We present Experiment 864's measurement of invariant antideuteron yields in 11.5A GeV/c Au+Pt collisions. The analysis includes 250x10(6) triggers representing 14x10(9) 10% central interactions ...sampled for events with high mass candidates. We find (1/2pip(t))d(2)N/dydp(t) = 3.5+/-1.5(stat)+0.9-0.5(syst)x10(-8) GeV-2 c(2) for 1.8<y<2.2, < p(t)> = 0.35 GeV/c ( y(c.m.) = 1.6) and 3.7+/-2.7(stat)+1.4-1.5(syst)x10(-8) GeV-2 c(2) for 1.4<y<1.8, < p(t)> = 0.26 GeV/c, and a coalescence parameter B2; of 4.1+/-2. 9(stat)+2.3-2.4(syst)x10(-3) GeV2 c(-3). Implications for coalescence and antimatter annihilation are discussed.
It is shown that the Fisher droplet model, percolation, and nuclear multifragmentation share the common features of reducibility (stochasticity in multiplicity distributions) and thermal scaling ...(one-fragment production probabilities are Boltzmann factors). Barriers obtained, for cluster production on percolation lattices, from the Boltzmann factors show a power-law dependence on cluster size with an exponent of 0.42+/-0.02. The EOS Collaboration Au multifragmentation data yield barriers with a power-law exponent of 0.68+/-0.03. Values of the surface energy coefficient of a low density nuclear system are also extracted.
Light nuclei can be produced in the central reaction zone via coalescence in relativistic heavy-ion collisions. Experiment 864 at BNL has measured the production of ten light nuclei with nuclear ...number A=1 to A=7 at rapidity y{approx_equal}1.9 and p{sub T}/A{<=}300 MeV/ c . Data were taken with a Au beam of momentum of 11.5A GeV/c on a Pb or Pt target with different experimental settings. The invariant yields show a striking exponential dependence on nuclear number with a penalty factor of about 50 per additional nucleon. Detailed analysis reveals that the production may depend on the spin factor of the nucleus and the nuclear binding energy as well. (c) 1999 The American Physical Society.
It is shown that thermodynamic scaling when applied to systems with few (∼150) constituents, in accordance with the theory of critical phenomena, is observed in nuclear multifragmentation. Yields of ...different nuclear fragments, obtained over a wide range of excitation energies, collapse with some scatter onto a universal curve. This curve is the nuclear scaling function, which is intimately related to the free energy of the system. The determination of the scaling function forms the basis for quantitatively predicting the critical behavior in nuclei.
A sample of
Λ's produced in 2
A GeV
58Ni +
natCu collisions has been obtained with the EOS Time Projection Chamber at the Bevalac. Low background in the invariant mass distribution allows for the ...unambiguous demonstration of
Λ directed flow. The
Λ
m
T
spectrum at mid-rapidity has the characteristic shoulder-arm shape of particles undergoing radial transverse expansion. A linear dependence of
Λ multiplicity on impact parameter is observed, from which a total
Λ+
Σ
0 production cross section of 112±24 mb is deduced. Detailed comparisons with the ARC and RVUU models are made.
Experiment E864 at the Brookhaven AGS accelerator uses a high sensitivity, large acceptance spectrometer, designed to search for strangelets and other novel forms of matter produced in high-energy ...heavy ion collisions. The spectrometer has excellent acceptance and rate capabilities for measuring the production properties of known particles and nuclei such as p̄, d̄ and
6
He
. The experiment uses a magnetic spectrometer and employs redundant time of flight and position detectors and a hadronic calorimeter. In this paper we describe the design and performance of the spectrometer.
We report on a search for metastable positively and negatively charged states of strange quark matter in Au+Pb reactions at 11.6 A GeV/
c in experiment E864. We have sampled approximately six billion ...10% most central Au+Pb interactions and have observed no strangelet states (baryon number
A < 100 droplets of strange quark matter). We thus set upper limits on the production of these exotic states at the level of 1–6 × 10
−8per central collision. These limits are the best and most model independent for this colliding system. We discuss the implications of our results on strangelet production mechanisms, and also on the stability question of strange quark matter.
A high mass trigger for the E864 experiment at the AGS accelerator Hill, J.C.; Huang, H.Z.; Barish, K.N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/1999, Volume:
421, Issue:
3
Journal Article
Peer reviewed
The E864 experiment at the AGS is designed to carry out high sensitivity searches for a variety of possible new particles using relativistic heavy ion Au beams on Pb and Pt targets. In order to reach ...the desired sensitivities, a level-2 “late energy” trigger was built to select events in which a heavy particle is detected in a hadronic calorimeter with deposited energy and time-of-flight from the target exceeding preset values. The physics motivation for the trigger is discussed and and details of its hardware and software design are given. Performance results from recent E864 data taking runs are presented.
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