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We theoretically propose one-dimensional composite photonic structures for high-resolution THz spectroanalysis. We compare the performance of two GaAs/AlAs composite photonic-structure devices, one with usual 1/4-wavelength layers of distributed Bragg reflectors (DBRs), and the other with the designed DBRs. The device with designed DBRs shows the optical-to-terahertz conversion efficiency up to 10−5 and wide frequency tunability ranging from sub-THz to 3 THz. We found that the composite photonic structure allows us to control photonic modes with a high degree of freedom by flexible structure designs. This device achieve a cw THz source with a highly narrow bandwidth operating at room temperature.

A prototype positron emission tomography (PET) scanner using CdTe semiconductor detectors was developed, and its initial evaluation was conducted. The scanner was configured to form a single detector ring with six separated detector units, each having 96 detectors arranged in three detector layers. The field of view (FOV) size was 82 mm in diameter. Basic physical performance indicators of the scanner were measured through phantom studies and confirmed by rat imaging. The system-averaged energy resolution and timing resolution were 5.4% and 6.0 ns (each in FWHM) respectively. Spatial resolution measured at FOV center was 2.6 mm FWHM. Scatter fraction was measured and calculated in a National Electrical Manufacturers Association (NEMA)-fashioned manner using a 3-mm diameter hot capillary in a water-filled 80-mm diameter acrylic cylinder. The calculated result was 3.6%. Effect of depth of interaction (DOI) measurement was demonstrated by comparing hot-rod phantom images reconstructed with and without DOI information. Finally, images of a rat myocardium and an implanted tumor were visually assessed, and the imaging performance was confirmed. Index Terms--CdTe, DOI, PET, semiconductor detector.

Homogeneity of the superconducting properties in controlled overpressure (CT-OP) processed Bi2223 tapes are analyzed. The results have shown that CT-OP processed Bi2223 tape can be improved by enhancing the performance of the edge parts of the tape.

Superconducting split magnets are developed for a high-resolution NMR spectrometer. An advanced superconducting shim system and negative current are adopted in the inner-most coils in order to improve the inhomogeneous magnetic field caused by the coil configurations.

The design and construction of superconducting shim coils for highly sensitive NMR spectrometer with a superconducting split magnet is described. Superconducting inner shim coils, superconducting periodically wavy coils and superconducting matrix shim system are adopted for achieving high correction capability for the split NMR spectrometer.

The various current transport properties of a 200 A-class Bi-2223 superconducting wire at various temperatures and magnetic fields are studied.

The various superconducting properties of the aromatic hydrocarbon added in situ-processed Powder-In-Tube (PIT) [MgB.sub.2]/Fe tapes are investigated. The analysis shows that such aromatic hydrocarbons lead to a sharp increase in the critical current density of the tapes.

The study describes the characteristics of the round and extracted strands of [Nb.sub.3]Al wires Rutherford cable with copper stabilizer, which exhibits very low packing factor. The strands can be used as future high field accelerator magnets due to the great fluctuation in their magnetization.

The analysis describes the fundamental relationship between the BCC (body-centered cubic)-deformation, the transition temperature and the microstructure of the [Nb.sub.3]Al wires. The results prove that the transformation temperature has a tendency of monotonic decrease along with the deformation.

The fabrication and operation of a rapid-heating, quenching and transformation (RHQT) [Nb.sub.3]Al insert coil generating 4.5 T at 4.2 K in 15 T back-up field are discussed. These coils are widely used as high-field magnets.

Effects of gamma-ray radiation damage on energy spectra and polarization of the CdTe radiation detector with the Schottky barrier are demonstrated for application to the gamma-ray imaging equipment in diagnostic nuclear medicine. In particular, the polarization recovery mechanism by momentary bias-off (bias refreshment) is incorporated into the detector system, and the effect of radiation damage on the bias refreshment is quantitatively evaluated. The Schottky barrier is formed by using In as the anode of the CdTe detector. The gamma-ray irradiation source for the radiation damage test is [sup.60]Co. Gamma-ray count rate in an energy window and leakage current between the cathode and the anode are not affected until irradiation at 6.83 kGy. Energy resolution is not affected until irradiation at 66.8 Gy, and there is significant deterioration when irradiation is more than 1.29 kGy. Polarization of the CdTe detector is hardly affected and can be recovered by the bias refreshment for irradiation at 66.8 Gy. However, complete recovery becomes impossible at more than 1.29 kGy irradiation. In conclusion, it is demonstrated that the CdTe detector can be used as the gamma-ray detector in SPECT (Single Photon Emission Computed Tomography) equipment for more than 20 years, and continuous SPECT examinations lasting more than 120 min become possible with the bias refreshment. Index Terms--CdTe radiation detector, energy spectra, polarization, radiation damage, Schottky barrier.

A study is conducted to enlarge a Nb/Al strand dimension to enhance current capacity of RHQT-Nb3Al further. Bcc phases could be formed even in the large cross-section rectangular strand by RHQ operation.

An experiment is conducted to determine the critical current I(sub c) and n-values of (rapidly heating and quenching treatment) RHQT processed Nb3Al conductors at 4.2K in a wide range fields from 14.5 to 25T in relation to the microstructures obtained. The results indicate that the n-value increased monotonously with decreasing field from 25T to 18T, but got saturated to be around 35 at 4.2K in field less than 18T.

Reporting the effects of area reduction of the tape and annealing conditions of MgB2/(stainless steel) tapes is presented. However, excess cold-rolling of the wires and tapes depressed the J(sub c) values because of the introduction of cracks in the MgB2 cores.

Development and testing of a cryocooler-cooled Bi-2212/Ag high-temperature superconducting (HTS) solenoid magnet system is described and discussed.