Energy of the ^{229}Th Nuclear Clock Isomer Determined by Absolute γ-ray Energy Difference

The low-lying isomeric state of ^{229}Th provides unique opportunities for high-resolution laser spectroscopy of the atomic nucleus. We determine the energy of this isomeric state by taking the absolute energy difference between the excitation energy required to populate the 29.2-keV state from the ground state and the energy emitted in its decay to the isomeric excited state. A transition-edge sensor microcalorimeter was used to measure the absolute energy of the 29.2-keV γ ray. Together with the cross-band transition energy (29.2  keV→ground) and the branching ratio of the 29.2-keV state measured in a recent study, the isomer energy was determined to be 8.30±0.92  eV. Our result is in agreement with the latest measurements based on different experimental techniques, which further confirms that the isomeric state of ^{229}Th is in the laser-accessible vacuum ultraviolet range.

Suppression of β-particle events using a capillary tube in liquid scintillation α spectrometry

A method to decrease photons generated by β particles by using a capillary tube in liquid scintillation α spectrometry is presented. Liquid scintillation counting of (241)Am and (152)Eu was performed with 200, 300, and 500 μm inner diameter (i.d.) PFA tubes as the detection cell. It was observed that the β component in the energy spectrum is located at the lower-energy region with a decreasing i.d. of the PFA tubes, and the α peak of (241)Am was separated from the β component.

Solvent extraction of trivalent actinides with di(2-ethylhexyl) phosphoric acid

We carried out solvent extraction on the trivalent actinides of Am, Cm, Cf, and Fm and the lanthanides (except Pm) using di(2-ethylhexyl)phosphoric acid (HDEHP) in benzene by a batch method. The extraction constants of the HDEHP complexes for these elements were determined systematically under identical conditions. The tetrad effect was clearly observed in the variation of the extraction constants of the lanthanide series. We found that the extraction constant for Fm(III) is much smaller than that for Dy(III), which have similar ionic radii. The extraction constants for Am(III), Cm(III), and Cf(III) are similar to those for corresponding Ln(III) having similar ionic radii. Two possibilities that account for the lower extraction constant of Fm(III) is suggested.

Separation of Am(III), Cm(III), and Cf(III) using capillary electrophoresis

Trivalent actinides Am(III), Cm(III), and Cf(III) were successfully separated for the first time using capillary electrophoresis in 2-hydroxyisobutyric acid/acetic acid. It was found that the ionic radius was primarily important for separation of trivalent actinides as well as lanthanides in this condition. The stability constants of the Am(III) complexes with 2-hydroxyisobutyrate were estimated using the correlations between the molar fraction ratio of lanthanides and their ionic radii.

Extraction behavior of rutherfordium into tributylphosphate from hydrochloric acid

The extraction behavior of rutherfordium (Rf) into tributylphosphate (TBP) from hydrochloric acid (HCl) has been studied together with those of the lighter group-4 elements Zr and Hf. The extractability of261Rf,169Hf, and85Zr into TBP was investigated under identical conditions in 7.2–8.0 M HCl by on-line reversed-phase extraction chromatography. The percent extractions of Rf, Hf, and Zr into the TBP resin increase steeply with increasing HCl concentration, and the order of extraction is Zr > Hf ≈ Rf. By considering the order of chloride complexation among these elements, it is suggested that the stability of the TBP complex of Rf tetrachloride is lower than those of Zr and Hf.

Target preparation by the precipitation method for nuclear reactions

A technique for preparing nuclear reaction targets of various thicknesses was developed by using common filtration technique of hydroxide precipitates with a porous Al(2)O(3) membrane filter. Uniformity was found to be within a few % in each thickness. Durability for beam irradiation was also confirmed. The preparation procedure is convenient and the method is appropriate for several target materials, including not only precious materials but also radioactive materials with low contamination.

[A case of advanced rectal cancer with unresectable liver metastasis for which chemotherapy was markedly effective]

We report a case of advanced rectal cancer accompanied by unresectable liver metastasis in which remission has been achieved for 7 years. The patient was a 64-year-old woman, and her chief complaints were a feeling of abdominal distention and melena. After low anterior resection (D3), oral administration of 600 mg/day of UFT-E and chemotherapy against the liver metastasis by hepatic arterial injection via a reservoir were started. Since the arterial injection via a reservoir became impossible due to infection, her clinical course was observed solely with oral administration of UFT-E. As a result, complete remission was achieved 7 months postoperatively, and the patient is still alive in good health without recurrences at present (7 years postoperatively). The reason why a favorable outcome has been achieved is probably that, although the initial operation resulted is non-curative resection, measures sufficient to enable the patient to lead an ordinary social life were taken at the beginning, and efforts to achieve a long-term survival were made while respecting the quality of life of the patient so that the patient would be able to coexist with the cancer.

[An assessment of extended lymphadenectomy including cervical node dissection for cancer of the thoracic esophagus]

An extended lymphadenectomy including cervical node dissection is one of the most difficult operations, therefore its merits and demerits should be assessed in order to evaluate whether it has the significance of extended radical operation or not. Extended lymphadenectomies including cervical node dissection became to be the standard procedures of lymphadenectomy for cases with cancer of the thoracic esophagus from 1986, and were carried out in 42 cases. Survival rates, disease free survival rates, sites of recurrences and incidences of postoperative complications were compared with the of cases with conventional lymphadenectomy excluding cervical node dissection. Concerning over all survival rates, no significant differences were observed between extended and conventional groups. However only in cases of stage 0 I II, significant difference in survival rates were observed between two groups. Therefore based on our experience, the merit of extended lymphadenectomy was observed only in stage 0 I II cases which had no lymph node metastasis. Concerning the incidence of postoperative complications, no significant differences were observed between two groups, therefore the significance of proceeding extended lymphadenectomy was confirmed.