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1.
An investigation of the γ-decay of the 1g92 analogue state in 59Cu has been performed using the 58Ni(p, γ)59Cu reaction. The (p, γ) excitation function has been taken in the range Ep = 3450–3650 keV. The decay schemes of the (p, γ) resonances at Ep = 3483, 3532 and 3547 keV, measured with Ge(Li) detectors, lead to eight new levels in 59Cu with excitation energies between 1.8 and 4.7 MeV and to spin assignments of several states. The spins of the first two resonances are found to be (12, 32) and (52). The spin of the Ep = 3547 keV resonan is, from angular distributions, uniquely determined to be Jπ = 92+ and this state is found to be the unfragmented analogue state of the E1 = 3.062 MeV, Jπ = 92+ parent state in 59Ni. The measured complete decay scheme of this resonance shows that its isovector M1 decay is in disagreement with all existing theoretical predictions.  相似文献   

2.
The probability distribution calculated for the decay sequence 12ΛB(g.s.) → 12C1π? → αααπ? passing through the (JPN) = (2+, 1) intermediate state 12C1 (16.11 MeV) is cast in a symmetrical form and used to calculate the likelihood for J = 1 relative to J = 2 for12ΛB(g.s.) on the basis of the 85 examples available for this decay process. This procedure has optimum sensitivity, is free from the uncertainties of the comparisons previously made using only projected angular distributions, and strongly indicates that JP = 1? holds for 12ΛB(g.s.). An appendix points out that all the data for the decay sequence passing through the (JPN, T) = (1+, 0) level of 12C1 is well fitted for J = 1 if the J = 1 → Jn = 1 transition amplitude as1 takes a value in the range as1/s = 0.08 to 0.09.  相似文献   

3.
From a study of (p,t) reactions on 31P and 30Si it is suggested that in 29P the states with Jπ=121+ and 122+, the pair 322+, 521+, and the pair 723+, 921+ are related by weak coupling of a s12 proton with the states 01+, 02+, 21+ and 41+ respectively of 28Si. Completely atypical L = 2 angular distributions have been obtained for the 321+ and 522+ states in 29P and it is suggested that this is due to contribution by two-step processes.  相似文献   

4.
Predissociations in the y1Πg and x1Σg? Rydberg states of N2 (configurations u?14pσ and u?13pπ, respectively) and their likely causes, are discussed. Peaking of rotational intensity at unusually low J values, without sharp breaking off, is interpreted as due to case c? or case ci predissociation. Λ doubling in the y state, attributed to interactions with the x1Σg? state and with another, 1Σ+, state of the same electron configuration as x, is analyzed. From this analysis the location of the (unobserved) 1Σg+ state, here labeled x′, is obtained. It is concluded that the predissociation in the Π+ levels of the y state is an indirect one mediated by the interaction with x′ coupled with predissociation of x′ by a 3Σg? state dissociating to 4S + 2P atoms: combined, however, with perturbation of the y state by the k1Πg Rydberg state (configuration g?14dπ), whose Π+ levels are completely predissociated.  相似文献   

5.
Accurate SCF computations are reported on the Rydberg states of N2 of electron configurations ---1πu3u, ---1πu3u, and ---3σg2πg, also on the valence states of the configuration ---1πu3g. The Rydberg state calculations supplement those of Lefebvre-Brion and Moser. A comparison is made between the ---1πu3u states and the parallel set of states of the u3g configuration. This comparison shows a sharp difference in the 1Σ+ states of the two configurations, the 1Σ+ state being very high in the latter but relatively low in the former configuration. Recknagel coefficients are given for the several states of the two configurations; as expected, these are much smaller for the u3u configuration. Also, the 1Δ state is relatively lower for the latter configuration.  相似文献   

6.
We analyze carefully the impact of non-analytic chiral corrections to the mass spectrum of the pseudoscalar meson octet JP = 0? and the baryon octet JP = 12+. We find that the quark mass ratios must lie in the range 21 ≤ msm? ≤ 32 and 1.6 ≤ mdmu ≤ 2.2. We also calculate the analogous corrections to the pion-nucleon sigma commutator σπN. It turns out that the value σπN = 60 MeV is not compatible with the structure of the meson and baryon spectrum, unless the nucleon mass is smaller than 600 MeV in the chiral limit mu = md = ms = 0.  相似文献   

7.
E. Hagn  E. Zech 《Nuclear Physics A》1982,373(2):256-266
The magnetic hyperfine splitting vM=|gμNBHF/h| of 196mAu (jπ=12?; configuration ¦(π112(v132+)〉12?; T12 = 9.7 h) as dilute impurity in Ni has been determined with nuclear magnetic resonance on oriented nuclei as 96.0(2) MHz. With the known hyperfine field BHF = ?264.4(3.9) kG corrected for hyperfine anomalies the g-factor and magnetic moment of 196mAu are deduced to be |g| = 0.476(7) and |μ| = 5.72(8) μN. Taking into account the known magnetic properties of π12? and v132+ isomeric states in the neighbouring odd Pt, Au and Hg nuclei the structure of the 12? state is discussed.  相似文献   

8.
A spin-parity analysis of the nπ+ system produced in the reaction π+p → π+π+n at 16 MeV/c has shown apart from the mass enhancements associated with the known resonances Δ+(1238), N1(1520) and N1(1688) there is an enhancement peaked at M(nπ+) ? 1.35 GeV, ∑0.2 GeV wide. For masses below M(nπ+) ? 1.35 GeV this enhancement is predominantly due to JP = 12? states, predominate. The presence of JP = 12? states indicates that the rule ΔP = (?1)ΔJ is strongly violated in the diffractive process N → Nπ, and hence it cannot be considered a specific characteristic of all diffractive processes.  相似文献   

9.
In lattice gauge theory, many computations such as the strong coupling expansions, mean field theory, or the few plaquette models require the evaluation of the one-link integral in the presence of an arbitrary N × N complex matrix source (J). For SU(N) gauge theories, we express our general solution to the external field problem as an integral over the maximal abelian subgroup [U(1)]N?1
dUe?r(J+U+U+J)=∫i=1Ndøp(Σøi)eS0+InG
where S0 = 2Σkzk cos(φk ? θ), zj are eigenvalues of √JJ+, e2iNθ=detJ/detJ+, and G is an appropriate jacobian determinant. Our explicit solution follows from differential Schwinger-Dyson equations cast in a separable form by using fermionic variables, and the special cases of N = 2, 3 and ∞ agree with earlier derivations.  相似文献   

10.
The level schemes of 98, 99Ru were studied with the reactions 98Mo(α, 3nγ) and 98Mo(α, 4nγ) at Eα = 35 to 55 MeV, using a large variety of in-beam γ-ray detection techniques and conversion-electron measurements. A search for the 3? state was carried out with the reaction 98Ru(p, p′). The ground-state band of 98Ru was excited up to Jπ = (12)+ and a negative-parity band up to (15)?. New levels in 98Ru were found at Ex = 2285 (Jπ = 4+), 2435 (Jπ = (3?, 4+)), 2671, 3540, 4224, 4847, 4915 (Jπ = (12)+), 4989 (Jπ = (12+)), 5521 (Jπ = (13)?), 5889, 6591 (Jπ = (15)?), and 7621 keV. New unambiguous spin and parity assignments were made for the levels at Ex = 2014 and 3852 keV, as Jπ = 3+ and 9?, respectively. New levels in 99Ru were found at Ex = 1976, 2021 (Jπ = (152+)), 2393, 2401 (Jπ = (172+)), 2875 (π = (+)), 3037, 3201 (Jπ = (232)?), 3460 (J = (172)), 3484 (Jπ = (212+)), 3985, 4224 (Jπ = (272?)), and 5359 keV. The 1070 keV, Jπ = 112? level in 99Ru has a half-life of 2.8 ns. A strongly excited negative-parity band is built on this level. A positive-parity band based on the ground state was excited up to Jπ = (212+). The level schemes are well reproduced by the interacting boson model in the vibrational limit.  相似文献   

11.
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   

12.
R. Eder  E. Hagn  E. Zech 《Nuclear Physics A》1984,413(2):247-254
The magnetic hyperfine splitting νM = |NBHF/h| of 175Ta (Jπ = 72+; T12 = 10.5 h) in Fe has been measured with the technique of nuclear magnetic resonance on oriented nuclei as 320.4(1) MHz. With the known hyperfine field BHF(TaFe) = ?648(13)kG the magnetic moment of the 72+[404] ground state of 175Ta is deduced to be ¦μ¦ = 2.27(5)μN.  相似文献   

13.
A complete set of conventional γ-ray spectroscopic techniques has been applied to investigate the level structure of 156Gd. A total of twenty-five new levels has been established; unambiguous spin assignments could be given for twelve of them on the basis of angular distributions and conversion electron measurements. The proposed level scheme contains 49 levels, which can be ordered in seven rotational bands. The ground-state band was excited up to Jπ = 14+, the β-band up to 10+, the γ-band up to (11+), the second Kπ = 0+ band tentatively up to (10+), the Kπ = 4+ band up to (8+). Two negative-parity bands, one with even spins and one with odd spins, were excited to Jπ = (12?) and (13?). An isomeric state was established with T12 = 1.3 μs, Jπ = 7?, Ex = 2137.7 keV. The properties of the Kπ = 4+ band and the isomeric state can be well explained by two-quasiparticle configurations. The negative-parity bands are interpreted as aligned octupole bands. Positive and negative-parity bands have been calculated in terms of the IBA model. Good agreement with the experimental results is obtained.  相似文献   

14.
15.
Gamma rays following the β? decay of 30Al have been investigated with a Ge(Li) detector. The 30A1 sources were produced by fast neutron bombardment of an enriched 30Si sample. Evidence for two previously unreported β? branches has been deduced. The existence of allowed β? transitions to Jπ = 2+and 3+ states and to the Jπ = 4+ level at 5.95 MeV determines Jπ = 3 + for the 30Al ground state (T12 = 3.56 ± 0.02 s). These results are compared to a recent shell-model calculation.  相似文献   

16.
High-spin states in 38K are investigated with the 24Mg(16O, pnγ)38K reaction at E(16O) = 36–44 MeV. A recently developed Compton-suppression spectrometer with 120 msr solid angle and a pulsed beam are employed to study their γ-decay. For the E4 transition from the isomeric level at Ex = 3458 keV to the ground state a branching ratio of (0.15 ± 0.02)% is found. On the basis of angular distribution and polarization measurements, in which the delayed feeding component is eliminated, spin-parity assignments are obtained of Jπ(2646 keV) = (2, 4)?, Jπ(3420 keV) = (4, 6)? and Jπ(3458 keV) = (5, 7)+. Prompt-delayed and prompt γγ coincidence experiments are performed to locate high-spin levels above the isomer. Hitherto unobserved levels of high spin are found at Ex = 5254, 7397, 8693, 8747 and 10980 keV and assignments of Jπ = (9+), (10?), (12?), (11?) and (13?) respectively, are suggested by weak-coupling considerations. The experimental results are compared with a large-scale shell-model calculation performed in a configuration space with a 28Si core and ten active particles distributed over the (2s12, 1d32, 1f72, 2p32) shells. The high-spin states appear to have a rather simple shell-model structure.  相似文献   

17.
No perturbation between two valence states of NO has ever been identified, although many valence-Rydberg and several Rydberg-Rydberg perturbations have been extensively studied. The first valence-valence crossing to be experimentally documented for NO is reported here and occurs between the 15N18O B2Π (v = 18) and B2Δ (v = 1) levels. No level shifts larger than the detection limit of 0.1 cm?1 are observed at the crossings near J = 6.5 [B 2Π(F1) ~ B′ 2Δ(F2)] and J = 12.5 [B 2Π(F1) ~ B′ 2Δ(F1)]; two crossings involving higher rotational levels could not be examined. Semi-empirical calculations of spin-orbit and Coriolis perturbation matrix elements indicate that although the electronic part of the B 2Π ~ B′ 2Δ interaction is large, a small vibrational factor renders the 15N18O B (v = 18) ? B′ (v = 1) perturbation unobservable. Semi-empirical estimates are given for all perturbation matrix elements of the operators Σia?ili·si and B(L±S? ? J±L?) which connect states belonging to the configurations (σ2p)2(π2p)412p), (σ2p)(π2p)412p)2, and (σ2p)2(π2p)312p)2.  相似文献   

18.
Levels in 208At were populated in the 209Bi(α, 5n) reaction, and the subsequent radiation was studied using γ-spectroscopic methods including γ-ray excitation function and angular distribution, γγ(t) coincidence and γt measurements, as well as measurements of conversion electrons. The excited spectrum of 208At is found to consist of two almost disconnected parts which are proposed to originate from seniority-three proton and neutron cascades. Two isometric states are observed. A T12 = 45 ± 2 ns state at 1090 keV is proposed to have the main configuration πh92j20+vi?1132j?20+ and Jπ = 10?. A high-spin isomer with T12 = 1.5 ± 0.2 μs at 2276 keV is assigned to be the π(h292i132)292+vf?152j?20+Jπ = 16? state. Shell-model arguments are used to assign configurations to most of the observed levels. Transition rates are discussed.  相似文献   

19.
The search for magnetic dipole transitions from the ground state-even Ca isotopes to high lying Jπ=1+ states by means of low momentum transfer but high resolution inelastic electron scattering is described. The previously detected strongly excited Jπ=1+ state EX=10.319 MeV [B(M1)↑=1.12±0.27μK2] in 40Ca has been confirmed, but - contrary to the expectations of the independent particle shell model - only a fairly weak M1 transition is observed in 42Ca [EX = 11.235 MeV, B(M1)↑=0.59±0.05 μ2K] and none in 44Ca between EX=8.2?12.2 MeV. In 48Ca, however, a very strong M1 transition [B(M1) ↑ = 4.0 ± 0.3 μ2K] to a single state at EX=10.227 MeV has been discovered.  相似文献   

20.
J/ψ production at 40 GeV/c by π±, K±, p and p incident on hydrogen has been studied and results compared with those obtained on tungsten in the same experiment. On hydrogen, J/ψ cross-section ratios relative to π? have been measured to be (for xF > 0) σ(π?) : σ(π+) : σ(p) : σ(p) = 1 : (0.78 ± 0.09) : (0.83 ± 0.35) : (0.07 ± 0.04). The suppression of the proton induced cross sections shows the importance of calence quark-antiquark fusiin J/ψ production at this energy (i.e. MJ2/ψ/s=0.13).  相似文献   

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