The New Development Of4Channels γ-ray Spectrometer

γ-ray spectrometry is an important radioactive geophysical methods. The newfour gamma spectrometer is mainly used for the direct measurement of the Fieldsurface rocks, soil and other materials in the uranium (U), thorium (Th), andpotassium (K) content and total channel count, obtain the relevant radionuclidesinformation. With the development of electronic technology, digital gammaspectrometer is moving in the direction of development. Accordingly, to beindependently developed a platform based on ARM7+CPLD, with touch screen,lightweight new four gamma spectrometer.Instrument design includes hardware and embedded software section. Hardwarecircuit including NaI, the pulse processing circuit, a digital circuit and a power circuit.Among them, the pulse processing circuit includes: pole-zero cancellation, with theoperational amplifier, reverse programmable amplification, screening and othercomparator circuit; digital circuit includes: a EPM570CPLD chip as the core part toSTM32F103Cortex-M3MCU is CPU core and peripheral circuits; supply circuitincludes the brightest rechargeable lithium battery power conversion circuits requiredfor circuits and systems. System operation is: NaI detector to detect radiation by thephotomultiplier tube is converted to an electric signal, into the pulse processingcircuit for conditioning; wave PWM control and the use of a threshold range of thesignal to be screened, the signal level-converting the processed circuit into digitalcircuits; within CPLD, completed pulse shaping, signal identification, counting,logic control, and data entered into the CPU via the parallel bus; CPU and peripheralsintegrated information processing, display on the touch screen to achieve fourmeasurement, data storage, communications equipment and other functions.Embedded software using C language in IAR for ARM platform, using theSTM32standard peripheral library functions implemented include: initialize thesystem hardware and configuration parameters; cesium source-based search andautomatic stabilization spectral peak detection function; four quick measurement,time measurement and continuous measurement; storing measurement data, viewand upload; touch the touch screen instructions to configure; and RS485,application-layer protocol instrument via Bluetooth to communicate with the hostmachine. Design the basic realization of the main functions of the instrument, somefunctions have to be perfect and testing.