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Dark noise is a dominant background in photomultiplier tubes (PMTs), which are commonly used in liquid-filled particle detectors for single-photon detection to see the results of particle interactions. A major contribution to dark noise is thermionic emission from the photocathode. The dark noise of Hamamatsu R7081-100 PMTs is characterised in a temperature and purity controlled water tank, with the thermionic emission contribution isolated. The results suggest that the intrinsic dark rate of PMTs does not depend on the medium, but does follow Richardson's law of thermionic emission. There are external contributions to the overall observed PMT count rate identified, but the intrinsic PMT dark rate in water matches that measured in air., Comment: 11 pages, 7 figures, 2 tables, published in Journal of Instrumentation

Antineutrinos from nuclear reactors have the potential to be used for reactor monitoring in the mid- to far-field under certain conditions. Antineutrinos are an unshieldable signal and carry information about the reactor core and the distance they travel. Using gadolinium-doped water Cherenkov detectors for this purpose has been previously proposed alongside rate-only analyses. As antineutrinos carry information about their distance of travel in their energy spectrum, the analyses can be extended to a spectral analysis to gain more knowledge about the detected core. Two complementary analyses are used to evaluate the distance between a proposed gadolinium-doped water-based liquid scintillator detector and a detected nuclear reactor. Example cases are shown for a detector in Boulby Mine, near the Boulby Underground Laboratory in the UK, and six reactor sites in the UK and France. The analyses both show strong potential to range reactors, but are limited by the detector design., Comment: 13 pages, 12 figures, 5 tables

Antineutrinos from a nuclear reactor comprise an unshieldable signal which carries information about the core. A gadolinium-doped, water-based Cherenkov detector could detect reactor antineutrinos for mid- to far-field remote reactor monitoring for non-proliferation applications. Two novel and independent reconstruction and analysis pathways have been developed and applied to a number of representative reactor signals to evaluate the sensitivity of a kiloton-scale, gadolinium-doped Cherenkov detector as a remote monitor. The sensitivity of four detector configurations to nine reactor signal combinations was evaluated for a detector situated in Boulby Mine, close to the Boulby Underground Laboratory in the UK. It was found that a 22~m detector with a gadolinium-doped, water-based liquid scintillator fill is sensitive to a $\rm \sim 3~GW_{th}$ reactor at a standoff of $\rm \sim150~km$ within two years in the current reactor landscape. A larger detector would be required to achieve a more timely detection or to monitor smaller or more distant reactors., Comment: 31 pages, 19 figures, submitted to Phys. Rev. Applied

This paper presents a phenomenon which sometimes occurs in tetravalent bipartite locally dart-transitive graphs, called a Base Graph -- Connection Graph dissection. In this dissection, each white vertex is split into two vertices of valence 2 so that the connected components of the result are isomorphic. Given the Base Graph whose subdivision is isomorphic to each component, and the Connection Graph, which describes how the components overlap, we can, in some cases, provide a construction which can make a graph having such a decomposition. This paper investigates the general phenomenon as well as the special cases in which the connection graph has no more than one edge., Comment: 19 pages, 10 figures, to be submitted to Discrete Mathematics

Crossword puzzles are popular word games that require not only a large vocabulary, but also a broad knowledge of topics. Answering each clue is a natural language task on its own as many clues contain nuances, puns, or counter-intuitive word definitions. Additionally, it can be extremely difficult to ascertain definitive answers without the constraints of the crossword grid itself. This task is challenging for both humans and computers. We describe here a new crossword solving system, Cruciform. We employ a group of natural language components, each of which returns a list of candidate words with scores when given a clue. These lists are used in conjunction with the fill intersections in the puzzle grid to formulate a constraint satisfaction problem, in a manner similar to the one used in the Dr. Fill system. We describe the results of several of our experiments with the system., Comment: based on feedback, we have determined that the paper needs more work

In this note we revisit the dart graph and the squared dart digraph constructions and prove that they yield strongly connected digraphs when applied to connected graphs of minimum valence at least 3., Comment: 4 pages, no pictures

This paper is to accompany the Census of Edge-Transitive Tetravalent Graphs, available at jan.ucc.nau.edu/~swilson/C4FullSite/index.html, which is a collection of all known edge-transitive graphs of valence 4 up to 512 vertices. The Census contains information for each graph. This information includes parameters such as group order, diameter, girth etc., all known constructions, relations to other graphs in the Census and intersting substructures such as colorings, cycle structures, and dissections. We try to present most graphs as members of one or more parameterized families, and one purpose of this paper is to gather together, here in one place, descriptions of each of these families, to show how each is constructed, what the history of each is and how one family is related to another. We also discuss in this paper the theory and techniques behind computer searches leading to many entries in the Census., Comment: 31 pages, 16 figures

This paper discusses consistent flag bicolorings of maps and maniplexes, in their own right and as generalizations of orientations and pseudo-orientations. Furthermore, a related doubling concept is introduced, and relationships between these ideas are explored.