Mountain Scholar :: Browsing by Author "Menoni, Carmen, committee member"

Browsing by Author "Menoni, Carmen, committee member"

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Application and effects of metal-based therapeutics on cancer cell lines in tissue culture
(Colorado State University. Libraries, 2024) Klugh, Kameron Leigh, author; Crans, Debbie, advisor; Paton, Robert, committee member; Menoni, Carmen, committee member
In recent years, metal-based drugs have emerged as significant players in the field of therapeutics, leveraging the unique properties of metals to enhance medical treatments. These compounds, incorporating transition metals such as vanadium and platinum, have shown remarkable efficacy in treating various conditions, most notably cancer. The ability of such metals to form complex structures with organic molecules allows for precise targeting and modulation of biological pathways, leading to improved drug efficacy and reduced side effects. Thus, this approach has opened new avenues for designing advanced therapeutics such as vanadium(V) Schiff base catecholate complexes for the treatment of cancer. This thesis aims to explore the potential of non-innocent Schiff base vanadium(V) catecholate complexes as promising agents against glioblastoma, an aggressive form of brain cancer. Two catecholate ligands, 3,5-di-isopropyl catechol and 3,4,6-tri-isopropyl catechol, were synthesized and coordinated to both known and novel vanadium(V) Schiff base scaffolds. Upon testing on glioblastoma T98g cell lines, two of the new complexes, namely [VO(3-tBuHSHED)(TIPCAT)] and [VO(3,5-tBuHSHED)(TIPCAT)], showed remarkable antiproliferative activity. Parallelly, the manuscript delves into the therapeutic applications of platinum-based drugs and how the resistance of platinum-based chemotherapeutics remains a significant challenge. This area of the manuscript identifies the newly discovered role of long non-coding RNAs in platinum-resistance in gastrointestinal cancer treatment. The interaction of these drugs with cellular RNA, in addition to DNA, contributes to this resistance. This manuscript examines the speciation of cisplatin and oxaliplatin, their interactions with DNA and RNA, and the resulting physiological responses of long non-coding RNAs. It identifies aberrantly expressed lncRNAs in platinum-resistant gastrointestinal cancer cell lines, including those from oral cavity, esophageal, gastric, and colorectal cancers. Despite testing different cell lines, similar patterns of aberrant expression compared to normal cells suggest consistent changes in gene expression and cellular pathways. Understanding these changes may help develop new therapeutic strategies for gastrointestinal cancer patients. Together, the vanadium(V) complex investigations and the new insights into platinum-resistance underscore progress in the understanding of the molecular interactions of metal-based drugs, offering pathways to enhance their efficacy and overcome resistance in cancer therapy.
Open Access
Brillouin light scattering: a powerful tool for magnonics research
(Colorado State University. Libraries, 2024) Swyt, Mitchell S., author; Buchanan, Kristen S., advisor; Patton, Carl, committee member; Menoni, Carmen, committee member; Field, Stuart, committee member
The slow down in generation-over-generation improvement in CMOS based logic and storage devices has spurred recent exploration into magnonic devices, those based on propagating perturbations of magnetic order called magnons, or spin waves. These devices are of particular interest due to their chargeless, low-power operation, scalability to the nanoscale, and compatibility with existing CMOS technologies. By exploiting spin waves, information may be transferred and operated upon without electrical currents. Magnetic textures like Neel domain walls, chiral transitions between magnetic domains, or skyrmions, magnetic vortices, represent additional avenues in magnonics for data storage and logic devices. Magnonic crystals, artificial crystals made by modulating magnetic properties in a periodic fashion, are one example of magnonic devices that have seen recent interest. With applicability in logic and signal processing, study of how spin waves propagate through these crystals is a necessity in the pursuit of new crystal designs. Brillouin light scattering (BLS) spectroscopy, an inelastic light scattering technique, is a powerful tool in this pursuit, as it allows for the spatial and temporal mapping of spin wave propagation. In this thesis, we will discuss three studies of spin waves by BLS: a 1D magnonic crystal, a 2D magnonic crystal, and a study of the interfacial Dzyaloshinskii-Moriya interaction. First, time-resolved BLS was used to study the band gap formation in a 1D magnonic crystal. By mapping the propagation of spin wave pulses through the crystal, complex two dimensional interference patterns were observed. These patterns are ignored by the simple models used to understand the behavior of this crystal design, and we provide a model to calculate these patterns from the spin wave dispersion relation. The temporal development of interference that forms the basis for band gap formation in this system is also observed. Second, time-resolved BLS was used to study spin wave caustic beams in a 2D magnonic crystal. This crystal design represents a new regime in magnonic crystals, in which the patterning dimensions are much smaller than the spin wave wavelength and generate caustic beams. The formation of a narrow (3 MHz) wide rejection band is observed and the possible mechanisms, including edge effects and interference between caustic beams, are explored. Third, the temperature dependence of the interfacial Dzyaloshinskii-Moriya interaction (iDMI) is measured in a Pt/Co film for temperatures ranging from 15 K to room temperature. Previous studies have been reported for temperatures above room temperature and this study serves to test theory over a greater range of temperatures. The iDMI parameter was quantitatively measured by measuring the frequency difference for counter-propagating surface spin waves by BLS. These three studies demonstrate that BLS is a versatile and powerful tool in the field of magnonics.
Open Access
Calibration of the Pierre Auger Observatory fluorescence detectors and the effect on measurements
(Colorado State University. Libraries, 2015) Gookin, Ben, author; Harton, John, advisor; Toki, Walter, committee member; Buchanan, Kristen, committee member; Menoni, Carmen, committee member
The Pierre Auger Observatory is a high-energy cosmic ray observatory located in Malargue, Mendoza, Argentina. It is used to probe the highest energy particles in the Universe, with energies greater than 10¹⁸ eV, which strike the Earth constantly. The observatory uses two techniques to observe the air shower initiated by a cosmic ray: a surface detector composed of an array of more than 1600 water Cherenkov tanks covering 3000 km², and 27 nitrogen fluorescence telescopes overlooking this array. The Cherenkov detectors run all the time and therefore have high statistics on the air showers. The fluorescence detectors run only on clear moonless nights, but observe the longitudinal development of the air shower and make a calorimetric measure of its energy. The energy measurement from the the fluorescence detectors is used to cross calibrate the surface detectors, and makes the measurements made by the Auger Observatory surface detector highly model-independent. The calibration of the fluorescence detectors is then of the utmost importance to the measurements of the Observatory. Described here are the methods of the absolute and multi-wavelength calibration of the fluorescence detectors, and improvements in each leading to a reduction in calibration uncertainties to 4% and 3.5%, respectively. Also presented here are the effects of introducing a new, and more detailed, multi-wavelength calibration on the fluorescence detector energy estimation and the depth of the air shower maximum measurement, leading to a change of 1±0.03% in the absolute energy scale at 10¹⁸ eV, and a negligible change in the measurement on shower maximum.
Open Access
Chained sweet: nanoconfinement of carbohydrates
(Colorado State University. Libraries, 2017) Wiebenga-Sanford, Benjamin P., author; Levinger, Nancy, advisor; Fisher, Ellen, committee member; Barisas, George, committee member; Menoni, Carmen, committee member; Graham, James, committee member
Sugars and other carbohydrates play critical roles in a vast array of chemical and biological systems. In biological systems, the carbohydrates' environments are highly heterogeneous, including interfaces in cells and subcellular organelles, and on proteins. Nanoconfined aqueous environments also feature in these naturally and artificially occurring systems. The studies reported here explore glucose and other carbohydrate molecules, specifically ethylene glycol, glycerol, meso-erythritol, xylitol, sorbitol, myo-inositol, and trehalose, in the nanoconfined environments offered by reverse micelles, also referred to as water-in-oil mocroemulsions. I investigate how the nanoconfinement affects the carbohydrate behavior and how the carbohydrates affect the reverse micelles. I report the effect of carbohydrates on report the loading-ability of carbohydrates into the reverse micelles, demonstrate the location of the carbohydrates in the reverse micelle water pools, and show an unexpected effect where the carbohydrates to add to the reverse micelle volume without appearing to take up space. I use EXSY or Z-Z exchange spectroscopy to show that that the exchange rate between water and carbohydrate hydroxyl groups is substantially slower than it is in bulk aqueous solution and that it does not depend on hydrogen bonding between the carbohydrate and surfactant headgroup. These reverse micellar environments can provide unique platforms for confinement and as model systems for biological constructs. Results from these studies provide fundamental information to help us understand, predict and control carbohydrates, in particular glucose, in biological systems. Finally, I report on experiments utilizing steady-state fluorescence spectroscopy to characterize the nature of the reverse micellar interior, specifically the local "viscosity" via the response of a dye probe molecule. I also detail experiments that aimed to measure the aggregation number, that is, the number of surfactant molecules in the reverse micelles of varying water and carbohydrate loading. Although interesting, these studies did not yield the desired results.
Open Access
Design, simulation, and prototyping of wavelength-shifting plate light collector for a large water Cherenkov detector
(Colorado State University. Libraries, 2014) Johnston, William Albert, author; Buchanan, Norm, advisor; Wilson, Robert J., committee member; Sites, James, committee member; Menoni, Carmen, committee member
A wavelength-shifting plate light collector has been investigated for a proposed water Cherenkov detector for the Long-Baseline Neutrino Experiment. Experimental prototypes were fabricated from four different wavelength-shifting plastics and tested under uniform illumination as well as with a point source scanner. These laboratory tests were used to study the wavelength and position dependence of the plate's light collection. These results were then used to develop an optical model for the plates that was then used to estimate their effect on measuring neutrino events in the full water Cherenkov detector simulation. These results showed that it was possible to guide between 34% and 49% extra light to a 12" hemispherical PMT. In addition the plates were not found to adversely affect the particle identification abilities of the detector.
Open Access
Development of a high energy diode-pumped chirped pulse amplification laser system for driving soft x-ray lasers
(Colorado State University. Libraries, 2012) Reagan, Brendan A., author; Rocca, Jorge, advisor; Menoni, Carmen, committee member; Marconi, Mario, committee member; Krueger, David, committee member
There is significant interest in the development of compact high repetition rate soft x-ray lasers for applications. This dissertation describes the development of a high energy, laser diode pumped, chirped pulse amplification laser system for driving soft x-ray lasers in the 10-20 nm spectral region. The compact laser system combines room temperature and cryogenically-cooled Yb:YAG amplifier to produce 1.5 Joule pulses at up to 50 Hz repetition rate. Pulse compression results in 1 J pulses of 5 ps duration. A room temperature pre-amplifier maintains bandwidth for short pulse operation and a novel cryogenic cooling technique for the power amplifier was developed to enable high average power operation of this laser. This laser was used to drive a soft x-ray laser on the 18.9 nm line of nickel-like molybdenum. This is the first demonstration of a soft x-ray laser driven by an all diode-pumped laser.
Open Access
Development of a high power high energy ultrafast laser
(Colorado State University. Libraries, 2021) Chi, Han, author; Rocca, Jorge, advisor; Menoni, Carmen, committee member; Marconi, Mario, committee member; Lee, Siu Au, committee member
This dissertation describes the development of high energy, high repetition rate laser technology based on cryogenically cooled diode-pumped Yb:YAG laser amplifiers. The key challenges of thermal management, the generation of high energy green pulses at high repetition rate, and the design of an ultrafast laser amplifier that uses the green pulses as pump are discussed in this dissertation. To aid the development of thermal management solutions, an accurate, in situ, noninvasive optical technique to generate three-dimensional (3-D) temperature maps of cryogenic amplifiers during operation at high average power was demonstrated. The temperature is determined by analyzing the fluorescence spectra of the laser material (Yb:YAG) with a neural network algorithm. The accuracy of the technique relies on a calibration that does not depend on simulations. Results are presented for a cryogenic Yb:YAG active mirror laser amplifier operating at different pump conditions, which include kW pump power level operation. Based on this temperature measurement technique, an analysis of the thermal behavior of a high-energy kilowatt-average-power diode-pumped cryogenically cooled Yb:YAG active mirror laser amplifier is presented. Maps of the temperature distribution in the laser amplifier crystal at pump powers up to 1kW were obtained for the first time by spectrally resolving the fluorescence induced by a scanning probe beam. The cryo-temperature measurement technique is applicable to other solid-state lasers materials. The wavefront distortions resulting from the front surface deformation and the overall deformation of the gain medium assembly were measured using a Mach–Zehnder interferometer. The measured deformations agree well with the results of finite element thermomechanical modeling simulations, and with the results of focal length shift measurements. The relative contributions to the optical path difference (OPD) of the mechanical deformations, refractive index changes, and electronic contribution are discussed. The pump-induced mechanical deformations of the assembly dominate the OPD changes in the kilowatt-average-pump-power cryogenically cooled Yb:YAG active mirror laser investigated. The generation of green (λ= 515 nm) Joule-level pulses at 1 kHz repetition rate was demonstrated. This was achieved by frequency doubling 1.2 J, 2 ns temporally shaped square pulses from a cryogenically cooled Yb:YAG laser in an LBO crystal. The generation of 0.94 J second-harmonic pulses at 1 kHz was demonstrated with 78% conversion efficiency. The unconverted light was sent through a second LBO crystal to generate an additional >100 mJ second-harmonic pulses to reach a total green average power of 1.04kW. A higher conversion efficiency of 89% was also achieved for 0.58 J green pulses at 1 kHz. An application of this green laser is the pumping of high average power ultrafast laser amplifiers. The design of a two-stage water-cooled Ti:Sapphire amplifier system to generate 300 mJ pulses pre-compression using this green laser as pump is discussed. The simulation of the gain and thermal distribution of the 1st and 2nd stage amplifier are presented. The first experimental results of the operation of the first amplification stage of this laser system are discussed.
Open Access
Development of a liquid argon purity monitoring system
(Colorado State University. Libraries, 2023) Fogarty, Samuel J., author; Harton, John, advisor; Mooney, Michael, committee member; Menoni, Carmen, committee member
Liquid argon time-projection chambers (LArTPCs) are used to detect charged particles and measure their properties. Charged particles that pass through the liquid argon (LAr) in a LArTPC ionize and excite argon atoms, producing ionization electrons and prompt scintillation light. The ionization electrons drift through the LAr volume in a uniform electric field and produce a signal at the anode. The scintillation light is used to determine the drift coordinate of an event, which allows for 3D reconstruction of tracks and interactions. Electro-negative impurities lead to the reduction of the ionization electrons and scintillation light. They worsen a detector's ability to perform event reconstruction by reducing the signal-to-noise ratios. A purity monitor is a device that is often used alongside LArTPCs to monitor the LAr purity. It extracts electrons from a photo-cathode via the photoelectric effect and drifts them through LAr to an anode using an electric field. When traversing the purity monitor, some of the electrons will be lost due to impurities along the way. As a result, the drift-electron lifetime, which is related to the LAr impurity concentration, can be determined by measuring the difference in charge between the cathode and anode. This method allows for continuous purity monitoring of the LAr used in a LArTPC. This thesis describes the development and testing of a purity monitoring system that is used in conjunction with a LArTPC at Colorado State University.
Open Access
FLASH holographic microscopy using a compact extreme ultraviolet table top laser
(Colorado State University. Libraries, 2015) Monserud, Nils C., author; Marconi, Mario, advisor; Menoni, Carmen, committee member; Wu, Mingzhong, committee member
Microscopes allow our eyes to visualize objects at micro- and nanoscales. But there application are not limited to static images. The visualization of dynamic processes is necessary to understand complex systems on the micro- and nanoscales, Thus the need for microscopes capable of visualizing nanoscale processes, to further extend the development on micro- and nano-electromechanical devices (MEMS and NEMS). Conventional microscopy will not be sufficient for this purpose for two reasons the first is the spatial resolution is not sufficient to capture nanoscale objects and secondly if the object is moving out of plane the image taken needs to be adjusted using methods of post processing. To this end Fourier transform holography using and EUV light source was utilized to provide us with a method recording sub-micron oscillators. We recorded the oscillation of sub-micron pillars using time resolved extreme ultraviolet (EUV) Fourier transform Holography. The source utilized was a 46.9 nm tabletop capillary discharge with an EUV wavelength of 46.9nm, which provided large flux of coherent illumination. The bright illumination allowed for a modified Fresnel Zone plate to be used as a beam splitter. The modified Fresnel zone plate was able to produce a reference and object beam. This reference and object beam interfered creating a hologram. The reference wave is created by the first order focus while a central opening in the zone plate illuminates the object. Single-shot holograms allowed for the composition of a movie featuring the fast oscillation. Three-dimensional displacements of the object were determined as well by numerical back-propagation, or "refocusing" of the electromagnetic fields during the reconstruction of a single holography.
Open Access
Fundamental and applied studies of polymeric photonic crystals: the role of polymer architecture and 3D printing
(Colorado State University. Libraries, 2020) Boyle, Bret Michael, author; Miyake, Garret, advisor; McNally, Andrew, committee member; Menoni, Carmen, committee member; Prawel, David, committee member
Block copolymers (BCP) provide a bottom-up, economical approach to synthesizing polymeric photonic crystals (PC) through the process of self-assembly. Photonic crystals (PC) are defined as periodic, dielectric nanostructures able to reflect certain wavelengths of light within a photonic band gap. The ability to directly tailor the synthesis, conformation, and self- assembly of a BCP to affect the properties of the resulting PC material creates a modular platform for PC materials design. Even though this platform exists for polymeric PC materials, the direct result of modulating the polymer architecture on the dynamics, self-assembly, and application of PC materials remains relatively unexplored. To help close this gap, this dissertation presents the polymer synthesis, characterization, and self-assembly of macromolecules within two unique classes of polymer architecture, dendritic block copolymers (DBCP) and bottlebrush block copolymers (BBCP). DBCPs were shown to possess many characteristics similar to those of bottlebrush polymers such as a rod-like conformation, a reduced capability for chain entanglement, and lower glassy moduli compared to non-rigid, linear polymers. Further, DBCPs possess high free energy parameters, as well as glass transition temperatures below melt extrusion 3D printing operating conditions, and were shown to self- assemble into PCs during the process of 3D printing. DBCP PCs represented the first example of 3D printing structural color. For BBCPs, the backbone composition's effect on the global BBCP conformation and in modulating self-assembly processes was examined. The backbone composition was shown to dramatically shift the wavelength of reflection of the PC material at similar molecular weights as well as improve the fidelity of the nanostructure morphology as the molecular weight increases from 50,000 g/mol to 2 million g/mol. The structure-property relationships illuminated herein have laid the groundwork for new research efforts into engineering BCPs for novel PC applications.
Open Access
Growth and characterization of ultra-low damping Co₂₅Fe₇₅ thin films
(Colorado State University. Libraries, 2020) Swyt, Mitchell, author; Buchanan, Kristen, advisor; Ross, Kate, committee member; Menoni, Carmen, committee member
This thesis focuses on the growth and characterization of ultra-low damping Co25Fe75 thin films. Ultra-low damping in a metal is of interest for the design of new spintronic devices because this offers the opportunity to move both electrons and spin waves over appreciable distances. In this work, the effects of seed and capping layers on the damping parameter and magnetization are investigated. A series of thin films were deposited using DC magnetron sputtering. A combination of X-ray reflectometry (XRR), vibrating sample magnetometry (VSM), and ferromagnetic resonance spectroscopy (FMR) were used to determine the film quality, saturation magnetization, and damping parameters of each film. The results show that the Ta seed layers promoted smooth film growth for Co25Fe75, but direct interfaces with Ta or Pt resulting in enhanced damping. Cu spacer layers can be used to disrupt the enhancement but promote rough film growth for the studied sample growth conditions. Damping values in agreement with published results were achieved for two films from the set, with α=0.0064 ± 0.0004 for Ta/Co25Fe75 and α=0.0063 ± 0.0011 for Ta/Cu/Co25Fe75/Cu/Ta.
Open Access
High-power deep-UV laser for improved and novel experiments on hydrogen
(Colorado State University. Libraries, 2019) Burkley, Zakary Neumann, author; Yost, Dylan, advisor; Roberts, Jacob, committee member; Bradley, Mark, committee member; Menoni, Carmen, committee member
This dissertation details the design, performance, and cavity enhancement of a novel, high-power coherent 243.1 nm laser system, and through simulations, its ability to trap hydrogen in a magic wavelength optical trap. This wavelength of light is necessary to address the 1S–2S two-photon transition in hydrogen, and the primary motivation behind development of this laser system is obtaining high enough 243.1 nm powers for two-photon cooling of hydrogen. Due to the light mass of hydrogen, high precision spectroscopy of hydrogen is limited by unwanted motional effects, which could be mitigated with laser cooling and confinement in an optical trap. Besides laser cooling, a high power deep-UV laser system at this wavelength has great utility for improving spectroscopy of hydrogen and other exotic simple systems. High-power fiber lasers from 1-1.2 µm have flourished as a result of advances in ytterbium(Yb)-doped fiber amplifiers. In addition, high-power Yb-fiber lasers between 975-980 nm have also been developed—a notable accomplishment due to gain competition in the > 1 µm spectral region. These systems initially lacked sufficiently narrow spectral bandwidth for efficient harmonic generation, motivating further development since there is significant interest in frequency doubling and quadrupling these sources to produce coherent blue radiation and deep-UV radiation. Here, we generate coherent, high-power deep-UV radiation through frequency quadrupling of a high-power, highly coherent Yb-fiber amplifier at 972.5 nm. The Yb-fiber amplifier system consists of a frequency stabilized master oscillator power amplifier (MOPA) that can be referenced to a coherent frequency comb. This MOPA can be amplified to > 10 W of narrow linewidth power at 972.5 nm in the Yb-fiber amplifier. This is a technically challenging and notable result for this wavelength as gain is much more readily obtained in Yb-doped fibers at the absorption/emission cross-section peak near 975 nm and in the > 1 µm spectral region where the emission cross-section is much larger than the absorption cross-section. This system successfully combated unwanted gain at these wavelengths by using a relatively short (≈ 10 cm), angle-polished Yb-fiber with a large core-cladding ratio, along with aggressive spectral filtering and large amounts of seed power at 972.5 nm. With this narrow linewidth Yb-fiber amplifier, efficient frequency conversion of high power 972-976 nm radiation to 243-244 nm radiation is possible through intracavity doubling. Through successive resonant doubling stages, this system demonstrates > 1 W of highly stable, continuous-wave (CW) 243.1 nm power. To the author's knowledge, this is a record amount of CW deep-UV power below 266 nm, and is made possible thanks to advances in the production of a relatively new non-linear crystal for robust deep-UV generation, cesium lithium borate (CLBO). The precise frequency control of this radiation is established via excitation of the 1S–2S transition in hydrogen, and the viability for two-photon laser cooling on this transition is shown through enhancement of this power to > 30 W of intracavity power in a deep-UV enhancement cavity. At these powers, UV-induced mirror degradation was observed and mitigated by flushing the enhancement cavity mirrors with ultra-pure oxygen. With these powers, rapid two-photon laser cooling of a hydrogen atomic beam approaches reality. The 243.1 nm powers offered by this laser system also offer unique methods for capturing hydrogen in an optical trap. Explored via simulations, single optical scatter capture of hydrogen in a magic wavelength dipole trap is demonstrated, promising exciting new avenues for high precision spectroscopy of hydrogen.
Open Access
Highly relativistic laser interactions with ordered nanostructures
(Colorado State University. Libraries, 2019) Hollinger, Reed, author; Rocca, Jorge J., advisor; Prieto, Amy L., committee member; Menoni, Carmen, committee member; Marconi, Mario, committee member
Heating high density matter to extreme temperatures has been one of the primary motivations behind the construction of high power laser facilities around the world. The creation of simultaneously hot (multi-keV) and dense (on the order of a solid) plasma with small scale and mid-scale lasers is a difficult problem due to the barrier that the critical electron density imposes to optical lasers, typically limiting the heating to a very thin plasma into which the laser is inefficiently coupled. Experiments conducted at Colorado State University with joule level laser pulses have demonstrated that using high contrast, relativistic laser pulses it is possible to efficiently heat near solid density nanowire arrays volumetrically to multi-keV temperatures. This dissertation extends these results to the highly relativistic regime, demonstrating extremely high ionization states for volumes >5μm in depth. These relatively large volume plasmas have longer hydrodynamic cooling times while their radiative cooling time is greatly decreased due to the near solid electron densities. This results in very efficient conversion of optical laser light into x-rays since the plasma is able to radiate away more of its' energy as x-rays before cooling due to hydrodynamic expansion. With this technique, an x-ray conversion efficiency of nearly 20% was measured for photon energies greater than 1keV. After a significant upgrade to the laser, these interactions were explored at highly relativistic intensities up to 4x1021 Wcm−2, nearly 1000 times higher than initial experiments. Measurements of the energy deposition dynamics, including the time limit for energy coupling and the volume of the nanowire plasma were carried out in comparison to solid targets. The results show that at these intensities, it is possible to generate unprecedented degrees of ionization never before obtained with ultrashort pulse lasers, such as H-like Ni (27 times ionized) and Ne-like Au (69 times ionized).
Open Access
Measurement of νμ induced charged current inclusive cross section on water using the near detector of the T2K experiment
(Colorado State University. Libraries, 2016) Das, Rajarshi, author; Toki, Walter, advisor; Wilson, Robert, committee member; Berger, Bruce, committee member; Menoni, Carmen, committee member
The Tokai to Kamioka (T2K) Experiment is a long-baseline neutrino oscillation experiment located in Japan with the primary goal to measure precisely multiple neutrino flavor oscillation parameters. An off-axis muon neutrino beam peaking at 600 MeV is generated at the JPARC facility and directed towards the 50 kiloton Super-Kamiokande (SK) water Cherenkov detector located 295 km away. Measurements from a Near Detector that is 280m downstream of the neutrino beam target are used to constrain uncertainties in the beam flux prediction and neutrino interaction rates. We present a selection of inclusive charged current neutrino interactions on water. We used several sub-detectors in the ND280 complex, including a Pi-Zero detector (P0D) that has alternating planes of plastic scintillator and water bag layers, a time projection chamber (TPC) and fine-grained detector (FGD) to detect and reconstruct muons from neutrino charged current events. We use a statistical subtraction method with the water-in and water-out inclusive selection to extract a flux-averaged, νμ induced, charged current inclusive cross section. We also outline the evaluation of systematic uncertainties. We find an absolute cross section of ⟨σ⟩Φ = (6.37 ± 0.157(stat.) (−1.060/+0.910(sys.)) × 10−39 (cm2/H2O nucleon). This is the first νμ charged current inclusive cross section measurement on water.
Open Access
Mobility and fluorescence of barium ions in xenon gas for the EXO experiment
(Colorado State University. Libraries, 2014) Benitez Medina, Julio Cesar, author; Fairbank, William, advisor; Berger, Bruce, committee member; Lundeen, Stephen, committee member; Menoni, Carmen, committee member
The Enriched Xenon Observatory (EXO) is an experiment which aims to observe the neutrinoless double beta decay of 136Xe. The measurement of this decay would give information about the absolute neutrino mass and whether or not the neutrino is its own antiparticle. Since this is a very rare decay, the ability to reject background events by detecting the barium ion daughter from the double beta decay would be a major advantage. EXO is currently operating a detector with 200 kg of enriched liquid xenon, and there are plans to build a ton scale xenon detector. Measurements of the purity of liquid xenon in our liquid xenon test cell are reported. These results are relevant to the research on detection of single barium ions by our research group at Colorado State University. Details of the operation of the purity monitor are described. The effects of using a purifier, recirculation and laser ablation on the purity of liquid xenon are discussed. Mobility measurements of barium in xenon gas are reported for the first time. The variation of mobility with xenon gas pressure suggests that a significant fraction of molecular ions are formed when barium ions interact with xenon gas at high pressures. The measured mobility of Ba+ in Xe gas at different pressures is compared with the predicted theoretical value, and deviations are explained by a model that describes the fraction of molecular ions in Xe gas as a function of pressure. The results are useful for the analysis of experiments of fluorescence of Ba+ in xenon gas. It is also important to know the mobility of the ions in order to calculate the time they interact with an excitation laser in fluorescence experiments and in proposed 136Ba+ daughter detection schemes. This thesis presents results of detection of laser induced fluorescence of Ba+ ions in Xe gas. Measurements of the pressure broadening of the excitation spectra of Ba+ in xenon gas are presented. Nonradiative decays due to gas collisions and optical pumping affect the number of fluorescence counts detected. A model that treats the barium ion as a three level system is used to predict the total number of fluorescence counts and correct for optical pumping. A pressure broadening coefficient for Ba+ in xenon gas is extracted and limits for p-d and d-s nonradiative decay rates are extracted. Although fluorescence is reduced significantly at 5-10 atm xenon pressure, the measurements in this thesis indicate that it is still feasible to detect 136Ba+ ions directly in high pressure xenon gas, e.g. in a double beta decay detector.
Open Access
Spin currents and ferromagnetic resonance in magnetic thin films
(Colorado State University. Libraries, 2017) Ellsworth, David, author; Wu, Mingzhong, advisor; Camley, Robert, committee member; Menoni, Carmen, committee member; Patton, Carl, committee member; Sites, James, committee member
Spin currents represent a new and exciting phenomenon. There is both a wealth of new physics to be discovered and understood, and many appealing devices which may result from this area of research. To fully realize the potential of this discipline it is necessary to develop new methods for realizing spin currents and explore new materials which may be suitable for spin current applications. Spin currents are an inherently dynamic phenomenon involving the transfer of angular momentum within and between different thin films. In order to understand and optimize such devices the dynamics of magnetization must be determined. This dissertation reports on novel approaches for spin current generation utilizing the magnetic insulators yttrium iron garnet (YIG) and M-type barium hexagonal ferrite (BaM). First, the light-induced spin Seebeck effect is reported for the first time in YIG. Additionally, the first measurement of the spin Seebeck effect without an external magnetic field is demonstrated. To accomplish this the self-biased BaM thin films are utilized. Second, a new method for the generation of spin currents is presented: the photo-spin-voltaic effect. In this new phenomenon, a spin current may be generated by photons in a non-magnetic metal that is in close proximity to a magnetic insulator. On exposure to light, there occurs a light induced, spin-dependent excitation of electrons in a few platinum layers near the metal/magnetic insulator interface. This excitation gives rise to a pure spin current which flows in the metal. This new effect is explored in detail and extensive measurements are carried out to confirm the photonic origin of the photo-spin-voltaic effect and exclude competing effects. In addition to the spin current measurements, magnetization dynamics were probed in thin films using ferromagnetic resonance (FMR). In order to determine the optimal material configuration for magnetic recording write heads, FMR measurements were used to perform damping studies on a set of FeCo samples with different numbers of lamination layers. The use of lamination layers has the potential to tune the damping in such films, while leaving the other magnetic properties unchanged. Finally, the sensitivity of the vector network analyzer FMR technique was improved. The use of field modulation and lock-in detection, along with the background subtraction of a Mach-Zehnder microwave interferometer working as a notch filter, is able to increase the sensitivity and lower the background noise of this measurement technique. This improved system opens the possibility of probing previously difficult samples with extremely low signals.
Open Access
Strategies for targeting cancer: small molecules, epigenetics and drug design
(Colorado State University. Libraries, 2020) Hassell, Kelly N., author; Crans, Debbie C., advisor; Brown, Mark A., advisor; Roess, Deborah, committee member; Menoni, Carmen, committee member
Cancer has plagued our human population since its early characterizations as abnormal cells and tissues in the mid-1900s. Initial treatment models included surgical removal of cancerous tissues. In the late 1960s, surgical removal and localized radiation were the only available options for treatment until the development of chemotherapeutics. These chemical cocktail treatments, designed to kill cancer cells, started in the late-1900s and even today remain a major line of defense in fighting this disease. The goal of the research described in this dissertation was to investigate current methodologies and techniques used to treat cancer; treatments utilizing chemotherapeutics, small molecule interactions, metallocage drug delivery, epigenetics and protein activity inhibition. The first part of my research focused on the significance of Cisplatin as a chemotherapeutic. My findings indicate the unexpected speciation of platinum in the human body as a revelation to be utilized in novel drug design. In my reverse micelle study, the hydrolysis of the Schiff-base compound was observed to be dependent on the size of reverse micelles; resulting in partial phase selectivity. The reverse micelle model provided ample support for engineering various types of liposomal delivery options for insoluble compounds like Cisplatin. My metallocage research explored the idea of utilizing a self-assembling Cisplatin protective capsule with fluorophores, equipped to monitor real-time cancer cell death as well as drug delivery. My findings support the efficacy of metallocages for delivery of cancer therapeutics and the necessity for continued methodology development for clinical applications. The second part of my research focused on the use of epigenetics for gene expression regulation and protein activity inhibition. My findings reported the most recent status of drugs developed using histone deacetylases (HDAC) and histone deacetylases inhibitors (HDACi) for targeting specific cancers. And in my final chapter of SET-domain proteins, my research focused on comparing the methyltransferase activity inhibition of SMYD3 in two different cancer cells lines. The data showed the A549 lung cell line is slightly more sensitive to the SMYD3 activity inhibitor. This dissertation describes work that has increased our collective understanding of cancer therapeutics. Furthermore, it vastly supports future cancer treatment investigations utilizing both small molecules and bioinformatics.
Open Access
Studies of tuning magnetic properties of ferromagnetic heterostructures
(Colorado State University. Libraries, 2020) Lauzier, Joshua, author; de la Venta Granda, Jose, advisor; Buchanan, Kristen, committee member; Gelfand, Martin, committee member; Field, Stuart, committee member; Menoni, Carmen, committee member
The magnetic properties of hybrid systems have increasingly become an area of intense focus in both fundamental research and technological application due to the inherent flexibility in material properties by mixing and matching various constituent components. One particularly interesting choice is hybrid heterostructures that consist of ferromagnetic (FM) materials and materials that undergo phase transitions, coupled via structural, electronic, and/or magnetic coupling. Two canonical examples of phase transition materials are vanadium dioxide (VO2) and iron rhodium (Fe50Rh50, abbreviated FeRh). Both materials undergo structural phase transitions (SPT). With increasing temperature, VO2 transitions from a low temperature monoclinic to high temperature rutile structure at 340 K. The SPT is concurrent with a 4-5 orders of magnitude metal to insulator transition (MIT) from a low temperature insulating phase to a high temperature metallic phase. Similarly, FeRh undergoes an isotropic 1% volume expansion at 370 K with increasing temperature. Coincident with the SPT, FeRh also undergoes a magnetic transition from a low temperature antiferromagnetic (AF) to a high temperature ferromagnetic (FM) phase, which is unusual for magnetic materials. The delicate nature of these transitions makes them sensitive to parameters such as stoichiometry, growth conditions, and external stimuli, which allows for high tunability of their respective phase transitions. In this thesis, we first show in Chapter 3 that the surface morphology and MIT properties of sputtered VO2 thin films can be tuned via deposition conditions such as deposition temperature and O2 flow rate during the sputtering process while maintaining the quality of the VO2 transition. Films grown at higher temperatures (>525 ℃) and low O2 flow rate show sub 2 nm surface roughness. Higher temperatures lead to a 'melted'-like surface morphology along with a 5 orders of magnitude MIT, comparable to single crystals. Choice of substrate allows another avenue to strongly tune both the morphology and the MIT characteristics while maintaining a strong VO2 transition due to lattice mismatch. In Chapter 4, we turn to a discussion of VO2/Ni bilayer structures, where the temperature induced VO2 SPT will impart a strain across the interface into the FM layer, which will then influence the magnetic properties via magnetoelastic coupling. Due to an inverse magnetostrictive effect the coercivity and magnetization of the FM layer can be strongly modified. Tuning the VO2 SPT via growth conditions or substrate choice then allows for tuning the coupled magnetic properties of the FM. For sufficiently smooth films, there is a strong enhancement in the coercivity localized close to their respective SPT Tc due to phase coexistence in the SPT material. This chapter is largely based on work previously published as "Coercivity enhancement in VO2/Ni bilayers due to interfacial stress" in Journal of Applied Physics.1 VO2/FM hybrid films also show a dependence on the growth conditions during the FM deposition, which is explored in Chapter 5. Films with the FM deposited above the VO2 phase transition critical temperature (Tc) show a high coercivity below Tc and a low coercivity above Tc, whereas films deposited below Tc show the opposite behavior. Films deposited below Tc also show an irreversibility in their magnetic properties the first time they are thermally cycled. A similar irreversibility is observed in the resistance vs. temperature (R vs. T) properties of bare VO2 films, and cracking as the VO2 crosses the SPT is proposed as a common mechanism. The plausibility of cracking as a mechanism is investigated via computational modeling of the R vs. T properties in a random resistor network, as well as probed directly via Atomic Force Microscopy (AFM). The work shown in this chapter has been previously published under the title "Magnetic irreversibility in VO2/Ni bilayers" in Journal of Physics: Condensed Matter.2 Sputtered FeRh/FM bilayer films show a similar sensitivity as the VO2/FM system to the growth conditions, with the coercivity below Tc tunable whether the FM is initially deposited above or below Tc. Above Tc, the magnetic FeRh phase adds an additional complication, dominating the magnetic response via exchange coupling. This effect is explored in FeRh/Ni bilayer systems in Chapter 6. Polarized neutron reflectometry (PNR) allows for depth dependent structural and magnetic characterization with nanometer resolution. PNR measurements show that the bilayer's magnetic behavior below Tc is likely driven by magnetoelastic effects due to the structural transition of the FeRh, rather than simple magnetic coupling or a pinned interfacial FM layer. The overall magnetic properties of the bilayers are therefore a product of both structural and magnetic coupling between the FeRh and the FM Ni layer. The results of this chapter have been previously published as "Using structural phase transitions to enhance the coercivity of ferromagnetic films" in Applied Physics Letters Materials.
Open Access
Study of collective beam effects in energy recovery linac driven free electron lasers
(Colorado State University. Libraries, 2016) Hall, Christopher C., author; Biedron, Sandra, advisor; Milton, Stephen, advisor; Menoni, Carmen, committee member; Fairbank, William, committee member
Collective beam effects such as coherent synchrotron radiation (CSR) and longitudinal space charge (LSC) can degrade the quality of high-energy electron beams used for applications such as free-electron lasers (FELs). The advent of energy recovery linac (ERL)-based FELs brings exciting possibilities for very high-average current FELs that can operate with greater efficiency. However, due to the structure of ERLs, they may be even more susceptible to CSR. It is therefore necessary that these collective beam effects be well understood if future ERL-based designs are to be successful. The Jefferson Laboratory ERL driven IR FEL provides an ideal test-bed for looking at how CSR impacts the electron beam. Due to its novel design we can easily test how CSR's impact on the beam varies as a function of compression within the machine. In this work we will look at measurements of both average energy loss and energy spectrum fragmentation as a function of bunch compression. These results are compared to particle tracking simulations including a 1D CSR model and, in general, good agreement is seen between simulation and measurement. Of particular interest is fragmentation of the energy spectrum that is observed due to CSR and LSC. We will also show how this fragmentation develops and how it can be mitigated through use of the sextupoles in the JLab FEL. Finally, a more complete 2D model is used to simulate CSR-beam interaction. Due to the parameters of the experiment it is expected that a 2D CSR model would yield different results than the 1D CSR model. However, excellent agreement is seen between the two CSR model results.
Open Access
The development of a thin film sputter deposition system using a novel hidden anode ion source and motion control
(Colorado State University. Libraries, 2020) VanGemert, Jack J., author; Williams, John D., advisor; Farnell, Casey, committee member; Menoni, Carmen, committee member; Wilson, Jesse, committee member
Thin films consist of metallic or dielectric materials that are commonly deposited onto surfaces where properties, intrinsic to the thin film, are desired. Ranging from a single atomic layer to several microns in thickness, thin films are found to be useful for a broad range of applications. Most thin film applications desire uniform, durable, and adherent coatings with specific optical, electrical, or tribological properties. Therefore it is important that deposition systems can produce thin films with properties suited for the application at hand. The development of a thin film sputter deposition system is presented. The system has been shown to produce large area art pieces at a low cost compared to current deposition systems. The deposition system uses a novel hidden anode ion source (HAIS) to sputter target material, assist film growth, and to clean substrates prior to deposition. To the author's knowledge, an ion source of this design has not been implemented in a deposition system prior to the one discussed. The characterization of a novel ion source is presented in detail along with the other system components. Deposition rates and thin film profiles are used to validate experimental results and predict thin film properties for various operating conditions. Coatings produced by the system are studied and used to determine film characteristics of interest to the application of outdoor art. Structural thin film properties of interest for long outdoor lifetime art work include film adhesion, density, and residual stress. Visual thin film properties important for the artwork are related to optical properties such as reflection, transmission, and absorption. The plasma-based deposition system is shown to be a tool of high potential for creating engaging, long lifetime art pieces.