This paper considers the problem of spectrum sensing in cognitive radio networks when the primary user employs Orthogonal Frequency Division Multiplexing (OFDM). We develop cooperative sequential detection algorithms based on energy detectors and the autocorrelation property of cyclic prefix (CP) used in OFDM systems and compare their performances. We show that sequential detection provides muc...

This study was performed to investigate the iterative reconstruction of a segment of a long object using cone-beam projections acquired with a practical-size detector. This reconstruction problem is commonly called the cone-beam long object problem. The cone-beam focal-point trajectories studied were either helical or helical with planar arcs. We assume that the long object is confined in a tal...

For the new ToF Barrel of FOPI, [1], a new beam detector based on polycrystalline-CVD diamond was developed. The new device replaces the existing beam monitoring system which comprise a ToF Start detector and a beam-halo detector, both built from plastic scintillator material. However, since the employed diamonds are not sensitive to minimum ionizing particles the new device can be used efficie...

We have developed a large CdTe pixel detector with dimensions of 23.7 × 13.0 mm and a pixel size of 448 × 448 μm. The detector is based on recent technologies of an uniform CdTe single crystal, a two-dimensional ASIC, and stud bump-bonding to connect pixel electrodes on the CdTe surface to the ASIC. Good spectra are obtained from 1051 pixels out of total 1056 pixels. When we operate the detecto...

For the sLHC phase I, the ATLAS detector will be upgraded by installation of an additional Pixel Detector layer. The new layer will be inserted between the B-layer of the existing pixel detector and a new smaller radius beam-pipe. This upgrade requires development of several new technologies to cope with increased radiation doses to which the apparatus will be exposed, signi cant rise of the pa...

We have developed a novel data acquisition system for measuring tracking parameters of a silicon detector in a particle beam. The system is based on a commercial Analog-to-Digital VME module and a PC Linux based Data Acquisition System. This DAQ is realized with C++ code using object-oriented techniques. Track parameters for the beam particles were reconstructed using off-line analysis code and...

This study was performed to investigate the iterative reconstruction of a segment of a long object using cone-beam projections acquired with a practical-sized detector. This reconstruction problem is commonly called the cone-beam long object problem. The cone-beam focal-point trajectories studied were either helical or helical with planar arcs. We assume that the long object is confined in a ta...

First images are presented from tests of a semi-insulating gallium arsenide X-ray imaging detector, flip-chip bonded to a current integrating CMOS readout chip. The detector is designed for applications in synchrotron X-ray imaging. The X-ray sensing part of the detector consists of a 150 mm thick GaAs photodiode containing an array of 92 100 pixels, each 150mm by 150 mm in size. Operating the ...

PURPOSE The variable resolution x-ray (VRX) CT scanner provides substantial improvement in the spatial resolution by matching the scanner's field of view (FOV) to the size of the object being imaged. Intercell x-ray cross-talk is one of the most important factors limiting the spatial resolution of the VRX detector. In this work, a new cell arrangement in the VRX detector is suggested to decreas...