A vertical coaxial sample holder and collimator design for gamma attenuation experiments on 3″x3" NaI(Tl) detector

• Published in: Journal of radiation research and applied sciences Vol. 17; no. 2; p. 100862
• Main Authors: Kuluöztürk, Muhammed Fatih, Kuluöztürk, Zehra Nur
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2024
• Subjects: 3D printer; FLUKA code; NaI(Tl) detector; Pb collimator; Sample holder; FLUKA code; NaI(Tl) detector; 3D printer; Sample holder; Pb collimator
• ISSN: 1687-8507; 1687-8507
• DOI: 10.1016/j.jrras.2024.100862

NaI(Tl) detectors, one of the detector types commonly used in gamma spectroscopy studies, are frequently used in gamma attenuation coefficient determination studies. The most important factors affecting the accuracy of the result in the experimental determination of the absorption coefficient are the shielding of the detector, the radiation source type and activity, the appropriate counting time and operating voltage, and the detector-source-sample geometric positions. The sample holder, which is one of the basic components of the experimental setup, allows the detector-source-sample positions to be adjusted as desired. When it is not positioned appropriately, it can be the most important user error. In this study, a coaxial sample holder stand was designed for a 3″x3″ NaI(Tl) detector, allowing the distances between the source, sample and detector be changed separately. The sample holder stand is 3D printed using PLA (Polylactic Acid) filament. In addition, a cylindrical collimator made of lead and copper materials has been added under the source holder layer in order to obtain a pencil beam and to eliminate the possible effect of the materials used in the production of the stand. Cylindrical collimator was manufactured by casting method. The performance of the produced stand was tested using 133Ba, 22Na, 137Cs, and 60Co point sources. In addition, the detector collimator system was simulated with the FLUKA Monte Carlo code to evaluate the collimator parameters and the study was supported with the simulation results. It has been observed that the gamma peak efficiency values obtained for the without-collimator and with-collimator setups in the 356–1332 keV energy range vary between 2.2–0.5 (%) and 0.11–0.08 (%), respectively. On the other hand, it was observed that peaks with better resolution values were obtained by using with-collimator setup. Resolution (%) values were found to vary between 8.7–4.8 and 9.1–5.3 for with-collimator and without-collimator setups, respectively.