TOPAZ-Pico Digital MCA

1Overview

The TOPAZ-Pico is a fully digital, compact Multi-Channel Analyzer designed to process the electronic pulses produced by a photomultiplier tube (PMT) coupled to a scintillation detector. Scintillation detectors of this type are widely used for gamma-ray radiation measurement, offering high detection efficiency, medium energy resolution, and a well-understood cost profile.

The instrument performs Pulse Height Analysis (PHA) to produce an energy spectrum from detected radiation events, storing data in on-board memory for retrieval and analysis by a connected PC. A Multi-Channel Scaling (MCS) mode is also available for time-resolved counting in a specific energy region. Both modes support spectral memory sizes of 256, 512, 1024, 2048, or 4096 channels.

Connection to a host PC requires only a standard USB 2.0 port. A bundled software package handles device control, data acquisition, and spectrum visualization, including an automatic device-discovery function that locates all compatible BrightSpec MCA units on the local network. Programming libraries for Windows and Linux are available for integration into existing radiation measurement systems.

2Features

3Description

Operating Modes

The TOPAZ-Pico operates in two distinct acquisition modes. PHA mode is the standard method for nuclear spectrometry and radiometry: the MCA measures the amplitude of each detector pulse, bins it into the appropriate channel, and accumulates a histogram that represents the energy distribution of detected events. MCS mode provides time-resolved counting within a user-defined energy region of interest (ROI) or nuclide window. This is useful in laboratory and industrial settings where the time dependence of a count rate matters, such as source assay, activation experiments, or process monitoring with radioactive tracers.

Digital Signal Processing

All signal conditioning is performed digitally. Coarse gain is set in factors of 1, 2, 4, or 8. Fine gain is continuously adjustable from 1 to 2 in steps of 1/4096, giving precise spectrum calibration without analog trimming. Rise time and flat-top shaping parameters are set digitally. A digital Baseline Restorer (BLR) maintains a stable zero-line under varying count rates, and the Pile-Up Rejector (PUR) discards overlapping events that would otherwise degrade spectral resolution.

High-Voltage Power Supply

A miniaturized HV supply is integrated directly into the MCA assembly. It provides a positive output adjustable from 0 to 1500 V in 4096 steps, covering the bias requirements of most PMT-based scintillation detectors including those used with large-volume crystals. Both HV bias and detector signal share a single Lemo ERA 0S 403 CLL connector, simplifying cabling and reducing connection points.

Connectivity and Software

The device connects to a host computer via USB mini-B. The included software provides a graphical interface for spectrum acquisition, display, and device configuration. An automatic device-discovery function identifies all compatible BrightSpec MCA units (bMCA-USB, bMCA-Ethernet, and TOPAZ-Pico) in the PC's neighborhood without manual IP entry or COM port assignment. Programming libraries for both Windows and Linux allow straightforward integration into custom acquisition frameworks or existing radiation measurement systems. Library access is available upon request.

Enclosure and PCB Options

The standard product ships in a rugged aluminum box with clearly labeled input and output connectors and three LED status indicators. For system integrators and OEM applications, the TOPAZ-Pico is also available as a bare printed-circuit board (80 mm x 60 mm), enabling direct installation into custom enclosures or instrument chassis.

4Technical Specifications

PHA Acquisition Mode

MCS Acquisition Mode

Digital Signal Processing

High-Voltage Power Supply

Data Communication

Physical

Connectors and Indicators

Software and OS Support

Certifications

5Applications

The TOPAZ-Pico is suited to any application that requires a portable, USB-connected digital MCA with an integrated high-voltage supply. Representative uses include:

• Nuclear spectrometry and radiometry: PHA mode provides energy spectra from NaI(Tl), LaBr3(Ce), LaCl3(Ce), CeBr3, and other PMT-coupled scintillators for isotope identification and activity measurement.
• Environmental and health physics monitoring: Continuous acquisition with MCS mode allows time-resolved counting to track dose rate or contamination levels over minutes to hours.
• Laboratory and R&D: The compact footprint and self-contained HV supply make the TOPAZ-Pico easy to deploy in benchtop setups without separate NIM or benchtop HV modules.
• Portable field measurements: Sub-150 g weight and pocket dimensions enable single-operator deployment in the field alongside a laptop or tablet.
• Industrial process monitoring: MCS mode with nuclide or ROI-based gating supports radiotracer experiments and source-assisted gauging or level detection.
• Neutron counting (optional): With the TTL counter input option, the TOPAZ-Pico can simultaneously accept digital pulses from a dedicated neutron detector alongside the scintillation detector signal.
• OEM and system integration: The bare PCB option and available programming libraries (Windows and Linux) simplify embedding the TOPAZ-Pico into custom instruments, portal monitors, and automated measurement systems.
• Education and training: Intuitive software and automatic device discovery reduce setup time in academic and vocational training environments.

6Ordering and Contact

The TOPAZ-Pico is available in two configurations: the standard aluminum enclosure with all connectors, and a bare PCB for OEM integration. The optional TTL counter input is a factory-fitted option; specify at time of order. Programming libraries for Windows and Linux are available upon request.