Curved radiation detector

As vertex detectors for smaller for smaller inner beam pipe diameters are required, the planar nature of the detector becomes more and more of a problem. We present a curved silicon vertex detector, whose radius of curvature can be adjusted to the beam pipe. The advantage of these curved detectors over conventional planar ones is twofold: The first advantage is that these detectors are curved to a specific curvature and shaped directly for the specific application (e.g. beam pipe radius), and second, the curvature of the backside is independent from the front surface, which allows thinning of the detector using standard semiconductor processing. Both strip detectors and pixel arrays (with Indium bump bonds) have been realized on the curved topography. The key micro-fabrication technique for curved topography, so called “gray-tone lithography”, will be introduced and discussed. We demonstrated low-noise performance by successfully detecting low-energy gamma-rays with a curved strip detector. The energy resolution was ∼ 1.73 keV FWHM at 59.5 keV for the pixel detector. There is excellent charge collection at the curved surface. The general fabrication method could also be applied for curved focal plane arrays to improve optical systems.