Semiconductor nuclear radiation detectors made from tertiary and quaternary compounds of cadmium telluride (CdTe) can operate at room temperature without cryogenic cooling. One of such materials that have become of gr...Semiconductor nuclear radiation detectors made from tertiary and quaternary compounds of cadmium telluride (CdTe) can operate at room temperature without cryogenic cooling. One of such materials that have become of great interest is cadmium zinc telluride selenide (CdZnTeSe). Compared to other CdTe-based materials, such as cadmium zinc telluride (CdZnTe), CdZnTeSe can be grown with much less Te inclusions and sub-grain boundary networks. Chemical etching is often used to smoothen wafer surfaces during detector fabrication. This paper presents the characterization of CdZnTeSe that is chemically etched using bromine methanol solution. Infrared imaging shows that the wafer has no sub-grain boundary networks that often limit detector performance. The current-voltage (I-V) characterization experiment gave a resistivity of 4.6 × 10<sup>10</sup> Ω-cm for the sample. The I-V curve was linear in the ±10 to ±50 volts range. An energy resolution of 7.2% was recorded at 100 V for the 59.6-keV gamma line of <sup>241</sup>Am.展开更多
The evaluation of gross alpha and beta activities in crude oil contaminated soil, sediment and water samples was conducted in ten oil polluted environment of Delta State using Gas-flow proportional counter. Samples we...The evaluation of gross alpha and beta activities in crude oil contaminated soil, sediment and water samples was conducted in ten oil polluted environment of Delta State using Gas-flow proportional counter. Samples were collected from the oil polluted environment in each oil field and samples were prepared and analyzed following standard procedures. The mean gross alpha and beta activities obtained are 331.4 ± 24.5 Bq kg<sup>-1</sup> and 11,335 ± 112 Bq kg<sup>-1</sup> respectively for soil, 259.2 ± 17.6 Bq kg<sup>-1</sup> and 4508 ± 96 Bq kg<sup>-1</sup> respectively for sediment, and 1.00 ± 0.09 Bq kg<sup>-1</sup> and 20.3 ± 1.7 Bq kg<sup>-1</sup> respectively for water. The estimated average values of the total annual effective dose equivalent (<i>AEDE</i><i><sub>T</sub></i> (<i>α,β</i>)), the total annual gonadal dose equivalent (<i>AGDE</i><i><sub>T</sub></i> (<i>α,β</i>))), and the total excess lifetime cancer risk (<i>ELCR</i><i><sub>T</sub></i> (<i>α,β</i>)) are 10.64 mSv y<sup>-1</sup>, 0.037 μSv y<sup>-1</sup> and 0.037 μSv y<sup>-1</sup> respectively. The gross alpha and beta activities values obtained in soil and sediment were relatively high compared to values reported in some parts of the country and other regions and countries of the world. The radiological risk parameters examined show that <i>AEDE</i><i><sub>T</sub></i> (<i>α,β</i>) and <i>AGDE</i><i><sub>T</sub></i> (<i>α,β</i>) are above recommended permissible limits while <i>ELCR</i><i><sub>T</sub></i> (<i>α,β</i>) is within the recommended permissible limit. The overall results obtained in this study indicate that the environmental samples have been radiologically impaired due to the crude oil spillage. An appropriate remediation technique was therefore recommended to remediate the polluted soil, sediment, and water to their near original state.展开更多
Cadmium zinc telluride selenide (CdZnTeSe) is a new semiconductor material for gamma-ray detection and spectroscopy applications at room temperature. It has very high crystal quality compared to similar materials such...Cadmium zinc telluride selenide (CdZnTeSe) is a new semiconductor material for gamma-ray detection and spectroscopy applications at room temperature. It has very high crystal quality compared to similar materials such as cadmium telluride and cadmium zinc telluride. The consistency of peak position in radiation detection devices is important to practical applications. In this paper, we have characterized a CdZnTeSe planar detector for bias voltages in the range of -20 V to -200 V and amplifier shaping time of 2, 3 and 6 μs. The peak position of the 59.6-keV gamma line of <sup>241</sup>Am becomes more stable as the absolute value of the applied voltage increases. The best energy resolution of 8.5% was obtained for the 59.6-keV gamma peak at -160 V bias voltage and 3-μs shaping time. The energy resolution was relatively stable in the -120 V to -200 V range for a 6-μs shaping time. Future work will be focused on the study of the peak position and energy resolution over time.展开更多
文摘Semiconductor nuclear radiation detectors made from tertiary and quaternary compounds of cadmium telluride (CdTe) can operate at room temperature without cryogenic cooling. One of such materials that have become of great interest is cadmium zinc telluride selenide (CdZnTeSe). Compared to other CdTe-based materials, such as cadmium zinc telluride (CdZnTe), CdZnTeSe can be grown with much less Te inclusions and sub-grain boundary networks. Chemical etching is often used to smoothen wafer surfaces during detector fabrication. This paper presents the characterization of CdZnTeSe that is chemically etched using bromine methanol solution. Infrared imaging shows that the wafer has no sub-grain boundary networks that often limit detector performance. The current-voltage (I-V) characterization experiment gave a resistivity of 4.6 × 10<sup>10</sup> Ω-cm for the sample. The I-V curve was linear in the ±10 to ±50 volts range. An energy resolution of 7.2% was recorded at 100 V for the 59.6-keV gamma line of <sup>241</sup>Am.
文摘The evaluation of gross alpha and beta activities in crude oil contaminated soil, sediment and water samples was conducted in ten oil polluted environment of Delta State using Gas-flow proportional counter. Samples were collected from the oil polluted environment in each oil field and samples were prepared and analyzed following standard procedures. The mean gross alpha and beta activities obtained are 331.4 ± 24.5 Bq kg<sup>-1</sup> and 11,335 ± 112 Bq kg<sup>-1</sup> respectively for soil, 259.2 ± 17.6 Bq kg<sup>-1</sup> and 4508 ± 96 Bq kg<sup>-1</sup> respectively for sediment, and 1.00 ± 0.09 Bq kg<sup>-1</sup> and 20.3 ± 1.7 Bq kg<sup>-1</sup> respectively for water. The estimated average values of the total annual effective dose equivalent (<i>AEDE</i><i><sub>T</sub></i> (<i>α,β</i>)), the total annual gonadal dose equivalent (<i>AGDE</i><i><sub>T</sub></i> (<i>α,β</i>))), and the total excess lifetime cancer risk (<i>ELCR</i><i><sub>T</sub></i> (<i>α,β</i>)) are 10.64 mSv y<sup>-1</sup>, 0.037 μSv y<sup>-1</sup> and 0.037 μSv y<sup>-1</sup> respectively. The gross alpha and beta activities values obtained in soil and sediment were relatively high compared to values reported in some parts of the country and other regions and countries of the world. The radiological risk parameters examined show that <i>AEDE</i><i><sub>T</sub></i> (<i>α,β</i>) and <i>AGDE</i><i><sub>T</sub></i> (<i>α,β</i>) are above recommended permissible limits while <i>ELCR</i><i><sub>T</sub></i> (<i>α,β</i>) is within the recommended permissible limit. The overall results obtained in this study indicate that the environmental samples have been radiologically impaired due to the crude oil spillage. An appropriate remediation technique was therefore recommended to remediate the polluted soil, sediment, and water to their near original state.
文摘Cadmium zinc telluride selenide (CdZnTeSe) is a new semiconductor material for gamma-ray detection and spectroscopy applications at room temperature. It has very high crystal quality compared to similar materials such as cadmium telluride and cadmium zinc telluride. The consistency of peak position in radiation detection devices is important to practical applications. In this paper, we have characterized a CdZnTeSe planar detector for bias voltages in the range of -20 V to -200 V and amplifier shaping time of 2, 3 and 6 μs. The peak position of the 59.6-keV gamma line of <sup>241</sup>Am becomes more stable as the absolute value of the applied voltage increases. The best energy resolution of 8.5% was obtained for the 59.6-keV gamma peak at -160 V bias voltage and 3-μs shaping time. The energy resolution was relatively stable in the -120 V to -200 V range for a 6-μs shaping time. Future work will be focused on the study of the peak position and energy resolution over time.
