bPAD

An Intelligent, Compact Single-Channel Analyser

The bPAD is an intelligent, compact Single-Channel Analyzer. Unlike traditional designs, this device is fully digitally controlled via USB: no scope or messing with screwdrivers is necessary. A simple PC application allows all the parameters (High Voltage level, amplification factor, discriminator thresholds) to be quickly set. More than that, a pseudo PHA mode is implemented, allowing to acquire an spectrum in order to set the discriminator window from the peak of interest. All the settings are stored in permanent memory, so the device can function in standalone mode every time the power is applied.

The device contains a Preamplifier-Amplifier-Discriminator with TTL digital output. The bPAD also includes its own high voltage power supply for operating standard 14-pin photomultiplier tubes, which are commonly used with scintillator-type radiation detectors (e.g. Plastic, NaI(Tl), LaBr, CeBr, etc).

The bPAD is a compact system used to monitor the count rate in an energy region of interest (ROI). The detected signal is output as a TTL pulse, making it compatible with most industrial, environmental and laboratory counting systems. In contrast with traditional SCAs the bPAD is fully controlled by a microprocessor, providing easy setup and “smart” modes of operations.

  • Acquisition mode 1: Differential
  • Acquisition mode 2: Integral
  • Upper and Lower Level Discriminator resolution: 2048 steps
  • Analog amplification factor from 1 to 256
  • TTL-compatible pulse output
  • High-voltage supply of up to 1500V
  • External power input of 6 to 36V
  • Size: 56mm diameter by 60mm long (71mm counting the connector length)

The bPAD is an advanced, microprocessor-based, compact electronic device that integrates a charge-sensitive preamplifier, a variable-gain amplifier and a window discriminator; all in a 14pin photomultiplier tube base. This electronic device outputs a TTL pulse per photo-event detected by a scintillator detector in the energy range of interest. This type of device is also often referred to as a Single Channel Analyser (SCA).

bPAD also includes a miniature, programmable and efficient high-voltage supply to provide the power necessary to operate the most widespread range of photomultipliers used with scintillator detectors. The output voltage can be set in the range from 0 to 1500 Volts with a resolution of 4096 steps.

Since the bPAD is a microprocessor-controlled device, it benefits from being easy to setup. The device connects to a PC via its USB interface, and by using the provided software all the operational settings can be configured and fine-tuned for any kind of scintillator detector. Once the setup is complete, all the settings are saved into the device’s non-volatile memory.

The PC software also comes with a “pseudo-PHA” acquisition mode. In this mode, the software slides the single-channel window over the whole input range, constructing in such a way an energy spectrum. By using this spectrum, the user can visually identify the energy range of interest and immediately set the boundaries of the bPAD discriminator window. This represents a large improvement over the traditional “blind” method used with most other SCAs.

bPAD has two modes of operation:

  • Integral, where counts are output for signals above a single energy threshold level
  • Differential, where counts are output for signals within a defined energy window (SCA)

The output pulses correspond to counted events in the energy window of interest. They are 5-volt TTL signals with 2.5 μsec duration. The bPAD can be ordered to output pulses with a duration of 10 μsec instead.

The bPAD can be powered via the USB connection or by an external DC power supply of 6 to 36 volts. Three colour LEDs are used for status indications: Red for detector high voltage, Yellow for incoming count rate (ICR) and Green for power and communication status.

The bPAD is a compact device with a size of 65 mm diameter by 71 mm high (60 mm not counting the TTL output connector) . bPAD weights less than 80 grams. All the above-mentioned features make the bPAD a very attractive component for industrial and automated

Our standard acquisition software package is provided for managing operations such as setup, control, data acquisition and visualisation. A digital oscilloscope function allows monitoring the input and filtered pulses to aid in fine-tuning the MCA parameters. The program also includes a few spectrometry-related functions for processing the spectral data: calibration, ROI analysis and peak search, to mention a few.

  • Control of the operation of the bMCA device
  • Setup of acquisition parameters
  • Data acquisition in Pulse Height Analysis (PHA) and Multi-Channel Scaling (MCS) modes
  • Visualisation of the energy spectrum
  • Peak search and energy calibration
  • ROI-based spectrum analysis
  • Saving of acquired spectra into files in ASCII format
  • Generation of reports
  • Creation and use of nuclide libraries
  • Possibility of calling an external application for further spectrum processing at the click of a button
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