A new photon-counting area detector, based on parallel-plate gas amplification with a resistive anode and remote readout electrode is described. The detector is sealed and has sensitive area of 14x14 cm2. The detector is unique in its ability to achieve high gain at high counting rates. A local counting rate >10e5 counts/mm2-sec has been achieved at a gain of 105 in a radiation-hard, non-polymerizing gas mixture. The global readout rate is limited by the delay line and electronics to <106 counts/sec but more sophisticated readout schemes should allow this rate to be increased by more than an order of magnitude. The operating characteristics of the detector are described and preliminary x-ray diffraction data are presented.
A new high efficiency, low-bandgap phosphor, ZnSe:Cu,Ce,Cl is described which exhibits a significantly higher quantum gain than conventional x-ray phosphors and more closely matches the spectral sensitivity of silicon sensors. For many imaging applications this phosphor thus promises significantly superior performance compared to conventional phosphors.
A novel sealed gaseous PPAC detector is described which is significantly less prone to discharges and can consequently achieve high gas gains at high counting rates. The detector has demonstrated stable gains greater than 104 at counting rates in excess of 107 counts/mm2-sec.
A novel type of light modulating micromirror device has been designed and fabricated. A unique hinge structure provides the device with the potential for modulating both the phase and amplitude of light signals, while its high thermal conductivity makes the device amenable to high power laser applications. An extremely high fill factor can be attained since the hinges lie entirely beneath the mirror surface. This hidden hinge structure is comprised of a single level and therefore involves a simple fabrication process. Micromirrors with dimensions ranging from 100 micrometers X 100 micrometers to 300 micrometers X 300 micrometers with maximum deflection angles from 2 degree(s) to 4 degree(s) were fabricated. The devices were characterized in terms of the reflecting surface optical quality, the operational modes attainable, the critical voltages (as low as 15 volts), and the response time (as short as 125 microsecond(s) ).