The chemical behavior of positive muons in condensed phase ammonia has been investigated in order to elucidate the phase and temperature effects on the chemical and physical behavior of the muon and muonium formation in a simple binary compound. Diamagnetic muon yield (PD) was constant at 0.67±0.01 in both solid and liquid above 125 K. Muonium formation in solids were observed above 100 K with slow muonium spin relaxation. In liquids, the muonium yield and its spin relaxation rate showed temperature dependence. Addition of metallic sodium increased PD in liquids.
Diamagnetic muon yields (PD) in (AlxCo1−x)(acac)3 and (GaxCo1−x)(acac)3 systems were investigated. Both in (AlxCo1−x)(acac)3 and (GaxCo1−x)(acac)3, Co(acac)3 was more influential on diamagnetic muon yield than Al(acac)3 and Ga(acac)3. Zerofield muon spin relaxation rate suggests that the diamagnetic muon resides in the vicinity of Co(acac)3 molecules.
Authors:T. Saito, Y. Kobayashi, M. Kubo, and Y. Yamada
For Mössbauer -rays in the in-beam Mössbauer experiments using various beams such as heavy ion, secondary short-lived isotope, and neutron beams, it is important to develop a detector. A parallel-plate avalanche counter (PPAC) is the most suitable gas counter for on-line measurements, because PPAC collects the internal conversion electrons emitted by the Mössbauer effect even under high -background. We evaluated the influences of the pressure and flow rate of the counter gas against the counting efficiency of PPAC, and determined the optimum conditions for use in the in-beam Mössbauer experiments.
Authors:Y. Sakai, M. K. Kubo, H. Matsue, and C. Yonezawa
By probing Doppler broadened line-shapes of prompt γ -ray at 478 keV emitted from moving 7*Li produced via the 10B(n, γ)7*Li reaction, matrix materials containing and/or surrounding boron species were non-destructively characterized for several growing stages of soybean. It was elucidated that boron is in the form close to each other for both the dry seeds for planting and the dry seeds harvested, while it was revealed that boron exists in an aqueous solution for the two stages of growing, swelling seeds with a bourgeon and a greenish sprout. This work is the first biological application of Doppler broadening of neutron induced prompt γ -rays.
Authors:Y. Sakai, M. Kubo, T. Tominaga, K. Nishiyama, and K. Nagamine
Chemical behaviours of positive muons implanted in crystalline tris/acetylacetonato/chromium/III/, iron/III/, and cobalt/III/ were investigated by means of the muon spin relaxation technique. The muon spin relaxation function was exponential in tris/acetylacetonato/iron/III/ and Gaussian in tris/acetylacetonato/cobalt/III/, suggesting that the muon spin relaxation may be ascribed to the interaction between the muon spin and a fluctuating electronic spin in the former and between the muon and a static nuclear spin in the latter. The yield of diamagnetic muon species was found to be nearly unity in these three complexes. Based on the analysis of the relaxation function, it is likely that the positive muon implanted in the cobalt/III/ complex will reside at a distance of about 1.7 A from the cobalt atom.
Authors:M. Kubo, Y. Sakai, T. Tominaga, K. Nishiyama, and K. Nagamine
Diamagnetic muon yields /PD/ in various metal acetylacetonates were measured at room temperature by the muon spin rotation technique. We have found a clear difference in PD between complexes of typical elements and those of transition elements. We suggest that partially filled inner orbitals play some important role in determining the diamagnetic yield in these complexes.
Authors:Y. Sakai, K. Ohshita, M. Kubo, C. Yonezawa, H. Matsue, H. Sawahata, Y. Ito, and S. Iwama
Iron and boron species in the products of thermit reaction of aluminum, iron oxide, and boron oxide were characterized by
Mössbauer spectroscopy, X-ray diffraction, and prompt γ-ray analysis. It was revealed that iron and boron products of the
thermit reaction are composed of intermetallic compounds with aluminum.
Authors:M. Kubo, H. Moriyama, Y. Tsuruoka, S. Sakamoto, E. Koseto, T. Saito, and K. Nishiyama
An elemental analysis method using muonic X-rays has been developed. Applying the unique features of the negative muon, this
method enables elemental distribution in an object to be obtained three dimensionally and non-destructively. Especially, by
choosing the incident muon beam energy, depth-profiling as deep as several cm from the surface can be achieved by detecting
the high energy muonic X-rays carrying the information of the atom which captured the muon. We obtained some preliminary results
and showed the applicability of the technique in future analytical facilities.
Authors:Y. Kobayashi, Y. Tsuruoka, M. Kubo, H. Nonaka, Y. Yamada, Y. Sakai, H. Shoji, W. Sato, A. Shinohara, Y. Watanabe, and H. Matsue
In order to investigate the physical and chemical effects of neutron capture reaction, a neutron in-beam Mössbauer spectroscopic
study on two isomorphs of iron disulfide: pyrite and marcasite, were carried out with a parallel plate avalanche counter at
room temperature. In both compounds only two major products accounted for the obtained spectrum: one with Mössbauer parameters
close to the parent compound and the other one considered to be a new product. The yield of the parent-like species was different
in the two isomorphs.
Authors:Y Kobayashi, M. Kubo, Y. Yamada, T. Saito, H. Ueno, H. Ogawa, W. Sato, K. Yoneda, H. Watanabe, N. Imai, H. Miyoshi, and K. Asahi
In-beam Mössbauer spectra of 57Fe, decayed from short-lived 57Mn (T1/2 = 1.45 min) implanted into potassium permanganate, KMnO4, were measured at temperatures between 11 K and 130 K. This is the first application of a secondary RI beam to the study of valence states after nuclear transformation. The in-beam Mössbauer spectra obtained below 90 K could be analyzed with two components, a doublet and a singlet. From the calculations of the molecular orbital wave functions, the singlet is suggested to be substitutional 57Fe atoms for Mn-sites in tetrahedral [MnO4]– with an unusually high valence state of Fe8+.