Mössbauer Spectrometer in the PXI/CompactPCI Modular System

Two commercially available modules, a digital oscilloscope (NI 5102) and a function generator (NI 5401) in the PXI (PCI eXtension for Instrumentation) or PCI standard from National Instruments Inc., supported by the driver software, have been used for building a computer‐based Mossbauer spectrometer. The RTSI (Real‐Time System Integration) bus is used for synchronizing the accumulation of the detector impulses to the Mossbauer spectrum with velocity of the “source‐sample” relative motion. The amplitude selection of the impulses from the detector output is based on the use of the Waveform Peak Detection.vi function. This function is available in the graphical programming environment LabVIEW 7 Express which serves for an implementation of the virtual instrument of the Mossbauer spectrometer. Mossbauer spectra can be accumulated in the constant and variable velocity modes; moreover, there is a possibility to register gamma‐ray spectra in the multichannel analyzer mode. Two types of the detectors (a NaI(Tl) and a resonance scintillation detector) have been used with the new Mossbauer spectrometer.