G. Gutierrez

High rate drift chambers

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.

Pion-pion correlations at low relative momentum produced in p-p collisions at 27.5 GeV/c.

We have measured the momentum correlation of pion pairs produced in the collisions of 27.5 GeV/[ital c] protons in liquid hydrogen. By considering events for which all final state particles have been measured, we have succeeded in reducing backgrounds due to particle misidentification below 5% for [pi][sup +] and 1% for [pi][sup [minus]]. Our use of a precision magnetic spectrometer has provided an accurate determination of particle momenta and excellent acceptance for particle pairs with small relative momentum essential for correlations studies. A large data sample of fully reconstructed events (1[times]10[sup 6]) allows us to analyze the correlations for [pi][sup +][pi][sup +] and [pi][sup [minus]][pi][sup [minus]] pairs separately, and also as a function of the final state multiplicity. We find that the pion pair correlations scale 0.98 fm describes the data well. We do not find any indication of multiplicity dependence of the correlation scale for multiplicities from 6 to 14 final state particles.

Search for exotic baryons in 800-GeV pp ---> p Xi+- pi+- X

We report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to {xi}{sup -}{pi}{sup -}, {xi}{sup -}{pi}{sup +}, {xi}{sup +}{pi}{sup -}, and {xi}{sup +}{pi}{sup +}. The only resonances observed are the well known {xi}{sup 0}(1530) and {xi}{sup 0}(1530). No evidence is found for the states near 1862 MeV, previously reported by NA49 [Phys. Rev. Lett. 92, 042003 (2003)]. At the 95% confidence level, we find the upper limit for the production of a Gaussian enhancement with {sigma}=7.6 MeV in the {xi}{sup -}{pi}{sup -} effective mass spectrum to be 0.3% of the number of observed {xi}{sup 0}(1530){yields}{xi}{sup -}{pi}{sup +}. We find similarly restrictive upper limits for an enhancement at 1862 MeV in the {xi}{sup -}{pi}{sup +}, {xi}{sup +}{pi}{sup -}, and {xi}{sup +}{pi}{sup +} mass spectra.We report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to

Pion-pion correlations at low relative momentum produced in [ital p]-[ital p] collisions at 27. 5 GeV/[ital c]

\Xi^-\pi^-

Preliminary results of the analysis of the centrally produced φφ system

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Λ0 Polarization in Exclusive pp Reactions From the FNAL e690 Experiment

\Xi^-\pi^+

Search for exotic baryons in 800 GeV/c pp → pX

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Exotic baryon searches in 800 GeV/c pp → pX

\bar{\Xi}^+\pi^-

Search for Exotic Baryons in 800 GeV pp{yields}p{xi}{sup {+-}}{pi}{sup {+-}}X Reactions

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

\bar{\Xi}^+\pi^+