High resolution studies of transitions in the decay chain146Gd to146Eu to146Sm

Transitions in¹⁴⁶Eu and¹⁴⁶Sm were studied using a double-focussing beta-ray spectrometer and a Ge(Li) detector. Internal conversion and gamma-ray intensities were determined. The internal conversion spectrum of the three 155, 115 and 116 keV cascading transitions in¹⁴⁶Eu was studied for all subshells.K-,L- andM-subshell ratios were determined andE2/M1 mixing ratios were deduced for these three transitions. Intensities from theN- andO+P-shells were determined and compared to theoretical calculations. All internal conversion intensities were found to be in agreement with theoretical data for pureM1 character with smallE2 admixtures for all the three transitions. Selected parts of the internal conversion spectrum of the transitions in¹⁴⁶Sm were restudied at 0.06% momentum resolution. This study was mainly concentrated on four transition doublets feeding and deexciting the close lying levels at 1,380 and 1,381 keV. A new transition with 702.20 keV energy was detected in the 702–703 keV transition group. Internal conversion coefficients were deduced using reported gamma-ray intensities. Multipole characters of the transitions were deduced and used as a basis for a discussion of the spins and parities of the lower lying excited states of¹⁴⁶Sm.     

Internal conversion coefficients of the transitions in Tm169

The conversion electron spectrum of Tm¹⁶⁹ has been measured by an iron-yoke double focusing spectrometer. Gamma-ray energies and gamma-ray intensities were measured by a bent crystal spectrometer. Conversion coefficients and conversion ratios were determined from the electron and gamma intensities. The conversion process of the retardedM 1 transitions of 177 keV and 198 keV was found to be normal, in agreement with our earlier directional correlation results. No penetration effects were found in the conversion process of the retarded 63 keVE1 transition.     

Study of Er171 decay by means of an electron-gamma coincidence technique

The decay scheme of Er¹⁷¹ (7.8 h) has been reinvestigated by means of an electron-gamma coincidence spectrometer and a scintillation spectrometer with a transistorized RIDL-400 channel analyser. A careful unfolding of the high energy region of the gamma-ray spectrum revealed the presence of photopeaks at energies of approximately 371, 404, 543, 572, 618, 675, 738, 796, 869, 910 and 962 keV. The existence of 32 transitions in Tm¹⁷¹ was confirmed. Also, it is proved that the 277, 362 keV transitions are in coincidence with the 210 keV and that the 175 keV transition is in coincidence with the 86 keV transition. We revealed the doubt for the existence of the 166, 210, 236, 277 and 419 keV transitions. From coincidence and single counting rates the followingK-conversion coefficients of the 111, 116, 124, 296 and 308 keV transitions were determined to be: α _K (111)=1.561±0.062, α _K (116)=0.699±0.035, α _K (124)=0.608±0.024, α _K (296)=0.0197±0.0010, α _K (308)=0.0183±0.0009, which give the 116, 124 keV transitions an electric quadrupole character; the 111 keV transition a magnetic dipole character withE2/M1 equal 0.4528; and the 296, 308 keV transitions an electric dipole character withM2/E1 equal 0.0058 and 0.0071 respectively.     

Energie- und Intensitätsmessungen an Konversionselektronen des Zerfalls75Se→75As

Energies and intensities of conversion lines of elevenγ transitions in the decay⁷⁵Se→⁷⁵As were measured with the Heidelberg (π/2)√13β-ray spectrometer. The experimental transition energies agree with the results of crystal diffraction spectrometer measurements; in some cases more precise values were obtained. The measured relativeK electron intensities for five transitions are in agreement with previous experiments. TheL group of the 97 keV transition was resolved for the first time and the multipolarity was determined to beE2 from theL subshell ratios.     

Levels in 156Gd studied in the (n, γ) reaction

Levels up to 2.3 MeV in ¹⁵⁶Gd have been studied using the (n, γ) reaction. Energies and intensities of low-energy γ-rays and electrons emitted after thermal neutron capture have been measured with a curved-crystal spectrometer, Ge(Li) detectors and a magnetic electron spectrometer. High-energy (primary) γ-rays and electrons have been measured with Ge(Li) detectors and a magnetic spectrometer. The high-energy γ-ray spectrum has also been measured in thermal neutron capture in 2 keV resonance neutron capture. The neutron separation energy in ¹⁵⁶Gd was measured as S_n = 8535.8 ± 0.5 keV.About 600 transitions were observed of which ~50% could be placed in a level scheme containing more than 50 levels up to 2.3 MeV excitation energy. 42 of these levels were grouped into 15 excited bands. In addition to the β-band at 1050 keV we observe 0⁺ bands at 1168, 1715 and 1851 keV. Other positive-parity bands are: 1⁺ bands at 1966, 2027 and 2187 keV; 2⁺ bands at 1154 (γ-band) and 1828 keV; and 4⁺ bands at 1511 and 1861 keV. Negative-parity bands are observed at 1243 keV (1^?), 1366 keV (0^?), 1780 keV (2^?) and 2045 keV (4^?). Reduced E2 and E0 transition probabilities have been derived for many transitions. The ground band, the β- and γ-bands and the 0⁺ band at 1168 keV have been included in a phenomenological four-band mixing calculation, which reproduces well the experimental energies and E2 transition probabilities.The lowest three negative-parity (octupole) bands of which the 0^? and the 1^? bands are very strongly mixed, were included in a Coriolis-coupling analysis, which reproduces well the observed energies. The E1 transition probabilities to the ground band are also well reproduced, while those from the higher-lying 0⁺ bands to the octupole bands are not reproduced. Absolute and relative transition probabilities have been compared with predictions of the IBA model and the pairingplus-quadrupole model. Both models reproduce well the E2 transitions from the γ-band, while strong disagreements are found for the E2 transitions from the β-band. The IBA model predicts part of the decay features of the higher lying 2⁺₂, 4⁺₁ and 2^?₁ bands.     

Radioactive decay of Os191 and Os191m

Beta and gamma spectra of Os¹⁹¹ were studied using a magnetic double-focusing beta-spectrometer and a scintillation spectrometer. The isomeric state Os^191m decays through the 74·4 ± 0·1 keV (E3/M4=50) transition with a half-lifeT _1/2=13·0 ± 0·5 hours. A continuous beta spectrum withE _max=147 ± 3 keV and the gamma transitions 41·83 ± 0·05 keV (E3), 82·5 ± 0·3 keV and 129·4 ± 0·1 keV (70%M1 + 30%E2) were observed in the decay of the ground state of Os¹⁹¹. The conversion coefficient of the last transition was determined as 1·94 ±± — 0·10. Gamma transitions with energies of 47 keV and 185·8 keV were not observed.     

The backscattering factor for the Au N67VV Auger transition

The Au N₆₇VV Auger transition may take place after direct ionization of the N₆₇ subshells or after ionization of the N₄₅ subshells followed by the Coster-Kronig transitions N₄₅N₆₇V. The subshells N₆₇ and N₄₅ have much different ionization energies, by a factor of four, and this creates a problem in quantification of the N₆₇VV signal. Calculations of the backscattering factor from the analytical expressions require knowledge of a single value of the ionization energy. Furthermore, a single value of the ionization energy is needed in calculations of the ionizations cross section. An attempt is made here to decide which ionization energy should be used in calculations by comparison of the experimental energy and emission angle dependence of the AES signal intensity with this dependence determined from theory using different ionization energies. It has been found that the N₆₇VV signal intensity is strongly dominated by ionizations of the N₅ subshell. Furthermore, the ionization cross section for the N₅ subshell is well described by the Casnati et al. formula.     

Radioactive decay of Ni65

The radioactive decay of Ni⁶⁵ was studied on a short-lens spectrometer and on a scintillation spectrometer with a two-hundred-channel amplitude analyzer. By means of a magnetic spectrometer 3 groups of the beta spectrum with energies of 2140±10 keV, 1020±25 keV and 650±30 keV with relative intensities of 58±5%, 11±3% and 30±5% were found. From gamma spectrum measurements the existence of another two beta transitions with energies of 520 keV and 420 keV follows. Seven transitions were found in the gamma spectrum: 370 keV (4·6%), 510 keV (0·37%), 610 keV (0·22%), 1115 keV (17%), 1480 keV (24%), 1620 keV (0·5) and 1720 keV (0·45%). Inasfar as there exist other gamma transitions, they are weaker than 0·03% at decay.     

Level structure of 42K from the 41(n, γ) and 41K(d,p) reactions

The γ-ray spectrum emitted after thermal neutron capture in ⁴¹K has been measured with pair and Ge(Li) spectrometers at the ILL high-flux reactor. About 630 transitions have been assigned to the decay of 133 excited states in ⁴²K. The level energies have been determined with a precison of 20 ppm; the neutron binding energy was determined to be E_B = 7533.82(15) keV. On the basis of the many transitions to known states, several spin-parity assignments have been made. In addition, high-resolution proton spectra of the reaction ⁴¹K(d,p) have been taken at 20MeV deuteron energy with the München Q3D spectrometer. These data have been essential in establishing the newly-found levels and in differentiating between primary and secondary transitions in the (n, γ) work. A statistical analysis of the level density and relative strengths of primary transitions is given.     

Levels and transitions in125Te

Gamma transitions and levels of¹²⁵Te following the decay of¹²⁵Sb have been studied using Ge(Li) detector and NaI(Tl)-NaI(Tl) sum-coincidence spectrometer incorporated with a fast-slow coincidence circuit. In all, twenty five gamma rays have been reported, out of which two weak gamma rays with energies 366·0 and 402·0 keV have been observed and confirmed for the first time. These gamma rays have been fitted by assigning a new level of 402 keV energy. An ambiguous transition of energy 122·1 keV has also been confirmed. No evidence was found for the existence of 145·9, 315·0, 489·8, and 497·4 keV transitions. The accurate intensities for various transitions have been determined.     

Temperature dependence of the band edge excitonic transitions ofa wurtzite-type Cd0.925Be0.075Se mixed crystal

We have performed a contactless electroreflectance (CER) study of the near band-edge interband transitions of a Bridgman-grown wurtzite-type Cd_0.925Be_0.075Se mixed crystal in the temperature range of 15–450 K. The transition energies and broadening function of the excitonic features are determined via a lineshape fit to the CER spectra. The parameters that describe the temperature dependence of the transition energies of excitons A and C, and the broadening function of the exciton A are evaluated and discussed.     

Internal conversion coefficients in the Hartree-Fock atomic model. Calculations and experiments for199Hg

The internal conversion coefficients were calculated for the transitions in¹⁹⁹Hg using both Hartree-Fock and Hartree-Fock-Slater atomic models. The relative conversion line intensities were measured with the magnetic spectrometers in Prague and Heidelberg. The multipolarities were determined to be:M1+(0.20±0.03)%E2, pure E2 and M 1+ (13.4 ±0.4)%E2 for the 50, 158 and 208 keV transitions, respectively. Allowing for the nuclear structure effect in M1 component we obtained: M1+(0.15±0.03) %E2,λ = 2.4±1.0 for the 50 keV and M1+ (10.9±0.7)% E2, λ=3.8±0.5 for the 208 keV transitions. Very good agreement was found between theory and experiment for the atomic subshells,K, L_1?3,M _1?5,N, andO + P.     

The electronic structures of the core and valence ion states of metal oxides

SCF-Xα SW MO calculations on metal core ion hole states and X-ray emission (XES) and X-ray photoelectron (XPS) transition states of the non- transition metal oxidic clusters MgO₆^10?, AlO₄^5? and SiO₄^4? show relative valence orbital energies to be virtually unaffected by the creation of valence orbital or metal core orbital holes. Accordingly, valence orbital energies derived from XPS and XES are directly comparable and may be correlated to generate empirical MO diagrams. In addition, charge relaxation about the metal core hole is small and valence orbital compositions are little changed in the core hole state. On the other hand, for the transition metal oxidic clusters FeO₆^10?, CrO₆^9? and TiO₆^8? relative valence orbital energies are sharply changed by a metal core orbital or crystal field orbital hole, the energy lowering of an orbital increasing with its degree of metal character. Consequently O 2p nonbonding → M 3d-O 2p antibonding (crystal field) energies are reduced, while M 3d bonding → O 2p nonbonding and M 3d-O 2p antibonding → M 4s,p-O 2p antibonding (conduction band) energies increase. Charge relaxation about the core hole is virtually complete in the transition metal oxides and substantial changes are observed in the composition of those valence orbitals with appreciable M 3d character. This change in composition is greater for e _g than for t_2g orbitals and increases as the separation of the e_g crystal field (CF) orbitals and the O 2p nonbonding orbital set decreases. Based on the hole state MO diagrams the higher energy XPS satellite in TiO₂ (at about 13 eV) is assigned to a valence → conduction band transition. The UV PES satellites at 8.2 eV in Cr₂O₃ and 9.3 eV in FeO are tentatively assigned to similar transitions to conduction band orbitals, although the closeness in energy of the crystal field and O 2p nonbonding orbitals in the valence orbital hole state prevents a definite assignment on energy criteria alone. However the calculations do clearly show that charge transfer transitions of the e_g bonding → e_g crystal field orbital type would generally occur at lower energy than is consistent with observed satellite structure.A core electron hole has little effect upon relative orbital energies and is only slightly neutralized by valence electron redistribution for MgO and SiO₂. For the transition metal oxides a core hole lowers the relative energies of M3d containing orbitals by large amounts, reducing O → M charge transfer and increasing M 3d crystal field → conduction band energies. Large and sometimes overcomplete neutralization of the core hole is observed, increasing from CrO₆^9? to FeO₆^10? to TiO₆^8?. as the O → M charge transfer energy declines.High energy XPS satellites in TiO₂ may be assigned to O 2p nonbonding → conduction band transitions while lower energy UV PES satellites in FeO and Cr₂O₃ arise from crystal field or O 2p nonbonding → conduction band excitations. Our “shake-up” assignment for FeO₆^10?, CrO₆^9? and TiO₆^8? are less than definitive because no procedure has yet been developed to calculate “shake-up” intensities resulting from transitions of the type described. However the results do allow a critical evaluation of earlier qualitative predictions of core and valence hole effects. First, we find that the comparison of hole or valence state ionic systems with equilibrium distance systems of higher nuclear and/or cation charge (e.g. the comparison of the FeO₆^10? Fe 2p core hole state to Co₃O₄) is dangerous. For example, larger MO distances in the ion states substantially reduce crystal field splittings. Second, core and CF orbital holes sharply reduce O → M charge transfer energies, giving 2e_g → 3e_g energy separations which are generally too small to match observed satellite energies. Third, highest occupied CF-conduction band energies are only about 4–5 eV in the ground states, but increase to about 7–11 eV in the core and valence hole states of the transition metal oxides studied. The energetic arguments presented thus support the idea of CF and/or O 2p nonbonding → conduction band excitations as assignments for “shake-up” satellites, at least in oxides of metals near the beginning of the transition series.     

Critical behavior of heat capacity in the vicinity of phase transitions in [NH2(CH3)2]5Cd3Cl11

The heat capacity of a [NH₂(CH₃)₂]₅Cd₃Cl₁₁ crystal was studied calorimetrically in the temperature interval 100–300 K. The C _p (T) dependence indicates that, as the temperature is lowered, phase transitions occur at temperatures T ₁ = 176.5 K and T ₂ = 123.5 K. The thermodynamic characteristics of this crystal were determined. It is shown that the transition at T ₂ = 123.5 K is an incommensurate-commensurate phase transformation and that the transition at T ₁ = 176.5 K is a normal-incommensurate phase transition.     

Measurements of a partial cross section for the reaction 58Ni(n, γ0)59Ni

The partial cross section for radiative neutron capture accompanied by gamma transitions to the ground state of the ⁵⁹Ni nucleus was measured as a function of energy by a new neutron-spectrometry method that employed the shift of a primary gamma transition in response to a change in the energy of the captured neutron. The reaction ⁷Li(p, n)⁷Be was used as source of neutrons for the present measurements. The protons that induced this reaction were accelerated by a Van de Graaff electrostatic generator to energies exceeding the reaction threshold by 60 keV, in which case an appropriate geometry of the experiment permitted irradiation of the sample under study with neutrons whose energy ranged between 10 and 120 keV. The partial widths of some resonances and radiative strength function for hard primary M1 gamma transitions were determined in addition to the above cross sections.     

Absolute X-ray yields of light muonic atoms

The intensities of X-rays from muonic atoms formed in low pressure Ne, O₂, N₂, He, and H₂ gas was measured. For the pressure chosen external electron refilling can be neglected. Absolute yields were extracted and compared to results of cascade calculations. Knowledge of the yields of the circular X-ray transitions allows an in situ efficiency calibration of X-ray detectors down to energies of 1.5 keV. This revised version was published online in August 2006 with corrections to the Cover Date.     

Gamma ray energies and 36Cl level scheme from the reaction 35Cl(n, γ)

The γ-ray spectrum emitted after thermal neutron capture in ³⁵Cl has been studied by use of the crystal and pair spectrometers installed at the ILL high flux reactor. We identified about 400 transitions in this reaction 326 of which were placed into the ³⁶C1 level scheme; several new states were found. The level energies up to 3.5 MeV were measured with a precision of 5–20 eV relative to the 412 keV ¹⁹⁸Au standard, those above 3.5 MeV with a precision of ¹⁰ppm. The neutron binding energy was determined to be E_B = 8579.68(9) keV.     

Energieniveaus und Gammaübergänge in Dy 164

The neutron capture Gamma ray spectrum of Dy 164 was measured with the curved crystal spectrometer at the DR-3 reactor at Risø. A level scheme was constructed from the energies (30 keV?1 MeV) and the intensities of the detected lines. The states obtained are: the groundstate rotational band with the levels at 73.392 (0.2+), 242.230 (0.4+), and 501.32 keV (0.6+), the Gamma vibrational levels 761.80 (2.2+), 828.19 (2.3 +), 915.98 (2.4+) and 1024.63 keV (2.5+) and a band withK=2?having the energies 976.88 (2.2?), 1039.30 (2.3-), 1122.76 (2.4?) and 1225.15 keV (2.5?). The precisely determined energies are compared with the collective model. The intensities of the transitions agree with the branching ratios expected from this model.     

Das Neutroneneinfangspektrum von Sm150

The internal conversion electrons and the gamma-rays emitted by Samarium after neutron capture were measured by means of a betaspectrometer and a bent-crystal spectrometer at the research reactor at Garching near Munich. Lines corresponding to 50 transitions between 59 keV and 1·7 MeV were found with the betaspectrometer. The measurement with the crystal spectrometer showed 11 lines between 250 keV and 740 keV. The multipolarity of a few lines was determined. A level scheme containing most of the measured lines is suggested.