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Three multiwire proportional chambers (MWPCs) with high-rate capability have been constructed for Fermi National Accelerator Laboratory experiment 705 (charmonium and direct photon production by pi /sup +or-/,p and p at 300 GeV/c). Each chamber, with a sensitive area of 308 cm/sup 2/, consists of three anode planes, wound with 12.5- mu m-diameter gold-plated tungsten/rhenium wire, facing 25- mu m graphite-coated kapton cathode planes at a distance of 3 mm. Wire spacing is 0.75 mm in two of the MWPCs and 1.00 mm in the third one. After a few weeks of running on 'magic gas' with a beam flux of up to approximately 10/sup 7/ particles/cm/sup 2/ s, severe damage occurred to the graphite coating. All cathode planes were replaced by aluminized kapton, and the chambers worked successfully for the next three months until the end of the run, when a 10% efficiency drop was observed after a total accumulated charge of approximately 1 C/cm of sense wire. After the end of the run the chambers were disassembled and inspected. A white deposit with a characteristic wire pattern etched away from the Al coating was observed in the region of the beam spot.<>

A 544-channel low-noise, high-rate precision charge-amplification and ADC (analog/digital converter) system was constructed for the Fermilab Experiment 705 electromagnetic calorimeter, which uses SCG1-C scintillating glass and SF5 lead glass instrumented with photomultiplier tubes. A general discussion of the system is given, and the charge amplification, fast-trigger-pulse generation, and analog/digital conversion aspects of the system are presented in more detail. Performance is evaluated using data from Experiment 705 and from offline tests. Short- and long-term pedestal stability, baseline recovery and rate capability, linearity of response, and crosstalk between channels are discussed.<>

The design and performance of a 4.2-radiation-length, lead-sandwich, gas tube hodoscope are discussed. The device, measuring 1*2 m/sup 2/ in area and 12 cm in depth, was used in Fermi National Accelerator Laboratory experiment 705. Multiple samplings of anode wires situated within three-walled aluminum tubes were used to generate an X coordinate; similarly, capacitively coupled copper-clad strips were ganged together to yield a Y coordinate. The results reviewed of an analysis of electron calibration data taken during a recent six-month running period are reviewed. The position resolution (in millimeters) is seen to be 0.8+3.3/ square root E+31/E for the 9.92 mm-spaced wires and 0.6+3.2/ square root E+32 for the 12.5-mm strips, where E represents the electron beam energy in GeV. The correlation between energy as measured by the wires and energy as measured by the strips is fairly tight, with an asymmetry RMS (root mean square) for 30-GeV electrons of about 4%.<>

A trigger processor for the selection of events in which photons of large transverse momentum are detected by a lead and scintillating glass calorimeter was designed, constructed, and operated at interaction rates ranging from 2 kHz to 2 MHz. The system achieved suppressions of the raw interaction rate of as much as 1*10/sup -5/. Raw distributions of transverse momenta and direct photon event sensitivities are presented for data taken with 300-GeV/c pion and proton beams on a lithium target.<>

A fine-grain hodoscope to measure the position of showers in the outer (>52 cm) region of the E-705 electromagnetic calorimeter is described. The hodoscope is constructed with two layers of vertical conducting plastic tubes for the X position measurement of showers. Y position measurement of showers was accomplished by cathode-induced horizontal strips. A 50/50-ethane mixture bubbled through isopropyl alcohol at 0 degrees C was circulated through the tubes in parallel. The tubes were operated at +1.925 kV on the wire (below the region of saturated avalanche) in the limited proportionality mode. The hodoscope is described, and results are presented for the position resolution, shower width, and charge detected as a function of calibration electron energy.<>

The effects of adenosine, and selective adenosine receptor agonists and antagonists on methylmercury (MeHg)-induced aspartate release were studied in neonatal rat primary astrocyte cultures. Whereas basal levels ofd-[3H]aspartate release were unchanged upon treatment with adenosine or selective A1 receptor agonists, N6-cyclopentyladenosine (CPA), cyclohexyladenosine (CHA), and R-phenylisopropyladenosine (R-PIA), all partially reversed the MeHg-induced release ofd-aspartate. Treatment of astrocytes with the xanthine derivative, theophylline, an adenosine antagonist, reversed the inhibitory effect of adenosine on MeHg-inducedd-[3H]aspartate release. Since the effect of MeHg ond-[3H]aspartate release is known to be associated with sulfhydryl (-SH) groups which are controlled by intracellular glutathione concentrations [GSH]i, we also evaluated the effects of adenosine, the A1 agonists CPA and CHP, and the adenosine antagonist, theophylline, on astrocytic [GSH]i. Attenuation of the stimulatory effect of MeHg ond-[3H]aspartate release by adenosine and its agonists occurred in the presence of reduced astrocytic [GSH]i, suggesting that other mechanisms must be invoked for this protective effect. Whilst the mechanism of MeHg-inducedd-[3H]aspartate release is not known, the data suggest a role for adenosine in its regulation.

A dual flame photometric detector has been used to relate responses of reactive low molecular weight sulfur compounds to area and height of the chromatographic peaks. An all-Teflon subatmospheric gas chromatographic (GC) system is described which provides for up to fifty-fold magnitude variation in the amount of sample available for injection from the same source. Repeatability of the system is demonstrated, and response correlations are presented for hydrogen sulfide (H2S), carbonyl sulfide (COS), sulfur dioxide (SO2), carbon disulfide (CS2), methyl mercaptan (CH3SH), and thiophene. Single and dual flame modes of the detector are compared for standard samples and coal gasifier effluents.

Analysis of the gases H2, CO2, H2S, C2H4, C2H6, O2, N2, CO, and CH4 is described using an automated gas chromatograph. These gases constitute more than 99.5 percent of a coal gasifier product gas. Maintaining the analysis system at its operating efficiency during shutdown requires that the molecular sieve 13X column, which is used in the analysis, be kept under nonflow conditions in dry helium.