Keith R. Rielage

Characterization of a multianode photomultiplier tube for use with scintillating fibers

Abstract The characteristics of a multianode photomultiplier tube (MAPMT; Hamamatsu R5900-00-M64) with 64 anodes have been studied. We report measurements that include single photoelectron sensitivity, electrical and optical cross-talk, dark count, and gain variation. Environmental test results relevant to use of these devices in space are also presented. The characteristics of the MAPMT make it well suited for detection of light from scintillating fibers as well as other applications.

The calibration of the Sudbury Neutrino Observatory using uniformly distributed radioactive sources

The production and analysis of distributed sources of 24Na and 222Rn in the Sudbury Neutrino Observatory (SNO) are described. These unique sources provided accurate calibrations of the response to neutrons, produced through photodisintegration of the deuterons in the heavy water target, and to low energy betas and gammas. The application of these sources in determining the neutron detection efficiency and response of the 3He proportional counter array, and the characteristics of background Cherenkov light from trace amounts of natural radioactivity is described.

Scientific capabilities of SIFTER for discovering and monitoring gamma-ray bursts and active galactic nuclei

An exciting possibility for the GLAST main instrument is a scintillating fiber system where the properties of both a tracker and a calorimeter are combined in one type of detector module. This instrument provides all the detector capabilities required to achieve the science goals of the GLAST mission, at a substantially reduced cost compared to the baseline technology, and with the benefit of increased effective area and superior low energy angular resolution.

FiberGLAST: a scintillating fiber approach to the GLAST mission

FiberGLAST is a scintillating fiber gamma-ray detector designed for the GLAST mission. The system described below provides superior effective area and field of view for modest cost and risk. An overview of the FiberGLAST instrument is presented, as well as a more detailed description of the principle elements of the primary detector volume. The triggering and readout electronics are described, and Monte Carlo Simulations of the instrument performance are presented.

Four methods for determining the composition of trace radioactive surface contamination of low-radioactivity metal

Four methods for determining the composition of low-level uranium- and thorium-chain surface contamination are presented. One method is the observation of Cherenkov light production in water. In two additional methods a position-sensitive proportional counter surrounding the surface is used to make both a measurement of the energy spectrum of alpha particle emissions and also coincidence measurements to derive the thorium-chain content based on the presence of short-lived isotopes in that decay chain. The fourth method is a radiochemical technique in which the surface is eluted with a weak acid, the eluate is concentrated, added to liquid scintillator and assayed by recording beta–alpha coincidences. These methods were used to characterize two ‘hotspots’ on the outer surface of one of the 3He proportional counters in the Neutral Current Detection array of the Sudbury Neutrino Observatory experiment. The methods have similar sensitivities, of order tens of ng, to both thorium- and uranium-chain contamination.

Design and performance of a low-power integrated circuit readout system for multi-anode photomultiplier tubes

A high-density, very low power (<<500 (mu) W/channel) readout system for the Hamamatsu R5900-00-M64 and similar multianode photomultiplier tubes (MAPMTs) is under development at NOVA R&D. It is intended for space-flight instruments involving a large number of channels, and provides for efficient readout of such a system at low to moderate event rates in the presence of a sparse hit pattern. Data is buffered within the readout ASIC while prompt summary information is made available to the instrument trigger system, which can then cause the data to be read from the buffer only when necessary. A prototype of the analog front- end has been designed and fabricated, and a prototype of the complementary digital functions has been designed and implemented in a field-programmable gate array (FPGA). We report here on these designs and on test results of the prototype readout system with the Hamamatsu MAPMT. Performance parameters such as gain, noise, and trigger threshold have been studied, and pulse height spectra with a single- photoelectron source and with a Sr90 source and scintillating fiber have been obtained.

Beam test results for the FiberGLAST instrument

The FiberGLAST scintillating fiber telescope is a large-area instrument concept for NASAs GLAST program. The detector is designed for high-energy gamma-ray astronomy, and uses plastic scintillating fibers to combine a photon pair tracking telescope and a calorimeter into a single instrument. A small prototype detector has been tested with high energy photons at the Thomas Jefferson National Accelerator Facility. We report on the result of this beam test, including scintillating fiber performance, photon track reconstruction, angular resolution, and detector efficiency.