No abstract available
Journal
[en] The DEMOS code system, which evaluates effective dose equivalent for a neutron exposure using the MIRD phantom model with the Monte Carlo method, has been developed for radiation protection management according to the recommendation of the ICRP Publication 26. The code system is verified by analyzing does distributions in cylindrical phantom irradiated by broad beam neutrons. The validity of the system are also confirmed by analyzing the neutron equivalent phantom experiments, performed by using monoenergetic neutron beam sources at the accelerator of Electro-Technical Laboratory. The effective dose equivalents as a function of neutron energy are estimated for MIRD phantom model
Source
Anon; vp; ISBN 0-89448-132-0; 
; 1987; vp; American Nuclear Society; La Grange Park, IL (USA); Topical conference on theory and practice in radiation protection and shielding; Knoxville, TN (USA); 22-24 Apr 1987
; 1987; vp; American Nuclear Society; La Grange Park, IL (USA); Topical conference on theory and practice in radiation protection and shielding; Knoxville, TN (USA); 22-24 Apr 1987
[en] In the third year of Tokyo City University, Department of Nuclear Safety Engineering, nuclear experiment learning is required as a compulsory subject. This paper explains the transition of experiment learning contents since FY2015, evaluates educational effects, and summarizes the direction of future efforts. At Tokyo City University Atomic Energy Research Laboratory in FY2017, five kinds of experiments such as 'solvent extraction,' 'X-ray/γ-ray analysis,' 'ion sources,' 'simulator,' and 'neutron measurement,' and the confirmation of understanding level were carried out. At Setagaya Campus, six kinds of experiments were performed. The educational effect was evaluated by the questionnaire that the students responded at the end of class. In FY2016, students' evaluation had been upgraded due to program expansion in the previous year. It is believed that the opportunities for teachers and students to contact with each other directly through students' reports upgraded the evaluation. In FY2017, a decline in performance was seen from the previous year, and mistake in minimum rules such as incompleteness of the basic composition of reports, typographical errors, miss-conversion, etc. were observed and this fact suggests the necessary to instruct students from the young age. It is necessary to look at the transition of effects in the future laboratory, but as the education for students, to make them prepare a guidance program for junior students may be one idea. To investigate past findings about what students want to know, to perform preliminary experiments, and to prepare texts and teach juniors can be said a preliminary exercise of research activities. (A.O.)
Journal
Tokyo Toshi Daigaku Genshiryoku Kenkyusho Kenkyusho-Ho; ISSN 2185-4025; ; (no.43); p. 22-27
; (no.43); p. 22-27
[en] In order to measure the energy spectra of 90Sr/90Y beta-rays emitted from the samples, we changed the thin (0.25 mmt) plastic scintillator used till last year to a thick (3mmtx3=9 mmt) one. After we explained on the changes of electric circuits, we showed the energy spectra of beta-rays emitted from 137Cs, 90Sr/90Y standard sources. Next, after we separated 90Sr nuclides chemically from the IAEA2015 Spiked Water using Solid-phase extraction method with 3M EmporeTM Rad Disk Sr, we measured the energy spectra for 90Sr/90Y beta-rays from the samples during about one month. In order to confirm the secular equilibrium phenomenon between 90Sr and 90Y nuclides, we obtained the time dependence of total counts for 90Sr and 90Y components calculated using a Least Square Method. Finally, we found the background counts in gamma ray shield box were reduced to 1/27 at 100 keV and 1/14 at about 1000 keV. (author)
Journal
Report of Research Center of Ion Beam Technology, Hosei University. Supplement; ISSN 0914-2908; ; (no.38); p. 63-68
; (no.38); p. 63-68
[en] In order to measure the energy spectra of 90Sr/90Y bate-rays emitted from the samples, we could obtain them by changing a thin (0.25 mm t) plastic scintillator to a thick (3mmtx3=9 mm t) plastic scintillator. However, as β ray backgrounds increased, it has been necessary to take much time, 1 week for obtaining 90Sr/90Y β ray energy spectrum of the sample, IAEA 2015 1a (2.17 Bq). By entering a thick (9 mm t) plastic scintillator + H7195 PMT Assembly in γ ray shield box, we could obtain during 2 days 90Sr/90Y β ray energy spectrum of 90Sr/90Y activities in the sample, IAEA 2015 1b (2.21 Bq), whose statistical dispersions were better than those of the same sample measured outside a γ ray shield box. We calculated the reduction rates for γ ray energy spectrum of background using Ge detector (Ortec, GEM20-70) and compared the reduction rates of β ray energy spectrum of background to those of γ ray energy spectrum of background. We investigated 90Sr/90Y β ray energy spectra which were measured with a thick plastic scintillator up to now and also the theoretical spectrum where Fermi function F(Z,E) and the selection rules were considered. (author)
Journal
Report of Research Center of Ion Beam Technology, Hosei University. Supplement; ISSN 0914-2908; ; (no.39); p. 19-24
; (no.39); p. 19-24
[en] We report the discovery of a 10 comoving megaparsec (cMpc)-scale structure traced by massive submillimeter galaxies (SMGs) at z ∼ 4.6. These galaxies are selected from an emission line search of ALMA Band 7 observations targeting 184 luminous submillimeter sources (S 850μm ≥ 6.2 mJy) across 1.6 degrees2 in the COSMOS field. We identify four [C ii] emitting SMGs and two probable [C ii] emitting SMG candidates at z = 4.60–4.64 with velocity-integrated signal-to-noise ratio of S/N > 8. Four of the six emitters are near-infrared blank SMGs. After excluding one SMG whose emission line is falling at the edge of the spectral window, all galaxies show clear velocity gradients along the major axes that are consistent with rotating gas disks. The estimated rotation velocities of the disks are 330–550 km s−1 and the inferred host dark-matter halo masses are ∼2–8 × 1012 M ⊙. From their estimated halo masses and [C ii] luminosity function, we suggest that these galaxies have a high (50%–100%) duty cycle and high (∼0.1) baryon conversion efficiency (SFR relative to baryon accretion rate), and that they contribute ≃2% to the total star formation rate density at z = 4.6. These SMGs are concentrated within just 0.3% of the full survey volume, suggesting they are strongly clustered. The extent of this structure and the individual halo masses suggest that these SMGs will likely evolve into members of a ∼1015 M ⊙ cluster at z = 0. This survey reveals a synchronized dusty starburst in massive halos at z > 4, which could be driven by mergers or fed by smooth gas accretion.
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