Spectral computed tomography (CT) is a promising technique with the potential for improving lesion detection, tissue characterization, and material decomposition. In this paper, we are interested in kVp switching-based spectral CT that alternates distinct kVp X-ray transmissions during gantry rotation. This system can acquire multiple X-ray energy transmissions without additional radiation dose. However, only sparse views are generated for each spectral measurement; and the spectra themselves are limited in number. To address these limitations, we propose a penalized maximum likelihood method using spectral patch-based low-rank penalty, which exploits the self-similarity of patches that are collected at the same position in spectral images. The main advantage is that the relatively small number of materials within each patch allows us to employ the low-rank penalty that is less sensitive to intensity changes while preserving edge directions. In our optimization formulation, the cost function consists of the Poisson log-likelihood for X-ray transmission and the nonconvex patch-based low-rank penalty. Since the original cost function is difficult to minimize directly, we propose an optimization method using separable quadratic surrogate and concave convex procedure algorithms for the log-likelihood and penalty terms, which results in an alternating minimization that provides a computational advantage because each subproblem can be solved independently. We performed computer simulations and a real experiment using a kVp switching-based spectral CT with sparse-view measurements, and compared the proposed method with conventional algorithms. We confirmed that the proposed method improves spectral images both qualitatively and quantitatively. Furthermore, our GPU implementation significantly reduces the computational cost.

The muon anomalous magnetic moment has been measured in a new experiment at Brookhaven. Polarized muons were stored in a superferric ring, and the angular frequency difference, v a , between the spin precession and orbital frequencies was determined by measuring the time distribution of highenergy decay positrons. The ratio R of v a to the Larmor precession frequency of free protons, v p , in the storage-ring magnetic field was measured. We find R 3.707 220͑48͒ 3 10 23. With m m ͞m p 3.183 345 47͑47͒ this gives a m 1 1 165 925͑15͒ 3 10 29 (613 ppm), in good agreement with the previous CERN measurements for m 1 and m 2 and of approximately the same precision.

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We report on performance results achieved for recently produced LAPPDs -largest comercially available planar geometry photodetectors based on microchannel plates. These results include electron gains of up to 10 7 , low dark noise rates (∼100 Hz/cm 2 at a gain of 6 · 10 6 ), single photoelectron (PE) timing resolution of ∼50 picoseconds RMS (electronics limited), and single photoelectron spatial resolution along and across strips of 3.2mm (electronics limited) and 0.8 mm RMS respectively and high (about 25% or higher in some units) QE uniform bi-alkali photocathodes. LAPPDs is a good candidate to be employed in neutrino experiments (e.g. ANNIE [1], WATCHMAN [2], DUNE [3]), particle collider experiments (e.g. EIC [4]), neutrinoless double-beta decay experiments (e.g. THEIA [5]), medical and nuclear non-proliferation applications.

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We report on the first measurement of the flux of upgoing muons resulting from interactions of atmospheric neutrinos in the rock below MACRO. The ratio of the observed to the expected number of events integrated over all nadir angles is 0.73 +/- .09stat. +/- .06sys. +/- .12theor.. The flux of upgoing muons as a function of nadir angle is presented and compared to Monte Carlo expectations. At the 90% confidence level, the data are consistent with no neutrino oscillations or some possible oscillation hypotheses with the parameters suggested by the Kamiokande contained-event analysis

We have performed a new evaluation of the hadronic contribution to a ϭ(gϪ2)/2 of the muon with explicit correlations of systematic errors among the experimental data on (e ϩ e Ϫ →hadrons͒. Our result for the lowest order hadronic vacuum polarization contribution is a had ϭ702.6(7.8)(14.0)ϫ10 Ϫ10 where the first error is statistical and the second is systematic. The total systematic error contributions from below and above ͱsϭ1.4 GeV are (13.1)ϫ10 Ϫ10 and (5.1)ϫ10 Ϫ10 , respectively, and are hence dominated by the low energy region. Therefore, new measurements on (e ϩ e Ϫ →hadrons) below 1.4 GeV can significantly reduce the total error on a had . In particular, the effect on the total errors of new hypothetical data with 3% statistical and 0.5-1.0 % systematic errors is presented. ͓S0556-2821͑96͒03117-7͔PACS number͑s͒: 14.60.Ef, 06.20.Dk, 13.65.ϩi I. ROLE OF HADRONIC CONTRIBUTION IN g؊2A new measurement of the anomalous magnetic moment of the muon, a ϵ(gϪ2)/2, to an absolute accuracy of expt a ϳϮ4.0ϫ10 Ϫ10 is proposed by the Brookhaven National Laboratory ͑BNL͒ E821 Collaboration ͓1,2͔. The theoretical value of the muon gϪ2 value consists of at least the three standard model contributions: quantum electrodynamics ͑QED͒, electroweak ͑EW͒, and hadronic. The latter arise from hadronic vacuum polarization effects caused by effective photon couplings to hadrons via charged quarks and consequent quantum chromodynamics ͑QCD͒ interactions with gluons ͑see Fig. 1͒. Any residual difference between the sum of the standard model contributions and the new experimental value a expt will be indicative of new physics: a residual ϭa expt Ϫa QED Ϫa EW Ϫa had .The new experimental value can only be sensitive to electroweak and possibly supergravity ͓3,4͔ and muon substructure effects ͓5͔ provided the errors on the standard model contributions are known better than the experimental accuracy. The QED and EW contributions have been calculated from theory and are known an order of magnitude better than the expected experimental accuracy (a QED ϭ11658470.6 Ϯ0.2ϫ10 Ϫ10 ͓6͔ and a EW ϭ15.1Ϯ0.4ϫ10 Ϫ10 ͓7͔͒. At the same time, the lowest order hadronic contribution cannot be calculated accurately enough by QCD and hence a phenomenological procedure must be used for its calculation. While

A negative search using, '& of the eventual MACRO detector has yielded nuclearite flux limits of 1.1&&10 ' cm sr 's ' for 10 ' & ni (0.1 g, and 5.5x 10 ' cm sr 's ' for m)O.l g. We have modified the formula of De Rujula and Glashow for the light yield of nuclearites to include the uv light absorbed and reemitted in the visible region, and proved that the MACRO sensitivity extends almost to the escape velocity of the Earth. Our Aux limit, therefore, can be used to address nuclearites that are possibly trapped in the solar system.