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Journal Articles

Formation of fullerene(C$$_{60}$$) by laser ablation in superfluid helium at 1.5K

Aratono, Yasuyuki; Wada, Akira*; Akiyama, Kazuhiko; Kitazawa, Shinichi; Hojo, Kiichi; Naramoto, Hiroshi*

Chemical Physics Letters, 408(4-6), p.247 - 251, 2005/06

 Times Cited Count:1 Percentile:3.19(Chemistry, Physical)

C$$_{60}$$ fulleren was detected in the deposit produced by the laser ablation in superfluid helium at 1.5K. From the mass spectrometry, it was found that the ratio, $$^{12}$$C$$_{60}$$/$$^{12}$$C$$_{59}$$$$^{13}$$C, differs from statistical one calculated by Poisson distribution for natural graphite. Assuming the recombination of atomic carbons to C$$_{2}$$ molecules as an initial stage for C$$_{60}$$ formation, the different isotopic ratio of C$$_{60}$$ from Poisson statistics was ascribed to the tunneling recombination between $$^{12}$$C and $$^{13}$$C atoms in the bubble state.

Journal Articles

CARS study of deuterium clusters stabilized in solid helium

Gordon, E. B.*; Kumada, Takayuki; Ishiguro, Masazumi; Aratono, Yasuyuki

Journal of Experimental and Theoretical Physics, 99(4), p.776 - 783, 2004/10

The solid Deuterium clusters for the first time isolated in a matrix of solid Helium have been investigated at T = 1.3K and P = 3 MPa by CARS (Coherent anti-Stokes Raman spectroscopy) technique. The Q1(J=0) and Q1(J=1) lines intensity, shape and positions have been studied as the functions of ortho- para content in the solid, as well as of clusters size. The strong effect of Raman scattering cross section sensitivity to the molecular environment nuclear spin state has been found in CARS; the ratio of probabilities for the scattering by para (J=1) and ortho (J=0) deuterium being equal to 1 in a gas is as high as 10,000 in nearly pure o-D2, whereas it is about 50 in spontaneous Raman scattering. This effect has been shown to give rise starting from cluster size corresponding to the phonon band onset.

Journal Articles

Use of liquid helium-3 as a neutron converter for a semiconductor-based neutron detector

Nakamura, Tatsuya; Katagiri, Masaki; Aratono, Yasuyuki; Kanno, Ikuo*; Hishiki, Shigeomi*; Sugiura, Osamu*; Murase, Yasuhiro*

Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.399 - 401, 2004/08

 Times Cited Count:1 Percentile:10.64(Instruments & Instrumentation)

We evaluated the neutron-detection characteristics of a cryogenic neutron detector operating at 1.6 K, which comprises a liquid helium-3 as a neutron converter and an InSb semiconductor detector. The InSb semiconductor detector detected the protons created in the nuclear reaction $$^{3}He + n rightarrow p + T$$ in the liquid helium-3, where the density of that is ~600 times larger than that of the gaseous helium-3 at room temperature.

Journal Articles

Cryogenic neutron detector by InSb semiconductor detector with high-density helium-3 gas converter

Nakamura, Tatsuya; Katagiri, Masaki; Aratono, Yasuyuki; Kanno, Ikuo*; Hishiki, Shigeomi*; Sugiura, Osamu*; Murase, Yasuhiro*

Nuclear Instruments and Methods in Physics Research A, 520(1-3), p.76 - 79, 2004/03

 Times Cited Count:8 Percentile:50.96(Instruments & Instrumentation)

The neutron-detection characteristics of a cryogenic neutron detector comprising an InSb semiconductor detector and a helium-3 gas converter were evaluated at a gas pressure of up to 12.5atm at 4.2K. The detector successfully detected stable neutrons under these conditions, where the density of the helium-3 gas is a few-hundred times higher than that at room temperature. It was found that the neutron detection efficiency was correlated with the gas pressure - even in a backward-detection configuration - in low-temperature, high-pressure helium-3.

Journal Articles

Cryogenic neutron detector comprising an InSb semiconductor detector and a supercritical helium-3 gas converter

Nakamura, Tatsuya; Katagiri, Masaki; Aratono, Yasuyuki; Kanno, Ikuo*; Hishiki, Shigeomi*; Sugiura, Osamu*; Murase, Yasuhiro*

Review of Scientific Instruments, 75(2), p.340 - 344, 2004/02

 Times Cited Count:6 Percentile:37.25(Instruments & Instrumentation)

We evaluated the neutron-detection characteristics of a proposed cryogenic neutron detector comprising an InSb semiconductor detector and a helium-3 gas converter. The neutron detector was operated at 4.2 K with helium-3 gas filling up to 1.5 atm, at which the density of the helium-3 nucleus corresponds to that at 160 atm at room temperature. The secondary particles generated by the $$^{3}$$He(n,p) T reaction were successfully detected by the InSb detector with a time response of $$sim$$80 nsec at all tested gas pressures.

Journal Articles

Low temperature chemistry in research reactor

Aratono, Yasuyuki

Hamon, 13(3), p.168 - 172, 2003/07

Recent works on hydrogen abstractions by tritium atom and on recombination reactions of tritium and hydrogen atoms at low temperature(1-2K), which were carried out at JRR-3M by the authors, were introduced.

Journal Articles

Influence of superfluidity on recombination reactions of H+T$$rightarrow$$HT and T+T$$rightarrow$$T$$_{2}$$ in $$^{3}$$He-$$^{4}$$He quantum media under saturated vapor pressure at 1.6 K

Aratono, Yasuyuki; Iguchi, Kazunari; Okuno, Kenji*; Kumada, Takayuki

Journal of Physical Chemistry A, 107(19), p.3741 - 3746, 2003/05

 Times Cited Count:4 Percentile:12.38(Chemistry, Physical)

An influence of superfluidity on recombination reactions of H+T$$rightarrow$$HT, T+T$$rightarrow$$T$$_{2}$$ in $$^{3}$$He-$$^{4}$$He quantum media was studied under saturated vapor pressure at 1.6 K. A change of reaction mechanism was observed at transition point from normalfluid to superfluid phase. Tunneling reaction mechanism by H and T bubble atoms was proposed on the basis of large isotope effect.

Journal Articles

Emission spectrum of the C$$_{2}$$ radical embedded in superfluid helium around 1.5 K

Wada, Akira; Aratono, Yasuyuki

Chemistry Letters, 32(2), p.200 - 201, 2003/02

 Times Cited Count:6 Percentile:30.97(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Non-statistical formation of ${it J}$=1 T$$_{2}$$ (${it ortho}$-T$$_{2}$$) in recombination reaction of T+T+M$$rightarrow$$T$$_{2}$$+M in liquid helium at 1.42-2.50K

Iguchi, Kazunari*; Kumada, Takayuki; Okuno, Kenji*; Aratono, Yasuyuki

Chemical Physics Letters, 349(5-6), p.421 - 425, 2001/12

 Times Cited Count:4 Percentile:12.83(Chemistry, Physical)

no abstracts in English

Journal Articles

Handbook of Rreactor Water Chemistry

Tachikawa, Enzo*; Hoshi, Michio; Aratono, Yasuyuki; Hashimoto, Kazuyuki

Genshiro Suikagaku Handobukku, p.57 - 66, 2000/12

no abstracts in English

Journal Articles

Effects of pressure on radiation processes in solid hydrogen; An ESR study

Kumada, Takayuki; Shevtsov, V.*; Aratono, Yasuyuki; Miyazaki, Tetsuro

Journal of Chemical Physics, 113(4), p.1605 - 1608, 2000/07

 Times Cited Count:4 Percentile:12.84(Chemistry, Physical)

no abstracts in English

Journal Articles

The Pressure effect on the recombination and relaxation of hydrogen atoms in solid hydrogen

Shevtsov, V.*; Kumada, Takayuki; Aratono, Yasuyuki; Miyazaki, Tetsuro

Chemical Physics Letters, 319(5-6), p.535 - 541, 2000/03

 Times Cited Count:14 Percentile:42.16(Chemistry, Physical)

no abstracts in English

Journal Articles

Trapping sites of hydrogen atoms in solid HD and D$$_{2}$$; An Electron spin echo study

Kumada, Takayuki; Noda, Tomoyoshi*; Kumagai, Jun*; Aratono, Yasuyuki; Miyazaki, Tetsuro

Journal of Chemical Physics, 111(24), p.10974 - 10978, 1999/12

 Times Cited Count:10 Percentile:31.93(Chemistry, Physical)

no abstracts in English

Journal Articles

Hot atom chemistry

Aratono, Yasuyuki

Nihon Genshiryoku Gakkai-Shi, 41(4), p.391 - 392, 1999/04

no abstracts in English

Journal Articles

Decay of H$$_{2-}$$ anions in solid parahydrogen via two-stage quantum tunneling diffusion process

Kumada, Takayuki; *; *; Kumagai, Jun*; Aratono, Yasuyuki; Miyazaki, Tetsuro*

Journal of Low Temperature Physics, 114(5-6), p.413 - 429, 1999/00

no abstracts in English

Journal Articles

Observation of electron bubbles in para-H$$_{2}$$-D$$_{2}$$(HD) mixtures by high-resolution ESR spectrosocpy

Kumada, Takayuki; *; Kumagai, Jun*; Aratono, Yasuyuki; Miyazaki, Tetsuro*

Journal of Physical Chemistry A, 103(45), p.8966 - 8968, 1999/00

 Times Cited Count:13 Percentile:40.08(Chemistry, Physical)

no abstracts in English

Journal Articles

An ENDOR spectrum of H atoms in solid H$$_{2}$$

Kumada, Takayuki; *; Noda, Tomoyoshi*; Kumagai, Jun*; Aratono, Yasuyuki; Miyazaki, Tetsuro*

Chemical Physics Letters, 288(5-6), p.755 - 759, 1998/00

 Times Cited Count:27 Percentile:65.72(Chemistry, Physical)

no abstracts in English

Journal Articles

Experimental observation of H$$_{2-}$$ anion and its para $$rightarrow$$ ortho conversion in solid para hydrogen using high-resolution ESR spectroscopy

Kumada, Takayuki; Aratono, Yasuyuki; Miyazaki, Tetsuro*

Journal of Low Temperature Physics, 111(3-4), p.509 - 514, 1998/00

no abstracts in English

46 (Records 1-20 displayed on this page)