Scintillating fiber tracking detectors are being developed for the SDC experiment at Superconducting Super Collider (SSC) and the upgrade of the D0 detector at the Fermilab Tevatron. The many ...attractive features of a fiber tracker include good position resolution, low occupancy, low mass in the active volume, and excellent resistance to radiation damage. An additional important feature, especially at the SSC, is the intrinsically prompt response time of a scintillating fiber. The photodetector of choice is the visible light phonon counter (VLPC), a device which combines high rate capability with high quantum efficiency at visible wavelengths. To realize the high rate capability of the VLPC requires the implementation of a suitable, fast preamplifier. Until recently, studies of fibers and VLPCs with radioactive sources and cosmic rays have been performed under low rate conditions using transimpedance amplifiers (TIAs). The authors report on the response characteristics of a fiber-VLPC system coupled to a variety of fast preamplifiers, including QPA02, VTX, and TVC devices. Their performance is compared with that of a transimpedance amplifier.< >
We have measured the cross section for production of psi and psiprime in ital bar p and pisup minus interactions with Be, Cu, and W targets in experiment E537 at Fermilab. The measurements were ...performed at 125 GeV/ital c using a forward dimuon spectrometer in a closed geometry configuration. The gluon structure functions of the ital bar p and pisup minus have been extracted from the measured ital dsigma/ital dxsub ital F spectra of the produced psi's. From the ital bar pW data we obtain, for ital bar p, ital xG(ital x)=(2.15plus minus0.7)1minusital xsup (6.83plus minus0.5) 1+(5.85plus minus0.95)ital x. In the pisup minus case, we obtain, from the W and the Be data separately, ital xG(ital x)=(1.49plus minus0.03)1minusital xsup (1.98plus minus0.06) (for pisup minusW), ital xG(ital x)=(1.10plus minus0.10)1minusital xsup (1.20plus minus0.20) (for pisup minusBe).
