Radiation effects in samarium-doped calcium fluoride

A study was conducted of the effects of gamma radiation on samarium (Sm)-doped calcium flouride (CaF₂) crystals. Optical absorption measurements indicate that many of the Sm³⁺ ions are converted to Sm²⁺ during irradiation. Heavy doses of 10⁶ rad also modify the trapping structures and enhance certain defects within the crystals. A comparison is provided between unirradiated and heavily irradiated CaF₂ crystals with three Sm concentrations: 0.01, 0.1, and 1.0 molar-percent. Thermoluminescence measurements indicate that the crystals with high Sm content provide less luminescence and that the activation energy is less than seen in the 0.01 molar-percent Sm crystals.     

A branch and search algorithm for a class of nonlinear knapsack problems

This paper discusses a class of nonlinear knapsack problems where the objective function is quadratic. The method is a branch and search procedure which includes an efficient algorithm to find the continuous (relaxed) solution and a reduction rule which computes tight lower and upper bounds on the integer variables.     

Wide bandwidth, high-repetition-rate optoelectronic modulation of millimetre waves in GaAs waveguide

The generation of ultrashort, chirped and coherent millimetre-wave pulses by an optical method is reported. Using this technique, the modulation of millimetre-wave signals at 94 GHz with a modulation bandwidth in excess of 1 GHz is readily achievable.     

Rotational excitation of H2 and N2 molecules by electron impact

The rotational excitation of the H₂ and N₂ molecules from (J→J+2,J=0) and (J→J+2,J=1) states by electron impact is studied, in the framework of the regional-plane-wave approximation. The empirical cut-off parameterρ, involved in these calculations, is varied to give the best fit to the experimental data of Srivastava and co-workers.     

A note on minimal topological spaces

Let (X,τ) be a completely Hausdorff space. LetP be any topological property which is implied by complete regularity. Let (X,τ), be minimal-P. Then it has been shown that (X,τ), is completely regular and hence compact.     

The electric quadrupole transition L2M3(β17) in the X-ray emission spectrum of erbium

A new diagram line corresponding to the electric quadrupole transition L₂M₃(β₁₇) in the X-ray emission spectrum of erbium is reported at λ = 1658.25 X.U., using a 40 cm curved mica crystal spectrograph of transmission type.     

Excitons and Bose–Einstein condensation in living systems

The problems connected with the transformations of energy in the living systems are reviewed. Possibility of Bose–Einstein condensation by input of radiant energy over a critical level is considered as a route for overcoming the barriers of activation energy under the conditions of a pump and a thermalizing environment. Molecular force fields constitute the pump. Under our scheme excitons constitute the major fraction of bosons to so condense. Instantaneous dipoles of London theory are then examined as excitons. Lastly an energy packet from a quantized dipolar field is suggested rather than the concept of “conformons.” Questions of charge and of other modes of energy transfer are briefly discussed.