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The set-up of the COMPASS experiment (NA58 at CERN SPS) consists of two spectrometers (a large-angle one followed by a small-angle spectrometer) both equipped with a gas RICH (RICH 1 and RICH 2) for hadron identification. RICH 1 is currently under construction, while RICH 2 will be added at a second stage. RICH 1 design parameters and technological choices are discussed.

A solid-state imager fabricated in CMOS technology is presented for depth information capture of arbitrary 3D objects with millimeter resolution. The system is based on an array of 32x32 pixels that independently measure the time-of-flight of a ray of light as it is reflected back from the objects in a scene. A single cone of pulsed laser light illuminates the scene, thus no complex mechanical scanning is required. Millimetric depth accuracies can be reached thanks to the rangefinder’s optical detectors that enable picosecond time discrimination. The detectors, based on a single photon avalanche diode operating in Geiger mode, utilize avalanche multiplication to enhance light detection. Optical power requirements on the light source can therefore be significantly relaxed. A number of standard performance measurements, conducted on the imager, are discussed in this paper. The 3D imaging system was also tested on real 3D subjects demonstrating the suitability of the approach.

An avalanche photodiode array uses single-photon counting to perform time-of-flight range-finding on a scene uniformly hit by 100ps 250mW uncollimated laser pulses. The 32x32 pixel sensor, fabricated in a 0.8μm CMOS process uses a microscanner package to enhance the effective resolution in the application to 64x64 pixels. The application achieves a measurement depth resolution of 1.3mm to a depth of 3.75m.

We present experimental results which test whether diffusion engineering can increase the energy resolution of a single-photon superconducting tunnel-junction spectrometer. When a UV photon is absorbed in superconducting Al, it creates an excess number of quasiparticles. If the superconducting absorber is the electrode of a tunnel junction, the quasiparticles tunnel across the voltage-biased junction. The collected charge is proportional to the number of excess quasiparticles. For small energy photons, the initiallycreated charge can be amplified by backtunnelling. The quasiparticles confined around the junction can backtunnel as holes after tunnelling, doubling the output charge, and then tunnel again. The charge multiplication is proportional to the confinement time. When the counterelectrode is terminated with a long, narrow lead, the quasiparticles diffuse out on a time scale set by the dimensions of the leads and of the electrodes, and the diffusion constant of the material. We show how the charge created by the photon varies with the purity of the Al film and with different lead geometries. The experimental results are compared to theoretical predictions of our model. We achieve an energy resolving power of 3 for a photon energy of 3.68 eV. Further investigation of losses in our materials should improve the energy resolution of our diffusion-engineered devices.

The design and characterization of an imaging system is presented for depth information capture of arbitrary three-dimensional (3-D) objects. The core of the system is an array of 32 /spl times/ 32 rangefinding pixels that independently measure the time-of-flight of a ray of light as it is reflected back from the objects in a scene. A single cone of pulsed laser light illuminates the scene, thus no complex mechanical scanning or expensive optical equipment are needed. Millimetric depth accuracies can be reached thanks to the rangefinder's optical detectors that enable picosecond time discrimination. The detectors, based on a single photon avalanche diode operating in Geiger mode, utilize avalanche multiplication to enhance light detection. On-pixel high-speed electrical amplification can therefore be eliminated, thus greatly simplifying the array and potentially reducing its power dissipation. Optical power requirements on the light source can also be significantly relaxed, due to the array's sensitivity to single photon events. A number of standard performance measurements, conducted on the imager, are discussed in the paper. The 3-D imaging system was also tested on real 3-D subjects, including human facial models, demonstrating the suitability of the approach.