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“A Carbon Nanotube-Based Radiation Sensor” by J. Ma, J. T. W. Yeow, J. C. L. Chow, and R. B. Barnett. Michael Foxe Physics 570X Carbon Nanophysics. Outline. Radiation Detection Background Proposed Detection Method Results from prototype detector Results when using CNT electrodes.
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“A Carbon Nanotube-Based Radiation Sensor” by J. Ma, J. T. W. Yeow, J. C. L. Chow, and R. B. Barnett Michael Foxe Physics 570X Carbon Nanophysics
Outline • Radiation Detection Background • Proposed Detection Method • Results from prototype detector • Results when using CNT electrodes
Radiation Detection Background • Incoming particle deposits energy in detecting medium. • Energy resolution usually based on number of electrons created by the incoming particle. • Base the quality of the detector based on its energy resolution and efficiency of the detection process
General Types of Detectors • Gas Ionization Detectors • Semiconductor Detectors • Scintillation Detector • Transition Edge Detector... Scintillation Detector with PMT Cryogenic Transition Edge Sensor
Proposed Detector • Two parallel plate electrodes. This produces the active volume for the detector. • A holder so the separation is variable • These ionized electrons are then drifted to the detector electrodes, where the signal is processed.
Experimental Methods • Using a photon beam to ionized the gas in the active volume, characterize the detector and the effect of CNT electrodes. • Compare the experimental detector to commercially available detectors
Results • Using different levels of exposure, the group shows linear response There is then also an approximately linear response to electrode separation
Results continued - Oblique Orientation • The prototype detector responded better to oblique orientation of the photon beam than the commercial detectors until the angle reached 70 degrees. This could be partly because of the different detector dimensions though.
CNT Effects • For the standard square electrodes, there was no change in charge collection
CNT Effects Continued • For the non-standard shaped electrodes, there was a LOSS in charge collection. Figure 16. (a) 6 MV photon beams with 1 x 1 cm2 field size
Conclusions • The current detector seemed to show good correlation compared to commercial detectors and increased gain for normal incident beams. • Present use of CNT Electrodes showed no improvement, and even acted to decrease the effectiveness of the detector. • I question their correlations on the oblique orientation of the detector
Future Possibilities • They did not talk about using CNT’s as the medium for detection which with their electrical properties could be of use. • On large scale, this could be an improved semiconductor detector.
References • J. Ma, et al., "A carbon nanotube-based radiation sensor," International Journal of Robotics & Automation, vol. 22, pp. 49-58, 2007. • http://en.wikipedia.org/wiki/Radiation_detector • http://en.wikipedia.org/wiki/Photomultiplier • S. Friedrich, "Nuclear diagnostics with cryogenic spectrometers," in 11th Symposium on Radiation Measurements and Applications, Ann Arbor, MI, 2006, pp. 157-160. • http://en.wikipedia.org/wiki/Carbon_nanotube