K Ikeda

Development of a spin flipper for an application of a neutron magnetic device

We have developed a radio-frequency gradient spin flipper for the effective utilization of the focused and polarized neutron beam obtained using a superconducting sextupole magnet developed for the practical application in the neutron-scattering experiment. The flipper was designed to be effective for the neutron beam with wavelengths longer than 4 A and the cross section of 50 mm in diameter. The flipper was tested using polarized cold neutrons, and good performance was obtained.

Normal incidence multilayer telescope for galactic EUV observation

Abstract We developed normal incidence multilayer telescopes for observing EUV radiation from celestial objects. A telescope consists of spherical mirror coated with Mo/Si multilayer and a position sensitive detector made of microchannel plate on the focal plane. Three kinds of multilayers were deposited on three mirrors, which are optimized for observations of 130–140A, 170–180A and 270–330A, respectively. The characteristics of these telescopes were measured by using monochromatized synchrotron radiation. The peak reflectivity of multilayered mirrors was obtained to be nearly 60% at the peak wavelength of 133A and 172A and 10% at 300A at the normal incidence, as expected. The quantum efficiency of MCP detector was 20% in the wave-band 100–200A. These telescopes were on board a sounding rocket, S-520-19 to observe EUV emission from HZ43, a hot white dwarf, and galactic hot plasma.

Development of superconducting tunnel junctions as an energy-dispersive detector for UV and visible photons

Abstract We are developing an energy-dispersive detector for UV and visible photons that uses superconducting tunnel junctions (STJs) with Al trapping layers. As a first step to achieve this, we evaluated the performance of the detector for extreme ultraviolet (EUV) photons by using a synchrotron radiation facility. We achieved an energy resolution of FWHM=17.8±0.6 eV (including electrical noise of 17.6±0.2 eV) for 55 eV EUV photons with a 100×100 μm2 STJ. The electrical noise was the main component of the energy resolution. We achieved the electrical noise of FWHM=2.1±0.1 eV for a 20×20 μm2 STJ by replacing the cables connecting the STJ to a preamplifier operated at room temperature. A stronger signal resulting from a thinner tunnel barrier will lead to better energy resolution for detecting UV and visible photons.

EUV Observation with Normal Incidence Multilayer Telescopes

The EUV emission from hot interstellar plasmas is observed by normal incidence telescopes on board a sounding rocket. It was performed on January 29, 1995, to observe the sky area around the HZ 43 close to the north galactic pole. The wave bands (δλ ∼ 10 A) are provided at 130 and 170 A by the multilayer coating on the reflectors of 20 cm in diameter and of 30 cm in focal length. The focal plane images are detected by CsI coated MCP’s. The observed flux of HZ 43 is 1.5 counts s-1 at 130 A and 3 counts s-1 at 170 A. The diffuse emission is 27 c/s/deg2 at 130 A and 20 c/s/deg2 at 170 A. Those preliminary numbers are subjects to change along with the data analysis.