Excitation of K X-Rays by bombardment of thick solid targets with 150 MeV Xe ions

The yield of K X-radiation arising from the interaction of ¹³⁶₅₄Xe ions with ₄₁Nb, ₄₂Mo, ₄₅Rh, ₄₆Pd, ₄₇Ag, ₄₈Cd, ₄₉In, ₅₀Sn, ₅₇La, ₆₄Gd, ₆₅Tb, ₇₀Yb, ₇₁Lu, ₇₃Ta, ₇₇Ir, ₇₈Pt, ₇₉Au and ₈₃Bi targets was measured using Si(Li) and Ge(Li) detectors. The dependence of the yield on the atomic number of the target material is discussed on the basis of the molecular orbital model.     

Quasimolecular KX-ray excitation by bombarding La targets with La and Xe ions

The X-ray emission from 85 to 150 MeV Xe and 115 MeV La bombardments of thick natural La targets has been measured. The spectra and yields of X-ray emission are obtained. Continuous X-ray distributions have been found to lie beyond the target and projectile characteristic X-ray energies. The high-energy parts of these continua are interpreted as K-radiation of quasi-molecules with effective atomic numbers Z = 111 and Z = 114, respectively.     

K X-ray transition energies for first row atoms and ions

X-ray energies are computed using screened, hydrogenic Slater integrals for all configurations [(1s^l2s^m2pⁿ) with l = 0 and 1, m = 0, 1, and 2, and n = 1 through Z-4] of all ionization stages of the elements boron through neon. The results include diagram lines, satellite lines, hypersatellite lines, and two-electron, one-photon lines. Excellent agreement is found between these results and those found by the Hartree-Fock-Slater method. In addition, X-ray energies associated with the spin-orbit forbidden decay of n = 2 three-electron quartet terms and four-electron quintet terms are calculated for the elements beryllium through neon. These results agree closely with those found by 1/Z perturbation theory.     

Giant-resonance excitation by 130 MeV 3He

Energy spectra of 130 MeV ³He scattered from ²⁴Mg, ⁹⁰Zr, ¹²⁰Sn and ²⁰⁸Pb have been measured. The spectra exhibit a pronounced giant resonance (GR) structure in the excitation energy region around $\text{E}{}_{\mathrm{<mtext>x</mtext>}}\text{≈ 63A}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>3</mtext>}}\text{MeV}$. The GR angular distributions as well as those corresponding to the first 2⁺ levels in ²⁴Mg and ¹²⁰Sn have been obtained for angles 7° ≦ θ_L ≦ 35°. Distorted wave calculations using the optical model parameters fitting the elastic data resulted in good fits to the 2⁺ levels. For ²⁴Mg, ⁹⁰Zr and ¹²⁰Sn the shapes of the GR angular distributions are well fitted by L = 2 curves alone. However, for ²⁰⁸Pb both L = 2 and L = 4 curves give fits of comparable quality.     

Nuclear excitation by electron transition in 189Os

A precise experiment on nuclear excitation by electron transition (NEET) was first performed on ¹⁸⁹Os. An osmium film was bombarded with electrons of 72–100 keV to measure the absolute values of the cross section for osmium isomer (^189mOs) production. The threshold energy for this process is 74 keV, and the cross section is, e.g., 1.1 nb at 100 keV. The NEET probability derived from the measured excitation function is (1.7 ± 0.2) × 10^?7     

Quasimolecular KX-ray excitation by bombarding As,Zr, Nb,Mo and Rh target with Nb ions

By bombarding various targets with 65 MeV and 40 MeV Nb ions continuous X-ray distributions have been obtained, which range up to the KX-ray energies of quasiatoms woth Z=Z₁+Z₂. The hogh-energy parts of these continua are interpreted as KX-radiation of quasimolecules transiently formed during the adiabatic heavy-ion atomic collisions.     

A new level at 192.5 keV in Ge

In the experiments on ⁷⁴Ge(d, pγ)⁷⁵Ge, a 52.5±0.1 keV γ-ray was found in ⁷⁵Ge with a half-life of 216±5 ns. From the analysis of the γ-ray spectra the conversion coefficient of the 52.5 keV γ-ray was determined. Then, a new level of is confirmed to exist at 192.5 keV. The reduced transition probabilities of the 52.5 keV transition are deduced to be (6.9^+5.6 _−2.1) × 10⁻⁵ for B(M1) and 31⁺³ ₋₂ for B(E2) in Weisskopf units.     

Nuclear excitation during atomic electron transitions

The nuclear excitation by electron transition (NEET) proposed by Morita is investigated. First a brief review of theory and experiment is given. A search is made for nuclear levels that can be excited by NEET for Z = l ～ 102 (A = l ～ 257), and some possible candidates are tabulated. The NEET probability P is evaluated for eight stable nuclei. In general P is found to be very small and its detection would be difficult, but future developments in experimental technique could make the detection possible. Two practical applications of NEET, isotope separation and γ-ray laseres, are briefly explained.     

A new measurement of the half-life of the Ge 0 state

With a Ge(Li) detector as the target, the half-life of the 0⁺ first excited state of ⁷²Ge has been remeasured. A value of 422±13 ns has been obtained.     

Evaporation residue excitation functions from fusion of 63Cu with 65Cu

Mass distributions of evaporation residues from the fusion of ⁶³Cu + ⁶⁵Cu have been measured at seven excitation energies from 55 to 105 MeV in a single irradiation experiment. They are interpreted as a mixture of residues produced by single nucleon evaporation cascades and cascades including α-particle evaporation. Compound nuclei with an average excitation energy of 55 MeV ($\text{51.5 ≦ E}{}^1\text{≦ 59}\text{MeV}$) are still found to have a probability as high as 0.3 % for decaying by emission of a single nucleon. The low-energy behaviour of the excitation function can be interpreted as a fusion barrier effect. The parameters of this barrier are determined. The evaporation residue cross section at higher energies is shown to be limited by the fission of the compound nucleus.     

Multiphoton ionization of atoms and ions by high-intensity X-ray lasers

Coulomb corrections to the action function and rate of multiphoton ionization of atoms and ions in a strong linearly polarized electromagnetic field are calculated for high values of the Keldysh adiabaticity parameter. The Coulomb corrections significantly increase the ionization rate for atoms (by several orders of magnitude). An interpolation formula proposed for ionization rate is valid for arbitrary values of the adiabaticity parameter. The high accuracy of the formula is confirmed by comparison with the results of numerical calculations. The general case of elliptic polarization of laser radiation is also considered.     

Beryllium double K X-ray emission by proton and helium ion bombardment

X-ray spectra from beryllium by proton and helium ion bombardment are studied. A clear peak due to double K-shell ionization is observed at 146.1 eV by helium ion bombardment. For proton bombardment, a peak of double K-shell ionization is not observable.     

On excitation and loss of an electron by incident ions in relativistic collisions with atoms

The excitation and loss of an electron by ions in relativistic collisions with atoms are studied in first-order perturbation theory. General expressions are obtained for the cross sections for the excitation and loss of an electron. In the limit of nonrelativistic collision velocities these expressions pass into the well-known nonrelativistic results. It is shown that, in contradistinction to the nonrelativistic collisions, in ultrarelativistic collisions the screening of the nucleus of the target atom by the atomic electrons is very important for excitation and loss of an electron by ions even for collisions of heavy ions with light atoms. Our computational results for the cross section for electron loss are in good agreement with existing experimental data.     

The elastic scattering of polarized 3He by 3He and excitation in the 6Be system

Angular distributions of the polarization in the elastic scattering of ³He by ³He have been measured at eight energies between 18 and 33 MeV, corresponding to excitation of ⁶Be between 20.5 and 28 MeV. The measurements were made using the 33 MeV polarised ³He beam at the University of Birmingham Radial Ridge cyclotron and a small gas target. The data have been analysed in terms of real and complex phase shifts. The deduced phase shift energy dependence cannot be associated with a single isolated level in ⁶Be, however an application of the two-level R-matrix formula reveals some broad L = 3 structures around E_x = 25 MeV.     

A study of low-lying states of 72As using the 72Ge(p,nγ)72As reaction

Several low-lying states of ⁷²As have been studied via the γ-rays following the bombardment of ⁷²Ge by protons in the energy range 5.1–6.2 MeV. Gamma-ray spectra were obtained using a Ge(Li) detector, and gamma-gamma coincidences between this detector and a NaI crystal were also investigated. Besides the single previously known excited state at 46 keV, 12 additional excited states were determined in ⁷²As at energies of 213, 242, 308, 317, 333, 343, 413, 438, 454, 512, 523 and (561) keV. The angular distributions of the γ-rays from the 213 and 242 keV levels have also been measured, and the results have been analyzed using the compound nucleus statistical model. The excited states at 213 and 242 keV were found to have spins of (2) and 3 respectively.     

Chemical effects on beryllium K X-ray spectra produced by heavy ion bombardment

Beryllium X-ray spectra from Be and BeO targets by proton, helium, nitrogen and argon ion bombardment have been measured. In the oxide, chemical shifts of K_α and K²_α X-ray lines are similar magnitude and the intense satellite KL and hypersatellite K²L lines are observed by heavy ion bombardment.     

Coulomb excitation of 182, 184, 186W and 166Er with 4He and 16O ions

The Coulomb excitation reaction induced by ⁴He ions selectively excites 2⁺ and 3^? states by direct E2 and E3 Coulomb excitation. In this paper, we present new results from γ-ray spectroscopy with 15 MeV ⁴He ions on a natural abundance target of W. In particular, a 3^? state in each isotope, ^{182, 184, 196}W, was observed by direct E3 excitation. In addition to obtaining B(Eλ, 0 → J = λ) for excitation of each state, information on the reduced transition probabilities for the different decay modes of these states is given. The Coulomb excitation probabilities of the 2'⁺ states at 786 keV in ¹⁶⁶Er and at 737 keV in ¹⁸⁶W were measured with ¹⁶O and ⁴He ions by the backscattered particle-gamma coincidence method in order to determine the static electric quadrupole moment Q_2'. We obtain for ¹⁶⁶Er Q_2' = 2.11 ± 0.37 e· b which is in agreement with (Q_2')_rot and for ¹⁸⁶W Q_2' = 1.17 ± 0.30 e · b which is in agreement with Kumar-Baranger model calculations and is significantly smaller than (Q_2')_rot. This deviation of the measured Q_2' from (Q_2'rot implies in the framework of the Kumar-Baranger calculations a strong coupling between β- and γ-vibrational bands. On the other hand, our observed upper limit for B(E2,2″ → 2′) does not confirm this implication.