Time-resolved Schottky mass spectrometry has been applied to uranium projectile fragments which yielded the mass value for the 208 Hg (Z = 80, N = 128) isotope. The mass excess value of ME=-13265(31) keV has been obtained, which has been used to determine the proton-neutron interaction strength in 210 Pb, as a double difference of atomic masses. The results show a dramatic variation of the strength for lead isotopes when crossing the N=126 neutron shell closure, thus confirming the empirical predictions that this interaction strength is sensitive to the overlap of the wave-functions of the last valence neutrons and protons.Atomic nuclei are many-body systems in which the strong, weak and electromagnetic fundamental interactions play a major role by acting between the nucleons. The sum effect of these interactions is reflected in the total binding energy of the nucleus, which is directly connected with its mass [1]. Therefore, nuclear masses often provide hints to new nuclear structure effects. Indeed, shell structure and pairing correlations have been discovered through nuclear masses. Nuclear masses and binding energies are important, however, in a much wider domain. Examples occur in the studies of various nucleosynthesis processes in stars, in weak interaction physics relating to the unitarity of the CabibboKobayashi-Maskawa matrix, in tests of QED and in the determination of fundamental constants [2].Dedicated filters can be constructed from mass differences to isolate specific nucleonic interactions. One such filter is the average interaction strength of the last proton(s) with the last neutron(s) denoted δV pn . The proton-neutron interaction-being of fundamental interest for nuclear structure-has been intensively discussed in the last decades [3][4][5][6][7][8][9][10][11][12][13][14]. It has been shown that it is essential for the development of configuration mixing and for the onset of collectivity and deformation in nuclei [6], for changes of the underlying shell structure [7], and for the microscopic origins of phase transitional behavior in nuclei [7][8][9]. Being the largest along the N=Z line, the p−n interaction can be related to Wigner's SU(4) symmetry [3]. The average value of the p−n interaction strength can also be related to the nuclear symmetry energy [10]. Moreover, treatment of the nucleon-nucleon correlations finds similarities in interpreting other many-body systems: for example, odd-even staggering effects were observed in ultrasmall superconducting metallic grains [15]. This Letter will present a mass measurement for 208 Hg isotope, that provides one of the most important δV pn values in the entire nuclear chart.For even-even nuclei, the average p − n interaction of the last two protons with the last two neutrons can be defined as [13]:where B is the binding energy of the nucleus. By assuming that the nuclear core remains essentially unchanged, δV pn , by its definition, largely cancels the interactions of the last nucleons with the core. A given δV pn value for an even-even nucleus ref...
Neutron sensors capable of real-time measurement of neutrons in high-flux environments are necessary for tests aimed at demonstrating the performance of experimental nuclear reactor fuels and materials in material test reactors (MTRs). In-core Micro-Pocket Fission Detectors (MPFDs) have been studied at Kansas State University for many years. Previous MPFD prototypes were successfully built and tested with promising results. Efforts are now underway to develop advanced MPFDs with radiation-resistant, high-temperature materials capable of withstanding irradiation test conditions in high performance material and test reactors. Stackable MPFDs have been designed, built, and successfully demonstrated as in-core neutron sensors. Advances in the electrodeposition and measurement of neutron reactive material, along with refinements to composition optimization simulations, have enhanced the capabilities of contemporary MPFDs.
This study focuses on the use of restaurant waste for production of ethanol. Food wastes (corn, potatoes, and pasta) were converted to ethanol in a two‐step process: a two‐part enzymatic digestion of starch using α‐amylase and glucoamylase and then fermentation of the resulting sugars to ethanol using yeast. Because of the low initial composition of starch in the food waste, low ethanol concentrations were achieved: at best 8 mg/mL ethanol (0.8% by mass). Ethanol concentration increased with increasing enzyme dosage levels. Calculations were conducted to evaluate whether waste heat from restaurant waste could be used to drive flash vaporization to purify ethanol. If the solution produced by fermenting food waste is flashed at a temperature of 99.7°C, 77% of the ethanol is recovered in a vapor stream with 1.14 mol % ethanol (2.87 mass %). Waste heat could provide over a third of the energy for this vaporization process. If 4 mol % ethanol could be produced in the fermentation step by increasing the initial starch content in the waste solution and improving the fermentation process, then a single flash at 98.9°C will recover nearly 99% of the ethanol, giving a mass concentration of ethanol of 10.3%, which is similar to that achieved in industrial grain fermentation. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1280–1283, 2013
Preparation of thin U-and Th-coated 0.3 mm diameter Pt working electrodes by the cyclic potential sweep method is described. Uranyl-and thorium hydroxide layers were electrodeposited from ethanol solutions containing 0.02 M natural uranyl and 0.02 M natural thorium nitrate, each with 3.6 M ammonium nitrate. The cell for electrodeposition was specially developed in order to accommodate the small working electrodes for this research by including a working electrode probe, 3-D translation stage, and microscope. The source material deposition was analyzed using digital microscopy and scanning electron microscopy, and confirmed using x-ray fluorescence measurements. The appropriate potential range for electrodeposition was determined to be-0.62 V to-0.64 V for a 0.3 mm diameter Pt working electrode placed 1 cm from the counter electrode. Smooth, uniform deposition was observed near the central region of the working electrode, while surface cracking and crystalline formations were found near the edge of the working electrode. The final procedure for sample substrate preparation, electrolytic solution preparation and electrodeposition are described.
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