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A thin-lens beta-ray spectrometer has been modified for collection of beta-rays at the position of the ring focus. This has increased the gathering power/line width ratio from ∽ 0.12 to ∽0.8. The focusing properties of the instrument have been investigated for various geometries. Using the modified spectrometer, the decay scheme of Sb 125 - Te 125 has been investigated. The primary beta spectrum, photoelectron spectra and beta-gamma coincidence spectra have been measured. From conversion coefficient measurements, the following radiative transition multipolarities were determined (energies in kev): 176(E2+M1), 428(E2+M1), 464(E2), 602(E2+M1) and 638(E2). Five primary beta groups have been identified with end point energies of 626, 450, 307, 246 and 133 kev. Previously unobserved transitions of 76, 143, 219, 355, 540 and 640 kev have been identified. Based on all experimental evidence the following states of Te 125 with spin and parity assignments have been proposed: ground state (S1/2+), 36 kev (d₃/2+), 145 kev (h₁₁/₂-), 321 kev (9/2-), 464 kev (5/2+), 525 kev (11/2- or 9/2-), 540 kev (11/2- or 9/2-), 638 kev (5/2+) and 676 kev (spin and parity undetermined). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The nuclear energy levels of As⁷⁵ have been investigated through the study of the Se⁷⁵ decay scheme. The internal conversion spectrum as well as the photoelectron spectra (using bismuth and lead radiators) were measured with a modified thin lens magnetic spectrometer. A technique was developed for accurate determination of the transmission of the spectrometer in order to obtain the absolute conversion electron transition intensities. The gamma ray intensities were determined from the spectrum measured with a NaI(T1) scintillation spectrometer in conjunction with the results from the photoelectron spectra. From these measurements the absolute conversion coefficients for eight transitions were obtained. In addition coincidence techniques employing a slow- fast coincidence system (resolving time 10⁻⁷ sec) were used to measure gamma-gamma coincidences, conversion electron-gamma coincidences and gamma-gamma directional correlations. A one hundred channel kicksorter was used to facilitate accumulation of the data at the relatively low coincidence counting rates. Multipolarities of the following transitions were determined, (energies in kev), 97(E2); 121(El); 136(El); 199(M1+E2); 265(Ml,-0.12<δ(E2)<+0.07); 279(M1+E2, δ =-0.46 ±0.16); 304(E3) and 401(El). Also detected but for which multipolarities could not be determined was a 66 kev transition and a very weak 572 kev gamma transition. In addition the existence of a 24 kev and a 77 kev transition was inferred from the intensity measurements. An energy level diagram for As⁷⁵ has been constructed with the following energy levels and spin assignments, (energies in kev), 572 (7/2 +), 477 (?), 401 (5/2 +), 304 (9/2 +), 279 (5/2 -), 265 (3/2 -), 199 (1/2 -), 0 (3/2 -). It was concluded that the ground state of Se⁷⁵ has even parity. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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The disposal of waste is a growing environmental, political, and economic problem. Low level radioactive waste (LLW) disposal is no exception. The major purposes of this dissertation are to examine the economic tradeoffs which arise in the process of LLW disposal and to derive a framework within which the impact of these tradeoffs on LLW disposal policy can be analyzed. There are two distinct stages in the disposal of LLW--the transportation of the waste from sources to disposal sites and the disposal of the waste. The levels of costs and risks associated with these two stages depend on the number and location of disposal sites. Having more disposal sites results in lower transportation costs and risks but also in greater disposal costs and risks. The tradeoff between transportation costs and risks can also be viewed as a tradeoff between present and future risks. Therefore, an alteration in the spatial distribution of LLW disposal sites necessarily implies a change in the temporal distribution of risks. These tradeoffs are examined in this work through the use of a transportation model to which probabilistic radiation exposure constraints are added. Future (disposal) risks are discounted. The number and capacities of LLW disposal sites are varied in order to derive a series of system costs and corresponding expected cancers. This provides policymakers with a cost vs. cancers possibility function. The marginal cost of reducing cancers by changing the number and location of disposal sites is calculated. A possible policy application of this information is illustrated by comparing these costs to an assumed value of life derived from experimental evidence found in the literature. A tentative conclusion is reached that the current movement toward a system of regional LLW disposal sites may be economically suboptimal.