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A turn-key PC-based control system has been developed for the AccSys line of compact ion linear accelerators and RF power amplifiers. The control interface is based on the DZERO Rack Monitor Module, communicating with a Ballard Technology MIL-STD-1553B controller board in a 286 or 386 personal computer. This cost-effective and easy to operate control system features real-time control and monitoring of the linac/RF amplifier and can be customized for automatic start-up and unattended operation. >

Monte Carlo calculations of a bismuth-germanate scintillator's efficiency agree closely with experimental measurements. For this comparison, we studied the absolute gamma-ray photopeak efficiency of a scintillator (7.62 cm long by 7.62 cm in diameter) at several gamma-ray energies from 166 to 2615 keV at distances from 30.5 to 152.4 cm. Computer calculations were done in a three-dimensional cylindrical geometry with the Monte Carlo coupled photon-electron code CYLTRAN. For the experiment we measured 11 sources with simple spectra and precisely known strengths. The average deviation between the calculations and the measurements is 3%. Our calculated results also closely agree with recently published calculated results.

An examination of 3.6\ifmmode\times\else\texttimes\fi{}${10}^{10}$ ${\ensuremath{\mu}}^{+}$ decays yields an improved upper limit for the branching ratio $\frac{\ensuremath{\Gamma}({\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}\ensuremath{\gamma})}{\ensuremath{\Gamma}({\ensuremath{\mu}}^{+}\ensuremath{\rightarrow}{e}^{+}{\ensuremath{\nu}}_{e}{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}})}l1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ with 90% confidence.

We report a new procedure for unfolding gamma-ray pulse-height distributions acquired with bismuth-germanate detectors. The equipment used for acquiring the distributions consists of a LeCroy 3500 data acquisition and analysis system and eight bismuth-germanate scintillation detectors 7.62 cm in diameter and 7.62 cm long. The system was calibrated and characterized from 0.12 to 8.28 MeV by using gamma-ray spectra from a variety of radioactive sources and from the 14 N(p,γ) 15 O reaction. By fitting these pulse-height distributions with a function containing 17 parameters, we determined theoretical response functions and used them to obtain the gamma-ray flux spectra at multiple space points from a variety of radioactive objects of interest to nuclear safeguards. We used two flux-spectrum-to-dose-rate conversion curves to obtain dose rates. For a composite source, consisting of several sources with accurately known strengths, the result of our procedure agreed with the expected value to within less than 10%. Direct use of measured spectra and the flux-spectrum-to-dose-rate curves to obtain dose rates avoids the errors that can arise because of spectrum dependence in simple gamma-ray dosimeter instruments.

We present the experimentally determined intrinsic photopeak efficiencies for bismuth germanate scintillators 7.62 cm in diameter and 7.62 cm in length over the energy range 0.1–5.0 MeV. We studied eight detectors individually with point sources at 30.8, 61.3, 91.7, and 152.7 cm from the crystal; two additional detectors, for a total of 10, were studied with sources at 61.3 and 91.7 cm. We present intrinsic photopeak efficiency curves, determined by averaging the data from all detectors and fitting the results at each of the four distances.

An array of 45 NaI(Tl) crystals modules, each in 20 in. in length and hexagonal in cross section with six 3 in. sides, has been operated as a detector of 50 MeV γ-rays in a search for the decay μ + →e + γ . The calibration procedure used for this detector and the resolutions achieved in γ-ray energy, time of detection and point of impact on the detector face are described.

This paper describes a kinematically complete search for the muon decay ..mu../sup +/..-->..e/sup +/..gamma... The experiment used a magnetic spectrometer outfitted with proportional chambers to measure the positron momentum vector and a large segmented NaI(Tl) array to determine the ..gamma..-ray energy and impact point. The positrons were mostly from normal muon decay while the ..gamma.. rays were mostly from internal and external bremsstrahlung. Approximately 3 x 10/sup 12/ muons were stopped in a 50-mg/cm/sup 2/ polyethylene target. The relative timing between the positron and the ..gamma.. ray was measured with a resolution of 1.9 ns full width at half maximum (FWHM) by the use of a plastic-scintillator hodoscope for the positron and by NaI(Tl) constant-fraction timing for the ..gamma.. ray. The positron energy resolution averaged over all data was 8.8% FWHM, and the ..gamma..-ray energy resolution was 8% FWHM, both at 52.8 MeV. When the ..gamma.. ray is assumed to originate at the same place in the target as the positron, the rms error in the measurement of the angle between the positron and ..gamma..-ray momentum vectors was 37 mrad. The acceptance of the apparatus for ..mu../sup +/..-->..e/sup +/..gamma.. events was (1.75 +- 0.04)%. A maximum-likelihood analysis established a 90%-confidencemore » upper limit for the branching ratio GAMMA(..mu../sup +/..-->..e/sup +/..gamma..)/GAMMA(..mu../sup +/..-->..e..nu nu..) of 1.7 x 10/sup -10/.« less