اکتساب داده ها برای یک ریزکاو هسته ای
Abstract
1- Introduction
2- Data acquisition and control system
3- Capabilities
4- Conclusion
References
Abstract
The application possibilities of the nuclear microprobe are constantly evolving which places new requirements on the data acquisition and microbeam control systems. MeV SIMS experiments for example, require the ability to pulse a continuous beam and steer it in the X-Y plane. For channeling RBS and STIM experiments, the sample needs to be rotated over two axes. Once it is positioned in the channeling direction, patterned irradiation may be needed. Additionally, with the evolution of digital electronics, it is now possible and sometimes preferred to perform signal processing in the digital domain as oppose to analogue signal chains in NIM modules.
In this work we present the most recent upgrades to the data acquisition and control system developed at Rudjer Boskovic Institute. A data acquisition/control system based on a Xilinx Virtex 6 FPGA was developed which can evolve with the microprobe and be reconfigured for various applications. The real time reprogrammable nature of the FPGA coupled with a modular design approach, allow for the ADCs, processing algorithms and communication protocols to be interchanged and upgraded while keeping a constant user interface through the SPECTOR software package.
Introduction
The modern nuclear microprobe is a very flexible platform on which a wide variety of experiments can be performed. To maintain this degree of flexibility, the data acquisition and control system has to be able to interconnect and synchronize the many different subsystems that make up a nuclear microprobe. Not every experiment performed on the microprobe is the same and therefore beam modification requirements, sample positioning and even the type of data acquisition varies. The standard solution is to use nuclear instrumentation modules (NIM) and manually connect only the modules that are required for the experiment. NIMs are the foundation of the nuclear data acquisition and control industry because they provide a flexible, reconfigurable, easy to use platform which can be adapted and used for a wide variety of experiments. However experiments today have become very complex and require precise control of many parameters. This in turn requires many interconnected modules, which limits the performance, increases complexity and introduces noise. Digital Field Programmable Gate Array (FPGA) technology has evolved significantly and can be used in conjunction with NIM for modern experiments. FPGA technology has been readily used for DAQ systems and many commercial solutions exist as described by Bettiol et al. [1]. However no ideal solution exists and there is always a balance between the complexity of the DAQ system and its usability. This paper builds upon the work of M. Bogovac et al. [2] by adapting more of a modular design philosophy and removing limitation of a closed system. The reprogrammable nature of FPGAs make it a versatile tool for a wide variety of applications and to fully take advantage of this, the hardware and software surrounding the FPGA has to be designed with this in mind. The implementation of this design philosophy to the upgrade of the data acquisition and control system for the nuclear microprobe and developments to the SPECTOR software package [3] are presented.