A flume study of ripple growth in fine sand.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Geology and Geophysics, 1968.Bibliography: leaves 82-84.M.S

Attenuation technique for measuring sediment displacement levels

A technique for obtaining accurate, high (spatial) resolution measurements of sediment redeposition levels is described. In certain regimes, the method may also be employed to provide measurements of sediment layer thickness as a function of time. The method uses a uniform light source placed beneath the layer, consisting of transparent particles, so that the intensity of light at a point on the surface of the layer can be related to the depth of particles at that point. A set of experiments, using the impact of a vortex ring with a glass ballotini particle layer as the resuspension mechanism, are described to test and illustrate the technique

Mitigation of backgrounds from cosmogenic 137Xe in xenon gas experiments using 3He neutron capture

136Xe is used as the target medium for many experiments searching for 0¿ßß. Despite underground operation, cosmic muons that reach the laboratory can produce spallation neutrons causing activation of detector materials. A potential background that is difficult to veto using muon tagging comes in the form of 137Xe created by the capture of neutrons on 136Xe. This isotope decays via beta decay with a half-life of 3.8 min and a Q ß of ~4.16 MeV. This work proposes and explores the concept of adding a small percentage of 3He to xenon as a means to capture thermal neutrons and reduce the number of activations in the detector volume. When using this technique we find the contamination from 137Xe activation can be reduced to negligible levels in tonne and multi-tonne scale high pressure gas xenon neutrinoless double beta decay experiments running at any depth in an underground laboratory

Mitigation of backgrounds from cosmogenic Xe-137 in xenon gas experiments using He-3 neutron capture

[EN] Xe-136 is used as the target medium for many experiments searching for 0 nu beta beta. Despite underground operation, cosmic muons that reach the laboratory can produce spallation neutrons causing activation of detector materials. A potential background that is difficult to veto using muon tagging comes in the form of Xe-137 created by the capture of neutrons on Xe-136. This isotope decays via beta decay with a half-life of 3.8 min and a Q(beta) of similar to 4.16 MeV. This work proposes and explores the concept of adding a small percentage of He-3 to xenon as a means to capture thermal neutrons and reduce the number of activations in the detector volume. When using this technique we find the contamination from Xe-137 activation can be reduced to negligible levels in tonne and multi-tonne scale high pressure gas xenon neutrinoless double beta decay experiments running at any depth in an underground laboratory.The work described was supported by the Department of Energy under Award numbers DE-SC0019054 and DE-SC0019223. The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the European Union's Framework Program for Research and Innovation Horizon 2020 (2014-2020) under the Marie Skodowska-Curie Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Economia y Competitividad of Spain under grants FIS2014-53371-C04, the Severo Ochoa Program SEV-2014-0398 and the Maria de Maetzu Program MDM-2016-0692; the GVA of Spain under grants PROMETEO/2016/120 and SEJI/2017/011; the Portuguese FCT under project PTDC/FIS-NUC/2525/2014, under project UID/FIS/04559/2013 to fund the activities of LIBPhys, and under grants PD/BD/105921/2014, SFRH/BPD/109180/2015 and SFRH/BPD/76842/2011. Finally, we are grateful to the Laboratorio Subterraneo de Canfranc for hosting and supporting the NEXT experiment.Rogers, L.; Jones, BJP.; Laing, A.; Pingulkar, S.; Smithers, B.; Woodruff, K.; Adams, C.... (2020). Mitigation of backgrounds from cosmogenic Xe-137 in xenon gas experiments using He-3 neutron capture. Journal of Physics G Nuclear and Particle Physics. 47(7):1-17. https://doi.org/10.1088/1361-6471/ab8915S117477Nygren, D. (2009). High-pressure xenon gas electroluminescent TPC for 0-ν ββ-decay search. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 603(3), 337-348. doi:10.1016/j.nima.2009.01.222Ferrario, P., Laing, A., López-March, N., Gómez-Cadenas, J. J., Álvarez, V., … Cebrián, S. (2016). First proof of topological signature in the high pressure xenon gas TPC with electroluminescence amplification for the NEXT experiment. Journal of High Energy Physics, 2016(1). doi:10.1007/jhep01(2016)104Monrabal, F., Gómez-Cadenas, J. J., Toledo, J. F., Laing, A., Álvarez, V., Benlloch-Rodríguez, J. M., … Felkai, R. (2018). The NEXT White (NEW) detector. Journal of Instrumentation, 13(12), P12010-P12010. doi:10.1088/1748-0221/13/12/p12010Martín-Albo, J., Muñoz Vidal, J., Ferrario, P., Nebot-Guinot, M., Gómez-Cadenas, J. J., … Cárcel, S. (2016). Sensitivity of NEXT-100 to neutrinoless double beta decay. Journal of High Energy Physics, 2016(5). doi:10.1007/jhep05(2016)159Felkai, R., Monrabal, F., González-Díaz, D., Sorel, M., López-March, N., Gómez-Cadenas, J. J., … Azevedo, C. D. R. (2018). Helium–Xenon mixtures to improve the topological signature in high pressure gas xenon TPCs. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 905, 82-90. doi:10.1016/j.nima.2018.07.013McDonald, A. D., Woodruff, K., Atoum, B. A., González-Díaz, D., Jones, B. J. P., Adams, C., … Azevedo, C. D. . (2019). Electron drift and longitudinal diffusion in high pressure xenon-helium gas mixtures. Journal of Instrumentation, 14(08), P08009-P08009. doi:10.1088/1748-0221/14/08/p08009Anton, G., Badhrees, I., Barbeau, P. S., Beck, D., Belov, V., Bhatta, T., … Cen, W. R. (2019). Search for Neutrinoless Double- β Decay with the Complete EXO-200 Dataset. Physical Review Letters, 123(16). doi:10.1103/physrevlett.123.161802Albert, J. B., Anton, G., Arnquist, I. J., Badhrees, I., Barbeau, P., Beck, D., … Brown, E. (2018). Sensitivity and discovery potential of the proposed nEXO experiment to neutrinoless double- β decay. Physical Review C, 97(6). doi:10.1103/physrevc.97.065503Gando, A., Gando, Y., Hachiya, T., Hayashi, A., Hayashida, S., … Ikeda, H. (2016). Publisher’s Note: Search for Majorana Neutrinos Near the Inverted Mass Hierarchy Region with KamLAND-Zen [Phys. Rev. Lett.117, 082503 (2016)]. Physical Review Letters, 117(10). doi:10.1103/physrevlett.117.109903Jones, B. J. P., McDonald, A. D., & Nygren, D. R. (2016). 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N., O’Conner, T., Kaufman, L. J., Couture, A., … Krtička, M. (2016). Measurement of neutron capture onXe136. Physical Review C, 94(3). doi:10.1103/physrevc.94.034617Batchelor, R., Aves, R., & Skyrme, T. H. R. (1955). Helium‐3 Filled Proportional Counter for Neutron Spectroscopy. Review of Scientific Instruments, 26(11), 1037-1047. doi:10.1063/1.1715182Gibbons, J. H., & Macklin, R. L. (1959). Total Neutron Yields from Light Elements under Proton and Alpha Bombardment. Physical Review, 114(2), 571-580. doi:10.1103/physrev.114.571Haesner, B., Heeringa, W., Klages, H. O., Dobiasch, H., Schmalz, G., Schwarz, P., … Käppeler, F. (1983). Measurement of theHe3andHe4total neutron cross sections up to 40 MeV. Physical Review C, 28(3), 995-999. doi:10.1103/physrevc.28.995Antolković, B., Paić, G., Tomaš, P., & Rendić, D. (1967). Study of Neutron-Induced Reactions onHe3atEn=14.4MeV. Physical Review, 159(4), 777-781. doi:10.1103/physrev.159.777Seagrave, J. D., Cranberg, L., & Simmons, J. E. (1960). 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Exploring Memory Interventions in Depression through Lifelogging Lens

Depression is a major affective disorder with significant socio-economic cost. Distinctive autobiographical memory impairments in depression include overgeneralization, negative-bias, and repetitive negative thinking. Some psychotherapeutic interventions are designed to address these impairments, with insufficient technological support. This paper reports on an analysis of four memory-based interventions proven effective in therapeutic practice for depression, while explores the memory impairments addressed by these interventions. We address these findings into three design implications for digital tools in this space. We suggest supports for enriched positive memory recall, strategically negative memory reappraisal and future episodic imagination

Volatile and Organic Compositions of Sedimentary Rocks in Yellowknife Bay, Gale crater, Mars

H₂O, CO₂, SO₂, O₂, H₂, H₂S, HCl, chlorinated hydrocarbons, NO and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. H₂O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, and amorphous materials. Thermal decomposition of carbonates and combustion of organic materials are candidate sources for the CO₂. Concurrent evolution of O₂ and chlorinated hydrocarbons suggest the presence of oxychlorine phase(s). Sulfides are likely sources for S-bearing species. Higher abundances of chlorinated hydrocarbons in the mudstone compared with Rocknest windblown materials previously analyzed by Curiosity suggest that indigenous martian or meteoritic organic C sources may be preserved in the mudstone; however, the C source for the chlorinated hydrocarbons is not definitively of martian origin

Elemental Geochemistry of Sedimentary Rocks at Yellowknife Bay, Gale Crater, Mars

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from approximately average Martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved indicating arid, possibly cold, paleoclimates and rapid erosion/deposition. Absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low temperature, circum-neutral pH, rock-dominated aqueous conditions. High spatial resolution analyses of diagenetic features, including concretions, raised ridges and fractures, indicate they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components and hydrated calcium-sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. Geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars

The Petrochemistry of Jake_M: A Martian Mugearite

“Jake_M,” the first rock analyzed by the Alpha Particle X-ray Spectrometer instrument on the Curiosity rover, differs substantially in chemical composition from other known martian igneous rocks: It is alkaline (>15% normative nepheline) and relatively fractionated. Jake_M is compositionally similar to terrestrial mugearites, a rock type typically found at ocean islands and continental rifts. By analogy with these comparable terrestrial rocks, Jake_M could have been produced by extensive fractional crystallization of a primary alkaline or transitional magma at elevated pressure, with or without elevated water contents. The discovery of Jake_M suggests that alkaline magmas may be more abundant on Mars than on Earth and that Curiosity could encounter even more fractionated alkaline rocks (for example, phonolites and trachytes)

A Habitable Fluvio-Lacustrine Environment at Yellowknife Bay, Gale Crater, Mars

The Curiosity rover discovered fine-grained sedimentary rocks, inferred to represent an ancient lake, preserve evidence of an environment that would have been suited to support a Martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. C, H, O, S, N, and P were measured directly as key biogenic elements, and by inference N and P are assumed to have been available. The environment likely had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars