[en] By using a helium metastable atom beam and butanethiol (BT) self-assembled monolayers (SAM), the metastable atom lithography to the gold film on muscovite mica having a flat surface was carried out. Large-area intact and clean patterns with a nanoscale width of the edge, approximately 50-70 nm, were obtained. Meanwhile, we found that the shorter chain molecules like the BT can be used as resist and may result in sharper edge of patterns, but the roughness of gold patterns with the BT SAM is larger than that with the Octanethiol (OT) SAM and similar to that with the Dodecanethiol (DDT) SAM. This observation can be interpreted by the presence of the liquid phase in the short-chain homologues. All information indicated that the BT SAMs on atomically flat surfaces could be used as a resist for exposure to metastable atom beams

[en] A pulsed helium metastable atom beam was generated by the pulsed nozzle-skimmer discharge and a high degree of spin polarization of the helium beam was obtained using the optical pumping method. Spin polarization of the outermost surface electron was detected for clean and sodium covered Fe(100) films deposited on MgO(100) by measuring the secondary electrons ejected by the irradiation of the spin-polarized helium metastable atom beam. Secondary electrons correspond to the Fermi level for a clean iron surface and those corresponding to the Na 3s level for the sodium-covered surface show a positive asymmetry, which indicates the negative polarization of electrons at these levels. The negative polarization of the Na 3s electrons rapidly decreases with the thickness increasing of the Na layer up to 0.5 ML but remains almost constant at a higher coverage (3ML)

[en] The study aims at developing new beam applications to surface researches, such as surface magnetization, spin polarization of absorbed layer, surface properties induced by surface microstructure. Spin polarization induced in molecular orbit of CuPc (copper phthalocyanines) vapor-deposited on Fe substrate surface was observed by SPMDS (spin polarization metastable de-excitation spectroscopy). Sputtering yields were measured for various element materials and compared with the calculated with a semi-empirical formula. Both were found to be consistent with each other, except for silicide. (H. Yokoo)

[en] In order to investigate the behavior of spin polarization at magnetic surfaces, spin-polarized metastable-atom deexcitation spectroscopy with slow He (2³S₁) beams has been utilized as one of the most surface-sensitive spin analysis tools. Recent progress in spin research has made another demand on microscopic images that clarify the spin polarization due to fine structures. Technologies have been developed for He (2³ S₁) focus and spin polarization using a sextupole magnet and for spin flip, which have enabled us to obtain two-dimensional scanning images of surface spin. The present performance is high enough to accomplish precise spin measurement of wedge samples. It is also concluded that the spatial resolution can be greatly improved by adopting an electron emission microscope. (author)

[en] The scattering of the electron-spin-polarized "4He"+ beam on paramagnetic materials has an anomalously large asymmetric scattering component (ASC) around 5%, which is 10"4 of that expected from the spin–orbit coupling (SOC) for the potential of the target nucleus. In addition, the ASC of some materials (for example, Au and Pt) changes sign near the scattering angle (θ) of 90° unlike the result predicted by using the potential scattering theory. When the "4He"+ approaches the target, virtual electron-transfer (ET) excitations between them occur. The effects of the SOC of electrons (SOEs) on the target atom in the ET intermediate state are studied within the frame of the lowest-order perturbation theory about the ET process. The ASC is caused through the combination of the quantum development of electron orbital states under the SOEs and the He nucleus motion in the intermediate state because the preferred orbital states for the ET depend on the position of the He nucleus. It is shown by a numerical calculation that the present process has the possibility of producing the ASC with a magnitude of around 0.1. In the present process, the ASC shows a θ dependence of cos θ sin θ, which changes sign at θ = 90° when the excited orbital in the ET state has the d-character like the Au and Pt cases. (author)

[en] The scattering of an electron-spin-polarized ⁴He⁺ beam on paramagnetic materials has an anomalously large asymmetric scattering component (ASC) around 10%, which is 10⁴ times that expected from the spin-orbit coupling for the potential of the target nucleus. The scattering angle (θ) dependence of the ASC has been measured. It changes sign near 90° for some materials (for example, Au and Pt), while it does not change sign for other materials (for example, Pb and Bi). It has been noted that the spin-orbit interaction of electrons on the target in the electron-transfer intermediate state causes the ASC of He nucleus motion, and it has also been predicted that the sign change in the θ dependence occurs when the d electron transfer is dominant. This seems to correspond to the cases of Au and Pt, but not to the cases of Pb and Bi. The previous approach is refined on the basis of the partial wave representation, which can give a more correct estimation of the ASC. It is shown that the sign change appears in the weak-resonance domain in the case of d electron excitation, whereas the sign change disappears in the strong-resonance domain. Our calculated results qualitatively agree with the material dependence of the ASC observed experimentally. (author)

[en] A compact accelerator for high energy carbon-ion radiotherapy (C-ion RT) has been studied in Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS) since 2004. Compact accelerators have already been used for treatment at several C-ion RT facilities (Gunma, Saga and Kanagawa). The Electron Cyclotron Resonance Ion Source (ECRIS) with all permanent magnets (Kei series) are used at these facilities for production of C⁴⁺ ion. These ion sources were designed based on Kei2 of a prototype installed in NIRS. In recent years, dirt sticking to extraction electrode has become a problem. It is thought that the cause of dirt sticking is putting many CH₄ gas into ion source. We thought that the gas mixing method is help with solving the problem. The gas mixing method is technique to help with production of highly charged ions. Therefore, we performed gas mixing test with helium gas at Kei2 ion source. In addition, we have performed long-term operation under the gas mixing parameter for measurement of the dark current at extraction electrode. As a result of gas mixing test, we confirmed that the beam currents of C⁴⁺ were obtained to more than 0.3 mA with CH₄ gas reduced around 40% of than an original parameter. A result of long-term operation, the dark current increased to 3 mA in the original parameter in 30 days, but was around 2 mA in the gas mixing parameter. We performed additional experiment under C₄H₁₀ gas using. As a result, C₄H₁₀ gas was not suitable for long-term operation, because increase of the dark current was faster than using CH₄ gas. (author)

[en] We observed that the current of a He⁺ ion beam generated from an RF ion source was enhanced by optical pumping (OP) using 1083 nm resonance radiation. The ion current enhancement became more remarkable with higher pressure and higher OP radiation density. The ion beam current with an OP irradiation of 0.5 W cm^-2 at 65 Pa was 1.25 times larger than that without OP. We interpreted this OP effect on the ion current in terms of Penning ionization (PI) of He (2³S) by He (2³P). From the pressure dependence of the OP effect, we analysed the ratio of the rate constant of PI (R_PI) to that of the total ionization process (R_Total). We verified the validity of this analysis for R_PI/R_Total from the relationship of spin polarization between He (2³S) atoms and He⁺ ions

[en] National Institute of Radiological Sciences (NIRS) is promoting multiple-ion therapy to form ideal LET and dose distribution by irradiating several kinds of ion to the target. Possible ions are Helium, Carbon, Oxygen, and Neon. However, in the case of compact accelerator for heavy ion radiotherapy facility, it is desirable to cope with one Electron Cyclotron Resonance (ECR) ion source with all permanent magnets-from the viewpoint of cost, operation and maintenance. We have conducted experimental supply and ion production tests with 18 GHz ECR Ion Source (NIRS-HEC) since 2018. The problem noticed in the supply and tests is that He and Ne take time to switch to other ions. We guessed the case of problem is remaining gas in line. Therefore, we test ions switching with new gas line. As result, we achieved ion switching within 1 minute. In sufficient confinement magnetic field for highly charged ion production of Ne is not obtained at ECR Ion Source with all permanent magnets. Because the mirror magnetic-filed is optimized for C⁴⁺. We decided to do a beam test with NIRS-HEC to develop a new ion source with all permanent magnets. The assumed ions were He²⁺, C⁴⁺, O⁶⁺, Ne⁷⁺, which can be used by linear accelerators used in the population type treatment factory. We performed four ions production tests using NIRS-HEC, and data were acquired to investigate whether the magnetic field distribution could be reproduced by permanent magnets. (author)

[en] National Institute of Radiological Sciences (NIRS) promotes multiple ion therapies that form LET and dose distribution with ideal relative biological effectiveness in cancer treatment by irradiating several types of ions to the target. We are developing a compact ECR ion source of all permanent magnets that produces four ions (He²⁺, C⁴⁺, O³⁺, Ne⁷⁺) used in multiple ion therapy. We produced four ions with NIRS-HEC in a fixed magnetic field. As a result, it was obtained ion beam with sufficient intensity for multi-ion treatment. At present, there is a request of high energy beams for biological/physical experiments in addition to therapeutic use in heavy ion radiotherapy facilities. Also, considering cost reduction of the injector, it is necessary to produce ions other than carbon in the ion source and to produce an ion beam having a higher charge than that during treatment supply. Therefore, it is confirmed whether the new ion source can be applied to applications other than treatment supply. We performed C⁴⁺ and C⁵⁺ production tests in a fixed magnetic field with NIRS-HEC. As a result of using two gases and afterglow tuning, it was obtained that sufficient ion beam of 800 μA for C⁴⁺ and 500 μA for C⁵⁺. (author)