Odziv termoluminiscentnih dozimetara 7LiF:Mg,Ti (TLD-700) u protonskim snopovima

master's thesis

• Title (english): Response of thermoluminescent dosimeters 7LiF:Mg,Ti (TLD-700) in proton beams
• Author: Mercedes Horvat
• Mentor: Marija Majer (mentor)
• Mentor: Tomislav Bokulić (komentor)
• Committee member: Tomislav Bokulić (predsjednik povjerenstva)
• Committee member: Marija Majer (član povjerenstva)
• Committee member: Mihael Makek (član povjerenstva)
• Committee member: Damir Bosnar (član povjerenstva)
• Committee member: Ivica Friščić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2024-03-15, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Cilj ovog diplomskog rada bio je ispitati odziv termoluminiscentnih dozimetara 7LiF:Mg,Ti (TLD-700) u snopu protona energije 5 MeV i usporediti s odzivom za fotonska zračenja. Dozimetrijski sustav činili su dozimetri TLD-700 (ϕ 4,5 mm×0,89 mm) i čitač Toledo 654 Vinten. Zračenja u polju gama zračenja izvora 60Co rađena su u Sekundarnom standardnom dozimetrijskom laboratoriju, a zračenja protonima na akceleratoru Tandem Van de Graaff Instituta Ruđer Bošković. Za pripremu i očitavanje dozimetara korištena su dva mjerna ciklusa, standardni (A) i viskotemperaturni (B), koja se razlikuju u vrijednosti maksimalne temperature do koje se dozimetri zagrijavaju tijekom očitavanja. Dozimetri zračeni fotonima, uz primjenu mjernog ciklusa A, pokazali su očekivane krivulje isijanja u kojim je prisutan samo glavni dozimetrijski vrh te je potvrđena linearnost odziva za raspon doza od 0,09 Gy do 0,92 Gy gdje su doze izražne kao doze u LiF. Za dozimetre zračene protonima i kalibracijske dozimetre zračene izvorom 60Co primjenjen je mjerni ciklus B. Krivulje isijanja dozimetara bile su u skladu s očekivanim i sadržavale su dva vrha: glavni i visokotemperaturni. Pokazano je kako je omjer visokotemperaturnog i glavnog vrha za dozimetre zračene protonima veći nego za fotone. Iz literature je poznato da omjer glavnog i visokotemperaturnog vrha ovisi o linearnom prijenosu energije (LET) upadnog zračenja te bi se mogao koristiti za mjerenje nepoznatog LET-a. Nažalost, u ovom radu nismo bili u mogućnosti zračiti protonima različitih energija niti sa težim ionima. Odziv u ovisnosti o dozi zračenja za oba vrha je ispitana provedbom linearne regresije i računom koeficijenta linearnosti. Zbog nestabilnosti snopa tijekom zračenja te velikih nepouzdanosti u frekvencijama, za oba vrha nije se mogla potvrditi linearnost odziva za ispitano područje doza od 0,26 Gy do 1,02 Gy.

Abstract (english)

The aim of this master thesis was to examine the response of thermoluminescent dosimeters 7LiF:Mg,Ti (TLD-700) in a 5 MeV proton beam and to compare it with the response in photon radiation. The dosimetry system consisted of TLD-700 do- simeters (ϕ 4.5 mm×0.89 mm) and a Toledo 654 Vinten reader. Irradiation with a 60Co gamma radiation source was preformed at the Secondary Standard Dosimetry Laboratory and irradiations with proton beams were performed at the Tandem Van de Graaff accelerator at the Ruđer Bošković Institute. Two heating cycles were used for the preparation and reading of the dosimeters, the standard (A) and the high- temperature (B). The main difference between the two cycles was the maximum temperature to which the dosimeters were heated during readout. Dosimeters irradiated by photons, to which cycle A has been applied, have shown expected glow curves that consisted of only the main dosimetric peak. The linear dose response was confirmed for the investigated doses ranging from 0.09 Gy to 0.92 Gy. Cycle B was used for the dosimeters irradiated with protons and calibration d simeters irradiated with 60Co. The glow curves showed two peaks as expected: the main peak and the high-temperature peak. The ratio of the high-temperature peak and the main peak was found to be greater than that for photon radiation. It is known from the literature that the ratio of the high-temperature peak to the main peak depends on the linear energy transfer (LET) of the indecent radiation and might be used to measure unknown LET. Unfortunately, we were not able to perform irradiations with protons of different energies or with other ions within the scope of this work. The dose dependence of the response for both peaks was tested by a linear fit and by calculating the linearity index. Due to the instability of the proton beam and large uncertainties in the frequency, linearity could not be confirmed for either of the peaks in the tested dose range (0.26-1.02) Gy.

• Keywords: termoluminiscentni dozimetri; LiF:Mg; Ti; protonska dozimetrija
• Keywords (english): thermoluminescent dosimeters; LiF:Mg; Ti; proton dosimetry
• Language: croatian
• URN:NBN: urn:nbn:hr:217:399790
• Project: Number: IP-2020-02-3593; Title: Karakterizicija radiofotoluminiscentnih dozimetara za mjerenja u poljima teško nabijenih čestica; Title: Characterisation of RadioPhotoLuminescent dosimeters for measurements in Heavy Charged Particle fields; Acronym: RPLforHCP; Leader: Marija Majer; Jurisdiction: Croatia; Funder: Hrvatska zaklada za znanost; Funding stream: Research Projects
• Study programme: Title: Physics; specializations in: Research; Course: Research; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra fizike (magistar/magistra fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-07-18 11:11:04