H. Yuki

Strongly enhanced DD fusion reaction in metals observed for keV D+ bombardment

The excitation functions of the yield of protons emitted in the D(d,p)T reaction in Ti, Fe, Pd, PdO and Au were measured for bombarding energies between 2.5 and 10 keV. It was found that the reacti...

Elemental analysis of cellular samples by in-air micro-PIXE

Abstract We developed a micro-PIXE system for the analysis of frozen cellular samples at atmospheric pressure under helium gas cooling. We analyzed bovine aortic endothelial (BAE) cells previously cultured in a medium containing bromodeoxyuridine (BrdU). It is known that these cells take BrdU into their nuclei at the S phase of their metabolic cycle. We examined the Br uptake for incubation times of 6, 12 and 24 h, respectively. The Br maps showed an accumulation in the nuclei and the Br concentration was found strongly dependent on the incubation time. We have demonstrated that in-air micro-PIXE analysis is a relevant technique for examining the molecular uptake in cells.

Anomalous enhancement of DD reaction in Pd and Au/Pd/PdO heterostructure targets under low-energy deuteron bombardment

Yields of protons emitted in the D+D reaction in Pd, Au/Pd/PdO, Ti, and Au foils are measured by a dE-E counter telescope for bombarding energies between 2.5 and 10 keV. The experimental yields are compared with those predicted from a parametrization of the cross section and stopping power at higher energies. It is found that for Ti and Au target the enhancement of the D(d,p)T reaction is similar to that observed with a deuterium gas target (several tens of eV). The dependence of the yields on the bombarding energy corresponds well to the screening potential parameters Us=250±15 eV for Pd and 601 ±23 eV for Au/Pd/PdO. Possible models of the enhancement obtained are discussed.

Development of a rapid source preparation method for high-resolution α-particle spectrometry

In order to prepare sources of short-lived actinides for alpha-particle spectrometry, a coprecipitation method with Sm hydroxide was developed. The preparation procedure can be completed within 5 min with a high chemical yield of over 90%. It was found that the uniformity of the produced sources was sufficient to provide a high resolution of better than 20 keV. Under this method, we successfully measured the alpha-particle spectrum of short-lived Cf isotopes produced in the (238)U((12)C, xn) reaction.

reaction in metal at bombarding energies below 5 keV

In order to study the electron screening effect on low-energy nuclear reactions in metals, the D+D reaction in Ti and Yb was investigated. Yields of protons emitted in the D(d, p)T reactions from the deuteron bombardment of Ti and Yb thick targets with bombarding energies between 2.5 and 7.2 keV were measured. The obtained yields were compared with those predicted by using the parametrization of cross sections at higher energies. It was found that the reaction rates in metals are enhanced over those of the bare nuclei for keV, and the enhancement can be interpreted as caused by the electron screening. The electron screening potentials in Ti and Yb are deduced to be eV and eV, respectively.

Bremsstrahlung emission in -decay and tunnelling motion of particles

In coincidence measurements with Si and Ge detectors, bremsstrahlung photons associated with the -decay of and were measured. Emission probabilities of the bremsstrahlung deduced for were for keV, and upper limits of the same order of magnitude were obtained for . They are much smaller than those predicted by a Coulomb acceleration model and are compared with a quasi-classical calculation in which the bremsstrahlung emission in tunnelling motion of particles is taken into account. It is shown that the data can be interpreted as a consequence of destructive interference of radiative amplitudes outside the Coulomb barrier with those in tunnelling.

Strongly enhanced Li + D reaction in Pd observed in deuteron bombardment on PdLix with energies between 30 and 75 keV

Thick target yields of α particles emitted in the 6,7 Li(d,α) 4,5 He reactions in PdLi x and AuLi x were measured as a function of the bombarding energy between 30 and 75 keV. It was found that the...

Measurement of the D(d, p)T reaction in Ti for 2.5 < Ed< 6.5 KeV and electron screening in metal

In order to study the electron screening effect on low-energy nuclear reactions in metals, the D+D reaction in Ti was investigated. Measured were thick target yields of protons emitted in the D(d, p)T reaction from the bombardment of Ti metal with deuteron energies between 2.5 and 6.5 keV. The obtained yields were compared with those predicted by using the parameterization of cross sections at higher energies. It was found that the reaction rates in Ti are slightly enhanced over those of the bare D+D reaction for Ed < 4.3 keV, and the enhancement can be interpreted as caused by the electron screening. The electron screening potential in Ti is deduced for the first time to be 19 ± 12 eV.

Alpha-decay from the 3.5 eV isomer of 229Th

The alpha-decay of a low energy isomer of 229Th at about 3.5 eV was sought by producing it through the (g,n) reaction on a 230Th target. Thorium isotopes in the reaction products were isolated and purified by anion exchange chromatography in a concentrated nitric acid medium to remove lanthanides fission products. The thorium fraction was further purified by samarium fluoride coprecipitation and the precipitate was mounted as a source for a-spectroscopy. Decaying a-signals were observed in the energy region that was expected for 229mTh, i.e., between 4.83 and 5.08 MeV. The half-life of the decaying component was determined from repeated experiments to be 13.9±3 hours.

Activation cross-sections of deuteron induced reaction of natural Ni up to 40MeV

Production cross-sections of (nat)Ni(d,x)(56,57)Ni, (55,56,57,58)Co, (52,54)Mn, and (51)Cr nuclear reactions were measured up to 40 MeV by using the stacked foil technique. The results were compared with the literature values, TALYS 1.4 and TENDL-2012. Spline fits were made on the selected data, from which physical yields were calculated and compared with the literature and our directly measured thick target yield values. (nat)Ni(d,x)(56,57,58)Co reactions were analyzed for beam monitoring and thin layer activation (TLA). Rate of production of (55)Co was compared between proton and deuteron induced reactions.