No abstract

FFT based 2D Dygital Lens is discussed comparing with Fourier synthesis. The sensitivity of constructing Large Array will be 50mJy. Precise manipuration of the radiation field is possible in it.

Hedoro that appears on the bottom of harbor is a low concentration sediment containing organic matters. To clarify the sound scattering or reflection by such a layer, the relationship between vertical profile of sound velocity and attenuation, and physical properties of a layer should be obtained. In order to simplify the measurements, a sediment layer was reformed artificially in laboratory tank by settling down the hedoro collected from harbor bottom. Velocity and attenuation were measured by pulse transmission method at 200–800 kHz on each sample extracted from several depths in this layer. Analyses of density, volume concentration, and grain size of sample were also made. Results of analyses show that these density, concentration, and mean grain size increase slightly and gradually with depth. Even though concentration of sample was enough low in this experiment, the measured velocity increases with concentration, acoustic frequency, and depth, but these tendencies agree with results of calculation by theoretical formula of suspensions taking acount of a factor of grain size distribution.

The SciBar Cosmic ray telescope (SciCRT) is installed on the top of the Sierra Negra volcano with the main goal of observing solar neutrons to investigate the ion acceleration process during solar flares. Using scintillator bars as a medium to stop energetic particles, the SciCRT is capable of recording both energy deposited on the bars and direction of the incoming particles with high resolution. The original DAQ system was used in neutrino oscillation experiment (low event rate), therefore operation of the electronics on cosmic ray experiment is limited. To improve the SciCRT performance as a solar neutron telescope, development of custom made DAQ electronics is essential. Our first step onto this task was the design and construction of a new fast readout back-end board using SiTCP. The installation of this new system on Sierra Negra and its further improvement on the data acquisition for the detector will be analyzed on separate paper on this conference. The development of new front end electronics is the next stage of the upgrading process. To achieve this goal, we are developing new electronics applying the time over threshold (ToT) technique, using a FPGA to process the signal from one 64-channel multi anode photomutiplier tube (MAPMT). In this paper we will present the details of this new system and several tests performed to guarantee its proper operation to detect solar neutrons.