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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Electroproduction Of Neutral Pion Off Helium-4, Bayram Torayev
Electroproduction Of Neutral Pion Off Helium-4, Bayram Torayev
Physics Theses & Dissertations
Deeply virtual exclusive processes offer a unique opportunity to study the internal structure of the nucleon and nuclei. The goal of this work is to extract the beam-spin asymmetry in deeply virtual coherent neutral pion electroproduction, e4He → e′4He′π0, using the CLAS detector in the experimental Hall B at Thomas Jefferson National Accelerator Facility. The data were collected in 2009 with a 6 GeV longitudinally polarized electron beam impinging on a 30 cm long, 6 atm Helium-4 gaseous target. In order to ensure that the process is coherent, a new Radial Time Projection Chamber …
Investigation Of Multi-Photon Excitation In Argon With Applications In Hypersonic Flow Diagnostics, Jack L. Mills
Investigation Of Multi-Photon Excitation In Argon With Applications In Hypersonic Flow Diagnostics, Jack L. Mills
Physics Theses & Dissertations
Non-intrusive flow diagnostics are essential for studying the physics of hypersonic flow wake regions. To advance the development of next generation hypersonic vehicles and to improve computational fluid dynamics techniques in the hypersonic regime, NASA needs a suitable non-intrusive diagnostic technique to measure velocity, density, and temperature. We will present our work on developing a seedless, non-intrusive diagnostic technique using excited state argon atoms, prepared via multi-photon excitation. In this dissertation, we report results on the first phase of this hypersonic wake measurement project. In particular, we have redesigned and characterized the performance of a high energy, nanosecond pulsed Ti:Sapphire …
Forward Light Scattering In An Extended Sample Of Cold Atoms, Stetson Roof
Forward Light Scattering In An Extended Sample Of Cold Atoms, Stetson Roof
Physics Theses & Dissertations
We present results on the forward emitted light from a cold atomic sample of 87Rb. Specifically,we study single-photon superradiance which is characterized by a rapid decay faster than the single atom lifetime with the light preferentially emitted in the forward direction. Additionally, we report measurements on its counterpart, the cooperative Lamb shift. The results are interpreted using microscopic light scattering theory as well as techniques from classical optics. The comparison of the two analytical techniques provides a new perspectiveon what is meant by cooperative and collective scattering effects in cold atomic physics.
Emergence Of Collective Light Scattering In Atomic 87Rb Samples, Kasie Jean Kemp
Emergence Of Collective Light Scattering In Atomic 87Rb Samples, Kasie Jean Kemp
Physics Theses & Dissertations
Over the past half century, atomic ensembles have been used to create sensors, clocks, and quantum information systems. As these devices become more compact, and as the number of atoms increases to improve the sensitivity for detection, the atomic samples are increasing in density and optical depth. As such, the spectroscopic properties of the atomic media are modified due to interactions among the particles in the ensemble. We report investigation of near-resonance light scattering from a cold atomic sample of 87Rb. Initially prepared in a magneto-optical trap, the atoms are loaded into a far-off-resonance optical dipole trap (FORT) in which …
Cebaf Upgrade Bunch Length Measurements, Mahmoud Mohamad Ali Ahmad
Cebaf Upgrade Bunch Length Measurements, Mahmoud Mohamad Ali Ahmad
Physics Theses & Dissertations
Many accelerators use short electron bunches and measuring the bunch length is important for efficient operations. CEBAF needs a suitable bunch length because bunches that are too long will result in beam interruption to the halls due to excessive energy spread and beam loss. In this work, bunch length is measured by invasive and non-invasive techniques at different beam energies. Two new measurement techniques have been commissioned; a harmonic cavity showed good results compared to expectations from simulation, and a real time interferometer is commissioned and first checkouts were performed. Three other techniques were used for measurements and comparison purposes …
Plasma Processing Of Superconducting Radio Frequency Cavities, Janardan Upadhyay
Plasma Processing Of Superconducting Radio Frequency Cavities, Janardan Upadhyay
Physics Theses & Dissertations
The development of plasma processing technology of superconducting radio frequency (SRF) cavities not only provides a chemical free and less expensive processing method, but also opens up the possibility for controlled modification of the inner surfaces of the cavity for better superconducting properties. The research was focused on the transition of plasma etching from two dimensional flat surfaces to inner surfaces of three dimensional (3D) structures. The results could be applicable to a variety of inner surfaces of 3D structures other than SRF cavities. Understanding the Ar/Cl2 plasma etching mechanism is crucial for achieving the desired modification of Nb …