Design of programmable current source for MOSFET based gamma dosimetry system

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2021-02, Vol.990, p.164944, Article 164944
• Main Authors: Jingar, Naresh, Khandelwal, Arpit, Pandya, Arun
• Format: Article
• Language: English
• Subjects: Digital potentiometer; Dosimetry system; MOSFET; Programmable current source
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2020.164944

In this paper, a programmable current source based simple, compact and low cost MOSFET dosimetry system is developed and characterized for the measurement of cumulative gamma radiation doses. The proposed readout system is microcontroller based which can be used to set-up different zero temperature coefficient currents (IZTC) (range: 200μA – 400μA) using digital rheostat and subsequently measuring changes in the threshold voltages of irradiated sensors. The proposed current source characterized by interfacing with six indigenously developed MOSFET sensors under gamma environments up to 1000 cGy with an average sensitivity of 5 mV/cGy and its performance is compared with commercially available Keithley’s source measurement unit, albeit at much lower cost and size. The comparison shows that the threshold voltage measured from both the systems differ less than 1%.