N. Shikazono

Wide variety of flower-color and -shape mutants regenerated from leaf cultures irradiated with ion beams

The efficiency of ion-beam irradiation combined with tissue culture in obtaining floral mutants was investigated and compared with those of gamma rays and X-rays in carnation. Leaf segments of carnation plants in vitro were irradiated with the 220 MeV carbon ions, and cultured till the shoot regenerated. The carbon ion had the highest effect in reducing the regeneration frequency, and the RBE value with respect to gamma-rays was four. The higher mutation frequency and the wider mutation spectrum were obtained in plants irradiated with the carbon ions than low LET radiations. Three new carnation varieties developed by ion-beam irradiation were applied for the registration of the Japanese Ministry of Agriculture, Forestry and Fisheries. The results indicate that ion beam irradiation could induce wide variety of flower-color and -shape mutants, and that the combined method of ion-beam irradiation with tissue culture is useful to obtain the commercial varieties in a short time.

Mössbauer Study of Invar-Type Iron-Nickel Alloys

By means of the Mossbauer effect intenal magnetic fields at iron atom in invar-type iron-nickel alloys were measured using fine powdered samples in which the γ→α martensitic transformation can be suppressed. The absorption spectra of 30 and 32% iron-nickel alloys have a marked feature that a paramagnetic absorption line coexists with normal ferromagnetic ones even at liquid nitrogen temperature which is well below the Curie temperature. The intenal magnetic field was found to be nearly constant at 330 kOe over the composition range and the sharp decrease of saturation magnetization of alloys around the composition can semiquantitatively be explained when both of intensities of ferromagnetic and paramagnetic lines are taken into consideration.

Magnetic Study of Fe3Si and Fe5Si3 by Mössbauer Effect

Mossbauer measurements were made on ferromagnetic Fe 3 Si and Fe 5 Si 3 to investigate the magnetic structure. In the ordered crystal of Fe 3 Si, two internal fields were found to be 320 kOe and 205 kOe at liquid nitrogen temperature, corresponding to the two crystallographically different sites, Fe(I) and Fe(II). Since Fe(II) has a small magnetic moment, a low internal field and a large isomer shift, its electronic structure may be fairly modified by a formation of covalent bond with Si atom. On the other hand, the situation of Fe(I) seems to be little changed from that of Fe atom in pure iron. Fe 5 Si 3 also has two different sites and two internal fields of 230 kOe and 130 kOe at liquid nitrogen temperature. Both kinds of Fe seem to be considerably different from Fe in pure iron.

Mutation induced with ion beam irradiation in rose

Abstract The effects of mutation induction by ion beam irradiation on axillary buds in rose were investigated. Axillary buds were irradiated with carbon and helium ion beams, and the solid mutants emerged after irradiation by repeated cutting back. In helium ion irradiation, mutations were observed in plants derived from 9 buds among 56 irradiated buds in ‘Orange Rosamini’ and in plants derived from 10 buds among 61 irradiated buds in ‘Red Minimo’. In carbon ion, mutations were observed in plants derived from 12 buds among 88 irradiated buds in ‘Orange Rosamini’. Mutations were induced not only in higher doses but also in lower doses, with which physiological effect by irradiation was hardly observed. Irradiation with both ion beams induced mutants in the number of petals, in flower size, in flower shape and in flower color in each cultivar.

Dose response and mutation induction by ion beam irradiation in buckwheat

Abstract The biological effects of ion beams were investigated to pursue the development of a method for breeding by mutation in buckwheat. Common buckwheat (Botansoba, Bot) and tartary buckwheat (Rotundatiem, Rot) seeds were exposed to various ions in linear energy transfer (LET) at 9–630 keV/μm. The lethal dose 50 (LD 50 ) of ion beams were 10–300 Gy (Bot) and 30–500 Gy (Rot). It was indicated that a penetrating depth in excess of 1.7 mm is necessary to thoroughly saturate the target, and ions with a penetrating depth of less than 2.2 mm were affected by the presence of hulls. The maximum values of the relative biological effectiveness were 17.7 (Rot) and 22.5 (Bot) at 305 keV/μm. The effective cross sections increased with the LET, and the maximum values were 2.7 (Rot) and 3.0 μm 2 (Bot). The mutation induction effects of He and C ions were higher than those of gamma rays.

Hyperfine Field in ZrFe 2 -UFe 2 Ternary System

The hyperfine fields in Zr1-x Ux Fe2, with x = 0. 0.2, 0.4, compared with the results of magnetization measurements. Resonance absorption of nuclear gamma rays of 14.4 kev from Co57 was measured as a function of relative velocity between source and absorber foi each specimen at liquid nitrogen temperature. The magnitudes for the hyperfine fields of Zr1-x UxFe2 at liquid nitrogen temperature are plotted as a function of atomic magnetic moment of iron in these compounds at 80 nif- K under the assumption that zirconium and uranium do not have a magnetic moment.

Induction of somatic instability in stable yellow leaf mutant of rice by ion beam irradiation

Abstract Any class II type active transposons have not been discovered in rice though transposon (mobile element) is very useful for gene isolation in several plant species. In order to capture somatic instability induced by an endogenous active transposon in rice, stable yellow leaf plants derived from a variegated yellow leaf ( yl-v ) mutant found in F2 of a cross between distantly related rice varieties were irradiated with carbon and helium ion beams. In M1 plants derived from the seeds irradiated with 50 Gy of 220 MeV carbon ions, a variegated yl plant was generated and this plant showed small or large sectors in leaves expanded later. Most of panicle-row M2 lines segregated into variegated and stable yl plants. In total, the ratio of variegated to stable yl plants was 3:1, suggesting that clear variegation observed on M1 plants might be caused by activation of a cryptic inactive autonomous element by carbon ion beam irradiation.

Recoil-Free Resonant Absorption of 35.3-keV Gamma Rays of Te125 and Hyperfine Structure of Absorption Spectrum

With the source of Sb 125 embedded in copper or iron metal, the recoilfree resonant absorption of 35.3-kev gamma rays by Te 125 atoms in the crystals of tellurium, α-TeO 2 , MnTe, and CrTe cooled with liquid nitrogen has been studied. For the crystals of tellurium and α-TeO 2 , large quadrupole splittings are observed. The values of | e 2 q Q |=1.6×10 -6 eV, or | e 2 q Q / h |=400 Mc are obtained for both the crystals of tellurium and α-TeO 2 , and the quadrupole moment of the first excited state of Te 125 is estimated to be about 0.2 barn under some assumptions. For the crystal of MnTe and the source embedded in copper, a simple Lorentz line is observed and from the half width the half life of the 35.3-keV level of Te 125 is calculated to be (1.8±0.3)×10 -9 sec. For the crystal of CrTe, line broadening due to the internal magnetic field is observed. The internal field in the CrTe crystal is evaluated to be about 50 Koe. With the source embedded in iron metal, Zeeman splittings are observed, although they...

JAERI magnetic spectrograph for heavy-ion research

Abstract The design of a magnetic spectrograph for heavy-ion reaction studies with the JAERI 20 MV tandem accelerator is described. The spectrograph consists of a quadropole (Q), a multipol (M1), a dipole (D1), a multipole (M2), a dipole (D2) and a multipole (M3). In order to obtain a unique mass identification over a wide mass range in combination with the time-of-flight measurement, the pain length difference ΔL is kept small: L/ΔL is designed to be larger than 210 for a horizontal angular spread of 5 mrad. A momentum resolving power P/ΔP of 7000 is obtainable for solid angles up to 16 msr. The M2 magnet is used to correct the kinematic effect in the range from k= −0.4 to 1.0. The dispersion is variable from 10 to 15.5 m along the focal plane for k = 0 by use of the M3 magnet.

Transfer cross sections for 28Si + 58,62Ni

Abstract Quasielastic reaction cross sections have been measured for 28 Si + 58,62 Ni at an energy ≈ 40% above the Coulomb barrier. A strong isotope dependence in the transfer cross sections, which are dominated by the one-neutron pickup reaction, has been observed. A simple DWBA analysis can give a consistent description of the experimental results.