Gamma- ray spectroscopy refers to either art or science of selecting and quantification of radionuclide through examination of gamma- ray films as generated by the spectrometer. Gamma-ray spectroscopy is extensively applied in areas such as geology, safeguarding nuclear materials, industrial processes, forensics, and radiopharmaceuticals among others. In this experiment, our main area of interest will be application of gamma-rays in solving environmental problems. Notably, monitoring gamma-rays in the environment will cover both the atmosphere and the larger part of the ground.1 The result of the experiment will be expected to give clear maps of areas with much radioactive elements. However, such radioactive analysis will aid in solving both environmental and geological challenges in various fields including prospecting and exploration of minerals, soil analysis for agricultural purposes, geochemical mapping and general assessment of the environment.2 More so, this science will be utilized to check on environmental destruction in cases of radioactive spill occasioned by radioactive waste or from nuclear reactors.
Set up and use of germanium detector
Germanium detector will be setup using 1010 cm3 atoms, which will eliminate the need of lithium concentration. This concentration will help manufacture high quality detectors. Germanium detectors are characterized by low levels of impurity concentration, increased atomic numbers, high speed response and resolution.3 However, due to decay counting, a co-axial with closed end dipstick will be used as a detector. Through use of Gamma-rays, the detector will show estimated man-made contamination, hence making radio graphical measurement of the environment easier by producing the general trend of radionuclide distribution.4 Surveys will be regularly carried out in areas of mining, waste sites and also routes followed in transportation of minerals. In addition, the detector will help estimate the magnitude of radioactive materials released to the environment. However, Gamma-ray technology requires high levels of accuracy, stability and reliable gamma rays for close environmental monitoring. More so, advanced spectroscopic skills are also required to run the state-of-art machines.
Measuring the calibration of the gamma ray spectrometer
In this experiment, a phosphate rock, which contains high level of uranium will be used as the experimental material together with Pb. To validate a correct calibration, we will regenerate the geometry applied in filter measurement. It is worth to note that, for energies more than 150keV; the f values will range from 0.96 to 0.99 based on the varying heights. For gamma ray of 46.5 keV, the values of f should be calibrated as 0.90, 0.81 and 0.90 for heights of 4mm, 3mm and 2mm respectively. However, we can assume that self –absorption process is small in calibration filters with f as 0.99.
Measuring the background in the gamma ray spectrometer
The background of any device shows the ability to detect any radioactive material and also cosmic rays.5 The background activity will be measured at three configurations given as 315,000,242,000 and 234,000 for 640- ULL anticoincidence detector, 50E- ULL detector and 510 models. The measure will identify which of the three detectors is highly effective based on the energy range of 2.5keV and 25keV.
Measuring the efficiency and energy calibration of the system
Efficiency forms a key parameter for a spectrometer detector. Nonetheless, the efficiency of any detector varies as the physical counting of the system changes.6 This means that the physical counting must be maintained at constant levels throughout the experiment. However, in this experiment, we will compute energy efficiency using the following relationship.
Efficiency, e (%) = CPS X100%
At X Ir
Where; CPS- Counts per second
At-Current activity
Ir- gamma ray per decay
Ba will be used to determine the efficiency of germanium detector. Ba, Na and Co when placed closer to the detector will produce a gamma ray with higher chances of coincidence loss, which should be eliminated by putting all the sources under consideration about 8cm above the detector. To determine the efficiency, a normalizing factor will be computed based on the efficiency ratios.
Environmental radioactivity measurements
The experiment will dwell on measuring artificial and natural radionuclide in soil samples derived from mining sites. The radioactivity estimated mean will be approximated at 226ba, 232na and 40Co with radionuclide of 22, 31 and 16 respectively. The radioactive elements to be considered are those absorbed in the atmosphere, excess cancer risk and the effective annual dose. The random measurement will be carried out in 50 mining sites and 65 settlement areas surrounding the mining sites. The study is expected to establish the mean annual radionuclide released to the environment from mining activities. Nonetheless, the results obtained will be compared with those from other parts to establish the possible relationship.
Conclusion
Application of germanium detector has completely changed gamma spectroscopy. With the advanced resolution, many nuclear energy levels are easily identified using detectors. Besides, these machines have boosted the level of intelligence necessary from monitoring not only the environment, but also the security using expert software.
Bibliography
Debertin K & G Helmer, Gamma- and X-Ray Spectrometry with Semiconductor Detectors, Oxford University Press, New York, 1988, pp.45.
ElBaradei M & W Burkart , ‘Handbook of Radioactivity Analysis’ in L‟annunziata (ed), Academic Press, Great Britain, 2003, pp.125-132.
Evans D, The Atomic Nucleus, McGraw-Hill New York, 1955, pp.30-37.
Knoll F, Radiation Detection and Measurement, Wiley, New York, 2000, pp. 98-105.
Lee, Y, A Deleplanque, & K Vetter, ‘Developments in large gamma-ray detector arrays’, Journal of Physics, Vol. 66, no.7, 2003 pp. 1095–1144.
Tavendale AJ & GT Ewan, ‘Nuclear Instruments’, Methods, vol. 25, no.3, 1963, pp. 125–87.
Footnotes
- D Evans, The Atomic Nucleus, McGraw-Hill New York, 1955, p.30.
- K Debertin & G Helmer, Gamma- and X-Ray Spectrometry with Semiconductor Detectors, Oxford University Press, New York, 1988, p.45
- AJ Tavendale & GT Ewan, ‘Nuclear Instruments’, Methods, vol. 25, no.3, 1963, p. 125.
- M ElBaradei & W Burkart , ‘Handbook of Radioactivity Analysis’ in L‟annunziata (ed), Academic Press, Great Britain, 2003, p.125.
- F Knoll, Radiation Detection and Measurement, Wiley, New York, 2000, p. 98.
- Y Lee, A Deleplanque, & K Vetter, ‘Developments in large gamma-ray detector arrays’, Journal of Physics, Vol. 66, no.7, 2003 p. 1095.