Nuclear Commons^™

Radiation Effects On The Electrical Properties Of Hafnium Oxide Based Mos Capacitors, Jesse C. Foster

Theses and Dissertations

Hafnium oxide-based MOS capacitors were investigated to determine electrical property response to radiation environments. In situ capacitance versus voltage measurements were analyzed to identify voltage shifting as a result of changes to trapped charge with increasing dose of gamma, neutron, and ion radiation. In situ measurements required investigation and optimization of capacitor fabrication to include dicing, cleaning, metalization, packaging, and wire bonding. A top metal contact of 200 angstroms of titanium followed by 2800 angstroms of gold allowed for repeatable wire bonding and proper electrical response. Gamma and ion irradiations of atomic layer deposited hafnium oxide on silicon devices both …

Characterization Of The Neutron Spectrum At The Indiana University Nrep Neutron Source, Matthew R. Halstead

Theses and Dissertations

The neutron source at the Indiana University Cyclotron Facility produces neutrons via proton bombardment of a natural beryllium (100% 9Be) target. This source has two beam lines: the LENS and the NREP. The energy spectrum of the neutrons produced on the NREP beam line has not yet been characterized. Through simulation using the GEANT and MCNP particle transport codes as well as neutron activation analysis experiments, an attempt was made to characterize the energy spectrum of the neutron production source. First, the neutron production spectrum of beryllium, simulated using GEANT, was compared with literature; there are significant deviations. Next, foils …

Investigation Of Yag:Ce Scintillating Fiber Properties Using Silicon Photomultipliers, Bradley S. Jones

Theses and Dissertations

The properties of thin, cerium activated, yttrium aluminum garnet (YAG:Ce), scintillating fiber-shaped crystals were investigated for particle tracking and calorimetric applications such as Compton imaging of Special Nuclear Material from remote platforms at standoff ranges. Silicon photomultipliers (SiPMs) are relatively new, efficient, single photon sensitive, solid-state photodiode arrays which are well suited for the readout of scintillating fibers. Using SiPMs, the scintillation decay time profiles of six 400 micrometers YAG:Ce fiber crystals were measured under alpha and gamma irradiation. Interestingly, the observed decay times in the thin fibers were substantially slower than values for bulk single crystal YAG:Ce reported in …

Improving The Efficiency Of Photon Collection By Compton Rescue, Alexander W. Stevenson

Theses and Dissertations

A method to improve the efficiency of photon collection in thin planar HPGe detectors was investigated. The method involved implementing a second HPGe detector to collect Compton scattered photons from the primary detector and incorporating coincident interactions in the two detectors that sum to the full energy event into the energy spectrum. This method is termed Compton rescue because the Compton scattered photons make a partial energy deposition in the primary detector and are added back to the spectrum after being detected by the second detector. This research has implications on improving the efficiency of positron annihilation spectroscopy (PAS) techniques …

Positron Annihilation Ratio Spectroscopy Study Of Electric Fields Applied To Positronium At Material Interfaces, Ariella C. Walker

Theses and Dissertations

The purpose of this research was to develop a new code to analyze the data from AFIT's positron annihilation of radiation spectrometer, PsARS, system. The PsARS was used to analyze positronium formation at the surface of a capillary tube coated with gold. Using energy and geometry filters, the PsARS code determined the ratio of ortho-positronium to para-positronium. An electric field applied across the capillary tube wall forced positrons to move towards the gold surface of the capillary tube and prevent them from dropping into the Ore gap before they reach the surface. Inside the Ore gap, the positrons are more …

Coherent Photoproduction Of Π+ From 3he, R. Nasseripour, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We have measured the differential cross section for the γ³He→ π⁺t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid ³He target. The differential cross sections for the γ³He→ π⁺t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, …

Centrality Dependence Of Two-Particle Number And Transverse Momentum Correlations In 200 Gev Au+Au Collisions At Rhic, Laurence Henry Tarini

Wayne State University Dissertations

We present plots of the pattern of particle formation in $sqrt{s_{NN}}=200$ GeV Au+Au heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) using three different two-particle correlation measurements of number and transverse momentum as a function of relative azimuth, pseudorapidity and centrality. All three observables show the onset of a ``ridge" feature of enhanced correlations in pseudorapidity with increasing centrality. The plots of real data are compared to plots of simulations using RQMD data and data from a simple ``cluster'' model. The intent of the analysis is to analyze the role of radial flow in the onset of the …

Proton-Proton Correlation Functions As A Probe To Reaction, Micha A. Kilburn '95

Doctoral Dissertations

In an experiment at NSCL, proton-proton (p-p) correlation functions were measured in ⁴⁰Ca+⁴⁰Ca and ⁴⁸Ca+⁴⁸Ca reactions, both at E/A = 80 MeV. The High Resolution Array (HiRA) detected light particles with excellent energy (<200 keV) and angular (~0.2^o) resolution. The MSU 4pi Array covered 77% of the total 4pi solid angle and was used to determine the impact parameter for collisions using transverse energy (E_t) as the relevant observable.

Two-particle correlation functions are employed in this work to measure the space-time …

Analysis Of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission, Alyssa Frey, Nicholas Wozniak, Timothy Nagi, Matthew Keller, J. Mark Lunderberg, Graham F. Peaslee, Paul Deyoung, Jennifer R. Hampton

Faculty Publications

The elemental composition of electrodeposited NiFe thin films was analyzed with particle-induced X-ray emission (PIXE). The thin films were electrodeposited on polycrystalline Au substrates from a 100mM NiSO₄, 10 mM FeSO₄, 0.5M H₃BO₃, and 1M Na₂SO₄ solution. PIXE spectra of these films were analyzed to obtain relative amounts of Ni and Fe as a function of deposition potential and deposition time. The results show that PIXE can measure the total deposited metal in a sample over at least four orders of magnitude with similar fractional uncertainties. The technique is …

Anisotropic Response Of Nanosized Bismuth Films Upon Femtosecond Laser Excitation Monitored By Ultrafast Electron Diffraction, Ahmed R. Esmail, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The lattice response of 5 nm thick bismuth film to femtosecond laser excitation is probed by ultrafast electron diffraction. The transient decay time after laser excitation is greater for diffraction from (012) lattice planes compared to (110) planes and is reduced for both planes with the increased laser fluence. These results indicate that different energy coupling mechanisms to the lattice occur depending on the crystal direction. The behavior of the diffraction peak width indicates partial disorder of the film upon photoexcitation that increases together with the laser fluence. © 2011 American Institute of Physics. [doi:10.1063/1.3652919]

Conceptual Design Of A Polarized Medium Energy Electron-Ion Collider At Jlab, S. Ahmed, A. Bogacz, Ya. Derbenev, A. Hutton, Geoffrey Krafft, R. Li, V. Morozov, F. Pilat, R. Rimmer, Y. Roblin, T. Satogata, M. Spata, B. Terzić, M. Tiefenback, H. Wang, B. Yunn, Y. Zhang, P. Chetsov, Jean R. Delayen, Subashini Desilva, Hisham Sayed, V. Dudnikov, R. Johnson, F. Marhauser, M. Sullivan, S. Manikonda, P. N. Ostroumov, S. Abeyratne, B. Erdelyi, Y. Kim, A. Kondratenko

Physics Faculty Publications

A medium energy electron-ion collider is envisioned as the primary future of the JLab nuclear science program beyond the 12 GeV upgraded CEBAF. The present conceptual design selects a ring-ring collider option, covers a CM energy range up to 65 GeV for collisions of polarized electrons with polarized light ions or unpolarized light to heavy ions, and reaches a luminosity at above 10³⁴ cm^-2s^-1 per detector over multiple interaction points. This paper presents a brief description of the current conceptual design of the accelerator.

Polarization Observables In Deuteron Photodisintegration Below 360 Mev, J. Glister, G. Ron, B. W. Lee, R. Gilman, A. J. Sarty, S. Strauch, D. W. Higinbotham, E. Piasetzky, K. Allada, W. Armstrong, J. Arrington, H. Arenhövel, A. Beck, F. Benmokhtar, B. L. Berman, W. Boeglin, E. Brash, A. Camsonne, J. Calarco, J. P. Chen, S. Choi, E. Chudakov, L. Coman, B. Craver, F. Cusanno, J. Dumas, C. Dutta, R. Feuerbach, A. Freyberger, S. Frullani, F. Garibaldi, J. -O. Hansen, T. Holmstrom, C. E. Hyde, H. Ibrahim, Y. Ilieva, C. W. De Jager, X. Jiang, M. K. Jones, Hyekoo Kang, A. Kelleher, E. Khrosinkova, E. Kuchina, G. Kumbartzki, J. J. Lerose, R. Lindgren, P. Markowitz, S. May-Tal Beck, E. Mccullough, D. Meekins, M. Meziane, Z. -E. Meziani, R. Michaels, B. Moffit, B. E. Norum, Y. Oh, M. Olson, M. Paolone, K. Paschke, C. F. Perdrisat, M. Potokar, R. Pomatsalyuk, I. Pomerantz, A. Puckett, V. Punjabi, X. Qian, Y. Qiang, R. D. Ransome, M. Reyhan, J. Roche, Y. Rousseau, A. Saha, B. Sawatzky, E. Schulte, M. Schwamb, M. Shabestari, A. Shahinyan, R. Shneor, S. Širca, K. Slifer, P. Solvignon, J. Song, R. Sparks, R. Subedi, G. M. Urciuoli, K. Wang, B. Wojtsekhowski, X. Yan, H. Yao, X. Zhan, X. Zhu

Physics Faculty Publications

High precision measurements of induced and transferred recoil proton polarization in d(γ→,p→)n have been performed for photon energies of 277–357 MeV and θcm = 20°–120°. The measurements were motivated by a longstanding discrepancy between meson–baryon model calculations and data at higher energies. At the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon–nucleon potential being used.

Precise Measurements Of Beam Spin Asymmetries In Semi-Inclusive Π0 Production, M. Aghasyan, H. Avakian, P. Rossi, E. De Sanctis, D. Hasch, M. Mirazita, D. Adikaram, M. J. Amaryan, M. Anghinolfi, H. Baghdasaryan, R. P. Bennett, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein

Physics Faculty Publications

We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sin phi(h) amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle φh of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations. (C) 2011 Elsevier B.V.

Evolution Of The Differential Transverse Momentum Correlation Function With Centrality In Au + Au Collisions At √Snn = 200 Gev, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, C. D. Anson, D. Arhipkin, G. S. Averichev, S. Bültmann, D. Plyku

Physics Faculty Publications

We present first measurements of the evolution of the differential transverse momentum correlation function, C, with collision centrality in Au + Au interactions at √^sNN = 200 GeV. This observable exhibits a strong dependence on collision centrality that is qualitatively similar to that of number correlations previously reported. We use the observed longitudinal broadening of the near-side peak of C with increasing centrality to estimate the ratio of the shear viscosity to entropy density, η / s , of the matter formed in central Au + Au interactions. We obtain an upper limit estimate of η / s …

Two-Body Photodisintegration Of 3he Between 7 And 16 Mev, W. Tornow, H. J. Karwowski, J. H. Kelley, R. Raut, G. Rusev, S. C. Stave, A. P. Tonchev, A. Deltuva, A. C. Fonseca, L. E. Marcucci, R. Schiavilla

Physics Faculty Publications

A comprehensive data set is reported for the two-body photodisintegration cross section of ³He using mono-energetic photon beams at eleven energies between 7.0 and 16.0 MeV. A ³He + Xe high-pressure gas scintillator served as target and detector. Although our data are in much better agreement with our state-of-the-art theoretical calculations than the majority of the previous data, these calculations underpredict the new data by about 10%. This disagreement suggests an incomplete understanding of the dynamics of the three-nucleon system and its response to electromagnetic probes.

Experimental Results In Dis, Sidis And Des From Jefferson Lab, Sebastian E. Kuhn

Physics Faculty Publications

Jefferson Lab’s electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering—DIS—at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum‐dependent (TMD) structure functions using Semi‐Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic …

Short-Distance Structure Of Nuclei, D. W. Higinbotham, E. Piasetzky, L. Weinstein, S. A. Wood

Physics Faculty Publications

One of Jefferson Lab's original missions was to further our understanding of the short-distance structure of nuclei, in particular, to understand what happens when two or more nucleons within a nucleus have strongly overlapping wave-functions – a phenomena commonly referred to as short-range correlations. Herein, we review the results of the (e, e'), (e, e'p) and (e, e'pN) reactions that have been used at Jefferson Lab to probe this short-distance structure as well as provide an outlook for future experiments.

Scaling Properties At Freeze-Out In Relativistic Heavy-Ion Collisions, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at √sNN=200 and 62.4 GeV. The data are studied with hydrodynamically motivated blast-wave and statistical model frameworks in order to characterize the freeze-out properties of the system. The dependence of freeze-out parameters on beam energy and collision centrality is discussed. Using the existing results from Au + Au and pp collisions, the dependence of freeze-out parameters on the system size is also explored. This multidimensional systematic study furthers our understanding of the QCD phase diagram revealing the importance …

Photoproduction Of The Φ(1020) Meson In Neutral Decay Mode Γp → Φp → K(S)K(L)P, Heghine Seraydaryan

Physics Theses & Dissertations

The Φ(1020) meson photoproduction cross sections in the neutral decay mode Φ → K_SK_L are measured for the first time. This work presents measurements of differential cross sections, dσ/dt, dσ/d cos θ^Φ_c.m.; Φ decay angular distributions, W(cos θ) and W(Φ), and spin-density matrix elements, ρ⁰, in the Helicity and Gottfried-Jackson frames, in the energy range 1.6 GeV < E_γ < 2.6 GeV. We analyzed the photoproduction data of the g11a experiment collected on an LH2 target using the CLAS detectector at Hall B, TJNAF. The measured cross sections show some differences from the charged decay mode Φ → K⁺ K⁻.