L. Fortney

Measurement of J / psi, psi-prime and upsilon total cross-sections in 800-GeV/c p - Si interactions

Abstract We report on the analysis of Charmonium and Bottomium states produced in p-Si interactions at s =38.7 GeV . The data have been collected with the open geometry spectrometer of the E771 Experiment at the FNAL High Intensity Lab. J ψ , ψ′ and γ total cross sections as well as the ratio B(ψ′ → μμ)σ(ψ′) (B( J ψ → μμ)σ( J ψ )) have been measured. Results are compared with theoretical predictions and with results at other energies.

A combination drift chamber/pad chamber for very high readout rates

Details of the construction of high-rate, mid-sized (1-m*2-m) pad chambers, intended for use in Fermi National Accelerator Laboratory (FNAL) experiment E-771, are described. Each gas volume module represents a chamber doublet: two identical anode wire planes, two transverse strip planes, and two pad planes. Wire signals, from 8-mm square cells, are recorded via TDCs; corresponding stripe and pad image signals are latched. Pad sizes range from 0.8 cm*3.6 cm to 3.2 cm*35 cm. In addition to facilitating pattern recognition, pad signals are also used as inputs to an online, high transverse momentum trigger processor.<<ETX>>

The experiment 705 electromagnetic shower calorimeter

Abstract Experiment 705 at Fermi National Accelerator Laboratory has designed, built, and operated a large acceptance, highly segmented electromagnetic shower calorimeter using SF5 lead glass, SCG1-C scintillating glass, and two types of gas-based fine-grained hodoscopes. The calorimeter was used to reconstruct photons and electrons with energies ranging from a few GeV/ c 2 to over 100 GeV/ c 2 in 300 GeV/ c pion and proton interactions on a lithium target at instantaneous interaction rates approaching several MHz. Construction details of the calorimeter are given. The readout electronics, calibration, and algorithms used to reconstruct the positions and energies of showering particles are discussed. Energy resolution, position resolution, and reconstruction efficiency are assessed using both calibration electron beams and electrons and π 0 mesons reconstructed in 300 GeV/ c interactions.

Results from the E-705 electromagnetic shower position detector

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. >

Performance of a lead radiator, gas tube calorimeter

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%. >

An on-line trigger processor for large transverse energy events

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. >

Precision charge amplification and digitization system for a scintillating and lead glass array

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 Fermilab E771 spectrometer: A large aperture spectrometer to study charm and beauty states as detected by decays into muons

This paper describes the final incarnation of the Fermilab High Intensity Lab spectrometer which operated for ten years in the Proton West Area of Fermilab in the execution of two experiments (E537 and E705) which studied hadroproduction of high mass dimuon pairs. The version of the spectrometer used in E771 differed from earlier versions of the spectrometer by the addition of a silicon microstrip detector, pad chambers and resistive plate counters. These additions were implemented to give the spectrometer the capability of detection of secondary decay vertices from B → μ or B → Jψ → μμ decays. As discussed, the spectrometer in a short data taking period was able to address many kinds of physics, other than beauty decays.

Characteristics of the radiation damage seen in the silicon microstrip detector of Fermilab experiment E771

The central region of the silicon microstrip detector used in Fermilab experiment E771 was subjected to a peak fluence of 9.5 × 1013 p/cm2 induced by 800 GeV protons over a two-month period. Fourteen 300 μm thick planes manufactured by Micron Semiconductor were operated at bias voltages ranging from 84 to 109 V. Analysis of data from low intensity beam triggers taken near the end of the run shows that the mean pulse height from our amplifiers began to decline at a fluence of approximately 2 × 1013 p/cm2 and fell to near zero by 6 × 1013 p/cm2. We show that the use of fast amplifiers contributed to this early loss of signal.

Hadroproduction of theχ1andχ2states of charmonium in 800-GeV/cproton-silicon interactions

The cross sections for the hadroproduction of the Chi1 and Chi2 states of charmonium in proton-silicon collisions at sqrt{s}=38.8 GeV have been measured in Fermilab fixed target Experiment 771. The Chi states were observed via their radiative decay to J/psi+gamma, where the photon converted to e+e- in the material of the spectrometer. The measured values for the Chi1 and Chi2 cross sections for x_F>0 are 263+-69(stat)+-32(syst) and 498+-143(stat)+-67(syst) nb per nucleon respectively. The resulting sigma(Chi1}/sigma(Chi2) ratio of 0.53+-0.20(stat)+-0.07(syst), although somewhat larger than most theoretical expectations, can be accomodated by the latest theoretical estimates.