Incident 0.5 to 2.5 MeV charged particle beams were used to ionize the inner-shells of selected targets and study their subsequent emission of characteristic x-rays. ⁹Be⁺ ions were used to examine K-shell x-ray production from thin F, Na, Al, Si, P, Cl, and K targets, L-shell x-ray production from thin Cu, An, Ge, Br, Zr and Ag targets, and M-shell x-ray production from thin Pr, Nd, Eu, Dy, Ho, Hf, W, Au, Pb and Bi targets. L-shell x-ray production cross sections were also measured for ²⁷Al⁺ ions incident upon Ni, Cu, Zn, As, Zr, and Pd targets. M-shell x-ray production cross sections were measure for ²⁷Al⁺ and ⁴⁰Ar⁺ ions incident upon Pr, Nd, Gd, Dy, Lu, Hf, Au, Pb, Bi, and U targets. These measurements were performed using the 2.5 MV Van de Graaff accelerator at North Texas State University. The x-rays were detected with a Si(Li) detector whose efficiency was determined by fitting a theoretical photon absorption curve to experimentally measure values. The x-ray yields were normalized to the simultaneously measured Rutherford backscattered (RBS) yields which resulted in an x-ray production cross section per incident ion. The RBS spectrum was obtained using a standard surface barrier detector calibrated for to account for the "pulse height defect." The experimental results are compared to the predictions of both the first Born and ECPSSR theories; each of which is composed of two parts, the direct ionization (DI) of the target electron to the continuum and the capture (EC) of the target electron to the projectile. The first Born describes DI by the Plane-Wave-Born-Approximation (PWBA) and EC by the Oppenheimer-Brinkman-Kramers treatment of Nikolaev (OBKN). ECPSSR expands upon the first Born by using perturbed (PSS) and relativistic (R) target electron wave functions in addition to considering the energy loss (E) of the projectile in the target and its deviation from straight line trajectory (Coulomb deflection (C)). The measurements presented show that the first Born theories overestimate the measured results rather significantly for all experiments using the ⁹Be beams to examine the inner shell x-rays, while the ECPSSR predictions fir the measured data much better. For incident ²⁷Al and ⁴⁰Ar ions, the measured results are not predicted by the theories. The first Born generally over-predicts the data for low target atomic numbers while under-predicting at high atomic numbers. The ECPSSR theory greatly under-predicts the results (factors of 10³ to 10²⁰). Reasons for this behavior are discussed as well as suggestions for future experiments.
| Identifer | oai:union.ndltd.org:unt.edu/info:ark/67531/metadc331170 |
| Date | 12 1900 |
| Creators | Price, Jack Lewis |
| Contributors | Duggan, Jerome L., McDaniel, Floyd Del. (Floyd Delbert), 1942-, Deering, William D., Redding, Rogers W., Mackey, H. J. |
| Publisher | North Texas State University |
| Source Sets | University of North Texas |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | x, 227 leaves: ill., Text |
| Rights | Public, Price, Jack Lewis, Copyright, Copyright is held by the author, unless otherwise noted. All rights reserved. |
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