Design and Development of an Isotope Identification Device (RID) Based on a Low Energy Resolution CsI(Tl) Detector Integrated with a Standard Radiation Portal Monitor (RPM)

EGE CAN KARANFİL

Design and Development of an Isotope Identification Device (RID) Based on a Low Energy Resolution CsI(Tl) Detector Integrated with a Standard Radiation Portal Monitor (RPM)

Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Ankara Üniversitesi, Nükleer Bilimler Enstitüsü, Medikal Fizik Bölümü, Türkiye

Tezin Onay Tarihi: 2025

Tezin Dili: İngilizce

Öğrenci: EGE CAN KARANFİL

Asıl Danışman (Eş Danışmanlı Tezler İçin): Bahadır Saygı

Eş Danışman: Haluk Yücel

Özet:

Today, Radiation Portal Monitors (RPMs) are widely deployed at transit points such as airports and border crossings to facilitate trade and ensure security during major public events like those held in stadiums, metro stations, and other high-traffic areas. However, most conventional RPMs in use today are only capable of measuring count rates (cps). When real-time radiation levels exceed a preset threshold, an alarm is triggered, initiating a time-consuming secondary inspection process that can disrupt operational flow.

In recent years, Spectroscopic Radiation Portal Monitors (SRPMs) have been developed to im- prove isotope identification accuracy and enhance the detection of Naturally Occurring Radioac- tive Materials (NORM) during the primary inspections. The primary advantage of SRPMs is their ability to acquire gamma-ray spectra in addition to count rate data, allowing real-time isotope iden- tification. In this study, a detector was developed to be integrated into standard RPMs, enabling them to collect spectral data and perform real-time isotope identification similar to SRPMs. The detector system developed in this thesis comprises a low-resolution CsI(Tl) scintillator coupled with a Silicon Photomultiplier (SiPM), resulting in a compact and cost-effective design. Ad- ditionally, a custom-designed microcontroller based 10-bit multi-channel analyzer (MCA) was developed for spectral data acquisition.

The isotope identification capability of the compact CsI(Tl) detector was tested using several point sources, uranium-thorium ore samples, and a certified reference material (ECNRM-171). Spectral data were automatically analyzed using a second-derivative method for photopeak detection, fol- lowed by determining extraction features via a Bayesian approach. A Python-based Graphical User Interface (GUI) was developed, for this data acquisition and analysis procedure. This software continuously communicates with the standard RPM using the MODBUS-RTU protocol and in the event of an alarm, the software automatically triggers spectral acquisition and real-time isotope identification.