Mulit-Photon Events with Large Missing energy in e+e- collisions at sqrt(s)=192-209 GeV

Events with a final state consisting of two or more photons and large missing transverse energy have been observed in e+e- collisions at centre-of-mass energies in the range 192 - 209 GeV using the OPAL detector at LEP. Cross-section measurements are performed within the kinematic acceptance of the selection and compared with the expectation from the Standard Model process e+e- -> nu nu gamma gamma(gamma). No evidence for new physics contributions to this final state is observed. Upper limits on sigma (e+e- -> XX) BR^2(X -> Ygamma) are derived for the case of stable and invisible Y. In the case of massive Y the combined limits obtained from all the data range from 10 fb to 60 fb, while for the special case of massless Y the range is 20 fb to 40 fb. The limits apply to pair production of excited neutrions (X=nu^*,Y=nu), to neutralino production (X=~chi^0_2, Y=~chi^0_1) and to supersymmetric models in which X=~chi^0_1 and Y=~G is a light gravitino.Comment: 18 pages, 4 figures, Submitted to Phys. Letts

Interline Transfer CCD Camera

An interline CCD sensing device for use in a camera system, includes an imaging area sensitive to impinging light, for generating charges corresponding to the intensity of the impinging light. Sixteen independent registers R1 - R16 sequentially receive the interline data from the imaging area, corresponding to the generated charges. Sixteen output amplifiers S1 - S16 and sixteen ports P1 - P16 for sequentially transferring the interline data, one pixel at a time, in order to supply a desired image transfer speed. The imaging area is segmented into sixteen independent imaging segments A1 - A16, each of which corresponds to one register, on output amplifier, and one output port. Each one of the imaging segments A1 - A16 includes an array of rows and columns of pixels. Each pixel includes a photogate area, an interline CCD channel area, and an anti-blooming area. The anti-blooming area is, in turn, divided into an anti-blooming barrier and an anti-blooming drain