F.R. Huson

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.

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

High speed simultaneous measurement of pulse area and time-of-flight for photomultiplier signals

Abstract A modular system to provide high speed simultaneous measurements of pulse area and time-of-flight for photomultiplier signals is described. By requiring a minimum pulse size and a time-of-flight signal within a gate before recording either measurement, the system achieves several advantages over other techniques. In particular, since no time is wasted reading channels without useful information, readout speed is enhanced. The system permits accurate measurements at rates exceeding 10 MHz per channel and can be read out without excessive dead time at rates up to approximately 100 kHz. Data storage problems are also reduced. Both pulse area and time-of-flight are measured using 128 bins (7 bits). Costs are less than

Radiation damage effects on liquid scintillating fibers

40 US per channel. Other advantages and design features are discussed.

Study of Λ0 polarization in exclusive pp reactions at 27.5 GeV/c

Abstract The effects of radiation on liquid scintillating fibers composed of borosilicate glass (Pyrex) tubing in combination with a high refractive index liquid scintillator are investigated. The fiber components (tubes, liquids and liquids in tubes), were irradiated in a nuclear reactor with doses exceeding 100 megarads. It was found that the discoloration of the glass tubing does not degrade the optical properties of the fibers - in fact, the attenuation length of fibers using irradiated tubes are longer than those using non irradiated tubes. The attenuation lengths of the liquids in this study appeared to be shortened by the radiation. However, it was found that no deposits or other surface damage occurred on the surfaces of the tubes containing the liquids so the irradiated fibers could be rejuvenated by simply adding fresh liquid.

Λ0 polarization in exclusive pp reactions at 27.5 GeV/c

We report a measurement of the xF and PTΛ0 polarization dependence; Λ0’s were produced in the specific channels: pp→pΛ0K+π+π−, pp→pΛ0K+π+π−π+π−, pp→pΛ0K+π+π−π+π−π+π−, and pp→pΛ0K+π+π−π+π−π+π−π+π− with 27.5 GeV/c protons incident on a liquid hydrogen target. We find that Λ0 polarization is independent of the final state.

Glass-liquid scintillating fibers for calorimetry

In Λ0’s created from the specific reactions: pp→pΛ0K+π+π−, pp→pΛ0K+π+π−π+π−, pp→pΛ0K+π+π−π+π−π+π−, and pp→pΛ0K+π+π−π+π−π+π−π+π−, using 27.5 GeV/c proton beam incident on a liquid hydrogen target, we measured Λ0 polarization as a function of xF and PT. We found that Λ0 polarization is independent of any particular final state and of any specific mechanism responsible of producing Λ0.

Liquid scintillating fiber calorimetry

Abstract An interesting calorimeter technology for possible use in high radiation and high rate applications is the liquid scintillating fiber spaghetti calorimeter. Once a leading candidate for use at the SSC, a considerable amount of research was done to find liquid scintillating fibers with properties (light output, attenuation length and radiation resistance) satisfying the requirements for use in this application. In this report, a summary of results from a search for long attenuation fibers constructed using high refractive index liquid scintillator in glass tubes is presented. Fibers with attenuation lengths exceeding 4 m were found which well satisfied the requirements. In addition, the test stand and fiber light coupling scheme used for this study are discussed.

Study of [Lambda][sup 0] Polarization in Four Different Exclusive pp Reactions at 27. 5 GeV/c

One of the leading candidate technologies being considered for use in the forward region at both the Superconducting Supercollider and the Large Hadron Collider is liquid scintillating fiber spaghetti calorimetry in which the fibers are constructed using liquid scintillator as the core in combination with a tube or channel with a lower refractive index for the cladding. In this report, R&D results on some of the most critical issues will be reviewed, including findings concerning attenuation lengths and radiation damage. Results from in situ tests used to study liquid fiber performance while in an intense radiation environment are also discussed.