The serendipitous observation of neutrinos and light from the recent supernova in the Large Magellanic Cloud has provided a wealth of new information about stellar collapse and about neutrinos. It is pointed out that, in addition, the nearly simultaneous arrival of the photons and neutrinos after a journey of some 160000 yr provides a new, stringent test of the Einstein equivalence principle on intergalactic distance scales. The relativistic time delays of the photons and neutrinos from SN1987A caused by the gravitational 6eld of our Galaxy are compared, and it is shown that they are equal, to an accuracy of approximately 0.2% of the predicted delay.

The vertical underground muon intensity has been measured in the slant depth range 3200-7000 hg cm(-2) (standard rock) with the completed lower part of the MACRO detector at the Gran Sasso laboratory, using a large sample of data. These observations are used to compute the surface muon flux and the primary ''all-nucleon'' spectrum. An analysis of systematic uncertainties introduced by the interaction models in the atmosphere and the underground propagation of muons is presented

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We have measured total cross sections for neutrons on protons, deuterium, beryllium, carbon, aluminum, iron, copper, cadmium, tungsten, lead, and uranium for momenta between 30 and 300 GeV/c. The measurements were carried out in a small-angle neutral beam at Fermilab. Typical accuracy of the data is 0.5 to 1%. The cross sections are consistent with an A 0"77+0"01 dependence over the entire momentum range. The cross sections are compared with theoretical predictions. Agreement is found only if inelastic screening is included. Nuclear radii obtained from our data are in good agreement with previous determinations. oT(Pn) would have been 0.9 mb larger. ** See, for example, Pumplin and Ross [27].

Flat-panel imagers consisting of the first large area, self-scanning, pixelated, solid-state arrays made with hydrogenated amorphous silicon (a-Si:H) are under development by the authors for applications in diagnostic x-ray and megavoltage radiotherapy imaging. The arrays, designated by the acronym MASDA for multi-element amorphous silicon detector array, consist of a two-dimensional array of a-Si:H photodiodes and thin-film transistors and are used in conjunction with scintillating materials. Imagers utilizing MASDA arrays offer a variety of advantages over existing technologies. This article presents initial megavoltage and diagnostic-quality x-ray images taken with several such arrays including the first examples of anatomical-phantom images. The external readout electronics and imaging techniques required to obtain such images are outlined, the construction, operation, and advantages of the arrays briefly reviewed, and the future potential of this new technology discussed.