3,363 research outputs found
An x-ray detector using PIN photodiodes for the axion helioscope
An x-ray detector for a solar axion search was developed. The detector is
operated at 60K in a cryostat of a superconducting magnet. Special care was
paid to microphonic noise immunity and mechanical structure against thermal
contraction. The detector consists of an array of PIN photodiodes and tailor
made preamplifiers. The size of each PIN photodiode is $11\times 11\times 0.5\
{\rm mm^3}$ and 16 pieces are used for the detector. The detector consists of
two parts, the front-end part being operated at a temperature of 60K and the
main part in room temperature. Under these circumstances, the detector achieved
1.0 keV resolution in FWHM, 2.5 keV threshold and 6\times 10^{-5} counts
sec^{-1} keV^{-1} cm^{-2} background level.Comment: 8 pages, 5 figures, submitted to Nucl. Instr. Meth.
Overcoming "Hinomaru-like" Views on Japan: An Introduction to a Study of Suzuki Bokushi and Country Literati in the Late Edo Period
The hinomaru flag can be an informative metaphor of views on Japan in historical studies as well as sociology or other disciplines. In the first instance, it .seems a. highly apt metaphor to represent conventional and persistent views:1 namely, Japan is likely to be an 'insular', 'single-centred', 'homogeneous' and 'mono-social' as in 'monolingual', 'monolithic', 'monotonous', 'monoracial' and 'monocultural'. Hinomaru symbolising the sun may imply 'uniqueness', 'eternity', 'unity', 'perfection' and 'self-sufficiency'
Tunnel-barrier-enhanced dc voltage signals induced by magnetization dynamics in magnetic tunnel junctions
We theoretically study the recently observed tunnel-barrier-enhanced dc
voltage signals generated by magnetization precession in magnetic tunnel
junctions. While the spin pumping is suppressed by the high tunneling
impedance, two complimentary processes are predicted to result in a sizable
voltage generation in ferromagnet (F)|insulator (I)|normal-metal (N) and F|I|F
junctions, with one ferromagnet being resonantly excited. Magnetic dynamics in
F|I|F systems induces a robust charge pumping, translating into voltage in open
circuits. In addition, dynamics in a single ferromagnetic layer develops
longitudinal spin accumulation inside the ferromagnet. A tunnel barrier then
acts as a nonintrusive probe that converts the spin accumulation into a
measurable voltage. Neither of the proposed mechanisms suffers from spin
relaxation, which is typically fast on the scale of the exponentially slow
tunneling rates. The longitudinal spin-accumulation buildup, however, is very
sensitive to the phenomenological ingredients of the spin-relaxation picture.Comment: 5 pages, 2 figure
Four-electron shell structures and an interacting two-electron system in carbon nanotube quantum dots
Low-temperature transport measurements have been carried out on single-wall
carbon nanotube quantum dots in a weakly coupled regime in magnetic fields up
to 8 Tesla. Four-electron shell filling was observed, and the magnetic field
evolution of each Coulomb peak was investigated, in which magnetic field
induced spin flip and resulting spin polarization were observed. Excitation
spectroscopy measurements have revealed Zeeman splitting of single particle
states for one electron in the shell, and demonstrated singlet and triplet
states with direct observation of the exchange splitting at zero-magnetic field
for two electrons in the shell, the simplest example of the Hund's rule. The
latter indicates the direct analogy to an artificial He atom.Comment: 4 pages, 3 figures, submitted to Physical Review Letter
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