[en] The energy spectra of X-rays produced by an LiTaO_3 single crystal have been measured at pressures of 1–20 Pa. The energy spectra showed that the endpoint energy and the amount of X-rays gradually increased with the decrease of pressure at 5–8 Pa and abruptly increased around 4 Pa and below. A maximum endpoint energy of 70 keV was obtained using the LiTaO_3 single crystal with 5 mm thickness at a pressure of 3 Pa. The change of X-rays produced by the LiTaO_3single crystal was discussed in relation to the breakdown potential at the pressures. - Highlights: • We measured the X-ray spectra produced by an LiTaO_3 single crystal at 1–20 Pa. • We simultaneously measured the X-ray count rate and the electron current. • The X-ray energy and counts are drastically changed around 4 Pa.

[en] In order to elucidate the effect of synchrotron radiation (SR) irradiation on crystal growth, crystallization of WO₃ films has been performed in vacuum under SR irradiation. The main results were compared with the results of heat treatment of the same film. Upon SR irradiation for 80 s using a toroidal mirror, a catastrophic change occurred, i.e. W₃O crystals (A-15 type) with a size of less than 30 nm appeared. Decomposition of the WO₃ film started at above 750 deg. C during vacuum heating. W, WO₂ and incommensurate WO₃ crystals appeared. W₃O crystal produced neither intense electron beam irradiation nor vacuum heating. These results will be discussed in terms of the differences caused by excitation with a SR beam, i.e. strong inner shell excitation and ionization of W and O may have taken place

No abstract available

[en] As the research on atomic nucleus physics and elementary particle physics has advanced, the increase of energy of accelerators advanced, and the research institutes in the world which possess the idle accelerators of medium energy have begun to search for their method of utilization. As the result, the research on physical properties by applying ion beam to it has become to be carried out actively. In this report, the Disctron type ion accelerator developed in Ritsumeikan University as one of the electrostatic accelerators in medium energy region and the method of its utilization for the research on physical properties are introduced. Electrostatic accelerators are composed of high voltage generator and ion acceleration tube, and the disc type uses the rotary disc on which metallic pellets are attached as the charge carrier of the high voltage generator. Ritsumeikan University has developed the RIONACK, the laminated Disctron type accelerator, which is explained in detail. The method of utilizing the ion beam obtained with the accelerators of medium energy range is roughly divided into that as microprobe and ion implantation. The state of utilizing the RIONACK is reported. (K.I.)

[en] Radioactive iodine isotopes are necessary to be handled carefully, because they scatter easily. As air concentration limits of the radioisotopes are very low levels, we should prepare the measurement technique using a large-volume aspirator and large-scale equipments for environment measurement in radiation controlled areas. In the present study, we designed and manufactured a simple set of holder and charcoal filter connected to a foot pump, and we examined the validity of the system. The collecting efficiency of airborne iodine-125 by this system was 0.379±0.107. However, in the case that 10 L air were filtered by this system and counted for 10 min by a NaI(Tl) well-type scintillation counter, it was shown that iodine-125 at air concentration limit could be measured. (author)

[en] To elucidate the various characteristic and their availabilities of the radioactivity and negative air ion originated from an artificial thoron hot spring, we simulated a hot spring, we simulated a hot spring condition using a monazite powder and measured the negative air ions and radioactivities in the condition. In the result, the radioactivity of the thorium series nuclide (²⁰⁸Tl) in monazite was 5.3 times of that of the uranium series nuclide (²¹⁴Bi). For the pH(3.5-12.5) dependence of the leaching nuclides from monazite in water, the thorium series nuclides (²²⁸Ac, ²¹²Pb) were well leached on the strong acid side because the monazite includes the rare earth element (REE) which was high ionization tendency and was substituted by the radioactive nuclide. On the other side, the uranium series nuclides (²¹⁴Bi, ²¹⁴Pb) leached in water were not detected because the specific activities of the uranium series nuclide are lower relative to those of the thorium series nuclide. Moreover, there were many negative air ions originated from monazite in the place within 10 cm away from the monazite surface. This is suggested that most negative ions exist within the range of the radiated α rays. Negative air ions increased with increasing atmospheric relative humidity (35-60%). This is suggested that negative air ions stably existed in the hydration type such as O₂-bar(H₂O)_n. Furthermore, for the hydrous rate dependence of the negative air ions originated from monazite, the negative air ions without supernatant fluid were larger than those with supernatant fluid, because α rays ionized water on the surface of monazite. (author)

[en] To investigate the energy response of an optically stimulated luminescence dosemeter (OSLD) with low energy photons, OSLDs were irradiated by low energy continuous X-rays which have various energy distributions. The effective energy of the X-ray was in the range 10.0-14.5 keV, and homogeneity factor was in the range 0.5-0.9. As a result, at 11.0 keV, the OSLD-to-ionization chamber ratio was maintained at almost a constant level from 1.03 at a 0.5 to 1.08 at a 0.7 homogeneity factor. However, the OSLD tended to overestimate measured value with an increase of effective energy. Probably, this error can be eliminated by calculating an appropriate correction factor. (author)

[en] The radioactive and thermal effects of radon hot spring were biochemically compared under a sauna room or hot spring conditions with a similar chemical component, using the parameters that are closely involved in the clinic for radon therapy. The results showed that the radon and thermal therapy enhanced the antioxidation functions, such as the activities of superoxide dismutase (SOD) and catalase, which inhibit lipid peroxidation and total cholesterol produced in the body. Moreover the therapy enhanced concanavalin A (ConA)-induced mitogen response and increased the percentage of CD4 positive cells, which is the marker of helper T cells, and decreased the percentage of CD8 positive cells, which is the common marker of killer T cells and suppressor T cells, in the white blood cell differentiation antigen (CD8/CD4) assay. Furthermore, the therapy increased the levels of α atrial natriuretic polypeptide (αANP), β endorphin, adrenocorticotropic hormone (ACTH), insulin and glucose-6-phosphate dehydrogenase (G-6-PDH), and it decreased the vasopression level. The results were on the whole larger in the radon group than in the thermal group. The findings suggest that radon therapy contributes more to the prevention of life-style-related diseases related to peroxidation reactions and immune suppression than to thermal therapy. Moreover, these indicate what may be a part of the mechanism for the alleviation of hypertension, osteoarthritis (pain), and diabetes mellitus brought about more by radon therapy than by thermal therapy. (author)

[en] Highlights: • We measured the X-ray spectra produced by an LiTaO₃ single crystal at 8 × 10⁻⁴−4 Pa. • The X-ray energy and intensity increased to saturation with a decrease of pressure. • The gap between the crystal surface and the target may affect the X-ray production. - Abstract: The energy spectra of X-rays produced by an LiTaO₃ single crystal have been measured at the pressures of 8 × 10⁻⁴−4 Pa. The energy spectra showed that the endpoint energy steadily increased with decrease of pressure at 2–4 Pa and gradually decreased with decrease of pressure at 0.1–2 Pa, and became almost constant below 0.1 Pa. The amount of X-rays steadily increased with decrease of pressure at 2–4 Pa and almost saturated below 0.5 Pa. The change of X-rays produced by the LiTaO₃ single crystal was compared with the previous works and discussed in relation to the distance between the crystal surface and the target.

[en] Radon inhalation using our radon exposure device activated anti-oxidative function in some organs of mouse. To assess the possibility of its application to veterinary care, healthy dogs and cats with chronic renal failure were inhaled radon at a concentration of 5500 Bq/m³ for 30 minutes every 2 days for 30 days. In result, radon inhalation within a relatively long time period significantly decreased the triglyceride level of dogs. On the other hand, some cats increased the volume of drinking water by radon inhalation and the creatinine level in blood of these cats was decreased to normal level. These findings suggest that radon inhalation may have curative properties against chronic renal failure. (author)