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Tominaga, Masahide*; Nagayasu, Yukari*; Sasaki, Motoharu*; Furuta, Takuya; Hayashi, Hiroaki*; Oita, Masataka*; Nishiyama, Yuichi*; Haga, Akihiro*
Radiological Physics and Technology, 14(4), p.381 - 389, 2021/12
Due to recent advance of diagnostic radiology, the increase of diagnostic radiation exposure to patient becomes problem. Diagnostic Reference Levels has been released to optimized the radiation exposure to patients in Japan recently. The evaluation of entrance surface dose (ESD) is recommended to assess the dose level for general X-ray examination. The ESD can be easily evaluated by multiplying the backscatter factor of the patient body on the free-in-air air kerma. The air kerma free-in-air value used to estimate ESD may contain X-rays scattered from obstacles located at the time of measurement, which may induce non-minor error in assessments. We therefore studied the influence of scattered X-rays on air kerma measurement under various environments (distances, field sizes, and materials). It was found that the dependence on the X-ray energy and field size was different for different materials. The X-ray contamination can be ignored for all the materials when the distance to the scatterer exceeds 35 cm.
Matsuura, Masato*; Yamada, Takeshi*; Tominaga, Taiki*; Kobayashi, Makoto*; Nakagawa, Hiroshi; Kawakita, Yukinobu
JPS Conference Proceedings (Internet), 33, p.011068_1 - 011068_6, 2021/03
The position dependence of the scattered intensity in the time-of-flight backscattering spectrometer DNA was investigated. A periodic structure for both vertical (pixel) and horizontal (PSD) directions was observed. The solar slit and over-bending of an analyzer crystal is discussed as a possible origin of the modulation in the intensity. We have developed software program for the systematic correction of the position-dependent intensity and offset energy for the elastic peak. This corrects the deviation from the true scattering intensity and improve the quality of the data, which includes the energy resolution.
Tominaga, Taiki*; Kawakita, Yukinobu; Nakagawa, Hiroshi; Yamada, Takeshi*; Shibata, Kaoru
JPS Conference Proceedings (Internet), 33, p.011086_1 - 011086_5, 2021/03
We developed a quartz double cylindrical sample cell optimized for a backscattering neutron spectrometer, especially for BL02 (DNA), MLF in J-PARC. A quartz glass tube, with one end closed, is shaved to obtain a wall thickness of 0.55 mm. The inner tube is properly centered using a protrusion into the outer tube such that the interstice between the outer and inner tubes keeps constant. This quartz cell can be used for samples that should not be in contact with the aluminum surface. We verified cell's background effect between the quartz cell and Al cell by QENS measurements using D
O buffer. The elastic intensity profiles of the buffer in a low Q region were identical between both quartz cell and Al cell (A1070). In a high Q region, however, the profiles were different caused by the first sharp diffraction peak of quartz glass. For this region the data should be analyzed by consideration of absorption correction and diffraction in individual thickness of quartz cell.
Shibata, Kaoru
Hamon, 28(1), p.26 - 28, 2018/02
We briefly introduce the pedigree of the backscattering neutron spectrometer and the specification of DNA; a time-of-flight (TOF) type near-backscattering spectrometer (n-BSS), with Si crystal analyzers which was constructed at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC).
Vacik, J.; Hnatowicz, V.*; Cervena, J.*; Naramoto, Hiroshi; Yamamoto, Shunya; Fink, D.*
Fullerene Science and Technology, 9(2), p.197 - 209, 2001/05
In this work, the stopping cross sections of 1H, 3H, 4He and 7Li were measured by Rutherford backscattering, Neutron depth profiling and alpha spectroscopy on fullerite on Si and steel. In addition, ion transmission through a thin Carbon film was also utilized. The measured stopping cross sections follow the theoretical predictions calculated for carbon, but are systematically higher than the theoreticqal values. The observed deviation can be explained by the chemical state of effects. The measured energy straggling exceeds Bohr's value, and this is reasobably explained by the thickness variation.
Shibata, Kaoru; Kawakita, Yukinobu; Nakajima, Kenji; Takahashi, Nobuaki*; Matsuura, Masato*; Tominaga, Taiki*; Yamada, Takeshi*
no journal, ,
We developed a simultaneous multiple incident band measurement method for broadband micro eV spectrum measurement on the Si crystal analyzer back scattering TOF spectrometer DNA at J-PARC.
Shibata, Kaoru; Takahashi, Nobuaki*; Kawakita, Yukinobu; Matsuura, Masato*; Tominaga, Taiki*; Yamada, Takeshi*; Nakajima, Kenji; Kobayashi, Makoto*; Inamura, Yasuhiro
no journal, ,
no abstracts in English
Shibata, Kaoru
no journal, ,
A time-of-flight (TOF) type near-backscattering spectrometer (n-BSS), DNA was built and started operation in 2012 at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). DNA is a unique instrument among spallation pulsed neutron facilities over the world in terms of n-BSS equipped with a high-speed pulse-shaping disc-chopper. On the other hand Si crystal analyzers with back-coated by neutron absorber extremely reduces unfavorable background scattering of the instrument so as to reach signal-to-noise ratio of ~100,000. Those factors gave big advantage to enlarge application fields to dynamical behaviors of atoms and spins in bio-molecules, soft-materials and strongly-correlated electron system in nanosecond timescale or in micro-eV energy region. I will present the performance of DNA spectrometer and their research results.
Shibata, Kaoru; Kawakita, Yukinobu; Nakagawa, Hiroshi; Yamada, Takeshi*; Tominaga, Taiki*; Matsuura, Masato*
no journal, ,
A time-of-flight (TOF) type near-backscattering spectrometer (n-BSS), DNA was built and started operation in 2012 at the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). It offers a high-energy resolution of about 1.6 micro eV and very wide energy scan range: -400 
E/[micro eV] +600 with signal-to-noise ration of 
100,000. Those factors gave big advantage to enlarge application fields to dynamical behaviors of atoms and spins in bio-molecules, soft-materials and strongly-correlated electron system in nanosecond timescale or in micro-eV energy region.
Shibata, Kaoru
no journal, ,
The silicon crystal analyzer is an important spectroscopic device for high energy resolution neutron inelastic backscattering spectrometer. Specification of this spectroscopic device is thought to determine energy resolution and background. In order to achieve a low background spectrum without degradation of the energy resolution, it was developed new crystal analyzer which were constracted by Si wafers coated by thin film of neutron absorbers on the back side of Si wafer, and used it for the new backscattering spectrometer DNA in MLF at J-PARC which were able to achieve the desired performance.
Kawakita, Yukinobu; Matsuura, Masato*; Tominaga, Taiki*; Yamada, Takeshi*; Tamatsukuri, Hiromu; Nakagawa, Hiroshi; Ouchi, Keiichi*
no journal, ,
Kawakita, Yukinobu; Matsuura, Masato*; Tominaga, Taiki*; Yamada, Takeshi*; Tamatsukuri, Hiromu; Nakagawa, Hiroshi; Ouchi, Keiichi*
no journal, ,
