• A versatile, integrated, alpha spectrometer for measuring low-activity samples that decay by alpha-particle emission
• Includes sample chamber, detector, bias supply, preamplifier, amplifiers, and calibration pulser in a NIM-standard double-width module
• Accommodates horizontal samples up to 5.1 cm (2 in.) in diameter with adjustable sample-to-detector spacing
• Available with low-background ULTRA-AS™ Series detectors up to 1200 mm² in active area
• Easy access to vacuum chamber through hinged door featuring a high-reliability, O-ring seal
• Removable, nickel-plated brass chamber simplifies decontamination
• Calibrated outputs and controls for selected energy ranges
• Complete, turn-key multiple-unit alpha spectrometer systems available

The SOLOIST is an integrated spectrometer for measuring low-activity samples that decay by alpha-particle emission. It incorporates all the necessary functions within a NIM-standard double-width module. The module includes vacuum chamber, detector, bias supply for the detector, complete amplifying chain (preamplifier, amplifier, and biased amplifier), and calibration pulser.

The SOLOIST offers three flexible methods for recording the alpha emission activity. The simplest is to record the gross counting rate above the 2.5-MeV threshold using an external counter and timer. To achieve much lower detection limits, the linear amplifier output can be fed to a multichannel pulse-height analyzer (MCA) for quantitative analysis of specific isotope peaks in the 3- to 10-MeV energy spectrum. The biased amplifier output of the SOLOIST offers selection of a restricted energy range (containing only the peaks of interest) for
analysis on the MCA. This feature allows a larger number of alpha spectrometers to be multiplexed into the limited memory size of a single MCA. A front-panel switch provides 6 selectable energy ranges at the biased amplifier output (3 to 8 MeV, 4 to 7 MeV, 3 to 5 MeV, 4 to 6 Mev, 5 to 7 MeV, and 6 to 8 MeV). Three front-panel adjustments permit precise calibration on any selected energy range.

The SOLOIST includes a robust, low-background, sample chamber. The chamber is cast in brass, then machined to close tolerances, before being nickel plated to ensure easy decontamination. In the event of severe contamination, the chamber may be easily isolated from vacuum, and then removed from the module. A compressed, high-performance O-ring, retained in a dove-tailed groove in the face of the chamber, provides an ultra-reliable vacuum seal for the chamber door. Nickel-plated brass sample trays slide into the chamber to provide an adjustable and precisely reproducible sample-to-detector spacing. Trays are available to handle sample sizes from 13 mm (0.5 in.) to 51 mm (2 in.), with sample-to-detector spacing selectable from 1 to 41 mm in increments of 4 mm. The front-panel PUMP/HOLD/VENT valve makes it easy to insert, count, and remove samples without disturbing the vacuum on other SOLOIST chambers attached to the same vacuum pump. A standard Swagelok® fitting on the rear panel simplifies connection of the valve and chamber to an external vacuum pump. An optional pump station (Model ALPHA-PPS-115 or -230) is available for this function, and the Model 576-VM Vacuum Manifold can be added to connect up to four SOLOIST modules to the same vacuum pump.

The SOLOIST is available with an ULTRA-AS Series detector installed. These ion-implanted silicon detectors from ORTEC are specially designed and fabricated for low-background applications in alpha spectrometers. Detector sizes up to 1200 mm² in active area can be accommodated. The SOLOIST is also available without the detector to permit installation of alternative types of silicon detectors, such as ORTEC Ruggedized™ R-Series surface barrier detectors, or other ORTEC surface barrier detectors. A front-panel adjustment and internal jumpers accommodate detectors requiring positive or negative bias voltage in the range of 0 to 100 V.

A variety of single-input or multiplexed-input multichannel analyzers are available from ORTEC for use with the SOLOIST. Quantitative alpha-spectroscopy software is also offered with most of these MCAs.