TheK-conversion coefficient of the 321 keVE1 transition in Hf177

TheK-conversion coefficient of the 321 keVE1 transition in Hf¹⁷⁷ has been measured by means of an iron free double focusing beta-ray spectrometer, using the internalexternal conversion method. The result obtained for α _K (321)=0.162±0.016 is in disagreement with the theoretical values for pureE1 transition (α _K =0.0154) calculated bySliv andBand. The large anomaly observed in theK-conversion process of the inhibitedE1 transition is compatible with a largeM2 admixture or, more probable with the presence of penetration matrix elements.     

Signature splitting in two quasiparticle rotational bands of <Superscript>180,182</Superscript>Ta

The signature splittings in K^π = 1 ⁺: 7 /2[404] _π?9 /2[624] _ν, K^π = 0^?: 9 /2[514] _π?9 /2[624] _ν bands of ¹⁸⁰Ta and K^π = 0^?: 7 /2[404] _π?7 /2[503] _ν, K^π = 1^?: 5 /2[402] _π?3 /2[512] _ν, K^π = 1⁺: 7 /2[404] _π?9 /2[624] _ν bands of ¹⁸²Ta are analysed within the framework of two-quasiparticle rotor model. The phase as well as magnitude of the experimentally observed signature splitting in K^π = 1⁺ band of ¹⁸⁰Ta, which could not be explained in earlier calculations, is successfully reproduced. The conflict regarding placement of a 12 ⁺ level in K^π = 1 ⁺: 7 /2 ⁺[404] _π?9 /2 ⁺[624] _ν ground-state rotational band of ¹⁸⁰Ta is resolved and tentative nature of K^π = 0^?: 7 /2[404] _π?7 /2[503] _ν, K^π = 1⁺: 7 /2[404] _π?9 /2[624] _ν bands observed in ¹⁸²Ta is confirmed. As a future prediction for experimentalists, these two-quasiparticle structures observed in ¹⁸⁰Ta and ¹⁸²Ta are extended to higher spins.     

Kinetic freeze-out s pectra of identified particles produced in p–Pb collisions at $$\sqrt {s_{NN} }$$ = 5.02 TeV

We study the transverse momentum spectra of identified pions (π^– + π⁺), kaons ((K ^– + K ⁺), K ₀ ^s ), protons (p + p?) and lambda hyperons (Λ + Λ?) produced at mid-rapidity (0 < y _cm < 0.5) in most central (0?5)% p–Pb collisions at \(\sqrt {s_{NN} }\) = 5.02 TeV in comparison with a Unified Statistical Thermal Freeze-out Model (USTFM). The measurements for pions are reported upto p _T = 3 GeV, the kaons (K ^– + K ⁺) are reported upto p _T = 2.5 GeV, K ₀ ^s is reported upto p _T = 7 GeV, and the baryons (protons and lambda hyperons) are reported upto p _T = 3.5 GeV. A good agreement is seen between the calculated results and the experimental data points taken from the ALICE experiment. The transverse momentum spectra are found to be flatter for heavy particles than for light particles. Bulk freeze-out properties in terms of kinetic freeze-out temperature and the transverse collective flow velocity are extracted from the fits of the transverse momentum spectra of these hadrons. The effect of resonance decay contributions has also been taken care of.     

On the correlation between supercooling,superheating and kinetic arrest in a magnetic glass Pr<Subscript>0.5</Subscript>Ca<Subscript>0.5</Subscript>Mn<Subscript>0.975</Subscript>Al<Subscript>0.025</Subscript>O<Subscript>3</Subscript>

We report a quantitative investigation of the magnetic field-temperature phase diagram by taking into account a simple phenomenological model arising out of the interplay of kinetic arrest and thermodynamic transitions in a magnetic glass Pr_0.5Ca_0.5Mn_0.975Al_0.025O₃, through magnetization measurements. Such studies are necessary as kinetic arrest plays an important role in the formation of “magnetic glasses”, which has been observed in systems undergoing first order magnetic phase transitions. It has been shown that disorder in a system results in the formation kinetic arrest (H _K ,T _K ) band, like supercooling (H ^*,T ^*) and superheating (H ^**,T ^**) band. Quantitative proofs are given to show that (H _K ,T _K ) band is anticorrelated with (H ^*,T ^*) and (H ^**,T ^**) bands, while the later two are correlated among themselves. Analysis of time dependence of magnetization at different temperatures is carried out to establish the fact that the kinetic arrested state is different from the supercooled state.     

Effect of vibronically induced spin-orbit coupling of electronic ππ* states on nonradiative intersystem crossing: Naphthalene

The effect of (I) S ₁(¹ B _2u ) ? T ₁(³ B _1u ) and (II) S ₁ ? T ₂ (³ B _3g ) ? T ₁ transitions in naphthalene on the rate constant K _ST ^s of the S ₁ ? T ₁ nonradiative transitions to all triplet sublevels s = z, y, x of the T ₁ state has been investigated in the approximation of vibronically induced spin-orbit couplings, taking into account all out-of-plane vibrational modes. The shapes of the vibrational modes that are most active in these transitions are determined. The calculated values K _ST = (0.33–0.75) × 10⁷ s^?1, obtained with allowance for the I and I + II transitions, are consistent with the experimental values (K _ST)_exp found by different researchers. It is established in all calculation versions that K _ST > K _ST ^z > k _ST ^x . This relation is in qualitative agreement with the known magnetooptical data.     

Stochastic model of angular distributions of fragments originating from the fission of excited compound nuclei

The anisotropy of angular distributions of fission fragments and the average multiplicity of prescission neutrons were calculated within a stochastic approach to fission dynamics on the basis of three-dimensional Langevin equations. This approach was combined with a Monte Carlo algorithm for the degree of freedom K (projection of the total angular momentum I onto the fission axis). The relaxation time τ _K in the coordinate K was considered as a free parameter of the model; it was estimated on the basis of a fit to experimental data on the anisotropy of angular distributions. Specifically, the relaxation time τ _K was estimated at 2 × 10^?21 s for the compound nuclei ²²⁴Th and ²²⁵Pa and at 4 × 10^?21 s for the heavier nuclei ²⁴⁸Cf, ²⁵⁴Fm, and ²⁶⁴Rf. The potential energy was calculated on the basis of the liquid-drop model with allowance for finiteness of the range of nuclear forces and for the diffuseness of the nuclear surface. A modified one-body viscosity mechanism featuring a coefficient k _s that takes into account the reduction of the contribution from the wall formula was used to describe collective-energy dissipation. The coefficient k _s was also treated as a free parameter and was estimated at 0.5 on the basis of a fit to experimental data on the average prescission multiplicity of neutrons.     

Band interaction in <Superscript>162</Superscript>Dy, <Superscript>168</Superscript>Er,and <Superscript>172</Superscript>Yb

Coriolis interaction between levels of two rotational bands in ¹⁷²Yb with K ^π = 2⁺ and 3⁺ and in ¹⁶⁸Er between levels with K ^π = 0^?, 1^?, and 2^? is studied. The values of the interaction parameters are obtained. The mutual influence of two bands in ¹⁶²Dy with ΔK = 2, K _i ^π = 0 ₂ ⁺ and 2 ₁ ⁺ due to Coriolis interaction is demonstrated.     

Die absolute Intensität der durch Elektronenstoß in einer dicken Cu-Antikathode erzeugtenKα-Strahlung

The numberN _Kα ^dir (produced) ofKα-photons produced by electron-bombardment in a thick target of copper per incident electron has been measured absolutely with the Ross-filter method and relatively with the crystal-spectrometer method in the energy-region up to the four times theK-ionization energyE _K . The result can be presented in the following empirical form:N _Kα ^dir (produced) = 4π·

     

Bond-breaking excitations with diverging coupling matrix of response density functional theory from highest-level functionals

Bond-breaking excitations ω _α are the problematic case of adiabatic time-dependent density functional theory (TDDFT). The calculated ω _α erroneously vanishes with the bond elongation, since the Hartree-exchange-correlation kernel and the corresponding response coupling matrix K of standard approximations lack the characteristic divergence in the dissociation limit. In this paper an approximation for K is proposed constructed from the highest-level functionals, in which both occupied and virtual Kohn-Sham orbitals participate with the weights w _p . The latter provide the correct divergence of K in the limit of dissociating two-electron bond. The present K brings a decisive contribution to the energy of the ¹Σ _u ⁺ in the prototype H₂ molecule calculated for various H-H separations. At shorter separations it improves ω _α compared to the zero-order TDDFT estimate, while at the largest separation it reproduces near-saturation of the reference excitation energy.     

Suche nach Zweiquantenprozessen beim Zerfall von Xe131m

The decay of Xe^131m was investigated in order to detect nuclear double decay processes, in which the transition energy is distributed either between twoγ-quanta or between oneγ-quantum and oneK-conversion electron or between twoK-conversion electrons. By analyzing the emittedγ-radiation in a two-dimensional way an upper limit of 2.2 · 10^?5 was derived for the ratio of theγγ- toγ-transition probability. An investigation of theγ-spectrum in coincidence withK-quanta yielded an upper limit of 3 · 10^?2 for the rate ofe _Kγ-transitions relative toγ-transitions. The simultaneous emission of twoK-quanta was actually observed. These doubleK-quanta result either from the doubleK-conversion that was sought or from the internal conversion of the internal Compton-effect. For the doubleK-electron emission toγ-emission probability a value of (3.6±0.7) · 10^?3 was obtained. TheK-conversion coefficient and the half-life of Xe^131m were measured to be 32.1±0.4 and 11.94±0.04 d, respectively.     

Absorptive corrections to associated production of strange baryon and meson resonances in πp scattering

Absorptive corrections are calculated for the reactionsπ ⁺ p→K ^*+∑⁺(K ^*+ Y ₁ ^*+ ) mediated byK-exchange andπ ⁺p→K⁺ Y ₁ ^*+ withK ^*-exchange. The effect of the finite width of the resonances is included. Numerical results are given for 5 and 8 GeV/c.     

Production of exotic Λ hypernuclei via mesonic beams

We study the production of neutron-rich hypernuclei _Λ ¹² Be, _Λ ¹⁶ C, and _Λ ¹⁰ Li by the (π^?, K⁺) and (K^?, π⁺) reactions in flight and treat two different mechanisms of production. The first mechanism is a two-step process with meson charge exchange (e.g., π^?p → π⁰n, π⁰p → K⁺Λ). The other mechanism is one-step production (π^?p → K⁺Σ^?) proceeding via a small Σ^? component, arising in Λ hypernuclei due to ΛN–ΣN coupling, as a doorway state. Typically, the two-step mechanism is more productive. The forward differential cross section of the ¹⁰B(π^?,K⁺) reaction is about 70 nb/sr at an incident momentum of 1.05 GeV/c. On the other hand, the one-step process can serve as a direct measurement of the Σ admixture if the two-step contribution is suppressed by a suitable choice of the reaction kinematics.     

Dasβ-Spektrum des Cs137

Theβ-ray spectrum of Cs¹³⁷ has been measured with an iron-free spectrometer. The energy of the soft component was found to beE ₀=514±2 keV. The parameterk of the hard-component shape factorC _2VA ⁽²⁾ (W)=q ²+kp ² was determined to bek=0.015±0.004. Theβ intensities amount to 6.5% (hard component) and 93.5% (soft component). TheK conversion coefficient of the isomeric transition was measured to beα _K=0.093±0.003, in excellent agreement withSliv's theoretical value.     

Effects of Final State Interactions in Pure Annihilation Decay of B+ → D+K0*

The decay of the B ⁺ meson to the D ⁺ and K ⁰* mesons is a pure annihilation decay. For this reason, in the framework of the quantum chromodynamics factorization (QCDF) approach, this decay has a small amplitude and a small branching ratio. In this research we find that, before the D ⁺ and K ⁰* mesons are produced in the final states, pair mesons such as D _s ⁺* and D _s ⁺ρ⁰ are produced. The intermediate-state mesons via the exchange of K ⁰(K ⁰*) and D ⁺(D ⁺*) go to the D ⁺ and K ⁰* final state mesons. However we calculate the B ₊ → D ⁺ K ⁰* decay in two different frameworks. The first framework is the QCDF method and the second one is final state interaction (FSI). The experimental branching ratio of B ₊ → D ₊ K ⁰* decay is less than 3 × 10^–6, and our results obtained by the QCDF method and FSI are (0.35 ± 0.04) × 10^–6 and (2.94 ± 0.10) × 10^–6, respectively.     

Radiative decays at LHCb

Precise measurements on rare radiative B decays are performed with the LHCb experiment at LHC. The LHCb results regarding the ratio of branching fractions for two radiative decays, B ⁰ → K ^*0 γ and B _s → ?γ, the direct CP asymmetry in B ⁰ → K ^*0 γ decay channel and the observation of the photon polarization in the B ^± → K ^±π^?π^± γ decay, are included. The first two measurements were performed in 1 fb^–1 of pp collisions data and the third one in 3 fb^–1 of data, respectively.     

Searching for signatures around 1920 MeV of a N<Superscript>*</Superscript> state of three hadron nature

We provide a series of arguments which support the idea that the peak seen in the \( \gamma\) p \( \rightarrow\) K ⁺ \( \Lambda\) reaction around 1920MeV should correspond to the recently predicted state of J ^P = 1/2⁺ as a bound state of K \( \bar{{K}}\) N with a mixture of a ₀(980)N and f ₀(980)N components. At the same time we propose polarization experiments in that reaction as a further test of the prediction, as well as a study of the total cross-section for \( \gamma\) p \( \rightarrow\) K ⁺ K ^- p at energies close to threshold and of dσ/dM _inv for invariant masses close to the two-kaon threshold.     

Niederenergetische Gammalinien vom Neutroneneinfang in Lu 175 und Lu 176

The low energy gamma-rays from neutron-capture in Lu 175 and Lu 176 have been investigated by means of the bent crystal-spectrometer at the DR-3-reactor at Risø. From the transitions in Lu 177 3 rotational bands have been determined. The levels of the (404)K=7/2⁺ groundstate rotational band are: 121,62 keV (I=9/2), 268,79keV (I=11/2), 440,66 keV (I=13/2), 636,22 keV (I=15/2), 854,34 keV (I=17/2). The level-sequence of the (514)K=9/2^?-band is: 150,39 keV (I=9/2), 288,99 keV (I=11/2), 451,49 keV (I=13/2), 637,05 keV (I=15/2) and 844,88 keV (I=17/2). At 457,92 keV is the basis for the (402)K=5/2⁺-band the higher levels of which are 552,05 keV (I=7/2), 671,89 keV (I=9/2), 816,63 keV (I=11/2), 985,23 keV (I=13/2), 1176,73keV (I=15/2) and probably 1389,5 keV (I=17/2). The energies of the levels apart from the 1389 keV-level have an accuracy of 7×10^?5. The energy differences between the 3 bands agree very well with the values expected from the Bohr-Mottelson-formulaE=A·I(I+1)+B·I ²(I+1)². The calculated branching-ratios within the 3 bands are in fairly good agreement with the experimental values. Theg _K -factors have been determined for 2 bands: It was found that for the (514)-bandg _K =1,16±0,04 and for the (402)-bandg _K =1,33±0,07.     

Electric quadrupole moments of light nuclei and transition probabilities for them in the multiquantum approximation of the orthogonal scheme

A method for calculating electric quadrupole moments of light nuclei and probabilities of electric quadrupole transitions in them in the multiquantum approximation of the orthogonal scheme is proposed. Specific calculations of these quantities are performed for the ₄ ⁸ Be nucleus with allowance for all U(3(A ? 1)) states characterized by the λ = [44] Young diagram, the quantum numbers K _min and K _min + 2 of the O(3A ? 1)) group, and the number E = K + 2N (N = 0, 1, …, 9) of oscillator quanta. It is shown that an extension of the basis from the E = K _min to the E = K _min + 2 approximation leads to an increase of 15 to 45% in the electric quadrupole moments and to an increase in the transition probabilities B(E2) by a factor of 1.6 to 2.8. The inclusion of E = K + 2N (N = 0, 1, …), states involving multiquantum excitations (ρ excitations) increases additionally the results by 10 to 30%. The results of these calculations are compared with their counterparts obtained in the multiquantum approximation of the unitary scheme.     

Nonradiative <Emphasis Type="Italic">S-T</Emphasis> intersystem crossing in α and β chlorine derivatives of naphthalene

The rate constants K _ST ^s of nonradiative S ₁ ? T ₁ ^s transitions to triplet sublevels s in molecules of chlorine derivatives of naphthalene (1,4-dichloro- and monosubstituted α-chloro- and β-chloronaphthalene) have been calculated within the model of vibronically induced spin-orbit (VISO) couplings. The contribution of the spin-orbit couplings in Cl atoms and carbon framework of the molecule to VISO couplings is determined. A dependence of the heavy-atom effect on the constant K _ST ^s in relation to the type of sublevel T ^s and α and β positions of chlorine in the molecule is established and explained.     

Bestimmung der Kerndipolmomente von171Yb und173Yb durch optisches Pumpen

The nuclear Zeeman levels of the odd isotopes of Ytterbium (¹⁷¹Yb,¹⁷¹ I=1/2;¹⁷³Yb,¹⁷³ I=5/2) were polarized in the atomic ground state (6s ^{2 1} S ₀) by means of optical pumping with the resonance line (6s ^{2 1} S ₀ ? 6s6p ¹ P ₁,λ=3988 å). The magnetic moments, calculated from the nuclear Hf-Zeeman transitions in a magnetic field of 228 Gauss are¹⁷¹ Μ _I=0.49188 (2)Μ _K ¹⁷³ Μ _I=0,67755 (3)Μ _K (with diamagnetic correction applied).