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Positron Annihilation Ratio Spectroscopy (Psars) Applied to Positronium Formation Studies Robert C

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Positron Annihilation Ratio Spectroscopy (Psars) Applied to Positronium Formation Studies Robert C Air Force Institute of Technology AFIT Scholar Theses and Dissertations Student Graduate Works 3-10-2010 Positron Annihilation Ratio Spectroscopy (PsARS) Applied to Positronium Formation Studies Robert C. Slaughter Follow this and additional works at: https://scholar.afit.edu/etd Part of the Atomic, Molecular and Optical Physics Commons, and the Elementary Particles and Fields and String Theory Commons Recommended Citation Slaughter, Robert C., "Positron Annihilation Ratio Spectroscopy (PsARS) Applied to Positronium Formation Studies" (2010). Theses and Dissertations. 2182. https://scholar.afit.edu/etd/2182 This Thesis is brought to you for free and open access by the Student Graduate Works at AFIT Scholar. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of AFIT Scholar. For more information, please contact [email protected]. POSITRON ANNIHILATION RATIO SPECTROSCOPY (PsARS) APPLIED TO POSITRONIUM FORMATION STUDIES THESIS Robert C. Slaughter, 2nd Lieutenant, USAF AFIT/GNE/ENP/10-M07 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED The views expressed in this prospectus are those of the author and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States Government. AFIT/GNE/ENP/10-M07 POSITRON ANNIHILATION RATIO SPECTROSCOPY (PsARS) APPLIED TO POSITRONIUM FORMATION STUDIES THESIS Presented to the Faculty Department of Engineering Physics Graduate School of Engineering and Management Air Force Institute of Technology Air University Air Education and Training Command In Partial Fulfillment of the Requirements for the Degree of Masters of Science Robert C. Slaughter 2nd Lieutenant, USAF March 2010 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED AFIT/GNE/ENP/10-M07 POSITRON ANNIHILATION RATIO SPECTROSCOPY (PsARS) APPLIED TO POSITRONIUM FORMATION STUDIES Robert C. Slaughter 2nd Lieutenant, USAF Approved: Date ____________________________________ Dr. Larry W. Burggraf, PhD (Chairman) ____________________________________ Dr. James Petrosky, PhD (Member) ____________________________________ Capt Benjamin Kowash, PhD (Member) ____________________________________ Dr. Ioana Pavel, PhD (Member) AFIT/GNE/ENP/10-M07 Abstract A Positron Annihilation of Radiation Spectrometer (PsARS) was developed and characterized. PsARS spectroscopy as well as digital Positron Annihilation Lifetime Spectroscopy (PALS) was applied to measure positronium formation on gold nanoparticles deposited through an evaporative method onto a thin capillary tube. This gold coated capillary tube was designed to be used for positronium lifetime studies in local electric field experiments. High local electric fields can polarize a positron-electron pair, which may result in an extended lifetime of the positron. These fields may be created through the interaction of an external electric field with silver nanoparticles deposited onto the surface of gold coated capillary tubes. The capability to control size and distribution of silver nanoparticles on such a surface is demonstrated. PsARS analysis of potassium dodecahydrododecaborate (dodecaborate) solutions was also performed to verify positronic dodecaborate species as well as potential positronium quenching. iv AFIT/GNE/ENP/10-M07 To my beautiful bride to be v Acknowledgements I want to thank my advisor Dr. Larry Burggraf for his motivation and never ending insight throughout this thesis experience. The countless number of extended conversations has lead me to a deeper understanding of the world around me. I want to thank my committee members Captain Benjamin Kowash and Dr. James Petrosky for their assistance throughout this thesis process. I also want to especially thank my other committee member Dr. Ioana Pavel and all of her students, for opening up her chemistry laboratory to me. Your continual shared expertise in a subject matter that I was not at all originally familiar with has greatly broadened my education. I also would like to especially thank Lt. Col Chris Williams for setting me up to hit the ground running on my thesis. Your time, assistance, and collaboration are insurmountably appreciated. Also, Mr. Eric Taylor who assisted me through a countless number of day to day technical issues, Dr. Michael Lindsay for his expertise regarding digital PALS and the opportunity to go TDY to Eglin AFB as well as present at the IEEE NSS. I most certainly also am grateful for the AFIT clean room expertise of Mr. Rick Patton and Mr. Rich Johnson whose technical expertise on the AFIT SEM and plasma deposition systems were essential in order for this research project to come to fruition. For Dr. Daniel Felker for his expertise and oversight for experimentation within the chemical hood, and Lt. Nick Herr for sharing his hard earned expertise on the AFM machine. I would also like to especially acknowledge Eglin AFRL Energetic Materials branch for their sponsorship, the Air Force Office of Scientific Research (AFOSR), and the Nation Nuclear Security Administer (NNSA) for their financial support of this research. Robert Slaughter vi Table of Contents Page Abstract .............................................................................................................................. iv Table of Contents .............................................................................................................. vii 1.Introduction .......................................................................................................................1 1.1 Motivation ............................................................................................................1 1.2 Overview ..............................................................................................................2 2.Positron Theory .................................................................................................................5 2.1 History .................................................................................................................5 2.2 Positron Sources ..................................................................................................5 2.3 Annihilation .........................................................................................................7 2.4 Positronium ..........................................................................................................9 2.5 Positron Interactions with Metals ......................................................................11 2.6 3γ/2γ Positron Annihilation Ratios ....................................................................11 2.7 Positron Lifetimes in External Fields ................................................................15 3.Design and Implementation of a PsARS Detector ..........................................................19 3.1 3γ/2γ Positron Annihilation Ratios ....................................................................19 3.1.1 3γ/2γ Positron Annihilation Experiment Overview .......................................19 3.1.2 PsARS Detector Calibration, Efficiency, and Resolution .............................24 3.1.3 3γ/2γ Positron Annihilation Chance Coincidence Correction .......................... Factors ............................................................................................................32 3.2 Coincidence PsARS Algorithm .........................................................................39 3.3 3γ Correction Terms ..........................................................................................41 3.4 PsARS Analysis of Copper ................................................................................46 3.5 Non-Coincident PsARS .....................................................................................52 3.6 Dodecaborate Solutions .....................................................................................54 3.6.1 Overview ........................................................................................................54 3.6.2 Dodecaborate Solution Preparation ...............................................................57 3.6.3 Dodecaborate PsARS measurements .............................................................58 3.6.4 Dodecaborate Conclusion ..............................................................................61 4.Silver Nanoparticle Array Construction on Gold Capillary Tube ..................................62 vii Page 4.1 Overview ............................................................................................................62 4.2 Gold Coating Capillary Tube .............................................................................64 4.3 XRF Images of Gold Coated Capillary Tubing .................................................66 4.4 SEM Images of Gold Coated Capillary Tubing ................................................68 4.5 AFM Images of Gold Coated Capillary Tubing ................................................73 4.6 Silver Nanoparticle Colloid ...............................................................................75 4.7 Silver Nanoparticle and Linker Construction ....................................................82 4.7.1 SEM Imaging of Silver Nanoparticles ...........................................................86 4.7.2 SEM Imaging of Silver Nanoparticles Conclusion .....................................104 4.8 AFM Images of
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