Studies On Double-Channel Multi-channel Scaler Data Acquisition System

Counting of radioactivity is a important method in nuclear detecting. Multi-channel Scaler(MCS) is a special counting device that measure the variety of counts with time. In the nuclear research and nuclear technology, for example, studying of radioactivity decay, measuring of low level radioactivity for long time, etc., it is necessary. In about latest ten years, MCS have been developed very well abroad. But in our country, there is no good MCS with zero dead time and with cooperating to portable computer so far.Based on the theory of sealer and the working principle of multi-channel sealer as well as according to the requirement of user, we have successfully designed the hardware and software of MCS system and tested it. To improve the function of the MCS, we also successfully designed the MCS by adopting Complex Programmable Logic Device (CPLD).In this paper, we have obtained some new and significant results:1. A multi-channel sealers data acquisition system with two channels has been successfully designed. It have the following characteristics: (1) zero dead time between channels. (2) The highest frequency is 10MHz. (3) two kinds of channel widths, and switch them automatically or by hand. (4) two channels acquisition. (5 ) It can cooperate with the personal computer, even portable computer.2. Propose a new method of Combined software with hardware to eliminate dead time between channels. This circuit is very simple.3. Using the computer print parallel port characteristic in data transferring and according to the requirement of the Windows application program, the virtualdriver (VXD) program have been developed to transfer data between the computer and one-chip computer. At the same time, we have developed the responding programs of two hardware interrupts, Real Time Clock (RTC) Interrupt (IRQ8) and Print Parallel Port Interrupt (IRQ7). We have developed the responding program of RTC interrupt to synchronize data transferring between the master computer and the one-chip computer. 4. We attempt to use field programmable logic technology in order to implement this data acquisition system., and have finished the design, simulation and the circuit board. The simulating results prove that this scheme can design this system with the narrowest channel-width 1 u s and the highest frequency 100 MHz.