38 research outputs found
The Development of Lithium Tetraborate Compounds for Thermal Neutron Detection
Due to the shortage of 3He [helium-3], the goal of this project was to develop replacement materials for slow neutron detection in mixed radiation fields. The U.S. Department of Homeland Security (DHS) indicated that replacement materials should have an absolute neutron efficiency of 2.5 cps/ng of 252Cf (Californium-252) and a neutron/gamma discrimination intrinsic efficiency of 1 x 10-6 [one gamma-ray response in a million counts]. In this work, the use of amorphous lithium tetraborate (Li2B4O7:Ce) is analyzed as a thermal neutron detector. Also discussed is the synthesis of the lithium tetraborate, using 6Li [lithium-6], to form a crystalline powder that is heated simultaneously with cerium oxide (CeO2) and excess boric acid to produce an optically clear glass. In this study, the structure of glass was probed, the abnormal reduction of Ce4+ [tetravalent cerium] to Ce3+ [trivalent cerium] observed in the fluorescence peak at 360 nm, and irradiation studies with alpha particles, beta particles, gamma-rays, and neutrons were performed. The resulting material was shown to have a light yield of 550 photons/neutron, which is 8% the light output of GS-20, a lithiated glass
Contribution of natural terrestrial sources to the total radiation dose to man
Ph.D.Geoffrey G. Eichhol
Laser-Induced Plasma Analysis for Surrogate Nuclear Debris
This work identifies analytical lines in laser-induced plasma for chemical analyses of major elements found in surrogate nuclear debris. These lines are evaluated for interferences and signal strength to insure they would be useful to measure relative concentrations. Compact, portable instruments are employed and can be included as part of a mobile nuclear forensics laboratory for field screening of nuclear debris and contamination. The average plasma temperature is measured using the well-established Boltzmann plot technique, and plasma\u27s average electron density is determined using empirical formulae based on Stark broadening of the H-alpha line. These measurements suggest existence of partial local thermal equilibrium
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A prelude to matching: Locus of control and belief in divine intervention among members of Alcoholics Anonymous and Rational Recovery.
The purpose of the study was to explore the relationship between locus of control orientation, belief in divine intervention and successful affiliation with Alcoholics Anonymous (AA) and Rational Recovery (RR). "Successful affiliation" was defined in the study by the following criteria. First, a history of problem drinking as measured by a score of 12 or above on the Michigan Alcoholism Screening Test (MAST). Second, at least three (3) months of continuous sobriety. Third, substantial involvement in AA or RR as measured by Reinert's (1992) Alcoholics Anonymous Involvement Scale (AAIS), or Auxier's (1994) Rational Recovery Involvement Scale (RRIS). Fifty-seven (57) subjects met the above criteria as successful AA or RR members for the study (AA n = 34, RR n = 23). Successful AA affiliates were then compared with successful RR affiliates on a locus of control measure, (the Rotter I-E Scale) and on a measure of belief in divine intervention, the Auxier (1994) Divine Intervention Scale (DIS). As hypothesized, the results of the locus of control measure showed that successful AA members were significantly more external in orientation than successful RR members (p < .016). Also as hypothesized, the results of the Divine Intervention Scale showed that successful AA members had significantly stronger beliefs in divine intervention than their RR counterparts (p < .001). These findings were interpreted using the framework of Leon Festinger's Cognitive Dissonance Theory (1957). It was suggested that AA's drop-out phenomena may be a reflection of cognitive dissonance processes. Individuals with a low belief in divine intervention and an internal locus of control may be expected to drop out of AA due to cognitive dissonance effects. A third hypothesis of the study predicted that external locus of control and strong beliefs in divine intervention would positively correlate. This prediction was not supported. This finding suggests that the impulse towards external locus of control in successful AA members has its source in non-spiritual aspects of AA's philosophy of recovery. It was concluded that locus of control and belief in divine intervention show promise as treatment matching criteria and further research using these dimensions as predictors of successful affiliation is warranted
Modern Advancements in Post-Detonation Nuclear Forensic Analysis
Deterring nuclear terrorism is a critical national asset to support the preclusion of non-state actors from initiating a nuclear attack on the United States. Successful attribution of a detonated nuclear weapon allows for timely responsive measures that prove essential in the period following a nuclear event. In conjunction with intelligence and law enforcement evidence, the technical nuclear forensics (TNF) post-detonation community supports this mission through the development and advancement of expertise to characterize weapon debris through a rapid, accurate, and detailed approach. Though the TNF field is young, numerous strides have been made in recent years toward a more robust characterization capability. This work presents modern advancements in post-detonation expertise over the last ten years and demonstrates the need for continued extensive research in this field
Exploring Rapid Radiochemical Separations at the University of Tennessee Radiochemistry Center of Excellence
The University of Tennessee formed its Radiochemistry Center of Excellence (RCoE) in 2013 with support from the U.S. National Nuclear Security Administration. One of the major thrusts of the RCoE is to develop deeper understanding of rapid methods for radiochemical separations that are relevant to both general radiochemical analyses as well as post-detonation nuclear forensics. Early work has included the development and demonstration of rapid separations of lanthanide elements in the gas phase, development of a gas-phase separation front-end for ICP-TOF-MS analysis, and the development of realistic analytical surrogates for post-detonation debris to support methods development