T. Ohama
KEK
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Publication
Featured researches published by T. Ohama.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2000
N. Ishihara; T. Inagaki; T. Ohama; K. Omata; Shigeru Takeda; Y. Yamada; T. Emura; R. Itoh; Y. Kato; Y. Sakamoto; K. Shimada; N. Tamura; S. Kitamura
Abstract A detector called Drift Chamber Beta-ray Analyzer (DCBA) will provide momentum information of each β-ray in double beta decay. The DCBA is expected to have good capabilities for particle identification, detection efficiency, background elimination and decay-source integration. Under the assumption of mass mechanism dominance in neutrinoless double beta decay, a simulation study shows that a combination method using both sum and single-energy distributions of double beta decay events can separate 0 ν - and 2 ν -events down to 0.05 eV of the effective neutrino mass with the help of a calculated nuclear matrix element, even though the DCBA has relatively poor energy resolution.
Physics Letters B | 1997
H. Hamasaki; K. Abe; K. Amako; Y. Arai; Y. Asano; M. Chiba; Y. Chiba; Motomasa Daigo; M. Fukawa; Y. Fukushima; J. Haba; H. Hanai; Y. Hemmi; M. Higuchi; T. Hirose; Y. Homma; N. Ishihara; Y. Iwata; J. Kanzaki; R. Kikuchi; T. Kondo; T. T. Korhonen; H. Kurashige; E. K. Matsuda; T. Matsui; K. Miyake; S. Mori; Y. Nagashima; Y. Nakagawa; Takashi Nakamura
Abstract The cross section of the γγ → p p reaction was measured at two-photon center-of-mass energy (Wγγ) between 2.2 and 3.3 GeV, using the two-photon process at an e+e− collider, TRISTAN. The Wγγ dependence of the cross section integrated over a c.m. angular region of | cos θ ∗ | is in good agreement with the previous measurements and the theoreticalv prediction based on diquark model in the high Wγγ region.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1996
N. Ishihara; T. Ohama; Y. Yamada
Abstract A magnetic tracking detector called DCBA (Drift Chamber Beta-ray Analyzer) is proposed for double beta decay experiments. The DCBA project is divided into two stages: DCBA-I and -II. DCBA-I will be able to measure the half life of the two-neutrino double beta decay of 150 Nd, though natural Nd is used as the decay source material. DCBA-II will make it possible to investigate the effective mass of the Majorana neutrino down to 0.5-0.1 eV, since it is expected to have the ability to measure the half-life limit up to 4 × 10 24 yr using enriched 150 Nd. A fundamental strategy of the DCBA project and some details of DCBA-I are described.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2003
Y. Kato; T. Emura; T. Inagaki; N. Ishihara; S. Kitamura; Y. Nagasaka; T. Ohama; K. Omata; Y. Sakamoto; N. Tamura; Y. Yamada
Abstract A flash analog to digital converter (FADC) board of low cost and power saving has been developed based on Compact Peripheral Component Interface (CompactPCI) for Drift Chamber Beta-ray Analyzer (DCBA), which is an experiment to study double-beta decay. This board has been designed and constructed with 8 channels, each of which has an 8-bit 100 MHz FADC chip and a double-buffered memory. The design philosophy using recent semiconductor technology is described together with the performance of the FADC board.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1993
Y. Yamada; K. Hayashi; N. Ishihara; S. Nakamura; T. Ohama; H. Sakamoto; T. Sumiyoshi; F. Hinode; Y. Narita; T. Oyama; M. Utsumi; F. Yabuki; Y. Hemmi; H. Kurashige; K. Miyake; A. Okamoto; Motomasa Daigo; N. Tamura
Abstract A high-precision drift chamber has been constructed in order to add vertex information to the VENUS detector at the TRISTAN e + e − collider. It is a jet-type drift chamber comprising 12 tilted drift sectors filled with pressurized slow gas. The structure and initial performance are described.
European Physical Journal C | 1990
K. Abe; K. Amako; Y. Arai; Y. Asano; M. Chiba; Y. Chiba; M. Daigo; T. Emura; I. Endo; M. Fukawa; T. Fukui; Y. Fukushima; J. Haba; D. Haidt; I. Hayashibara; Y. Hemmi; M. Higuchi; T. Hirose; Y. Hojyo; Y. Homma; Y. Hoshi; Y. Ikegami; N. Ishihara; T. Kamitani; Nobuyuki Kanematsu; J. Kanzaki; R. Kikuchi; T. Kondo; T. Koseki; K. Kubo
AbstractThe angular distributions of the reactione+e−→μ+μ− ande+e+→τ+τ− have been measured betweenn
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1988
N. Fujiwara; Naoko Iida; S. Noguchi; R. Sugahara; T. Suwada; T. Ohama; Kasuke Takahashi
Journal of Physics: Conference Series | 2010
N. Ishihara; Go Iwai; Hiroshi Iwase; Y. Kato; M. Kawai; Yoshinari Kondou; T. Haruyama; T. Inagaki; Y. Makida; T. Ohama; Kasuke Takahashi; Shigeru Takeda; Y. Yamada; H. Igarashi; T. Ishikawa; T. Sumiyoshi; E. Tashiro; Takeharu Ishizuka; Shoichi Kitamura; Y. Teramoto; I. Nakano; Y. Sakamoto; Y. Nagasaka; N. Tamura; K Tanaka; R Ito
sqrt s = 50
Physics Letters B | 1999
K. Yusa; J. Kanzaki; Y. Yonezawa; S. Odaka; Y. Fukushima; K. Ogawa; K. Miyake; J. Haba; M. Takita; Y. Asano; K. Okabe; S. Uehara; F. Yabuki; J. Pennanen; Takashi Nakamura; A. Okamoto; H. Ohyama; M. Higuchi; T. Watanabe; N. Ishihara; T. Yamagata; T. Hirose; M. Fukawa; F. Takasaki; T. Ohsugi; Y. Hemmi; R. Kikuchi; H. Yoshida; N. Tamura; M. Sato
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1998
T. Ohama; N. Ishihara; Shigeru Takeda; H. Okuma; K. Konno
n and 60.8 GeV with the VENUS detector at TRISTAN. The average total cross section and the forward-backward charge asymmetry for μ-pair production are observed to be 28.3±1.4±0.8 pb and (−29.0−4.8+5.0±0.5)%, and those for τ-pair production are 27.6±1.7±1.0 pb and (−32.8−6.2+6.4±1.5)% atn