Study of Plastic Scintillator Properties for Radioactive Sources Dosimetry - Paper 108
- Graduate University for Advanced Studies - SOKENDAI, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
- SOKENDAI and the High Energy Accelerator Research Organization - KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
Plastic scintillator is a simple material which has the density close to that of human soft tissue (1.06 g/cm{sup 3}). Its energy response is close to that of human soft tissue and it is relatively energy independent. This prospect provide a desired characteristics in measuring dose by plastic scintillator either for radiation monitoring or personal dosimeter. Generally the energy calibration of organic scintillator will be done by using gamma ray sources. The positions of Compton edge in pulse height spectra, which have known energy values will be identified. However the Compton edge normally is very broad and difficult to determine the point corresponding to that particular Compton electron energies. Many researchers used several fitting functions and Monte Carlo simulations to determine the position of Compton edge. For example, Proctor and Wellman (2012) used a straight line fit to the linear part of Compton edge and extrapolated to zero count. While L. Swiderski et al. used a method based on a back-scattered coincidence measurement to measure in a wide energy range the position of Compton edge in organic scintillators. For a simple and quick approach of calibration, we used a Gauss-error function to fit the Compton edge region of interest by assumed that the location of maximum energy of Compton electrons is half-height of the Compton maximum (CM). The reasons is because the CM position could be determined easily from the spectra throughout wide energy range. Interpreting gamma dose rates from accumulated plastic scintillation detector spectra is often a complex task because the probability of a full energy deposition event in the detector is often negligible. Despite no full energy peaks in plastic scintillator spectra, several attempts have been made by the other researchers to obtain the dose from the energy distribution spectra of gamma radiation. For example, Proctor and Wellman used the modified spectrum dose index (SDI) to calculate the exposure rates by multiplying the energy corresponding to its channel and all products are summed before multiply by a calibration constant to yield an exposure rate. While Lobdell and Hertel calculated dose using a response matrix based on spectral unfolding technique. From these points of view, we have made an attempt to correlate the counts obtained in scintillator with absorbed dose or ambient dose equivalent. We aimed to calibrate the plastic scintillator energy deposition for dose, by correlate the counts obtained with a particular value of dose. By designed the scintillator to measure at 1 cm tissue depth might be helpful to be used as radiation monitoring or personal dosimeter since the energy response of plastic scintillator is relatively energy independent compared to that of inorganic scintillators. The energy calibration proposed from simple fitting approach had been verified with calculated spectra. This might be considered as a practical approach for technician or radiation workers with sufficient accuracy. The linear behavior of counts per absorbed dose give promising to calibrate scintillator energy deposition to read dose (equivalent dose or absorbed dose) for photons. Thus the scintillator could provide both the energy and dose response simultaneously, which may important in some radiation field of measurements. Currently the scintillator is able to give dose rate value for gamma sources of Cs-137 and Mn-54. The number of counts per unit absorbed dose would likely to vary somewhat with photon energy, although the plastic scintillator should have a tissue dose response that is relatively energy independent. Further analysis will be done on conversion factor parameters so that it could be used in such situations where the radiation field is complex or unknown. (authors)
- Research Organization:
- American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 23082930
- Resource Relation:
- Conference: RPSD 2014: 18. Topical Meeting of the Radiation Protection and Shielding Division of ANS, Knoxville, TN (United States), 14-18 Sep 2014; Other Information: Country of input: France; 9 refs.; available on CD Rom from American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (US)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ABSORBED RADIATION DOSES
AMBIENT DOSE EQUIVALENTS
ANIMAL TISSUES
CALIBRATION
CESIUM 137
COMPUTERIZED SIMULATION
DOSE RATES
DOSEMETERS
DOSIMETRY
ENERGY ABSORPTION
ENERGY LOSSES
ENERGY SPECTRA
GAMMA RADIATION
HUMAN POPULATIONS
MANGANESE 54
MONTE CARLO METHOD
PLASTIC SCINTILLATION DETECTORS
PLASTIC SCINTILLATORS
RADIATION MONITORING