H.R. Gustafson

Search for disoriented chiral condensate at the Fermilab Tevatron

We present results from MiniMax (Fermilab T-864), a small test/experiment at the Fermilab Tevatron designed to search for the production of a disoriented chiral condensate (DCC) in p-p(bar sign) collisions at {radical}(s)=1.8 TeV in the forward direction, {approx}3.4<{eta}<{approx}4.2. Data, consisting of 1.3x10{sup 6} events, are analyzed using the robust observables developed in an earlier paper. The results are consistent with generic, binomial-distribution partition of pions into charged and neutral species. Limits on DCC production in various models are presented. (c) 2000 The American Physical Society.

Analysis of charged-particle–photon correlations in hadronic multiparticle production

In order to analyze data on joint charged-particle/photon distributions from an experimental search (T-864, MiniMax) for disoriented chiral condensate (DCC) at the Fermilab Tevatron collider, we have identified robust observables, ratios of normalized bivariate factorial moments, with many desirable properties. These include insensitivity to many efficiency corrections and the details of the modeling of the primary pion production, and sensitivity to the production of DCC, as opposed to the generic, binomial-distribution partition of pions into charged and neutral species. The relevant formalism is developed and tested in Monte-Carlo simulations of the MiniMax experimental conditions.

A calorimeter for 300 GeV neutrons and protons

Abstract A total-absorption calorimeter for determining the energies of hadrons has been built and tested in beams at the National Accelerator Laboratory. The calorimeter is being used in an experiment to measure neutron total cross sections. The design of the calorimeter is described and its performance is reported. The resolution of the calorimeter for 300 GeV protons is found to be 12.8% fwhm.

Neutron-nucleus total cross sections at 5.7 GeV/c☆

Abstract The neutron total cross sections for He, Be, C, Al, Fe, Cu, Cd, W, Pb and U have been measured to an accuracy of 2% at 5.7 ± 0.6 GeV/c. The total cross section versus atomic weight data was fit to an absorbing uniform grey sphere optical model. The best fit parameters are R = a o A 1 3 where ao = 1.27 ± 0.01 fm, and a nucleon mean free path in nuclear matter of 3.0 ± 0.2 fm. The energy dependence of the nucleon-nucleus total cross sections is discussed in terms of the nucleon-nucleon total cross sections and a screening terms.

Neutron-proton and neutron-deuteron total cross sections at 4.0 and 5.7 GeV/c

Abstract The np and nd total cross sections have been measured directly with a neutron beam with momenta of 4.0 ± 0.6 and 5.7 ± 0.6 GeV/ c . The data are compared with the previous nucleon-nucleon and nucleon-deuteron results, and the deuteron screening term was also evaluated. The measured total cross section are 43.1 ± 0.6 and 80.3 ± 1.9 mb at 4.0 GeV/ c and 42 ± 0.6 and 77.8 ± 1.3 mb at 5.7 GeV/ c .

First Results from the Chicago-Fermilab-Michigan Cosmic Ray Magnetic Monopole Detector

The design and performance of a prototype detector with two 60 cm diameter superconducting loops is presented. During one month of data-taking, no candidate events are observed and an upper limit on the flux of cosmic ray magnetic monopoles Fm ≲ 6.9 × 10−11 cm−2 s−1 sr−1 is set. This exposure corresponds to 21 times the original exposure of Cabrera.1 The detector demonstrates the possibility of large, high-ambient-field inductive detectors.

Search for anomalous multiphoton production at 100–300 GeV

Abstract We have carried out a search for anomalous multiphoton production in neutron-Ch 2 collisions at Fermilab. Both anomalous γ events as might be produced in the annihilation of a magnetic monopole pair, as well as events with smaller opening angles, such as those observed in cosmic ray emulsions by Schein et al. and others were sought. No evidence for either type of event was found. An upper limit ∼2.7 μb is placed on the production cross section for “Schein” events or ∼10 −2 that deduced from the cosmic ray data.

Experience with a static magnetostrictive readout system for wire chambers

Abstract Bespalova et al. have described a scheme for wire chamber readout which makes use of the permanent magnetization of the magnetostrictive line for temporary storage of coordinate information. The advantage of this scheme is that it can significantly reduce the cost of the electronics needed to read out a system with many chambers. We have adopted this technique to read out spark coordinates in an array of spark chambers to detect γ showers. This array has been used successfully in an experiment in which bsim ; 10 7 events were recorded. We discuss our experience with this type of readout and its advantages and disadvantages relative to the more common “prompt” readout system.

Observation of Parity Violation in the Omega-minus -> Lambda + K-minus Decay

The alpha decay parameter in the process Omega-minus -> Lambda + K-minus has been measured from a sample of 4.50 million unpolarized Omega-minus decays recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 +/- 0.19(stat) +/- 0.16(syst)]{times}10^{-2}. This is the first unambiguous evidence for a nonzero alpha decay parameter, and hence parity violation, in the Omega-minus -> Lambda + K-minus decay.

Observation of parity violation in the Ω−→ΛK− decay

The alpha decay parameter in the process Omega-minus -> Lambda + K-minus has been measured from a sample of 4.50 million unpolarized Omega-minus decays recorded by the HyperCP (E871) experiment at Fermilab and found to be [1.78 +/- 0.19(stat) +/- 0.16(syst)]{times}10^{-2}. This is the first unambiguous evidence for a nonzero alpha decay parameter, and hence parity violation, in the Omega-minus -> Lambda + K-minus decay.