D.J. Judd

A measurement of the energy resolution and related properties of an SCG1-C scintillation glass shower counter array for 1–25 GeV positrons

We report the measurement of the energy resolution of a 4×4 array of SCG1-C scintillation glass counters (Ohara Optical Glass Manufacturing Co., Ltd.) exposed to positrons in the energy range of 1 to 25 GeV. Each element of the array was 20.5 radiation lengths long. The resolution of the array was measured both with and without a 3.5 radiation length SCG1-C scintillation glass active converter and 0.2 radiation length hodoscopes used to measure shower position. We obtained an energy resolution ¿/E = (1.63 + 1.46/¿E)% without the active converter and ¿/E = (0.64 + 3.94/¿E)% with the active converter. Performing a partial correction for the average energy loss in the 0.2 radiation length hodoscopes resulted in an energy resolution of ¿/E = (0.50 + 3.43/¿/E)% for the active converter measurement. We also report on the measurement of the absolute number of photons produced by 1 GeV showers, the optical attenuation length for the light produced by showers, the fraction of the total light output that is due to Cerenkov light relative to scintillation light for showers, and the radiation darkening sensitivity of the scintillation glass.

A Measurement of the Energy Resolution and Related Properties of an SCG1-C Scintillation Glass Shower Counter Array for 1-25 GeV Positrons

We report the measurement of the energy resolution of a 4×4 array of SCG1-C scintillation glass counters (Ohara Optical Glass Manufacturing Co., Ltd.) exposed to positrons in the energy range of 1 to 25 GeV. Each element of the array was 20.5 radiation lengths long. The resolution of the array was measured both with and without a 3.5 radiation length SCG1-C scintillation glass active converter and 0.2 radiation length hodoscopes used to measure shower position. We obtained an energy resolution ?/E = (1.63 + 1.46/?E)% without the active converter and ?/E = (0.64 + 3.94/?E)% with the active converter. Performing a partial correction for the average energy loss in the 0.2 radiation length hodoscopes resulted in an energy resolution of ?/E = (0.50 + 3.43/?/E)% for the active converter measurement. We also report on the measurement of the absolute number of photons produced by 1 GeV showers, the optical attenuation length for the light produced by showers, the fraction of the total light output that is due to Cerenkov light relative to scintillation light for showers, and the radiation darkening sensitivity of the scintillation glass.

A measurement of the response of an SCG1-C scintillation glass array to 4–14 GeV/c pions

An SCG1-C scintillation glass detector consisting of a 3.5 radiation length SCG1-C active converter followed by scintillation and gas tube hodoscopes and a 4 × 4 array of a 20.5 radiation length SCG1-C counters has been exposed to pions in the 4–14 GeV/c momentum range. The response of this detector to pions is compared with the response to electrons of the same momentum in order to study the capability of such a detector to distinguish the two types of particles. Using only longitudinal and tranverse shower development criteria, the electrons and pions can be separated such that on average 1.1 × 10−1 of all pions in the range of 4–14 Gev/c would be misidentified as electrons of any energy. If the momentum of the incident particle is known and can be used in the identification technique, this average fraction is reduced to 6.4 × 10−3 of all pions misidentified as electrons of the same momentum.

Measurement of electromagnetic shower position and size with a saturated avalanche tube hodoscope and a fine grained scintillation hodoscope

A hodoscope has been constructed from 100 μm diameter wires and brass tubes (1.2 × 0.7 cm2 cross section) filled with a mixture of argon, ethane and ethyl alcohol. It has been tested in the saturated avalanche mode in an SCG1-C electromagnetic shower detector to determine its properties for the measurement of the position and size of electromagnetic showers. Two of these tube hodoscopes were positioned 3.5 radiation lengths deep in the detector and the profiles of 1–25 GeV electromagnetic showers were measured. Simultaneous measurements were performed using a plane of twenty, 0.5 cm wide scintillation counters positioned immediately behind the gas tube hodoscope. In addition the transition between saturated avalanche and limited streamer modes was observed for the tube hodoscopes.

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. >

Measurement of Electromagnetic Shower Position and Size with a Saturated Avalanche Tube Hodoscope and a Fine Grained Scintillation Hodoscope

A hodoscope has been constructed from 100 ¿m diameter wires and brass tubes (1.2 × 0.7 cm2 cross section) filled with a mixture of argon, ethane and ethyl alchohol. It has been tested in the saturated avalanche mode in an SCG1-C electromagnetic shower detector to determine its properties for the measurement of the position and size of electromagnetic showers. Two of these tube hodoscopes were positioned 3.5 radiation lengths deep in the detector and the profiles of 1-25 GeV electromagnetic showers were measured. Simultaneous measurements were performed using a plane of twenty, 0.5 cm wide scintillation counters positioned immediately behind the gas tube hodoscope. In addition the transition between saturated avalanche and limited streamer modes has been measured for the tube hodoscopes.

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. >

A large aperture spectrometer at Fermilab to study high mass dimuons

A large acceptance forward spectrometer located in a unique antiproton enriched beam has been used at Fermi National Accelerator Laboratory by Experiment 537 to study the production of high mass muon pairs. When the beam was operated at a momentum of 125 GeV/c, it had a flux of 1.5 × 107 particles per second of which 18% were antiprotons. The spectrometer was of closed geometry design and used drift chambers as the tracking elements. Operating over a relatively short period, the experiment accumulated the largest sample of antiproton-induced high mass dimuons of any experiment to date. The contamination of this data by pion-induced dimuons was less than 0.5%.