C. T. Murphy

Beam extraction studies at 900 GeV using a channeling crystal

Luminosity-driven channeling extraction has been observed for the first time in a 900 GeV study at the Fermilab Tevatron. This experiment, Fermilab E853, demonstrated that useful TeV level beams can be extracted from a superconducting accelerator during high luminosity collider operations without unduly affecting the background at the collider detectors. Multi-turn extraction was found to increase significantly the efficiency of the process. The beam extraction efficiency was about 25%. Studies of time dependent effects found that the turn-to-turn structure was governed mainly by accelerator beam dynamics. An investigation of a pre-scatterer using the accelerator flying wire system showed that a fiber could produce a significant extracted flux, consistent with expectations. Based on these results, it is feasible to construct a parasitic 5-10 MHz proton beam from the Tevatron collider.

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 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 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>>

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.

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.

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.