An electrostatic ion trap was designed for the study of vibrational states of molecular ions. The trap consists of two einzel lenses and two parallel-plate reflectors. An optical model that is analogous to the present trap predicts that a range of focal lengths of lenses exists where ions can be stored irrespective of the reflector's focal length. Beam tests with 1.2-keV ion beams showed that ions can be stored in this range. That storage time is 0.1 s for an Ar⁺ beam at vacuum pressure of 2 × 10^-8 Torr.

Interactions of 150 MeV/amu ³He⁺⁺ projectiles with solid gold targets have been studied at the isochronous cyclotron of the RCNP in Osaka. The ³He⁺ ions resulting from capture of the target electrons to the projectile were observed with the use of large magnetic spectrograph, Grand Raiden, set at θ = 0° with respect to the beam. The yield ratio of singly to doubly ionized helium ions emerging from thin gold foils, He⁺/He⁺⁺, has been measured as a function of the foil thickness. Extrapolating the results to zero Au target thickness permits to determine the cross section values for electron stripping from ³He⁺ ions, σ_STRIP = 1.05 × 10^-17 cm², and for electron capture to ³He⁺⁺ ions, σ_CAP = 1.12 × 10^-25 cm². The results obtained extend significantly the existing systematics for both processes to high (semi-relativistic) velocities. The collision strength deduced from the stripping cross sections deviates strongly from the theoretical predictions of Gillespie in absolute values as well as in the velocity dependence. It can, however, be well approximated by the simple Bohr formula for mid Z atoms. Also the capture data indicate the need to improve the theoretical approximations. A more detailed treatment of electrons captured from different shells in a high Z target is presumably needed. The astrophysical interest in the data of this kind for very light ions (hydrogen, helium) is indicated.

Electron-DNA anion collisions were studied using an electrostatic storage ring with a merging electron-beam technique. The rate of neutral particles emitted in collisions started to increase from definite threshold energies, which increased regularly with ion charges in steps of about 10 eV. These threshold energies were almost independent of the length and sequence of DNA, but depended strongly on the ion charges. Neutral particles came from breaks of DNAs, rather than electron detachment. The step of the threshold energy increase approximately agreed with the plasmon excitation energy. It is deduced that plasmon excitation is closely related to the reaction mechanism.

Dissociative electron capture accompanied by target ionization (DECI) was studied for collisions of 20 keV H₂⁺ with Ar. A three-dimensional fragment imaging technique in combination with a recoil-ion time-of-flight method was used to measure the kinetic-energy release and the dissociation angle of the H-H fragment pair arising from the DECI process. We observed that the distribution of the dissociation angle is strongly anisotropic. A three-body simulation suggests that collisions between the individual fragments and the target significantly influence the two-body dissociation of the H-H pair at impact parameters where the DECI process occurs.

Electron-biomolecular ion collisions were studied using an electrostatic storage ring with a merging beam technique for singly protonated peptides (angiotensin I, II, and III). A strong neutral-particle emission at around 6.5 eV was found in addition to neutrals from recombination at low energies. The rates of the high-energy peak greatly decreased with a slight decrease in the number of amino-acid residues from angiotensin I to III. These results suggest that some peptide bonds were selectively cleaved.

It was found that the energy loss straggling of 10 MeV/amu ³He¹⁺ and ⁶Li²⁺ ions transmitted through thin carbon foils exhibits a bump structure at the foil-thickness region where the charge-changed H-like component becomes comparable to the frozen-charged one. This characteristic behavior could be reproduced well by a Monte Carlo simulation taking account of the electron loss and capture processes. An abrupt increase of the straggling values were also observed for ¹²C⁵⁺ and ¹²C⁴⁺. In order to improve a quantitative understanding, not only the attenuation of H-like and He-like beams as a function of the foil thickness but also the electron-captured fractions for the incidence of bare and H-like beams have been measured and charge changing cross sections among the bare, H-like and He-like charge states are evaluated. A computer simulation taking account of charge exchanges can reproduce quite well the measured energy losses and straggling of partially clothed C ions in the thicker foils.

The energy losses of 10 MeV/amu ³He^2+,1+, ⁶Li^3+,2+, ¹²C^6+,5+,4+ and ¹⁶O^7+,6+,5+ ions passing through carbon foils of 5-110 μg/cm² in thickness were measured with a high resolution magnetic spectrograph. The measurement was carried out for ions emerging from foils in the same charge state as the incident beam. The measured fixed-charge stopping powers have been reported in our previous papers. In this paper, the energy loss straggling of partially clothed ions in the charge-state nonequilibrium region is reported for the first time. A double peak structure in energy loss spectra of ³He¹⁺ and ⁶Li²⁺ ions transmitted through carbon foils of 40-50 μg/cm², which is due to charge changing contributions, was also described before. The present study shows that these contributions also bring about a characteristic behavior in the foil thickness dependence of the straggling values. For partially clothed C and O ions, a linear relation between the foil thickness and the straggling does not hold in the thicker foil region and the straggling exhibits an abrupt increase, although the double peak structure did not appear in the energy loss spectra. A Monte Carlo simulation taking account of the charge exchange can well reproduce the energy loss straggling of ³He¹⁺ and ⁶Li²⁺ emerging from thicker foils.

The vibrational cooling of H₂⁺ and D₂⁺ , having no dipole moment, has been studied at the storage ring TARN II. A two-dimensional imaging technique was used to measure the kinetic-energy release (KER) in the dissociative recombination of H₂⁺ and D₂⁺ as a function of the storage time at a relative energy of 0 eV. The vibrational-level populations of the H₂⁺ and D₂⁺ beams were estimated from the KER data. The estimation shows that the relative population of H₂⁺ ions in their vibrational ground states reaches more than 90% at a storage time of 26 s. This result is in agreement with the recent result in TARN II [T. Tanabe et al., Phys. Rev. Lett. 83, 2163 (1999)]. The relative population of D₂⁺ ions in their vibrational ground states is estimated to be more than 90% for a storage time of 10 s.

We have measured elemental concentration of old Japanesecopper coins made in the Edo period (1600-1860) by PIXE and XRF to study the availability of elemental concentration analysis for production place identification of copper-based archaeological alloys. We also aimed to compare the effectiveness of these two methods for this purpose. For XRF measurement we operated a XRF equipment with rhodium target at 50 kV. Scince elemental uniformity is indispensable for concentration analysis, we also measured the elemental distributions by SEM at 25 kV. Two dimensional images obtained by SEM showed nearly uniform distribution for iron, tin and antimony but not for lead. Besides of main conponents, copper and lead, many minor components were measured by PIXE and XRF. The relative concentrations of arsenic, silver, antimony and tin showed clear difference by the place the coins were made.

銅合金の考古遺物の鋳造地同定に微量元素分析が適用できるかどうかを調べるために、PIXEおよびXRF法を用いて江戸時代に鋳造された日本の古銭の微量元素濃度を測定した。 また、これら二つの方法の実効性を比較することも目的とした。 PIXE測定には2.5MeVのプロトンビームを用いた。XRF測定には50kVでのロジウムからのX線を用いた。 試料中における微量元素の均一さが濃度分析には必須なので、25kVでのSEM法で微量元素分布を測定した。 SEM法によって得られた２次元イメージから、鉄やスズ、アンチモンの分布はほぼ一様であるが、鉛に関しては一様でないことがわかった。 PIXEおよびXRF法によって、銅や鉛の主成分以外に、他の微量元素が測定された。 ヒ素や銀、アンチモン、スズの相対濃度は、古銭の鋳造地によって異なっていることがわかった。

The dissociative recombinations rate of H₂⁺ was measured as a function of the storage time with an ultracold electron beam in a storage ring. The H₂⁺ ions vibrationally relax with time, and almost reach the vibrational ground state at a time of 25 s after injection. The magnitude of the ground-state population after 25 s far exceeds that expected based on the initial ground-state population and its decay. This indicates the existance of a superelastic collision process, where electrons are scattered from excited molecular ions and gain energy by vibrational deexcitation.

蓄積リングの極冷電子ビームを用いたH₂⁺の解離性再結合を蓄積時間の関数として測定した。 で生成した1meVのオーダーの低温電子ビームを用いて研究した。 H₂⁺イオンは時間とともに振動脱励起し、入射後25秒でほとんどのイオンが振動基底状態に落ちた。 25秒後に振動基底状態にあるイオンの割合は、入射直後の振動基底状態の割合と励起状態にあるイオンの崩壊から予想される値を大きく越えている。 これはスーパーエラスティック衝突の存在を示している。 スーパーエラスティック衝突とは、振動励起した分子イオンと電子が衝突し、振動励起状態が脱励起する際のエネルギーを電子が得る衝突のことである。

The dissociative recombinations of ³HeH⁺, ⁴HeH⁺, ³HeD⁺ a,d ⁴HeD⁺ were studied with an extreamly low-temperature electron beam of the order of 1 meV produced by a superconducting electron cooler at the storage ring TARN II.. The disociative recombination spectra show a fine new structure and a clear isotope dependence in the low-energy region. Those features are well reproduced by the theoretical calculations based on a multichannel quantum-defect theory including rotational motion and discretized dissociative states. According to the theory, the newly observed structure is evidence for a new indirect mechanism where the intermediate states are not vibrationally excited Rydberg states but virtual dissociative statets.

³HeH⁺, ⁴HeH⁺, ³HeD⁺ a,d ⁴HeD⁺の解離性再結合を蓄積リング TARN IIの超伝導電子冷却装置で生成した1 meVのオーダーの低温電子ビームを用いて研究した。解離性再結合のスペクトルには、低エネルギー領域に新しい微細構造とはっきりとした同位体依存が見られた。 この測定結果は、分子の回転状態を考慮した多チャンネル量子欠損理論の計算結果とよく一致する。 理論によれば、スペクトル中の新しく観測された構造は新たなインダイレクトメカニズムの証拠である。

Recent advances in studies of electron-ion recombination processes at low relative energies with the electron cooler of the heavy-ion storage ring CRYRING are shown. Through thr use of an adiabatically expanded electron beam, collisions down to 10^-4 eV relative energies were measured with highly charged ions stored in the ring at around 15 MeV/amu energies. Examples of recombination measurements for bare ions of D⁺, He²⁺, N⁷⁺, Ne¹⁰⁺ and Si ¹⁴⁺ are presented. Further on, results of an experiment measuring laser-induced recombination (LIR) into n=3 states of deuterium with polarized laser light are shown.

重イオン蓄積リングCRYRINGの電子冷却装置を用いた低エネルギーでの電子ーイオン再結合の研究の最近の前進を紹介する。 断熱膨張電子ビームの使用によって10^-4 eVの低エネルギーでの衝突実験が15 MeV/amuで蓄積された高電荷イオンに対しておこなわれた。 D⁺, He²⁺, N⁷⁺, Ne¹⁰⁺ , Si ¹⁴⁺の裸のイオンの再結合測定の例を紹介する。 さらに、重水素のn=3状態への偏向レーザー光を用いたレーザー誘起再結合の測定結果を紹介する。

We have measured capture- and loss-ionization cross sections differential in the projectile scattering angles for 2-MeV C³⁺ - Ar collisions. The scattering angles ranged from 0.1 - 1.0 mrad. The obtained differential cross sections were  reproduced fairly well by a classical-trajectory Monte Carlo (nCTMC) method.

2-MeV C³⁺ イオンと Ar 原子の衝突における、衝突後の散乱角度に相関づけられた捕獲および損失電離断面積を測定した。 散乱角度の測定範囲は0.1mradから1.0mradである。 得られた微分電離断面積は古典軌道モンテカルロ法(nCTMC)によってよく再現された。

We have measured differential cross sections of multiple ionization in coincidence with projectile final charge states and scattering angles in 2-MeV C³⁺ - Ar collisions. The scattering angles from 0.1 to 1.0 mrad were studied. The results show that recoil ions of low charge states are dominantly produced at small scattering angles while those of higher charge states are significantly enhanced as the scattering angle increases. The obtained differential cross sections are well reproduced by a classical-trajectory Monte Carlo method (nCTMC).

2-MeV C³⁺ イオンと Ar 原子の衝突における微分電離断面積を測定した。 この微分電離断面積はC³⁺ イオンの衝突後の荷電状態と散乱角度に相関づけられている。 散乱角度の測定範囲は0.1mradから1.0 mradである。 測定結果より、C³⁺ イオンが微小角度に散乱されるときには主に低電荷状態の反跳イオンが生成され、一方、散乱角度が大きくなるほど高電荷状態の反跳イオンの生成が高められることがわかった。 得られた微分電離断面積は古典軌道モンテカルロ法(nCTMC)によってよく再現される。

Mean energy losses of 10.4-MeV neutral hydrogen atoms penetrated through thin carbon foils of 3.7-13.4 ug/(cm²) were measured using a high-resolution magnetic spectrograph. The measured particles are those entered into the carbon foil as H^O and emerged from it as H^O. From the attenuation measurement of H^O in the foils, we can regard the energy losses as those of H⁰ in a frozen charge state. The measured stopping power of carbon for 10.4-MeV H⁰ is 21.3+-1.8 eV/( ug/(cm²)) and is about one-half that for H⁺ at the same speed. This result agrees well with the theoretical predictions based on the first-order Born approximation.

3.7から13.4 ug/(cm²)の厚さを持つ炭素薄膜標的を通過した10.4-MeVの中性水素原子の平均エネルギー損失を、高分解能磁場分析によって測定した。 薄膜中でのH⁰の減衰より、測定されたエネルギー損失はフローズン電荷状態にあるH⁰のエネルギー損失であるとみなせる。 10.4-MeV H⁰の阻止能の測定値は21.3+-1.8 eV/( ug/(cm²))で、同速度におけるH⁺の阻止能の約1.5倍である。 この結果は一次ボルン近似による理論予想値とよく一致する。

Electron-impact detachment of H^- was studied with the TARN II storage ring (at the Institute for Nuclear Study, University of Tokyo) and the associated high-resolution electron beam. The relative cross sections were measured for the relative energies between electron and ion from 0 to 60 eV in search of the H^2- resonances that were reported earlier. No evidence was found for the existence of these resonance states.

H^-イオンの電子衝撃電離を高分解能電子ビームを持つTARN IIストレージリング（東京大学原子核研究所）によって研究した。 以前報告されたH^2- 共鳴の研究と同じように、電子とイオンの相対エネルギーが0から60eVの範囲で相対断面積を測定した。 その測定で共鳴状態の存在を確認できなかった。

We have measured absolute cross sections of multiple ionization in coincidence with final charge states of projectiles for collisions of C³⁺ ions with Ar atoms at 2 MeV. At this collision energy, the recoil ions with low charge states were mainly produced by pure ionization while capture and loss ionization were important processes for the production of recoil ions with higher charge states. In an analysis of the data, an independent-electron model was applied. The results indicate that the ionization probability of target electron depends on the impact parameter in ionization processes, such as pure-, capture-, and loss-ionization. The obtained values were compared with calculations by a classical-trajectory Monte Carlo (nCTMC). The experimental cross sections are in good agreement with the calculated values for pure, single-capture and single-loss ionization.

[要旨]

2-MeV C³⁺ イオンと Ar 原子の衝突における多重電離断面積の絶対値を測定した。 この電離断面積はC³⁺ イオンの衝突後の荷電状態に相関づけられている。 この衝突エネルギーにおいては、低電荷状態の反跳イオンは主に純粋電離によって生成されること、さらに、高電荷状態の反跳イオンの生成には捕獲電離や損失電離過程が大きく寄与することがわかった。 得られたデータは独立電子モデルによって解析された。解析結果より、標的電子の電離確率は衝突径数に依存することがわっかた。 得られた電離断面積は古典軌道モンテカルロ法(nCTMC)と比較されその計算値とよく合うことがわかった。

Dissociative recombinations of HD⁺ was studied with an adiabativally expanded low-temperature electron beam in a cooler ring TARN II. Measurements were performed over a wide energy range from 0 to 40 eV in the center of mass system. The spectrum at low electron energies less than 1 eV cleary shows structures even in the energy region of the order of 1 meV. The results agree well with the theoretical calculations based on a multichannel quantum defect theory including rotational motions and off-the-energy-shell effects.

HD⁺ イオンの解離性再結合を断熱膨張低温電子ビームを備えたTARN IIクーラーリングによって研究した。 重心系で0から40eVの衝突エネルギーの範囲で測定をおこなった。 1eV以下の低エネルギースペクトルを見ると、1meVの低エネルギーにおいても構造の存在することがはっきりとわかる。 この測定結果は、分子の回転状態を考慮した多チャンネル量子欠損理論の計算結果とよく一致する。

Trace elements in five kinds of flour which were made in Japan, America and Canada, have been measured by means of in-air PIXE. Twelve kinds of trace elements were detected, such as Cl, K, Ca, Sc, Cr, Mn, Fe, Co, Ni, Cu, Zn and Br. The concentration of these elements varied depending on the place they were made. In order to check the target preparation procedure, two types of sample preparation have been used, such as wet ashing by nitric acid in a microwave oven and making a paste by an internal standard solution. Comparisons of the results of both samples ensures that bromine was not lost during micro-wave oven heating. Analytic fitting of PIXE spectra by a personal computer and a commercial apllication software was successfully used.

日本、アメリカ、カナダ産の5種類の小麦粉中の微量元素を大気引き出しビームPIXE法によって測定した。 その結果、塩素、カリウム、カルシウム、スカンジウム、クロム、マンガン、鉄、コバルト、ニッケル、銅、亜鉛、臭素の12種類の微量元素を検出した。 生産地によって、それらの濃度は異なっていた。 電子レンジを用いた硝酸湿式灰化法によって作成した試料と、標準試料を加えてペースト状に加工した試料の2種類の試料を、同じ小麦についてそれぞれ準備した。 この2つの試料の分析より、臭素は電子レンジによる湿式灰化によって失われてしまうことを確認した。 市販のアプリケーションソフトを用いた重畳波形の分離によって、PIXEのスペクトルをかなり良く解析することができた。

Keyword: In-Air PIXE, soybean, salt, bromine

Dissociative recombination of HeD⁺ was studied ussing a stroage ring and compared with the results on HeH⁺. A strong peak at around 20-eV electron energy was observed in addition to a peak at nearly zero energy. Their shapes are very similar to corresponding ones on HeH⁺. The relative strengths of these peaks, however, are quite different between HeH⁺ and HeD⁺, which is clear evidence of isotope effect. By mixing O₂ gas into the helium hydride ion source, it was confirmed that the peaks originate from the ground state of molecular ions. The dissociation energy for the low-energy component occurs primarily to He + H^*(n=2), although the possibility of some branching to n=1 cannot be excluded.

HeD⁺ イオンの解離性再結合をストレージリングによって測定し、HeH⁺ イオンの結果と比較した。 0eV付近のピークの他に20eVあたりに巨大なピークを観測した。 これらのピークの形はHeH⁺ のものとよく似ている。 しかし、二つのピークの相対強度はHeH⁺ と HeD⁺ の間で同位体効果によりまったく異なっている。 HeHのイオン源の中にO₂ ガスを混入することによって、これらのピークが基底状態の分子イオンからのものであることを確認した。 n=1の状態へいくらかの分子は解離するであろうが、低エネルギー部分の解離は主にHe + H^*(n=2)の衝突によって起こる。

Trace elements in four kinds of soybean and three kinds of salt have been measured by means of in-air PIXE. In soybeans, which were made in Japan, America, Canada and China, six kinds of trace elements were detected, such as Mn, Fe, Ni, Cu, Zn and Br. The concentration of these elements varied depending on the place they were made. American soybean showed characteristic feature compared with other soybeans. As to the bromine concentration, American soybean contains ten times as much as Japanese one. In salts Br and Sr were detected.

4種類の大豆および3種類の塩中の微量元素を大気引き出しビームPIXE法によって測定した。 その結果、日本、アメリカ、カナダ、中国産の大豆から、マンガン、鉄、ニッケル、銅、亜鉛、臭素の6種類の微量元素を検出した。 生産地によって、それらの濃度は異なっていた。 アメリカ産の大豆は他の大豆にない特徴を示した。 アメリカ産大豆は日本産大豆に比べて10倍高い濃度の臭素を含んでいた。塩からは、臭素とストロンチウムが検出された。

Keyword: In-Air PIXE, soybean, salt, bromine

Trace elements in soy sauce have been measured by means of in-air PIXE. Six kinds of trace elements were detected, such as Mn, Fe, Ni, Zn, Cu and Br. Concentrations of Mn, Fe, Zn and Br which were observed in all samples, have been determined. Each analyzed sample contained considerable amount of bromine about 160 ppm. We analyzed domestic and imported raw materials of soy sauce, namely soybeans and wheat, and some soybean products to find out the origin of Br. From the comparison of the imported and the domestic materials, the origin of Br is attributed to the residual fumigation chemicals in the imported ones.

醤油中の微量元素を大気引き出しビームPIXE法によって測定した。 その測定結果より、マンガン、鉄、亜鉛、臭素の濃度が決定された。 160 ppmの高濃度の臭素が検出される醤油もあった。我々は醤油の原料である国産および輸入された大豆と小麦の分析を行った。 その結果、検出された臭素は、ある種類の大豆からの臭素であることがわかった。 国産大豆と輸入大豆の測定結果の比較より、臭素の起源は輸入原料の残留農薬であると思われる。

Keywords: In-Air PIXE, soy sauce, residual chemicals