IMS Instrumentation I: Isolated data acquisition for ion mobility spectrometers with grounded ion sources

The drift voltage required for operating ion mobility spectrometers implies high voltage isolation of either the ion source or the detector. Typically, the detector is grounded due to the sensitivity of the small ion currents to interferences and thus higher requirements for signal integrity than the ion source. However, for certain ion sources, such as non-radioactive electron emitters or electrospray ionization sources, or for coupling with other instruments, such as gas or liquid chromatographs, a grounded ion source is beneficial. In this paper, we present an isolated data acquisition interface using a 16 bit, 250 kilosamples per second analog to digital converter and fiber optic transmitters and receivers. All spectra recorded via this new data acquisition interface and with a grounded ion source show the same peak shapes and noise when compared with a grounded detector, allowing additional freedom in design.

Zero Drift Automatic Suppression Technology for Non-Inertia Integrating Circuit Based on C8051F350 MCU

The non-inertia integration circuit is a basic segment for the reduction of DC or low-frequency small signals. Whether the circuit can work normally or not depends on zero drift. Through a detailed study of a certain non-inertia integrating circuit, this paper has proposed a kind of zero drift technology based on C8051F350 to automatically suppress the drift voltage from the input of the operational amplifier by injecting the suppression signals into the input of the amplifier directly. This technology is designed to ensure that the integrating circuit can work accurately for more than 10 seconds. The experiments have shown that the technology is effective and feasible.

ENERGY RESOLUTION AND COUNTING PROPERTIES OF MICRO-STRIP GAS COUNTER FOR X-RAY DETECTING

A two-dimensional micro-strip Gas Chamber (MSGC) with a 20 × 20 mm2 detection area had been developed. The MSGC had a thin diamond film of 10 μm deposited on a silicon wafer as substrate and lots of micro-strip anode and cathode electrodes made by multi-chip module technology. Energy resolution and pulse signal under 5.9 keV 55 Fe X-rays were measured by a multi-channel energy spectrometer with different voltage under room temperature in atmospheric pressure. Results indicated high signal-to-noise ratio, count rate ≥103 Hz and stable gas gain of the MSGC were obtained. When Ar : CH 4=90:10, drift voltage, cathode voltage and anode voltage was -1000 V, -650 V and 0 V, respectively. However, the energy resolution of 12.3% for 5.9 keV 55 Fe X-rays was achieved. The effects of cathode voltage and drift voltage on energy resolution and count rate were also obtained.