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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.

A 10T Bi-2212/Ag solenoid magnet system is being developed and first results of trial operation of the inner coil are presented.

A Bi-2223 magnetic separation system was developed and tested at various temperatures and excitation speeds.

Issues concerning the production of Bi2Sr2Ca1Cu2Ox superconducting tape using Ag/Ni and Ag/Ni/Ag clad tapes manufactured by diffusion and deformation, therfore improving the mechanical properties of the tapes and reducing costs, is discussed.

Bi-2212/Ag composite tapes were studied to determine formation and growth mechanisms.

A refrigerator cooled magnet composed of 10 double stacked pancake coils manufactured from silver-alloy sheathed Bi-2212 multilayer superconducting tapes has been tested. The results indicate that the magnet is capable of operating at temperatures of 12 degrees Kelvin (K) at an operating current of 45 Angstrom (A). The magnet, which carried a critical current of 57A at 12K, did not exhibit any sign of thermal runaway even at a ramp rate of 10T/min.

An analysis on how the chemical reaction during partial melting and solidification is affected by the per-annealing and intermediate rolling (PAIR) process. The thermal analysis found no remarkable difference in the partial melting behavior between PAIR processed and control samples. However, results of the analyses using high temperature X-ray diffraction and scanning electron microscopes suggest that the (CaSr)CuO2 crystals did not grow in the samples processed by the PAIR technique.

The effect of Ag substrates on the grain alignment and critical current density (Jc) of Bi-2212 tape conductors has been studied. Results indicated that the grain alignment of Bi-2212 in the oxide/Ag interface was higher than in the free surface of the oxide. The Jc value increases as the oxide/Ag interface area increases accompanied by a reduction in the oxide layer thickness. Grain alignment and Jc decreases in the presence of micrometer-size roughness of the Ag substrate.

A combination of the wind-and-react method and power-in-tube/dip-coating method was employed in developing small Bi-2212 insert magnets. The magnets were then installed in a 21 T superconducting magnet and performance tested at several bias fields at 4.2 K. Results reveal that all of the magnets are capable of sustaining high levels of electromagnetic force at high magnetic fields.

A continuous heat treatment method using a Ag-0.2at% Mg sheath was employed in fabricating a flexible 100m-class Bi-2212 multilayer superconducting tape. The sheath material enhanced tensile stress tolerance without degrading the critical current density value of the multilayer superconducting tape. The react-and-wind technique was also utilized in developing a stacked pancake coil carrying 120A at 10K and 90A at 20K.

Silicon semiconductor detectors for a nuclear radiation monitor of various rays ([Gamma] rays, neutrons and charged particles) have been developed. These detectors are diffused p-n junction type devices with low leakage current. The [Gamma] ray detector is produced, using high resistivity p-type silicon (2-10 k [ohms]-cm). to increase thickness of the depletion layer. This detector has been applied as an area monitor and a computerized personal dosimeter with an IC card. For the neutron detector, proton radiators and boron convertors are coated on the surface of the detector element. Neutrons are detected as recoil protons by interaction of the proton radiator and, as [Alpha]-particles generated by the nuclear reaction 10B(n, [Alpha])7Li. The energy response of this detector meets the ICRP recommendation for a radiation monitor. The charged particles ([Alpha], [Beta] rays) detector having a large sensitive area (up to 6000 [mm.sup.2]) is coated with double passivation layers ([Si.sub.3][N.sub.4]/Si[O.sub.2]) on the surface of the detector element in order to reduce leakage current due to surface stress. The leakage current of less than 220 nA is achieved for the sensitive area by application of the double layers. The charged particles detector can be applied as a radioactive dust monitor and a contamination monitor, and the neutron detector is suited as an area monitor and a personal dosimeter.

The flux pinning behavior of single and double (Cu,C)-layer oxycarbonate superconductors was investigated. Specifically, the irreversibility lines and critical current densities of (Cu0.5C0.5)Ba2Ca(n-1)CunO(2n+3) and (Cu0.5C0.5)Ba3Ca(n-1)CunO(2n+3) where (n=3,4) were calculated and measured. The results showed that the critical current densities of (Cu,C)-based oxides fall more slowly as the temperature rises than mercury-based and bismuth-based oxides.

The suitability of Si-SSD as a detector for high energy X-ray CT has been investigated. Two types of Si-SSDs which can take the place of ordinary scintillation detectors were proposed. Their predicted responses were compared with that of a CWO scintillation detector of almost the same dimensions by using the EGS4 Monte Carlo simulation code. The sensitivities of the sole-silicon detector and the metal-sandwiched detector were about ten times higher than that of the CWO scintillation detector at X-ray energies above 1 MeV. The metal-sandwiched detector was judged more useful than the sole Si-SSD when the width of X-ray beam was less than about 0.2 mm. Then the silicon semiconductor detector for high energy X-ray CT was fabricated and actual measurements of the depletion layer width and the electronic noise contribution were made.

A study is conducted to fabricate 100 m long MgB2 multifilament wires with stainless steel (SUS316)Cu double sheath. The multifilament structure and densification of MbB2 core is found to be effective in improving the transport properties of MgB2 wires.

An attempt was made to incorporate the Cu stabilizer internally to the Ta-matrix jelly-roll RHQT Nb3Al roundwire, based on less-reactivity of Cu with Ta at elevated temperatures during the RHQ operation of wire. Compared to the conventional internal stabilization technique using Ag filaments jacketed with Nb, the present round wire has several advantages; (1) less induced-radioactivity when irradiated with fast neutrons, (2) higher mechanical strength at both elevated and cryogenic temperatures, and (3) less reactivity with Ga-coolant. The overall residual resistance ratio RRRov of the internally Cu stabilized Ta matrix RHQT Nb3Al round-wire is as much as 75 in spite of a smaller stabilizer-ratio, and magnetoresistance is comparable to that of the conventional Cu clad stabilized Nb matrix RHQT Nb3Al flatwire. Core Jc is also comparable to that of the Nb matrix wire. [ABSTRACT FROM AUTHOR]