with Shell Model predictions

Pion Interferometry of sNN=130\sqrt{s_{NN}} = 130 GeV Au+Au Collisions at RHIC

Two-pion correlation functions in Au+Au collisions at $\sqrt{s_{NN}} = 130$ GeV have been measured by the STAR (Solenoidal Tracker at RHIC) detector. The source size extracted by fitting the correlations grows with event multiplicity and decreases with transverse momentum. Anomalously large sizes or emission durations, which have been suggested as signals of quark-gluon plasma formation and rehadronization, are not observed. The HBT parameters display a weak energy dependence over a broad range in $\sqrt{s_{NN}}$.Comment: 6 pages, 3 figures; accepted to Phys Rev Lett; data tables available at STAR web site http://www.star.bnl.gov/ Click on "Publications" in menu ba

Antideuteron and antihelion production in root(s) = 130 GeV Au+Au collisions

The first measurements of light antinucleus production in Au+Au collisions at RHIC are reported. The observed production rates for antideuterons and antihelions are much larger than in lower energy nucleus-nucleus collisions. A coalescence model analysis of the yields indicates that there is little or no increase in the antinucleon freeze-out volume compared to collisions at SPS energy. These analyses also indicate that the antihelion freeze-out volume is smaller than the antideuteron freeze-out volume.Comment: Submitted to Phys. Rev. Let

Identified Particle Elliptic Flow in Au+Au Collisions at sNN=130\sqrt{s_{_{NN}}}=130 GeV}

We report first results on elliptic flow of identified particles at mid-rapidity in Au+Au collisions at $\sqrt{s_{_{NN}}}=130$ GeV using the STAR TPC at RHIC. The elliptic flow as a function of transverse momentum and centrality differs significantly for particles of different masses. This dependence can be accounted for in hydrodynamic models, indicating that the system created shows a behavior consistent with collective hydrodynamical flow. The fit to the data with a simple model gives information on the temperature and flow velocities at freeze-out.Comment: REVTeX style include