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1.
The structure of negative-parity states in odd-mass N= 82 isotones (135 ≦ A ≦ 145) is investigated in the framework of a model which is based on coupling one 1h112 proton to π = + 1 states of the appropriate doubly-even isotonic core. It is shown that an effective model-space truncation can be achieved if only core states in the vicinity of the yrast line are taken into account. These have been selected from the several hundreds or even thousands of states obtained from shell-model calculations, where the 1g72, 2d52, 2d32 and 3s12 single- are assumed to be occupied. Spectroscopic data are calculated and predictions on the structure of low-lying π = ? 1 states are discussed and compared as far as possible to experimental findings. Thereby, the particle-core coupling approach is shown to be capable of describing essential properties of negative-parity levels in the N = 82 nuclei considered.  相似文献   

2.
Free energies g(m, ms) and f(m, q) of the spherical spin glass (SG) model due to Kosterlitz et al. are calculated explicitly as functions of the uniform magnetization m, and SG order parameter ms and the Edwards-Anderson order parameter q. It is shown that g(0, ms) and f(0, q) below the transition temperature Tg are constant in the ranges 0 ≦ msms0 and 0 ≦ qq0 respectively, where q0 = (1 -? TTg) = m2s0. The proper equilibrium values of ms( = ms0) and q( d=q0) are then fixed from the inspection of their behaviors under infinitesimal uniform field proproportional to N-a(a ≧ 0).  相似文献   

3.
The temperature coefficient of the CdxHg1?xTe energy gap dEg/dT as a sum of lattice dilatation and the phonon-electron interaction terms has been calculated as the function of molar composition x, for 0?x?0.3, in the temperature range 4.2–300 K. A non-linear dependence of dEgdT vs x and a strong effect of temperature on dEgdT values have been obtained and a comparison with experimental data is discussed.  相似文献   

4.
The absorption and MCD spectra of the 4A2g4T2g, 4A2g, 4A2g4T1ga and 4A2g4T1gb spin-allowed transitions of Cr3+ in K2NaGaF6 are reported. It is shown that transitions to the 4T1g. states are induced by T1u vibratio the other spin-allowed transition, 4A2g4T2g, there are three competing intensity mechanisms: electric dipole induced by T1u vibrations, electric dipole induced by T2u vibrations and magnetic dipole, and an estimate is made of the relative importance of these. The magnetic dipole 4A2g2Eg zero-phonon line is observed to be accompanied by a vibrational sideband for which the coupling is predominantly with T2u vibrations. Other weak transitions are observed in MCD spectra and their origin briefly discussed.  相似文献   

5.
Systematic ΔJ = 2 bands have been observed on the d52, g72 and h112 quasi-proton states in A = 117?127 odd-I nuclei. The ΔJ = 2 energy spacings decrease (relative to the Te cores) as A decreases for the h12 band but not for the others. Also ΔJ = 1 bands on unsually low-lying g92 proton-hole states exist.  相似文献   

6.
Experimental evidence using Josephson junction devices has suggested that Johnson noise in copper fails to be proportional to absolute temperature below 10 millikelvin. A microscopic theory is presented which gives the Johnson noise temperature TJ = ?01XT0 coth (XT0T) dX where T0 = F2kN. For copper, the calculated T0 = 3.84 mK agrees closely with the value extracted from experimental data, 3.89 mK. Within a few percent, TJ ? (T02) coth (T02T), and this adequately fits the available experimental data. νF is the fermi velocity and N is the length of the resistor. The Johnson noise parameter “T0” presumably can measure νF along different crystal orientations.  相似文献   

7.
In-beam measurements of nanosecond lifetimes applying the method of delayed γ-γ coincidences were performed in the (p, n) reaction. Analysing the time spectra with the centroid shift method, the following half-lives of excited nuclear states in the subnanosecond region could be found: T12(353.2 keV in161Ho) = 0.52±0.15 ns, T12(252.7 keV in161Ho) ≦ 0.2 ns, T12(579.4 keV in161Ho) ≦ 0.2 ns, T12(431.2 keV in163Ho) = 0.37±0.15 ns, T12(439.9 keV in163Ho) = 0.35±0.15 ns, T12(471.3 keV in163Ho) ? 0.2 ns, T12(612.8 keV in163Ho) ? 0.3 ns, T12(295.6 keV in171Lu) = 0.85±0.20 ns, T12(469.2 keV in171Lu) ≦ 0.2 ns, T12(357.0 keV in173Lu) = 0.40±0.08 ns and T12(449.0 keV in173Lu) = 0.58±0.12 ns. Following half-lives in 173Lu have been remeasured: T12(425.3 keV) = 0.84±0.20 ns and T12(434.9 keV) = 0.38±0.10 ns. Absolute γ-ray transition probabilities are deduced and compared with Nilsson model predictions including pairing correlations. Coriolis mixing calculations are performed for K-allowed as well as for K-forbidden transitions.  相似文献   

8.
The C33 constant is discontinuous for the lock-in transition at T1 = 169 K. The variation ΔT1 of the temperature of transition is a linear function of the applied electric field E and we find dT1dE=0.82 deg.cm kV?1.Above a mean field E = 10 kV cm?1 the transition observed for a first heating spreads on several degrees because damages appear in the incommensurate phase and the electric field becomes inhomogeneous.The results obtained at low fields are in very good accordance with the value of dT1dE calculated from the Clapeyron formula.Taking into account of the incommensurability of the phase above T1, it can be shown that
dT1dE = C2πPo33 ? 2
The knowledge of the spontaneous polarisation P0 gives for the Curie constant C = 2.1 × 103 K in qualitative agreement with the value deduced from measurements of the dielectric constant in the ferroelectric direction.  相似文献   

9.
It is shown that the thermal fluctuations depin the charge density wave of the Peierls Fröhlich state pinned by impurities at absolute zero temperature. The critical temperature, Td, of this depinning is estimated as Td = 0.55√m10 where m1 and γ0 are the mass of the collective mode and the pinning frequency at T = 0.  相似文献   

10.
We study the potentials of the form U(r)=?r?1+λV(r), (ddr)(r2dVdr)?0, and show that the energy levels satisfy the inequalities E(Nc, l)?E(Nc, l+1) to first order in λ, where Nc denotes the coulombic principal quantum number and l the angular momentum. Similarly for potentials U(r)=r2+λV(r), (ddr2)2V(r)?0, we prove to first order in λ that E?(NH,l)?E?(NH,l+2), where NH denotes the harmonic oscillator quantum number. In the latter case, we give also quantitative restrictions on the relative positions at the lth and (l+1)th states.  相似文献   

11.
The helicity, h?, of μ? in π-decay has been determined as positive (h??+0.90) from the average polarization, Pav≡〈JB·sμ〉, of 12B produced in the μ?+12C→νμ+12B reaction. We obtain also dynamical information on μ-capture: (i) the weak magnetism form factor, μ=4.5±1.1, and (ii) the sum of the induced pseudoscalar (gp) and the 2nd class induced tensor (gT) couplings versus gA, (gP+gT)gA=7.1±2.7. The latter result, adopting the “canonical” value of gPgA, leads to gTgA=+1±2.7 which is compatible with zero and in strong contradiction with the value ?—6 recently advocated by Kubodera, Delorme and Rho.  相似文献   

12.
Absolute cross sections are presented for the reactions 37Cl(α, γ)41K for 2.90 MeV ≦ Elabα ≦ 5.23 MeV, 62Ni(α, γ)66Znfor 5.07 MeV ≦ Eα?2lab ≦ 8.64 MeV, 62Ni(α, n)65Zn for energies near the (α, n0) threshold at Eαlab = 6.90 MeV up to 8.76 MeV, 64Ni(α, γ)68Zn for 4.50 ≦ Eαlab ≦ 7.45 MeV, and for 64Ni(α, n)67N from Eαlab = 5.30 MeV up to Eα = 7.45 MeV. Substantial competition cusps were observed in the excitation function for all three (α, γ) reactions. The data were found to be in reasonable agreement with the predictions of the current versions of global Hauser-Feshbach models used in nucleosynthesis calculations. Including width fluctuation corrections and realistic neutron strength functions generally improves the ability of the models to predict the depth of the (α, γ) competition cusps; the depths of the predicted (α,γ) cusps are insensitive to the degree of isospin mixing. Taken together with studies of competition effects in proton-induced reactions, the present data confirm the importance of width fluctuation and strength function effects, and indicate essentially complete isospin mixing between T< and T> states in the compound nucleus.  相似文献   

13.
The magnetic susceptibility measurements of orthorhombic U(OH)2SO4 within the temperature range 4.2–300 K have revealed a magnetic anomaly at TD = 21 K associated with crystallographic transition induced by the cooperative Jahn-Teller effect. Above 21 K the magnetic susceptibility of the uranium (4+) ion corresponds to the electronic ground doublet ¡MJ = ± 2〉 confirming thus the antiprismatic symmetry (D4d) of the crystal field at the uranium site. Below TD the system of two singlets (1√2)|2〉 ± (1√2)|2〉 separated by δ(T) is the ground state of the uranium ion.  相似文献   

14.
The emission of Ni2+ ions in MgO, KMgF3, KZnF3 and MgF2 crystals has been investigated. The fine structure on the bands at about 20 000 cm-1 and 13 000 cm-1 has been studied in detail and from this and the excitation spectra these bands are assigned to 1T2g3A2g and 1T2g3T2g transitions respectively.  相似文献   

15.
The complex polar Kerr effect (rotation and ellipticity) of magnetite single crystals has been measured at room temperature between 0.5 and 4.3 eV. From the magneto-optical data and the optical constants, the off-diagonal elements (?xy) of the dielectric tensor has been derived. Three well separated magneto-optical transitions have been indentified. At about 0.75 eV one strong magneto-optical structure with a diamagnetic line shape is assigned to a 3d6→3d5(6A1g) 4s transition from Fe2+ in octahedral sites. Two other structures with paramagnetic line shapes near 1.85 and 2.90 eV are assigned to the orbital promotion processes 3d6(Fe2+oct)→3d5(4T1g) 4s and 3d5(Fe3+tet)→3d4(5T2) 4s, respectively, which take into account Fe 3dn?1 final state effects.  相似文献   

16.
The reactions 17O(d, t) 16O and 17O(d, τ)16N have been investigated at Ed = 52 MeV. Energy spectra of tritons and τ-particles have been measured simultaneously up to excitation energies of 22 MeV in 16O and 10 MeV in 16N, respectively. Spectroscopic factors have been obtained by a DWBA analysis of the measured angular distributions. From the comparison of the t- and τ-spectra analog (T = 1) states in 16O could be identified and the distribution of T = 0 and T = 1 spectroscopic strengths could be deduced. Nearly the total 1p12 and 1p32 hole strengths have been found and the 1d521p12?1and 1d521p32?1 particle-hole multiplets could be located both for T = 0 and T = 1. The average residual interactions in both shell-model configurations turned out to be strikingly different.  相似文献   

17.
The general solution to the Wess-Zumino consistency equation is constructed. It does not depend on the antighost, nor on the sources, but only on the gauge and ghost fields through the geometrical combination A? = Aμdxμ+c. In dimension d, the anomalies with ghost number g are related to the off-BRS (d+s)-closed exterior forms I(A?, F), of degree d + g + 1 and at most g-linear in A?.  相似文献   

18.
The emission spectrum of the He2 molecule has been rephotographed in the ~4000–~5700 Å region and the 4d(3Σu+, 3Πu, 3Δu) → 2pπ3Πg, 4d(1Σu+, 1Πu, 1Δu) → 2pπ1Πg, 4s3Σu+ → 2pπ3Πg and 4s1Σu+ → 2pπ1Πg transitions analyzed. The 4dδj3Δu, 4dπj3Πu, 4dσj3Σu+ and 4sh3Σu+ states have been characterized through v = 2 and the 4dδJ1Δu, 4dπJ1Πu, 4dσJ1Σu+, and 4sH1Σu+ states for v = 0. The term levels for these perturbed and l-uncoupled states have been confirmed (a) by analyses of bands with common levels from Δv = 0, ±1 sequences and (b) by analyses of the transitions between the above states from 4d and 4s and the c3Σg+ and C1Σg+ states associated with 3. Molecular constants are reported which have been partially corrected for the effects of l-uncoupling and the homogeneous perturbations between the state pairs J, H and j, h.  相似文献   

19.
Negative-parity levels in the doubly even N = 82, Z nuclei, with 3.0 MeV ? Ex? 6.0 MeV are described in an extended unified-model approach, where neutron hole states in the Z = 50, N = 82 closed shell core, (i.e. 2d32?1,3sS12?1,2d52?1,1g72?1) are coupled to the low-lying levels (Ex ? 2.0 MeV) of the odd-neutron N = 83, Z nuclei. This particular configuration space of generalized neutron particle-hole states (GNPH) is particularly suited for describing negative-parity levels obtained in proton inelastic scattering through isobaric analogue resonances (IAR), corresponding to the N = 83, Z low-lying nuclear levels. Level schemes as well as partial decay widths and angular distributions are calculated and compared extensively with the available experimental data. Also spectroscopic factors, as well as wave functions, deduced from the experimental results are studied in detail. Thus in the cases of 136Xe, 138Ba, 140Ce, 142Nd and 144Sm, some of the important neutron particle-hole configurations can uniquely be determined in the energy region 3.0 MeV ?Ex ? 6.0 MeV.  相似文献   

20.
The results of high-resolution studies of the 91Zr(d, p) reaction at Ed = 12 MeV and the 90Zr(t, p) reaction at Et = 11.85 MeV are presented. Absolute cross sections have been measured for both reactions and (d, p) spectroscopic factors determined. A comparison of these results with earlier data has been made, and although many of the previous assignments have been confirmed, many new features concerning the structure of 92Zr have been discovered. Shell-model calculations have been performed for 91Zr and 92Zr using a neutron space which includes the 2d52, 3s12, 2d32, 1g72 and 1h112 orbits and a proton space comprising the 1g92 and 2p12 orbits. Realistic proton-neutron and neutron-neutron interactions based on the Sussex matrix elements were used in the calculations. Spectroscopic factors have been calculated for the 90Zr(d, p) and 91Zr(d, p) reactions and cross sections calculated for the 90Zr(t, p) reaction. In general, good agreement between the theoretical and the experimental results has been obtained.  相似文献   

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