Thesis Archive



Radiation detection and measurement is necessary for a wide variety of people working with radiation in two ways. First, they need to know basic concepts of radiation effects to handle radioactive materials safely and secondly to make research in any field related with radiation. The equipments and laboratory setup needed for radioactivity measurement are expensive and difficult to assemble due to the large variety of the type of experiments that are desirable to cover. First of all, in a basic laboratory, one needs to have gamma, beta, alpha and neutron sources, at least one detector to detect each type of radiation and other supplemental instrumentation to perform experiments. Furthermore shielding and a private secured place are needed to protect people from the effect of these radioactive sources. Nearly two hundred thousand dollars is needed to construct such a basic laboratory described as above. This project based on LabView is a good, inexpensive and easy to use solution for Radiation Detection and Measurement in the industries, power plants, hospitals or in laboratories.

The whole process can be subdivided into four basic blocks: First of all, the radio activity of particles is measured by a Scintillator detector. Every radio-active particle radiate energy. One needs to convert this energy into voltage in order to detect the radio activity. For this purpose Scintillator detector is used. It gives us pulses which is a function of radioactivity of that particle. Radio activity is a function of the pulse genereted by the particle. The more pulse a particle generates at a given time the more radio active the particle is. For example, if particle A gives 10 pulses in 1 hour and particle B gives 1000 pulses in 1 hour, then particle B is 100 times more radio active than particle A.
The pulse from Scintillator detector is then connected to DAQ card NI USB 6341, which is installed in our PC. After that LabVIEW programme is used to make interface between DAQ card and PC to measure radio activity. It measures the pulses for peak. Then it counts the number of peaks for a given time and stores it in the PC. The radio activity of a material is propotional to the number of pulses it generates at a given time. Then recorded radio activity data can be observed at a given month from LabView code and it can also be stored in the PC.



LabVIEW- Laboratory Virtual Instrumentation Engineering Workbench
DAQ- Data Acquisition
MCA- Multi Channel Analyzer
SCA- Single Channel Analyzer
QDE- Quantum detection efficiency
PET- Position Emission Tomography
PMT- Photomultiplier Tube
PHA- Pulse height spectroscopy
FWHM- Full width at half maximum
VI- Virtual instruments
USB- Universal Serial Bus
GM- Geiger-Mueller
HV- High Voltage
ADC- Analog to Digital Converter
NI- National Instrument
PCI- Peripheral Component Interconnect
PXI- PCI Extensions for Instrumentation
RTSI- Real Time System Integration


Pre requisites:

LabVIEW, DAQ cards, radio activity, Scintillation detector


Important Outcomes:

To conclude, an inexpensive and easy to use simulation environment for Radiation Detection and Measurement is implemented in our project. Most commonly used detectors, sources and additional instrumentation are modeled in an extensible way. Also the computer resource requirements are kept so low that with a modern personal home computer, one can use this Labview based software efficiently. So the general cost of the necessary detection & measurement is lowered to a computer price, which is easily affordable in the current century. Additionally, in Labview’s virtual window one can setup experiments which may be impossible to construct in real life. Furthermore, it creates a safe environment for the student, since there is no real radiation risk and also no possible damage risk to the expensive instruments, while learning radiation detection and measurement.


Major Problems Faced:
i. Our LabVIEW code does not work at very high frequency, because of the resolution limit of NI 6341 DAQ card. This issue can be solved by using high resolution DAQ card.
ii. We did not use any noise removal hardware. So because of the external noise, results can be varied a little bit. It can be resolved by using noise removal circuitry between scintillator detector and NI DAQ card.


Further work:
Since this Labview based software is not developed with a professional team of developers and is quite new to this field, there are some bugs to be fixed. However currently it is operational and usable and will be developed in near future for more accuracy and to make it more user friendly. Neutron activation analysis is used to determine the concentrations, ingredients of a known or unknown material. This requires a nuclear reactor available to irradiate the sample and a radiation detection laboratory to analyze. Furthermore while during such an experiment the experimenter needs to predict the activity of the sample after irradiation. So the neutron activation analysis and spectroscopy module will be added to this in order to enable activity, dose and spectrum prediction and also simulation, prior to neutron activation experiments. Thus, the experimenter will be able to make changes before irradiating materials to get the best results needed. We are also looking forward to make the project an on-line monitoring system in near future.