Microburst of TeV gamma rays from the Crab pulsar

Data on Crab pulsar from atmospheric Cerenkov array at Ooty have shown emission of TeV gamma rays in the form of microbursts. These are a series of events which are unusually closely spaced in time with time separations of less than 1.5 milliseconds. The phasogram of events in the bursts when analyzed with the Crab pulsar period shows significant peaks. Data further show that the signal is at the same absolute phase as the radio peak. Monte Carlo calculations show that the probability of peaks being due to chance is very small

Growth Stress Induced Tunability of Dielectric Constant in Thin Films

It is demonstrated here that growth stress has a substantial effect on the dielectric constant of zirconia thin films. The correct combination of parameters - phase, texture and stress - is shown to yield films with high dielectric constant and best reported equivalent oxide thickness of 0.8 nm. The stress effect on dielectric constant is twofold, firstly, by the effect on phase transitions and secondly by the effect on interatomic distances. We discuss and explain the physical mechanisms involved in the interplay between the stress, phase changes and the dielectric constant in detail.Comment: 11 pages, 5 figure

The Index of (White) Noises and their Product Systems

(See detailed abstract in the article.) We single out the correct class of spatial product systems (and the spatial endomorphism semigroups with which the product systems are associated) that allows the most far reaching analogy in their classifiaction when compared with Arveson systems. The main differences are that mere existence of a unit is not it sufficient: The unit must be CENTRAL. And the tensor product under which the index is additive is not available for product systems of Hilbert modules. It must be replaced by a new product that even for Arveson systems need not coincide with the tensor product

Search for gamma rays of energy 10(15) eV from Cygnus X-3

Finite flux of excess radiation of energy 10 to the 15th power has been reported by two groups from the direction of Cygnus X-3, with the characteristic periodicity of 4.8 hrs. Samorski and Stamm find that the muon content of the showers generated by this excess radiation is about 77% of that in normal cosmic ray showers, whereas the expectation for gamma ray showers is less than 10%. It is thus difficult to understand the nature of the radiation arriving from the direction of Cygnus X-3. Samorski and Stamm measured the muon densities close to the core (approx. 10 m), where contamination due to other components is severe. Even though this does not explain the high ratio of muon densities, measurements should be carried out away from the core to establish the nature of the radiation. In order to establish the signal from Cygnus X-3 and its muon content with better statistical significance, an extensive air shower array, specifically designed for this purpose was operated at Kolar Gold Fields (longitude: 78 deg .3 E; latitude: + 12 deg .95; atmospheric depth: 920 q/square centimeters) since September, 1984. The details of the array and the accuracy of arrival direction measurements are discussed

Maximal Commutative Subalgebras Invariant for CP-Maps: (Counter-)Examples

We solve, mainly by counterexamples, many natural questions regarding maximal commutative subalgebras invariant under CP-maps or semigroups of CP-maps on a von Neumann algebra. In particular, we discuss the structure of the generators of norm continuous semigroups on B(G) leaving a maximal commutative subalgebra invariant and show that there exists Markov CP-semigroups on M_d without invariant maximal commutative subalgebras for any d>2.Comment: After the elemenitation in Version 2 of a false class of examples in Version 1, we now provide also correct examples for unital CP-maps and Markov semigroups on M_d for d>2 without invariant masa