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It has been known for nearly 30 years that the theoretical and experimental values for the energy of the 2s3s S-1 level in singly ionized boron, B it, differ strongly. Since there is much better agreement for other B II levels, it has been concluded that the experimental value for 2s3s S-1 must be revised. Despite a number of recordings over the years of sliding-spark, hollow cathode and beam-foil spectra, this level has not been located. We have now performed another beam-foil experiment, using higher resolution and sensitivity than in most previous studies. By combining these new data with previous results, we have identified transitions from the 2s4p, 2s5p and 2p3s P-1 levels to 2s3s S-1, the excitation energy (137 622 +/- 3 cm(-1)) of which is now well established and in excellent agreement with theoretical predictions. (Less)

The single-electron capture processes in collisions of ions with He atoms have been studied at a collision velocity of 3.17 atomic units (au) through a state-selective measurement of differential cross sections. Cold-target recoil-ion momentum spectroscopy (COLTRIMS) has been employed to identify the final state of the captured electron and the momentum transfer between the collision partners. Relative differential cross sections for the capture to 3s, 3p n = 4, and n = 5 orbitals of Ar ions are obtained and are in qualitative agreement with a semiclassical close-coupling calculation using the molecular-state expansion method. The electron is dominantly captured to the n = 5 orbitals, which is in accordance with recent observations at lower velocities.

We have measured the fluence dependence of the c -axis lattice parameter in EuBa 2 Cu 3 O y (EBCO) irradiated with various ions from He to Au over the wide energy range from 0.85 MeV to 3.80 GeV. We have observed a linear increase of the c -axis lattice parameter with increasing fluence for all irradiations. The slope of c -axis lattice parameter against fluence, which corresponds to the defect production rate, is separated into two contributions; the effect via elastic displacement and the effect via electronic excitation. The former contribution exhibits a linear increase against the nuclear stopping power, S n . The latter contribution is scaled by the primary ionization rate, d J /d x , rather than by the electronic stopping power, S e , and is nearly proportional to (d J /d x ) 4 .

Using high resolution recoil-ion momentum spectroscopy we have measured differential cross sections of single-electron capture from He atoms by multiply charged boron ions, bare and hydrogen-like , at 0.5 - 1.0 MeV/u. From the measurements of the longitudinal momentum distribution of the recoil ions, the final states of the captured electron in and ions were analysed and the n = 1 ground states were clearly separated from the other excited states. Capture to the excited states gives the dominant contribution to the capture cross section. However, the fraction of captures to the ground state increases with the collision energy. Theoretical calculations based on the eikonal approximation well reproduces the experimental transverse recoil-ion momentum distribution of capture to both the ground and excited states.

The importance, feasibility and method for measuring the photo-ionization cross-section of multi-charged ions using the RIKEN Electron Beam Ion Source (REBIS) is discussed. Specifically the cases for the 2 s and 1 s photo-ionization of Ar14+ is explored. It is concluded that such measurements are possible today and in future (3rd generation) synchrotron radiation facilities, and will be carried out upon modifications of the apparatus. Also described, is the first test of a PHOton Beam Ion Source using REBIS. It's potential advantage over other ion sources is that in the ion production mechanism photoionization the recoil ions obtain only near thermal energies to making ion beams with very low energy spread possible.

Using a photon - ion merged-beam technique, we measured the relative yield spectra of and ions created by photoionization of ions as a function of the photon energy in the 4d ionization region. The ion production, i.e. the double-electron ionization process is found to be dominant throughout the energy range investigated. A broad structure of 4d excitation ionization around 100 eV photon energy was observed in the yield spectrum. A spectral shoulder was observed for at around 85 eV, which was absent in the photoionization of neutral Xe. Some discrete lines were observed for both the - and -yield spectra below 75 eV. The experimental spectra were analysed by a multiconfiguration Dirac - Fock calculation. The largest structure at around 100 eV is attributable to (n=6,7) two-electron transitions. The discrete lines were found to be due to , n f transitions. A serious 4f-orbital collapse is suspected in the 4 fn p two-electron excited states, whereas the collapse is moderate in the singly excited 4f-orbitals.

Ejected electrons from the doublet and quartet states of doubly excited ions, produced by 60 keV collisions have been measured with high resolution zero-degree electron spectroscopy. Only the doublet states were observed in collisions with gas. Both doublet and quartet states were observed when was used as the target. Two theoretical methods, perturbation theory or Z-expansion (MZ code) and multi-configurational Hartree - Fock (Cowan code) were used for identification of peaks observed in ejected-electron spectra. Contributions of correlation effects are discussed by comparison with other theoretical energies.

Spectra of L X-rays emitted from Fe and Cu targets have been measured by 0.75 MeV/u H, He, Si and Ar ion impacts with a crystal spectrometer. The spectra produced by H and He ion impacts are very similar. The X-ray transition energies in the Fe target for Lι, Lη, Lα1,2 and Lβ1 lines are determined to be 616, 628, 704.9 and 717.7 eV, respectively, which are in good agreement with those given in the reference. The spectra produced by heavier Si and Ar ions have more complicated structures due to multiple vacancy production. These spectra are compared with the calculated ones based on the multiconfiguration Dirac-Fock method. The origin of the broadening of the Lα1,2 line to the lower energy is attributed to one 2p plus one 3d electron vacancy production.

By using a photon-ion merging-beam apparatus, the relative photoion-yield spectra for Sr2+ and Sr3+ from Sr+ ions in the ground state were measured around the 3d-ionization region. In the Sr3+-yield spectrum, some discrete lines are observed and a broad structure which reflects the giant resonance corresponding to the 3d- epsilon f transition is found. The observed spectra were analysed with the results of a multiconfiguration Dirac-Fock calculation code. The computation reveals that the observed discrete lines are composed of many lines which have a character due to the strong 5s-4d mixing effect. This is understood from the fact that after the 3d-hole creation, the final 4d-wavefunction collapses and its orbital energy sits beneath that of the 5s orbital.

Using high-resolution recoil-ion momentum spectroscopy we have measured the differential cross sections of single-electron capture and target single-ionization processes for 8.7 MeV O7+-He collisions as functions of scattering angle. A transverse momentum resolution of +or-0.2 au, which corresponds to an angular resolution of about +or-1.5*10-6 rad for the projectile scattering angle, was obtained by intersecting a well collimated O7+ beam with a target of a supersonic He jet from a pre-cooled gas and by measuring the recoil-ion transverse momentum. For the single capture reaction, information on the n-value of the electron final state in O6+ (1snl) is obtained from the longitudinal momentum of the recoil ions. In pure single-electron capture, the dominant contributions to capture were found to be those from the n=4 and higher states, whereas single capture accompanied by the ionization of the second target electron mainly populates n=2 to n=4 states. Furthermore, the measured transverse momentum distribution differs significantly between pure single capture and capture with simultaneous ionization. The measured data for the pure capture process compare favourably with theoretical results based on a molecular-state expansion method. Other experimental data are discussed in terms of the classical overbarrier model.

Relativistic binary-encounter electrons produced in very fast collisions of bare and H-like Ar with carbon foils are studied as a function of laboratory frame emission angle. It is found that the velocity of the binary-encounter peak is consistent with a relativistic billiard ball model. The cross section for binary-encounter electron production is not in good agreement with a simple Rutherford scattering model. It is also found that the ratio of H-like to bare projectile cross sections is 1 at 0 degrees and becomes less than 1 at large emission angles.

We have used the technique of beam-foil spectroscopy to investigate transition probabilities for Na-like Nb 30+ and Mg-like Nb 29+ . In the former case the lifetimes of the 3 p 2 P 1 2 , 3 2 levels were determined using the ANDC method of cascade correction. For the Mg-like ion we have studied the decay of the 3s3p 3 P 1 level which gives rise to a spin-forbidden transition to the 3s 2 1 S 0 ground term.

Projectile {ital K}{alpha} satellite and hypersatellite x-ray yields were measured in collisions of Ar ions with energies of 43, 52, 65, 80, 95, and 300 MeV with targets of C, Mg, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Nb, Mo, Sn, Nd, Tb, Ho, Ta, and W with atomic number {ital Z}{sub {ital t}}=6--74. The intensity ratio of hypersatellite to satellite lines is reported as functions of the target atomic number {ital Z}{sub {ital t}} and incident energy {ital E}{sub {ital p}}. The vacancy-sharing model was found to predict the {ital Z}{sub {ital t}} dependence of the intensity ratio at 43 MeV in near symmetric collisions. At energies above 80 MeV, the direct Coulomb processes, exspecially the electron-capture processes, determine the {ital Z}{sub {ital t}} dependence. Average {ital L}-vacancy probabilities are reported for projectiles at energies of 43--95 MeV that acquire single and double {ital K} vacancies in the targets.

In 89-MeV Sc{sup 8+}+He collisions, the light target atom He was used to ionize selectively the 2{ital p} shell of the scandium projectile. The subsequent {ital L}-shell Auger emission from Mg-like Sc{sup 9+} was measured with high resolution using the method of zero-degree Auger spectroscopy. The spectra are dominated by three peak groups that are attributed to transitions from the various initial states belonging to the configuration 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 5}3{ital s}{sup 2}3{ital p} to the final states 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital s} {sup 2}{ital S}, 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital p} {sup 2}{ital P}, and 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital d} {sup 2}{ital D}. The {sup 2}{ital P}{sub 1/2-}{sup 2}{ital P}{sub 3/2} fine-structure splitting was resolved for the final configuration 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital p}. The branching ratio for the transition to 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital d} {sup 2}{ital D}, which involves three electrons and, thus, must be ascribed to correlation, is compared to earlier results for the isoelectronic ions Al{sup +} and Ar{sup 6+}. Good agreement between observed and calculated branching ratios to the three final states is obtained by including onlymore » correlation in the initial state. A discrepancy for the branching to the 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital d} {sup 2}{ital D} term, which was observed already in the earlier investigation of Ar{sup 6+}, has been removed by including correlation in the {ital n}=2 shell in addition to the correlation in the {ital n}=3 shell, which was the only correlation introduced previously.« less

Ejected electron spectra from the doubly-excited helium-like ions produced by the double electron capture collisions of bare ions B5+ and C6+ with He have been measured using zero-degree Auger electron spectroscopy with a high energy resolution. Electrons from the configuration of (2lnl') have been observed for n>or=2 in B5+-He collisions and n>or=3 in C6+-He collisions. Experimental energy values of ejected electrons from the (2l2l') and (2l3l') states of B3+ ions and the (2l3l') states of C4+ ions are determined by comparing the observed spectra with the theoretical calculations. Spectral features have also been observed at different collision energies. The population mechanisms to those states are briefly discussed.

The presence of the magnetic quadrupole term in addition to the electric dipole one in the multipole expansion of the radiation field is reflected in the angular distribution of the X-ray transition. To extend the previous works the authors studied the angular distribution of different L3 X-ray lines of Ba, Sm and Er experimentally for proton impact at 0.23, 0.28 and 0.35 MeV bombarding energies respectively, using a Si(Li) detector. The anisotropy parameter ratios of the Ll and L alpha transitions were found to be 5.2+or-2.8, 5.5+or-0.7 and 6.9+or-1.5. Angular distributions of Tb L-shell X-rays were also measured by a high resolution crystal spectrometer for 0.556 MeV amu-1 nitrogen ions, a value of 3.5+or-2.5 was obtained for the anisotropy parameter ratio. These ratios deviate significantly from the theoretical ones.

Singly excited states of sodiumlike argon and sulfur have been investigated by means of high-resolution 0{degree} Auger spectroscopy at high projectile energies. The Auger-electron spectrum is due to the decay of states populated by monopole, dipole, and quadrupole excitation of the 2{ital p} and 2{ital s} electrons. Collision strengths calculated by means of the configuration-interaction Hartree-Fock program by Cowan ({ital The} {ital Theory} {ital of} {ital Atomic} {ital Structure} {ital and} {ital Spectra} (University of California Press, Berkeley, 1981)) in the plane-wave Born approximation (PWBA) have been used to describe the relative intensities found in the measured spectrum. The intensities due to monopole excitation are significantly higher than the prediction by PWBA for a Coulomb perturbation potential. The structure of the emitted electron spectrum is found to be significantly influenced by the configuration interaction.

The angular distribution of Ti K X-rays and Sn L X-rays and their satellites due to 6 MeV/nucleon N-ion impact have been measured using an Si(Li) detector and an X-ray crystal spectrometer. The X-rays are observed to be isotropic.

Zero-degree electron spectra were measured with high resolution for 64 MeV S5+ ions on He and 64 MeV S12+ ions on He and C, and for 90 MeV Sc8+ ions on He. In 64 MeV S ion collisions, a series of intense lines have been observed, which are attributed to the Auger transitions from 1s22s22p53snl to 1s22s22p6 for S5+ ions on He, and to the Coster-Kronig transitions from 1 s 2 2 p nl to 1 s 2 2 s ϵ l l′ for S12+ ions on He or C foils. The angular-momentum (l) distribution of the S12+ ions in the Rydberg state with n = 9 has been obtained and it is found that the high-l components are significantly enhanced for the solid target. In 90 MeV Sc8+ +He collisions, three groups of intense lines have been observed, which are attributed to the transitions from 1s22s22p53s23p to 1s22s22p63s, 1s22s22p63p, and 1s22s22p63d. The last transition, in which three electrons are involved via electron correlation, is studied and compared with previous results for the isoelectronic ions Al+ and Ar6+.

Current models describing the ionic charge states in solids have been reconsidered by noticing the shell effect of ionic charge distributions observed behind a solid target. For this purpose, the source of the shell effect has been investigated by performing Monte Carlo calculations. As a result, the shell effect, which originated inside the foil, has been found to be preserved outside the foil, which leads to the argument that the post-foil Auger electron emission plays only a minor role in the explanation of the difference of heavy ion mean charges between solid and gaseous media. It is concluded that the Betz-Grodzins (BG) model representing the density effect of ionic charge states is not adequate for most of the collisions.

Ejected electrons from doubly-excited helium-like carbon ions, produced by 67 keV C6++He collisions, were measured with high resolution zero-degree electron spectroscopy. Electrons from the configuration of 2lnl' (n>or=3) were observed in a wide energy range. Ejected electron energies from the 2l3l' configuration were determined and compared with theoretical calculations.

Electrons emitted from projectile ions were measured with high resolution in collisions of 64 MeV S 12+ ions with He atoms and C foils by 0° electron spectroscopy. A series of intense lines have been observed, which are attributed to the Coster-Kronig transitions of 1s 2 2p nl -1s 2 2sϵ l' with n = 9 to 19. The angular-momentum ( l ) distribution of ions in the autoionizing states of n = 9 has been obtained and evidence for high l enhancement has been found in C-foil targets.

Photon–ion merged-beam apparatus using a compact ECR ion source and a high-brilliance light source has been designed for the study of photoabsorption processes of multiply charged ions. Photoion spectroscopy will be performed along isoelectronic, isonuclear and isoionic sequences. The main features of this apparatus are described.

The effects of columnar defects produced by swift heavy-ion irradiation on magnetic flux pinning were studied for the polycrystalline La1.85Sr0.15CuO4. The bulk specimens were irradiated with 3.5 GeV 136Xe31+ ions from a single direction or multi-directions in order to investigate the effects of columnar defect configuration. The magnetization hysteresis was measured with a super-conducting quantum interference device (SQUID) magnetometer, and the critical current density Jc and irreversibility line were observed. In the specimens irradiated from multi-directions, more enhancement of the critical current density and larger shifts of the irreversibility line to higher fields were observed than in the specimens irradiated from a single direction.

Projectile Kα satellite and hypersatellite X-ray yields are measured in collisions of Ar ions with energies of 43–95 MeV with solid targets, ZT = 6–74. These high resolution X-ray measurements are analyzed using a statistical model with theoretical fluorescence yields to obtain the average probability of ionization of 2s and 2p subshells. Comparison of the measured relative intensities of Kα satellites with the best theoretical fits are presented.

The total cross section of radiative electron capture to the K shell of bare Ar ions has been measured and the value of (1.7 ± 0.2) × 10−22 cm2 is obtained. The theoretical value from a formula by Bethe-Salpeter, 1.96 × 10−22 cm2, is about 15% larger than the present result.

By measuring photoion‐yield spectra for Sr2+ and Sr3+ from Sr+ ions in the ground state, we have determined relative photoionization cross section of Sr+ ions in the energy range from 135–210 eV. The 3d‐ionization of charge‐selected Sr+ ions by photon‐impact was studied for the first time. The yield‐spectrum for Sr2+ has no structure, while that for Sr3+ shows prominent discrete peaks around 140 eV. For the assignment of discrete lines observed, we used a multiconfiguration Dirac‐Fock calculation code. The calculation indicates very strong s−d mixing for the observed peaks. This is understood that after the creation of 3d‐hole, the orbital energy of 4d‐orbital almost coincides with that of 5s‐orbital due to the collapse of the wavefunction.

We have studied projectile K x-ray satellite yields in collisions between 50-MeV ${\mathrm{Ar}}^{\mathit{Q}+}$ ions (Q=4,6,11,12,13) and C foils with various thicknesses (2--100 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$). For foil thicknesses below about 10 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$, Q dependence of the yields has been observed, reflecting the nonimmediate L-shell equilibrium. For this region, it has been shown that the mean K-hole formation cross section also varies with the target thickness and Q. The variation has been attributed to the varying chance of K-to-L excitation with the increase or decrease of L holes in solid. The projectile charge fractions after passage through the target have also been measured for the foil-thickness region 2--20 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$ including the thicknesses for which charge-state equilibrium is not attained. By combining these data, the K-hole formation cross section specifying the number of L holes at the initial stage of a collision has been estimated. The results have been compared with theoretical predictions for cross sections of K-to-continuum ionization and K-to-L excitation.

Using a photon-ion merged-beam technique, we studied the photoionization of multiply charged Xeq+ (q = 1-3) ions in the 4d excitation region (50-140 eV). Relative yield spectra of photoions created by single (q → q + 1) and double (q → q + 2) photoionization were measured as a function of photon energy. A broad "4d giant resonance" peak with some preceding discrete peaks appears in each total ion spectrum. The intensities of discrete peaks observed at around 4d ionization threshold strongly depend on the target charge state. Those for Xe3+ target are very strong, whereas those for Xe+ are weak. Peaks due to 4d → 5p transition, which cannot occur in the neutral Xe case, has also been observed for each ion-target. The experimental spectrum for Xe+ has been analyzed by a multiconfiguration Dirac-Fock calculation. This calculation shows that results observed may be explained in terms of the correlation of valence and excited orbitals, and the effect of 4f-orbital collapse, of which the degree varies strongly with the change of the effective nuclear charge.

A four-body classical trajectory Monte Carlo method and a simple binary encounter model was applied in the study of K-shell vacancy production in N7+ and Ti collisions in the impact velocity range 12–30 a.u. The total cross sections of the single and double K-shell vacancy productions are calculated and the ratios between them are compared with experimental data. Independent electron approximations fail to reproduce the measured double/single vacancy production ratios.

A thin back-illuminated CCD based photon detector system has been installed on the Rowland circle of a 2.2 meter grazing incidence spectrometer, replacing the previously used Ceratron single channel detector. For reasons to be described the CCD chip surface was not angled tangential to the spectrometer Rowland circle. The spectrometer is used for beam-foil spectroscopy experiments at the RIKEN laboratory. The performance of the CCD was tested using a beam of 183 MeV Nb ions.

Energy spectra of radiative electron capture (REC) X-rays have been studied for 110 MeV Ne ion bombardment on gaseous targets of H2, He, CH4, N2, O2 and Ne. A Si(Li) detector placed at 90 degrees to the beam direction was used for the measurements. The width and peak energy of the REC peak are compared with the impulse approximation calculation and fair agreement is obtained. The REC X-ray yield and the peak energy have been measured for the H2 target as a function of the gas pressure and the results are discussed in relation to the charge equilibration process of the ions in the gas.

The stopping powers of Ni, Ag, Au, and Pb for approx.7-MeV/N (where N means nucleon) C ions and ..cap alpha.. particles have been measured. For the 7.00-MeV/N C ion, the stopping powers of Ni, Ag, Au, and Pb are found to be 1.353 +- 0.016, 1.080 +- 0.010, 0.832 +- 0.006, and 0.825 +- 0.006 MeV/mg cm/sup 2/, respectively. From these results, the Z/sub 1//sup 3/ deviation from the Bethe-Bloch formula is evaluated comparing with our experimental stopping power for ..cap alpha.. particles. In the course of analysis we employed appropriate effective-charge corrections. Pierce and Blann's effective-charge correction, e.g., gives a reasonable value (1.38) of the b which appears in the Ritchie-Brandt theory, if a chi value of 1.29 in their theory is assumed.

Energy distributions of electrons ejected in Ar3++Ar collisions were measured at collision energies of 4.3 and 6.6 MeV. The L-MM Auger peaks from the targets were distributed through 100 to 200 eV. The isolated peaks located at about 101 eV were observed for the first time; they were attributed to the L23-M1M2 Auger electrons from the target Ar ions which have six vacancies in the M23 shell.

Beam-foil experiments were carried out in RILAC(RIKEN heavy ion linear accelerator). Decay curves of Al X 2s21S-2s2p 1P and cascade transitions were measured and the lifetime of 2s2p1P was obtained by the ANDC method, taking into account the cascade transitions. The resulting lifetime is 0.192 ± 0.015 ns. Also, a transition array of Al X 2p3d-2p4f was identified by comparing an experimental spectrum with a theoretically calculated one, and the Slater integrals and parameters of configuration interactions were determined.

High resolution measurements are made for K α and K β X-rays from 33 MeV Ar ions passing through various foil targets. The average L-vacancy fraction at the K α X-ray emission, the intensity ratio of the K α hypersatellites relative to the K α satellites and that of K β satellites relative to the K α ones are obtained as a function of the atomic number of the targets, Z 2 . All of them show an oscillatory dependence on Z 2 and discussions are made about this dependence by comparison with the previous work, particularly with the results of Watson et al. for 64 MeV S ions.