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PACS 24.80.+y -Nuclear tests of fundamental interactions and symmetries PACS 23.40.-s -β decay; double β decay; electron and muon capture PACS 02.50.Ey -Stochastic processes Abstract -Claims for a "cosmogenic" force that correlates otherwise independent stochastic processes have been made for at least 10 years, based on visual inspection of histograms whose shapes were interpreted as suggestive of recurrent patterns. Building on our earlier work to test nuclear alpha, beta, and electron-capture decay processes for non-randomness, we searched for correlations in the time series of e + e − annihilations deriving from the β + decay of 22 Na. Coincident gamma photons were counted within narrow time and energy windows over a period of 167 hours leading to a time series of more than 1 million events. Statistical tests for correlated fluctuations in the time series and its histograms were in all cases consistent with statistical control, giving no evidence of a "cosmogenic" force.

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We derive expressions for the exact probability distribution functions and statistical moments of measurements represented as products and quotients of independent random variables, test these relations by means of the α and β branching decays of Bi212, and discuss the implications of our theory for the measurement of lipid-panel analytes in the assessment of the risk of coronary heart disease.

An ultrasharp electron field-emission source, with emission region on the order of atomic size (i.e., fraction of a nanometer), produces a bright, strongly self-focused, highly coherent electron beam—indeed the brightest particle beam currently known to science. Employed in the configuration of a point-production microscope, this ‘‘nanotip’’ source facilitates low-energy electron imaging of fragile structures at atomic-scale resolution. When slightly out of focus, the microscope serves as perhaps the world’s simplest electron interferometer providing Fresnel diffraction patterns from which important information like effective source size, source brightness, and beam degeneracy can be determined. One remarkable feature of point sources is the perfect (i.e., aberration-free), lensless imaging of periodic structures at a denumerable set of focal planes with complete suppression of nonperiodic detail. The high degeneracy and coherent emission of an electron pointlike source can be exploited in new types of quantum interferometry involving correlated electrons.

An unusual form of glass with bulbous head and thin tail, known as Rupert's drops, can withstand high impact or pressure applied to the head, but explodes instantly into small particles when the tail is broken. The mechanism is not well understood. To examine this, we performed macro- and microstatistical analyses of a sample of 500 g of fragments of exploded Rupert's drops to determine the mass and particle distributions and associated fractal dimensions. To our knowledge, this is the first such statistical study of the fragmentation of a metastable material with large internal energy. The resulting fractal dimension D = 1.06 ± 0.09, derived from the scaling region of the mass and particle distribution functions approximated by power laws, differs from fractal dimensions (usually ⩾2) previously reported for many brittle materials. The observed distribution functions place constraints on proposed mechanisms for the explosive disintegration of the drops and presumably other physical systems characterized by high compressive stress at the surface and tensile stress within the core.