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We present results of design and simulation of the n-substrate reverse type avalanche photodiode (APD), which internally amplifies the photocurrent by an avalanche process, with the diffusion and the epitaxial methods. We aim to develop the APD which is coupled with scintillating materials for X-ray and y-ray detections. The purpose of this simulation is to investigate optimal design parameters including guarding of the reverse type APD to meet device performance requirement as one of detector components. These optimized conditions obtained from simulation study can be applied in fabrication of the reverse type APD. In this simulation, both process and device simulations of APDs have been done by using a 2D simulation package, Athena and Atlas, from Silvaco International. The n-substrate reverse type APD based on the optimized design parameters will be fabricated and tested in near future. Index Terms--Avalanche process, gain, photodiode, PMT.

We present the luminescent and scintillation characteristics of CsI:C[O.sub.3] single crystals. The CshC[O.sub.3] single crystals were grown by using Czochralski method for different concentrations of C[O.sub.3] from 0.007 to 0.1 mole %. The crystals were cut into a size of 10 mm x 10 mm x 5 mm. The luminescent characteristics were measured with X-rays to study the emission spectra of the CsI:C[O.sub.3] crystals. The scintillation properties of the CsI:C[O.sub.3] crystals such as fluorescence decay time, energy resolution, pulse height spectra, proportionality, and relative light output were studied by using various -y-ray sources with a photomultiplier tube (PMT) at room temperature. The absolute light outputs of the crystals were also measured with an avalanche photo-diode (APD). Index Terms--CsI:C[O.sub.3], crystal growth, scintillation detector.

The fabrication and the testing of the conduction cooling system for the 600 kJ class high temperature superconductor (HTS) superconducting magnetic energy storage (SMES) are described. The results have shown that the developed conduction cooling system has adapted to 600 kJ HTS SMES system and have coped with the unexpected sudden heat impact.

The aim of this study is to develop scintillation crystals for the study of neutrinoless [[beta].sup.+]/EC decay process. The [sup.84]Sr isotope is one of the potential candidates for the neutrinoless [[beta].sup.+]/EC decay process. None of the scintillation crystals containing a strontium element up till now were used for the study of neutrinoless [[beta].sup.+]/EC decay process. In general our crystal growth program include studies of starting material preparation, growth procedures and characterization of grown crystals. We grew a Sr[Cl.sub.2] single crystal by using Czochralski method. The cylindrical shape of the Sr[Cl.sub.2] crystal was cut into the dimensions of [PHI] 2 x 1.5 [cm.sup.3]. The scintillation properties were studied by using various gamma ray sources and an alpha source. The scintillation properties such as energy resolution, fight output, linearity and decay time were presented. In particular, the [alpha]/[beta] light ratio and possibility of a pulse shape discrimination between [alpha] and [gamma] quanta using a [sup.210]Po alpha source were studied. Index Terms--Alpha particles, crystal growth, gamma-ray spectroscopy, neutrinos.

In this paper, we present scintillation properties of the new developed single crystals of [Ba.sub.x][Sr.sub.1-x][Cl.sub.2] for different concentration of x. We manufactured [Ba.sub.0.12][Sr.sub.0.88][Cl.sub.2], [Ba.sub.0.20][Sr.sub.0.80][Cl.sub.2], [Ba.sub.0.22][Sr.sub.0.78][Cl.sub.2] crystals, and CsI(Tl) crystal as reference by using the Czochralski method. The crystals were cut into a size of 5 x 10 x 10 [mm.sup.3]. The X-ray diffraction technique was used to verify the structure of crystals. The emission spectra were measured with X-ray excitation at room temperature. Scintillation properties of the crystals such as pulse height spectra, energy resolution, [alpha]/[beta] ratio, relative light output, proportionality, and fluorescence decay time were measured with the various radioactive [gamma] sources at room temperature. The light output of these crystals were compared with that of the CsI(T1) crystal. The differences in relative light outputs, energy resolutions, and decay times among these crystals were studied in detail. Index Terms--Chlorine compounds, crystal growth, scintillation detectors.

The response of CsI(T1) crystals to nuclear recoils and [gamma]s down to 3 keV has been studied, and it has been demonstrated that the pulse shape discrimination capability for CsI(T1) is better than that for NaI(T1). Extensive study of internal background of CsI powder was performed and a lot of efforts have been made to reduce the internal background sources such as [sup.137]Cs and [sup.87]Rb. The [sup.137]Cs concentration of 2 mBq/kg was achieved successfully in the CsI powder using ultra-pure water for whole extraction process. The Rb concentration was successfully reduced to be less than 1 ppb by the recrystallization method. The CsI(T1) crystal used for the experiment was grown with the ultra-low background CsI powder and a dimension of the CsI(T1) crystal is 8 x 8 x 30 [cm.sup.3] which corresponds to weight of 8.7 kg. The number of photoelectrons is measured to be about 4-6/keV with a RbCs photocathode PMT. The background of CsI(T1) crystals were measured in the shielding of 30 cm thick mineral oil, 15 cm thick lead, 5 cm thick polyethylene and 10 cm copper at the 700 m minimum depth of underground laboratory at YangYang Pumped Storage Power Plant in Korea. The WIMP search with low background CsI(T1) crystals has been carried out by the Korean Invisible Mass Search (KIMS) Collaboration and the lower limit on WIMP-nucleon cross section are reported. Index Terms--Dark matter, CsI(T1), internal background, pulse shape discrimination, WIMP.

We grew a Gd-doped lead chloride single crystal by the Bridgman method and investigated scintillation properties of the crystals at low temperature. We measured the relative light yield, energy resolution, fluorescence decay time, and proportionality of the crystals for the [gamma]-ray at low temperature. The energy resolution is measured to be 25.6% for the [sup.137] Cs 662 keV [gamma]-ray, and the fluorescence decay time of the crystal is composed of two components with decay times of 1.35 and 6.20/[micro]s at 173 K. Index Terms--Crystal growth, gadolinium, lead compound, scintillation detector.

Crystal growth, luminescence, and scintillation properties of a Ce[Br.sub.3] crystal are presented. The crystal was grown with Bridgman method using two-zone transparent furnace and cut to [phi]10 x 10 [mm.sup.3]. The investigation of luminescence and scintillation properties of the Ce[Br.sub.3] was performed under the excitation by ultraviolet and [gamma]-rays at room temperature. The emission spectrum of the Ce[Br.sub.3] was observed in the range of near ultraviolet to violet, which is due to 5d [right arrow] 4f transition of the [Ce.sup.3+]. The decay time of the [Ce.sup.3+] emission was measured to be approximately 20 ns. The energy resolution of the Ce[Br.sub.3] single crystal was obtained to be 4.9% for the [sup.137] Cs 662 keV [gamma]-ray. The relative signal of the Ce[Br.sub.3] crystal by the [sup.137] Cs [gamma]-ray is about three times higher than that of a CsI:TI crystal when bi-alkali PMT was used. The nonproportionality in the [gamma]-ray energy of the crystal was also measured. The study showed that the Ce[Br.sub.3] crystal is the promising candidate for the PET application. The Ce[Br.sub.3] crystal with high light output and fast decay time affords its use for the particle detection in high counting rate environment such as nuclear and high-energy physics. Index Terms--Cerium compound, crystal growth, luminescence, scintillation detector.

The article discusses the design and analysis of cryogenic conduction cooling system of High Temperature Superconducting (HTS) superconducting magnetic energy storage (SMES). Findings reveal that the new conduction cooling system is capable of cooling the HTS Coil under temperature of 20 K on proper conditions.

The electrical insulation design and experimental results of a 22.9 kV/50 MVA class High Temperature Superconducting (HTS) power cable system is discussed. Findings reveal satisfactory insulation characteristics in 30 m prototype cable.

The electrical insulation design of a 154 kV class high temperature superconducting (HTS) cable and termination is discussed. The insulation thickness of the 154 kV class HTS cable is 23 mm, whereas the insulation thickness of the termination is 100 mm.

The insulating properties between cryocooler and magnet coil of conduction cooled high temperature superconducting (HTS) superconducting magnetic energy storage (SMES) are discussed. Findings reveal similar surface flashover voltage and breakdown voltage of AIN, [Al.sub.2] [O.sub.3] and sapphire.

A research conducted to study the effects of oxidized [alpha]-tocopherol on the oxidative stability of soybean oil and to postulate the formation and prooxidant mechanisms of oxidized [alpha]-tocopherol compounds during soybean oil oxidation is illustrated. Tocopherols are the most important natural antioxidants present in vegetable oils and protect lipids from oxidation by donating hydrogen from their phenolic group on the chromanol ring to peroxy radical in propagation step.

Scintillation properties of calcium molybdate are investigated. The emission spectrum is broad with a maximum at 520 nm. At room temperature the light yield is 4% of CsI(TI) (400 photoelectrons/MeV) and the decay time is 17 [micro]s. During cooling the light yield and decay time increase. Prospects of optimization of this scintillator are also discussed. The feasibility of the material for the search of neutrinoless double beta decay of [sup.100]Mo is analyzed. A half life limit of [T.sub.1/2] = 1 * [10.sup.25] years (68% CL) seems feasible with CaMo[O.sub.4] scintillator, running with 10 kg of [sup.100]Mo for 5 years. The background due to two neutrino double beta decay of [sup.48]Ca is also considered. Requirements for new scintillators for double beta decay search are formulated. Index Terms--Crystal growth, low background, molybdenum compounds, neutrinos, scintillation detectors.

Korea Electrotechnology Research Institute has developed a 3MJ Superconducting magnet energy storage (SMES) system to improve power quality control of a sensitive electric load. The design, fabrication and experimental results for the magnet made by using the design code of an AMES device are described.

A new compact superconducting coil for SMES systems is described and discussed.

A magnet system for minimizing convection during growth of semiconductor crystals is described and discussed.

Improvements are achieved involving current capacity and AC loss of large superconducting solenoids by means of soldering.

A small-sized superconducting magnetic energy storage (SMES) magnet is described. Factors affecting stability are discussed.

A model coil for a small-sized superconducting magnetic energy storage (SMES) system was designed, fabricated and tested. Design features and test results are discussed.

Researchers at Korea Electrotechnology Research Institute (KERI) have developed a 1-MJ superconducting magnetic energy storage (SMES) system that can be used as an uninterruptible power supply (UPS). The SMES can be adapted for use as a power-system stabilizer.

We designed a switchless event building farm for the Belle experiment at the KEKB [e.sup.+] [e.sup.-] collider, as a replacement of the existing event builder and the online farm systems. In the new system, PCs are directly interconnected with multiple point-to-point Fast and Gigabit Ethernet connections. The PCs build the detector data in two steps to perform distributed event processing. We set up a test system and confirmed the event building performance meets our new requirements using a realistic prototype software. The system is being installed as sceduled using the summer shutdown time in 2001. Index Terms--Data acquisition, data transfer, event building, event filtering.

Conceptual design of high temperature superconducting cable in Seoul is examined and the application of such cables based on the power system analysis.

The kA class conductor for a mu superconducting magnetic energy storage coil was investigated and stability and quench test results are reported.

Current leads for a superconducting magnetic energy storage magnet have been designed and constructed. Numerical analysis was used in determining the optimum shape factor and the optimum varying rate of the cross-sectional area of the HTS lead resulting in minimum refrigeration power consumption and evaporation rate. The leads are rated at 2.1 kA and made of conventional gas-cooled copper leads and high-temperature superconductors (HTS). The HTS parts of the lead are made with Bi-2223/99.8%AgO.2%Au tape.

A new reference signal generation method for high-density MRAM is reported. 0.4 x 0.8 [micro][m.sup.2] magnetic tunnel junction (MTJ) elements were successfully integrated with 0.24-[micro]m CMOS technology. By using a 90-degree rotated MTJ as a new reference signal generator, the reference resistance could be always located in the exact midpoint between high-resistance state [R.sub.H] and low-resistance state [R.sub.L] regardless of applied voltage. When tested in 8 x 8 MTJ arrays, it is found to show good fidelity to our expectations. So it is supposed that this new method is more favorable for high-density MRAM. Index Terms--Magnetic tunnel junction (MTJ), magnetic random access memory (MRAM), reference call, tunneling magnetoresistance (TMR).

We have demonstrated fully integrated 64-kb magnetoresistive random access memory (MRAM) using 0.24-[micro]m CMOS technology and discussed some key issues in process integration. Optimal tunneling magnetoresistive (TMR) properties of MRAM bits (37% of TMR ratio and 5-10 k[OMEGA].[micro][m.sup.2] of RA) were obtained mainly by the control of bottom electrode roughness, and electrical shorting was avoided by some commercialized wet solutions. In viewpoint of process integration, excellent TMR properties of magnetic tunnel junction (MTJ) fresh films and prevention of their degradation in post patterning process are two crucial factors, and especially, electrical shorting requires some careful control. Index Terms--Magnetic tunnel junction (MTJ), magnetoresistive random access memory (MRAM), process integration, shorting failure.

A key requirement for spin valves (SV) with nano-oxide layers (NOL) are the formation of the smooth and uniform interface between NOL and magnetic layer for specular electron scattering. We investigated the natural oxidation conditions using mixed gases ([O.sub.2]/[N.sub.2] and [O.sub.2]/Ar) for the uniform NOL formation in specular SVs. We have compared the magnetoresistance (MR) properties and thermal stability of SVs with NOL formed in mixed gases with those formed using pure [O.sub.2]. We can optimize oxidation conditions using mixed gases for enhanced MR ratio and reduced interlayer coupling field. Index Terms--Nano-oxide layer, specular scattering, spin valve.

[([Fe.sub.57][Pt.sub.43]).sub.100-x][Cu.sub.x] ternary films with x = 0-4 at. % were prepared on Corning 7059 glass by dc magnetron sputtering in order to investigate the effect of Cu addition on the transformation rate of Felt alloy films. The structural and chemical analysis revealed that Cu was very effective in promoting the transformation to the [L1.sub.0] ordered phase and to suppress the grain growth of the [L1.sub.0] ordered phase when films were annealed at 400[degrees]C-700[degrees]C in vacuum. During the annealing, Cu atoms diffused onto the film surface, probably yielding many defects remain inside the film. This Cu diffusion may be the reason for the rapid transformation. Index Terms--Diffusion, FePt film, [L1.sub.0] structure, order-disorder transformation.

Si microcantilevers coated with giant magnetostrictive Sm-Fe or Tb-Fe thin films are fabricated and the deflection of the cantilevers is measured as a function of magnetic field. In the case of a microcantilever with the dimension 3.7 mm (length) x 1.0 mm (width) x 13 [[micro]meter] (thickness), for example, a very large deflection of 52 [[micro]meter] is achieved at 150 Oe from the first ascending magnetic field, by the coating of a [Sm.sub.42.7][Fe.sub.56.9][B.sub.0.4] thin film with the thickness of 1.2 [[micro]meter]. Total deflection doubles when a magnetic field of the same amplitude (150 Oe) is applied alternately in the length and the width directions. Relatively large deflections are also observed for Tb-Fe thin film based microcantilevers as well as other Sm-Fe based cantilevers. The level of deflection achieved in the present magnetostrictive microcantilevers is considered to be suitable for microdevices applications. Index Terms - Magnetostrictive thin films, microcantilevers, Sm-Fe alloys, Tb-Fe alloys.

There have been remarkable advances in semiconductor industry but the miniaturization of magnetic devices is progressed very slowly. So many studies are carried out overcoming the gap. To develop small size devices, proper design and property simulation of the devices are requested to spare the efforts before fabrication processes. However, there is a few of simulation studies have been reported. In this work, we fabricated thin film toroidal inductors using permalloy as a core material and measured the properties to estimate 2D and 3D simulation in the magnetic devices. The 3D simulation shows more agreeable results than the 2D simulation. On the other hand, when we changed core materials, the inductor using Fe-Hf-C-N nanocrystalline alloys as core material shows the better properties than using permalloy and Fe-Zr-C-N alloys. Index Terms - simulation, thin film toroidal inductor

The magnetostriction of TbFe and TbFeB thin films is systematically investigated over a wide composition range from 40.2 to 68.1 at.% Tb for the B-free alloys and from 44.1 to 66.6 at.% Tb for the B containing thin films. The films were fabricated by rf magnetron sputtering. The microstructure mainly consists of an amorphous phase at low Tb contents and, at high Tb contents, a mixture of an amorphous phase and an [Alpha] Tb phase. Excellent magnetostrictive characteristics, particularly at low magnetic fields, are achieved in both TbFe and TbFeB thin films; for example, a magnetostriction of 138 ppm is obtained in a TbFeB thin film at a magnetic field as low as 30 Oe. These excellent magnetostrictive properties of the present thin films are supported by the excellent magnetic softness, the coercivity below 10 Oe and a typical squared-loop shape with the saturation field as low as 1 kOe. It is considered that, due to the excellent low field magnetostrictive characteristics, the present TbFe based magnetostrictive thin films are suitable for Si based microdevices.

The structure and magnetic properties of Fe-[Si.sub.3][N.sub.4] thin films fabricated by a co-sputtering technique were studied by X-ray diffractometry and magnetometry. With increasing area fraction of [Si.sub.3][N.sub.4] pieces on Fe target magnetization of the films decreased due to reduced Fe content and reduced grain size of bcc crystalline phase. Temperature dependence and field dependence of magnetization of co-sputtered thin films can be explained by a mixture of two types of particles showing paramagnetism and ferromagnetism.

The magnetostrictive characteristics of the melt-spun ribbons of [([Tb.sub.0.33][Fe.sub.0.67]).sub.1-x][B.sub.x] (x = 0, 0.02, 0.05, 0.1 and 0.15) alloys are investigated as a function of wheel speed during melt-quenching. It is found that the magnetic softness at low fields is improved substantially by the addition of B to the alloys, but the value of [Lambda] at 8 kOe obtained for the ribbon quenched at an optimum condition decreases continuously as B content increases from x = 0 (1300 ppm) to x = 0.15 (630 ppm). The present ribbons have a nanocrystalline grain structure even in the as-spun state and exhibit better magnetostrictive characteristics than the bulk and similarly melt-spun ribbons with an additional annealing process.

We have studied the structure and soft magnetic properties of Fe-ceramic([Si.sub.3][N.sub.4], [Al.sub.2][O.sub.3]) thin films fabricated by an rf magnetron sputtering apparatus using a composite target. The concentration of solute in the film increases linearly with the area fraction of ceramic pieces in the target. In the case of [Si.sub.3][N.sub.4], the concentration of O increases largely with the Ar pressure, especially at high Ar pressures of more than 20 mTorr. In [Al.sub.2][O.sub.3], the composition of Al and O exhibits a maximum at the Ar pressure of 20 mTorr. As the area fraction of the ceramic increases, the structure of the film changes from a crystalline phase to an amorphous phase. The electrical resistivity increases significantly with increasing area fraction of the ceramics. The saturation magnetization decreases inversely with the logarithm of the electrical resistivity. The gradient of the decrease in saturation magnetization against electrical resistivity is lower in the [Al.sub.2][O.sub.3] system than that in the [Si.sub.3][N.sub.4] system. The Ar pressure dependences of the electrical resistivity and the saturation magnetization are similar to that of the thin film composition. Fe-[Si.sub.3][N.sub.4] films exhibited a saturation magnetization of about 8 kG, a hard-axis coercivity of 0.2 Oe, an electrical resistivity of about 800 [Mu] [Omega]-cm and a permeability(100 MHz) of higher than 400.

The magnetic properties of nanocrystalline FeHfC single layered and FeHfC/ceramics (AlN, [Al.sub.2][O.sub.3], [Si.sub.3][N.sub.4], Si[O.sub.2]) multilayered films were investigated. The soft magnetic properties of the multilayered films laminated by the Al-based ceramics were better, but those of films laminated by the Si-based ceramics were worse than the magnetic properties of single layered films. An analysis of multilayered structure revealed that FeHfC/AlN and FeHfC/[Al.sub.2][O.sub.3] films maintained better periodic structure than FeHfC/[Si.sub.3][N.sub.4] and FeHfC/Si[O.sub.2] films. The present results suggest that the interdiffusion effect plays an important role in determining the magnetic properties of the multilayered films.

This paper reports on a method for measuring magnetostriction, Young's modulus of a substrate or film, and [Delta]E effect with one apparatus. A substrate with thin magnetic film deposited on it is in parallel with and cantilevered above a metal plate electrode, and they form a capacitive cell. The cantilever deflects due to own weight, applied electric and magnetic fields. The small change of capacitance caused by this deflection is measured by a sensitive capacitance bridge. Young's modulus, magnetostriction, and [Delta]E effect can be calculated by a theoretical analysis with the measured deflection data.

The effects of the melt temperature on the magnetic properties of the nanocrystalline Fe73.5Cu1Nb3(Si0.6B0.4)22.5 alloy were previously investigated and it was found that the soft magnetic properties improve with increased melt temperature. In this paper, in order to examine the melt temperature effects of alloys with varying degree of glass forming ability, we investigate the magnetic properties of nanocrystalline Fe73.5Cu1Nb3(SixB1-x)22.5 (x=0.4-0.8) alloys. It is found that for all the alloys, except for x=0.8, the soft magnetic properties of the ribbons quenched at the high melt temperature are better than those of the ribbon fabricated at the low melt temperature, in agreement with the previous observation, but the magnitude of improvement in the magnetic properties with increased melt temperature decreases with decreasing glass-forming ability. The present result emphasizes that the glass-forming ability of an alloy should be taken into account in considering the melt temperature effects.