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The excitation function for the (63)Cu(n,p)(63)Ni reaction has been measured by activation method using the 4.5 MV Dynamitron accelerator of the Fast Neutron Laboratory of Tohoku University. Copper plates and hollow spherical copper shells were irradiated by neutrons of various energy up to 14.9 MeV produced by the T(p,n), D(d,n), and T(d,n) reactions. The (63)Ni produced in the irradiated copper target was chemically separated. The beta-rays emitted from the extracted (63)Ni were measured by a liquid scintillation method. The cross sections obtained were compared with the evaluated data files of JENDL-3.3, ENDF/B-VI and FENDL/A-2.0. Consequently, it is found that FENDL/A-2.0 is consistent with our experimental data in the energy range studied in this work. The effect of proton shell appeared in the excitation function obtained is also discussed.

The upper and lower limits of the excitation function of the (63)Cu(n,p)(63)Ni reaction were experimentally determined, and the number of (63)Ni nuclei produced in copper samples exposed to atomic bomb neutrons in Hiroshima was estimated by using the experimental excitation functions and the neutron fluences given in the DS02 dosimetry system. The estimated number of (63)Ni nuclei was compared with that measured and with that calculated using the DS02 dosimetry system and the corresponding ENDF/B-VI cross section. In comparison with DS02, there is about a 60% maximum difference in (63)Ni production at the hypocenter when the experimental upper cross section values are used. The difference becomes smaller at greater distances from the hypocenter and decreases, for example, to less than 30 and 5% when using the upper and lower experimental cross sections at 1,000 m, respectively.

Summary We produced 229Th in the nuclear reaction 232Th(γ, p2n) 229Ac, followed by disintegration to 229m,gTh. The 229mTh α-decay was searched for. Alpha-particle events of energy between 4.93 MeV and 5.05 MeV were observed in the separated thorium sample of β-decay products from an actinium source highly purified from the 232Th + γ reaction products. The energies of the α-particles coincide with those expected for 229mTh.

Trace amount of nickel in high-purity iron and iron oxide samples was determined by photon activation analysis (PAA) using the Electron Linear Accelerator at the Research Center for Electron Photon Science, Tohoku University. It was confirmed that about 0.015 μg of nickel in the high-purity iron oxide sample could be determined with an experimental uncertainty of 20% by PAA, that is, it was possible to determine 1% of nickel at least in a few μg of cosmic spherules. PAA was applied to the nickel-determination in cosmic spherules. Nickel in cosmic spherules was determined by PAA more accurately than by instrumental neutron activation analysis done in a reactor neutron spectrum with the fluence rate ratio of thermal neutrons to fast of 4–5 which has so far been applied to the analysis of spherule samples. Additionally, trace amount of nickel in the reference material Giant Clam JCt-1 supplied by the Geological Survey of Japan was determined by PAA with radiochemical treatment.

The hyperfine interactions of99Ru(←99Rh) in YBa2Cu3O7−x withx

The electrochemical calorimetry of the electrolysis of D2O has been carried out using a Pd cathode in an undivided, open cell fashion, together with measuring the total volume of the evolved gases....

Radiochemical yield measurements are reported for barium isotopes from $^{133}\mathrm{Cs}$(\ensuremath{\gamma},${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$xn${)}^{133\mathrm{\ensuremath{-}}\mathit{x}}$Ba for x=0, 2, 4, 5, 6, 7, and 9 for bremsstrahlung maximum end-point energies ${\mathit{E}}_{0}$=30--1050 MeV and for $^{133}\mathrm{Xe}$ from $^{133}\mathrm{Cs}$(\ensuremath{\gamma},${\mathrm{\ensuremath{\pi}}}^{+}$${)}^{133\mathit{m},}$gXe for ${\mathit{E}}_{0}$=300--1000 MeV. Emphasis was placed on Ba measurements near the pion threshold and for different target thicknesses in order to assess interfering secondary particle-induced reactions. Clear evidence of secondary reactions was found in the form of a shoulder in the yield curves for a range of values near ${\mathit{E}}_{0}$\ensuremath{\lesssim}${\mathit{Q}}_{\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$, the ${\mathit{Q}}_{\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ value of $^{133}\mathrm{Cs}$(\ensuremath{\gamma},${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$xn) reaction. This result was used for the correction of yields at ${\mathit{E}}_{0}$\ensuremath{\gtrsim}${\mathit{Q}}_{\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ with the aid of reported measurements of photoproton spectra from $^{12}\mathrm{C}$ and other complex nuclei and cross sections of ${(}^{133}$Cs+p) reactions. The yields corrected for the secondaries ${\mathrm{\ensuremath{\sigma}}}_{\mathit{q}}$(${\mathit{E}}_{0}$) were unfolded into cross sections per photon of energy k, \ensuremath{\sigma}(k). The characteristic features of ${\mathrm{\ensuremath{\sigma}}}_{\mathit{q}}$(${\mathit{E}}_{0}$) and \ensuremath{\sigma}(k) are then discussed in terms of ${\mathit{E}}_{0}$ and k dependences and product mass (${\mathit{A}}_{\mathit{p}}$=133-x) by comparing the present results with those for other systems currently obtained by our group. It was found that the present results of \ensuremath{\sigma}(k) are generally reproduced by a cascade-evaporation calculation based on the pica code of Gabriel and Alsmiller, only if the calculated values are shifted up in photon energy by 30 MeV and the neutron cutoff energy is chosen to be 1 MeV.

The electrochemical calorimetry of the electrolysis of D2O has been carried out using a Pd cathode in an undivided, open cell fashion, together with measuring the total volume of the evolved gases....

The Hiroshima and Nagasaki atomic bombs resulted in the worst reported exposure of radiation to the human body. The data of survivors have provided the basis for the risk estimation for ionizing radiation, and thus are widely used as the basis of radiation safety. In this report we have studied a new method to detect the low-level 63Ni activity in copper samples in order to estimate the fast neutron fluence from the Hiroshima atomic bomb. Only 0.8 x 10(-3) Bq g(-1) of 63Ni is expected to be produced by the atomic bomb in a copper sample with the 63Cu(n, p)63Ni reaction at a distance of 500 m from the hypocenter. Our method has the required level of sensitivity for determination of the fast neutron fluence out to distances of at least 500 m, and perhaps as far as 1,000 m. We have already investigated and collected some bomb-irradiated copper samples for further study.

Photonuclear production yields of 51 Ti und 51,49,48 Cr from 51 V were redetermined for bremsstrahlung end-point energies ( E 0 ) of 30 to 1000 or 1050 MeV with the aid of radiochemical separation of Cr. The yield curves for 51 Ti, 51 Cr, 49 Cr and 48 Cr show a clear evidence for two components in the production process; one tor secondary-proton reactions at E 0 Q π and the other for photopion reactions, at E 0 > Q , Q π being Q -values for (γ, π + ) and ( γ , π + x n) reactions. The contributions of the secondary reactions for production of the Ti and Cr isotopes at E 0 > Q π were then estimated by fitting calculated secondary yields to the observed ones at E 0 Q π , and found to be about 40%, 20%, 4% and 4% for 51 Ti, 51 Cr, 49 Cr and 48 Cr, respectively, at E 0 = 400 to 1000 MeV. The calculation of the secondary yields was based on the excitation functions for 51 V(n, p) and (p, x ′n) calculated with the ALICE code and the reported photoneutron and photoproton spectra from 12 C and some other complex nuclei. The present results for 49 Cr are close to the reported ones, while the present 48 Cr yields differ by a factor of about 50. For the 51 Ti and 51 Cr yields, there are some discrepancies between the present and reported ones. The yield corrected for the secondaries, in units of μb/equivalent quantum, were unfolded into cross sections per photon, in units of μb, as a function ol monochromatic photon energy with the LOUHI-82 code. The results for the 51 Ti and 49 Cr are in disagreement in both the magnitude and shape with the theoretical predictions based on DWIA and PWIA. A Monte Carlo calculation based on the PICA code by Gabriel and Alsmiller does reproduce the gross feature of the present results.

The nuclide53Mn was produced by the following three nuclear reactions,52Cr(d, n)53Mn,51V(3He n)53Mn and50Cr(α, n), (α, p)53Mn. Enriched52Cr and50Cr metal targets were prepared on copper plate holder by electrodeposition. The commercially available natural vanadium foil was used for the51V(3He, n)53Mn reaction. Each target was bombarded in a cyclotron. Manganese was extracted and purified without using carrier from the bombarded targets by anion and cation exchanges and solvent extraction. The isotopic ratio53Mn/55Mn was measured by mass spectrometry and the amount of55Mn was determined by neutron activation analysis. The activity of53Mn obtained was 7 dpm by 750 millicoulombs in3He bombardment (E3He=20 MeV). The activity due to by-product54Mn was about several thousands times higher than that of53Mn in3He and deuteron bombardments, which were produced through51V(3He, γ)54Mn and53Cr(d, n)54Mn. In alpha bombardment (Eα=15 MeV), the activity of53Mn produced was 8 dpm by 95 millicoulombs. The activity ratio, dpm54Mn/dpm53Mn, was about 3, and this ratio was the best one among the results so far obtained.

Langmuir—Blodgett (L/B) films of tritiated fatty acid were prepared to measure the electron antineutrino mass. The measurement requires that a source should be highly radioactive, homogeneous, very thin, uniform, and nonvolatile in vacuo . With regard to the volatility, the L/B film of fatty acid is, in general, not very stable in vacuo , and desorption of the source molecules results in the main background rates of the measurement and reduces the sensitivity of the mass determination. In the present work, we examined the stability of the L/B film in vacuo , and tried to improve the stability of the film by (i) perfect formation and deposition of metal soap molecules that are more resistant against evaporation than the original fatty acid molecules, and (ii) cooling of the 3 H source with liquid nitrogen in order to reduce the evaporation. Finally, a uniform and highly radioactive 3 H source, which is nonvolatile even at a pressure of 10 −4 Pa, was obtained using the Langmuir—Blodgett film of cadmium [ 3 H]icosanoate (sp act 200,000 Ci/mole).

Mass spectrometry was applied to the measurement of production cross section for the nuclear reaction 52Cr(d, n)53Mn. Enriched 52Cr metal target of about 60 mg/cm2 was prepared on a copper plate holder by electrodeposition and was bombarded with deuterons in a cyclotron. Manganese was extracted and purified without using carrier from bombarded targets by anionuexchange and solvent extraction. The isotopic ratio 53Mn/ 55ccMn was measured by mass spectrometry and the amount of 55Mn was determined by neutron activation analysis.The ratio was up to2×10-2.The activity due to byproduct 54Mn was about 5000 times higher than that of 53Mn and it was attributed to 53Cr impurity occurred at a level of 0.1% in the target through 53Cr(d, n)54Mn. The activities of 53Mn obtained were 5-80dpm by60-160 millicoulombs of 8.3-20.0 MeV, deuterons. The average cross sections were estimated in each experiment and were compared with those of the analogous nuclear reactions.

The distribution of the nuclear reaction product 51Cr between alloys in an iron meteorite was investigated by leaching with dilute sulfuric acid. The meteorite sample wrapped with a cadmium plate was irradiated with neutrons and cooled. The sample was leached and the r rays from 51Cr, 54Mn, 58Co and 59Fe induced by 54Fe(n, a), 54Fe(n, p), 58Ni(n, p) and 58Fe(n, r), respectively, were measured in each step of leaching. The chromium content was determined by atomic absorption spectroscopy (AAS)

Thirty-eight spherules from the Antarctic ice sheet were analyzed using neutron activation analysis under two different conditions to investigate their origin. In almost all of these spherules, the contents of iron, cobalt, and manganese were determined to be 31% to 88%, 17 mg/kg to 810 mg/kg, and 0.017% to 7%, respectively. A detectable iridium content of 0.84 mg/kg was found in only one spherule, which was judged to be extraterrestrial in origin. A comparison of elemental compositions of the Antarctic spherules analyzed in this study with those of deep-sea sediment spherules and those of terrestrial materials revealed that most of the Antarctic spherules except for the sample in which iridium was detected could not be identified as extraterrestrial in origin.

Many studies of actinides, especially of transuranium elements, have been performed mainly owing to scientists’ endeavors to discover new elements and nuclides. (1) In spite of these efforts, the mechanism of the formation of transuranium nuclides by heavy-ion bombardment and the nuclear and chemical properties of the synthesized actinide nuclides have not been clearly elucidated, and a great deal remains to be examined in more detail. In this context, we have begun the investigation of heavy-ion nuclear reactions(2): A system in which a uranium target is irradiated by oxygen ions (160 + 238U), was chosen. For this reaction seventeen nuclides (250Fm) 244,245,248Cf, 242Cm, 233,239Np) 237,239U 225,226,227,228Th, 224,225Ac, and 223,224Ra) were identified and the condition of formation for these nuclides was clarified. This paper deals with a novel method of mutual rapid separation of the synthesized transuranium elements by ion exchange and a discussion of the mechanism which governs the heavy-ion nuclear reactions.

Large sized and uniformly deposited 169Yb sources were prepared with the following properties: the intensity variation and the deposited thickness were 2, respectively, for the source sizes of 35×45 mm2 and 20×100 mm2 with the deposited activity of 20-50 µCi, as an energy reference source for the neutrino mass measurement at INS. The technical details of the preparation: the processes of chemical separation and purification, and vacuum-deposition, are here reported.