A simple geometry of real pixel gas detectors has been evaluated that circumvents the limitations of a microstrips, namely aging, gain drift and flux limitation due to the dielectric

A new technique is described which is capable of observing the stability of specific states of doubly charged molecular ions with vibrational level resolution. The method is based on the process of double photoionization using synchrotron radiation. Pairs of threshold electrons identify the initial state, and the resulting ions are characterized by their times of flight. Lifetimes have been measured for specific levels of CO 21 and confirm, except for the very lowest levels, the intrinsic instability of this species on the ms time scale. [S0031-9007(98)

We report the use of high magnetomechanical coupling ferrites in magnetoelectric (ME) layered composites. Bilayer samples combining (Ni 0.973 Co 0.027 ) 1-x Zn x Fe 2 O 4 ferrites (x=0-0.5) synthetized by non conventional reactive Spark Plasma Sintering (SPS) and commercial lead zirconate titanate (PZT) were characterized in term of ME voltage coefficients measured at sub-resonant frequency. Strong ME effects are obtained and we show that an annealing at 1000°C and a quenching in air improve the piezomagnetic behavior of Zn-rich compositions. A theoretical model that predict the ME behavior was developed, focusing our work on the demagnetizing effects in the transversal mode as well as the longitudinal mode. The model shows that: (i) high ME coefficients are obtained when ferrites with high magnetomechanical coupling are used in bilayer ME composites, (ii) the ME behavior in transversal and longitudinal modes are quite similar, and differences in the shapes of the ME curves are mainly due the demagnetizing effects, (iii) in the transversal mode, the magnetic field penetration depends on the ferrite layer thickness and the ME coefficient is affected accordingly. The two later points are confirmed by measurements on ME samples and calculations. Performances of the ME composites made with high magnetomechanical coupling ferrites are compared to those obtained using Terfenol-D materials in the same conditions of size, shape, and volume ratio. It appears that a ferrite with an optimized composition has performances comparable to those obtained with Terfenol-D material. Nevertheless, the fabrication processes of ferrites are quite simpler. Finally a ferrite/PZT based ME composite was used as a current sensor.