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Asymmetric-dual-grating-gate high-electron-mobility-transistors (ADGG-HEMTs) are expected for on-chip, sensitive, room-temperature operating, high-speed THz detectors. In this paper, we experimentally verify the high-speed response of an ADGG-HEMT by measuring its response to THz pulse generated from an injection-seeded THz-wave parametric generator (is-TPG). From the pulse response waveform of the...
A new method using a stopped cosmic-ray beam for the calibration of an electro-magnetic calorimeter which consists of several hundreds of modules has been established. Cosmic muons stop in the calorimeter, and positrons (and electrons) from the muon decays with the maximum energy of 53 MeV are used for the energy calibration. These events could be identified as double pulses observed by a flash ADC...
We examine array configuration and silicon-lens integration of asymmetric-dual-grating-gate high-electron-mobility transistors (A-DGG HEMTs) as plasmonic terahertz detectors in order to enhance their external coupling efficiencies. We demonstrate 4-fold enhancement of the efficiency by an array of four series-connected detectors and 6-fold enhancement by the hyper-hemispherical silicon-lens integration...
We experimentally verify that the low external responsivity of nanostructured asymmetric-dual-grating-gate high-electron-mobility transistors (A-DGG HEMTs) as plasmonic terahertz detectors developed so far is attributed to their low external coupling efficiency. We separately demonstrate (1) 4-fold enhancement of the efficiency by an array of series-connected 4×1 detectors due to the increase in the...
We propose a positron detector with 8 layers of scintillation fibers whose length is 1 m and whose diameter is 0.2 mm. The shape of this detector is like as endoscope but one layer of fibers is spirally rolled clockwise, and another layer is counter-clockwise. The pitch of inner and outer spiral fibers are 85 and 75mm, respectively. This detector can be installed into the intestines from the anus,...
Because of the disaster of Fukushima No.1 nuclear power plant in 2011, a large amount of radioactive substance (including 90Sr and 137Cs) was released into the Japanese coast of the Pacific Ocean. 90Sr can be more dangerous than 137Cs. Since 90Sr does not emit γ rays, it is very difficult to measure its radioactivity. We have made threshold-type Cherenkov counter using silica aerogel with a refractive...
Usual TOP (time of propagation) detectors have several disadvantages. We propose a new TOP detector which overcomes those by using clear fibers (these have high transparency than general optical fibers). We performed Monte Carlo simulations with Geant4 and tested a prototype with e+ of 0.7 to 1.0 GeV at SPring8 BR33LEP beam line. We propose this detector to E-36 experiment at J-PARC.
In March 2011, a large earthquake hit Japan and damaged seriously. Because of this disaster, accidents was happen at Fukushima No.1 nuclear power plant and many radioisotope has been released into the Japanese coast of the Pacific Ocean. We pay attention to 90Sr and propose the method to detect it in an hour.
We are developing a PET system integrated with a birdcage RF coil for PET-MRI to realize highly sensitive PET system for simultaneous measurements. The PET detectors which consist of a scintillator block, photo sensors and front-end circuits with four-layer DOI encoding capability are placed close to the objective. Therefore, the proposed system can achieve high sensitivity without degradation spatial...
The depth of interaction (DOI) PET detector is one way to achieve high resolution image by determining the depth where most of gamma ray energy is deposited in a scintillator. Because a 2D or 3D profile is obtained for each element, the large amount of data makes the image reconstruction difficult. In this study, we propose a new type of DOI PET detector and estimate a photon yield of a channel and...
The work presented here proposes local I/Q phase correction and carrier leakage suppression techniques for WiMAX transceivers. Local I/Q calibration was able to compensate for process and supply voltage variations, and the measured I/Q phase errors after calibration are within 3 degrees. The measured carrier leakage after calibration substantially meets WiMAX specifications, and the proposed sequence...
A method for attacking an additive watermark is proposed. A watermark pattern is estimated by applying a local Wiener filter to each frequency band of the stego signal. The method exploits local differences in power spectrum density (psd) between the watermark and the host signals. Experiments have shown that the attack is more than 10 times effective compared to the existing global Wiener attack...
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