Mjerenje zaustavne moći za ione vodika MeV-skih energija u dijamantu

master's thesis

• Title (english): Stopping power measurement for hydrogen ions with MeV energies in diamond
• Author: Matija Matijević
• Mentor: Zdravko Siketić (mentor)
• Mentor: Petar Žugec (komentor)
• Committee member: Petar Žugec (predsjednik povjerenstva)
• Committee member: Zdravko Siketić (član povjerenstva)
• Committee member: Matko Milin (član povjerenstva)
• Committee member: Ivica Friščić (član povjerenstva)
• Committee member: Nils Paar (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2022-06-23, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Dijamant je poluvodički materijal širokog zabranjenog pojasa i izvrsnih mehaničkih svojstava. Posljednjih godina raste zanimanje za umjetno proizvedenim dijamantima visoke čistoće koji se primjenjuju kao čestični detektori u fizici visokih energija, što u radioterapiji kao dozimetri, a potencijalno i u kvantnim računalima u kojima se istražuje primjena NV (engl. nitrogen vacancy) centara pri izradi kvantnih bitova (engl. qubits). Upravo iz tih razloga veliki se napori ulažu u detaljnu karakterizaciju svojstava dijamanta poput: električne otpornosti, širina zabranjenog pojasa (engl. band gap), mobilnosti nosioca naboja, zaustavne moći, itd. U ovom radu je mjerena zaustavna moć za protonske snopove energija u rasponu od 1.6 do 6 MeV-a koji prolaze kroz tanki kristal sintetičkog dijamanta, realiziran kao samopodržavajuća membrana mikrometarske debljine. Najprije, kako bi se moglo precizno odrediti zaustavnu moć, bilo je potrebno odrediti debljinu same membrane te su za to korištena dvije različite metode: indirektno mjerenjem apsorpcije x-zraka u membrani tzv. PIXE (engl. particle-induced x-ray emission) metodom i direktno iz snimaka ruba membrane dobivenih pretražnom elektronskom mikroskopijom (engl. scanning electron microscopy, SEM). Nakon toga je izmjeren gubitak energije protonskog snopa pri prolasku kroz membranu tzv. STIM (engl. scanning transmission ion microscopy) metodom te je iz dobivenih mjerenja određena zaustavna moć protona MeV-skih energija u dijamantu. Dobiveni rezultati uspoređeni su s vrijednostima zaustavne mo´ci dobivene u Monte Carlo simulacijama unutar SRIM (engl. Stopping and Range of Ions in Matter) programskog paketa i eksperimentalnim rezultatima drugih autora. Naposlijetku, određen je energijski rasap u dijamantu te su rezultati također uspoređeni s vrijednostima dobivenim pomoću SRIM programskog paketa.

Abstract (english)

Diamond is a semiconductor material with a wide band gap and excellent mechanical properties. In the last few years interest for high purity synthetic diamonds is growing due to its various applications ranging from high energy physics (particle detectors), radiotherapy (dosimeters) to quantum computing in which nitrogen vacancy (NV) centers in diamond are being researched as a possible way of creating qubits. For these reasons extensive efforts are being made to characterize the properties of synthetic diamond such as: electrical resistivity, band gap width, mobility of free charge carriers, stopping power, etc. In this work, stopping power for proton beams of energies ranging from 1.6 to 6 MeV pass through a thin crystal of synthetic diamond which is made as a self-supporting membrane of micrometer thickness. Firstly, in order to properly calculate the stopping power, the thickness of the membrane needed to be measured for which two different methods were used: indirectly by measuring the absorption of x-rays in the membrane via the so-called PIXE (particle induced x-ray emission) method and directly from pictures of the membrane’s edge obtained with scanning electron microscopy (SEM). After the membrane thickness was calculated, the energy loss inside the membrane was measured using the so-called STIM (scanning transmission ion microscopy) technique from which the stopping power for MeV protons in diamond was calculated. The stopping power for diamond was calculated and cross referenced with stopping power data obtained by Monte Carlo simulations from SRIM (Stopping and Range of Ions in Matter) and experimental data from other authors. Finally, energy straggling was calculated and cross referenced with values obtained via the SRIM program.

• Keywords: dijamantna membrana; zaustavna mo´c; energijski rasap; SRIM; PIXE; SEM; STIM
• Keywords (english): diamond membrane; stopping power; energy straggling; SRIM; PIXE; SEM; STIM
• Language: croatian
• URN:NBN: urn:nbn:hr:217:173607
• 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: 2022-07-01 08:31:03