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1.
Lifetime measurements of the excited states of 130Xe were carried out by delayed coincidence measurements between the β-spectrum of 130gI and the conversion lines that de-excite the levels, using a double-lens coincidence spectrometer. The mean lifetimes of the 2362 keV and 536 keV levels were determined as τ = 13.5±2 psec and 12.0±3 psec, respectively. The sum of the mean lifetimes of the 1204 keV and 1944 keV levels was measured as 4.0±1.6 psec. Conversion coefficients were measured for the most prominent transitions. The 2362 keV state was assigned as a g72πd52)6+ two-quasi-particle configuration and its de-excitation mode to the ground quasi-rotational band could be accounted for by a small amplitude admixture of the 6+ rotational configuration. The present B(E2; 0+ → 2+) value for the 536 keV state is in excellent agreement with a pairing plus quadrupole calculation for spherical nuclei. On the other hand, the energy spacings in this nucleus can be reproduced by the asymmetric rotational model with the parameters μ = 0.60, γ = 24°. The predicted sum of the lifetimes for the 4+ and 6+ rotational states agrees with our result within the experimental errors.  相似文献   

2.
Using the OSIRIS on-line isotope separator facility, the decays of 130Sn and 130, 132Sb have been studied. On the basis of singles γ and γ-γ coincidence Ge(Li) spectra and conversion electron Si(Li) measurements, level schemes for 130Sb, 130Te and 132Te have been constructed. The corresponding half-lives have been measured using multiscaling technique. The 3.8 min ground state of 130Sn populates only positive parity states in the πν?3 nucleus 130Sb: the energetically lowest 5+ state with the (π1g72, ν2d32) configuration assignment; the T12 = 3.6 ± 0.3 ns 4+ state at 70.0 keV; the 2+ state at 262.5 keV; the (0, 1)+ state at 697.2 keV; the 3+ state at 813.1 keV and the 1+ state at 1042.3 keV excitation energy. A 1.7 min isomeric state in 130Sn, with the tentative spin assignment (7?), populates several odd parity levels in 130Sb. These arise from the (π1g72, ν1h112-1) and/or (π2d52, ν1h112-1) configurations and are located 84.7 keV (6?), 144.9 keV (7?), 688.5 keV and 1044.0 keV above the 40 min 8? β- decaying state. No transitions between odd and even parity states have been observed.The most important excited states in 130Te found in the β? decay of the 6.6 min 130Sb 5+ state are: 839.4 keV, 2+; 1632.8 keV, 4+; 1815.1 keV, 6+; 2100.8 keV, 5?.Levels in the π2ν?2 nucleus 132Te were observed in the β? decays of the 2.8 min 132Sb (4+) and the 4.2 min 132Sb (8?) states. Unique spin and parity assignments have been given to the following states: 973.9 keV, 2+; 1670.7 keV, 4+; 1774.1 keV, 6+; 1924.7 keV, 7?; 2053.0 keV, 5?.  相似文献   

3.
The reactions 12C(d, α)10B, 18O(d, α)16N and34S(d, α)32P have been investigated at Ed = 52 MeV. Vector analyzing powers as large as ¦iT11¦=0.85 are observed. They exhibit patterns characteristic for final spins I = |L?1|, L or L + 1 and provide spin determinations at least for states of unique L-transfer. Local, zero-range DWBA calculations assuming deuteron-cluster pick-up reproduce qualitatively the observed effects. The method has been tested for states of known spin, and then has been applied to determine spins of states with stretched coupling in 16N: Jπ = 3+(3.96 MeV), 4?(6.17 MeV) and in 32P: Jπ = 5+(4.75 MeV). There is strong evidence for further 5+ states in 32P at 6.43, 7.96, 8.09 and 8.54 MeV.  相似文献   

4.
Low-lying 0+ states have been excited in the (p, p′) reaction via thes12 isobaric analog resonance in 114,116Sn and in radioactive decay in 118Sn. From conversion electron measurements, values of X = B(EO;0+ → 01+)B(E2; 0+ →21+) are obtained from the 1953 keV state in 114Sn, 1757 and 2027 keV states in 116Sn and 1758 and 2056 keV states in 118Sn.  相似文献   

5.
Differential cross sections for 87Sr(d, t)86Sr transitions to the (1g92)?2 states of 86Sr were obtained with the Pittsburgh 18 MeV deuteron beam and the Enge split-pole spectrograph. States of 86Sr up to 3.82 MeV in excitation were studied with a total resolution of 12 keV. Successful distorted-wave Born approximation (DWBA) predictions for 87Sr(d, t) 86Sr angular distributions permitted the extraction of l-values and spectroscopic strengths. The sum-rule value agrees with the observed value for the (1g92)?2 configuration. The observed g92 strength is spread over 13 states. Contrary to an earlier interpretation, the 0+ ground state is found to contain only 65% of the (g92)20+ strength. Similarly, the full 4+ strength is not located in a single state. The new data change the interpretation of the (g92)?2 spectrum of 86Sr. They significantly alter the deduced low-spin matrix elements and bring them into much closer agreement with those derived from 88Y. Several new negative-parity states dominated by l = 1 orbital angular momentum transfer have also been identified.  相似文献   

6.
The 62Ni(d, α)60Co reaction has been studied with 78 MeV vector polarized deuterons. Angular distributions of the differential cross section and vector analyzing power have been measured for strongly populated states in 60Co up to an excitation energy of 5 MeV. The transferred orbital and total angular momenta L and J were determined from the characteristic shapes of the differential cross sections and vector analyzing powers yielding a number of new spin assignments. The Jπ = 7+ stretched [(62Nig.s.)0+?(1f72)7,0?2] configuration was found to be distr least over nine states located at 1.51, 3.09, 3.46, 3.67, 3.78, 4.04, 4.55, 4.70 and 4.80 MeV.  相似文献   

7.
Levels of the N = 81 nucleus 145Gd have been investigated by in-beam γ-ray and conversion electron spectroscopy with the 144Sm(3He, 2n) reaction. Fourteen new low- and medium-spin states between 1.0 and 2.4 MeV excitation, the known yrast levels up to spin 212+, five other high-spin non-yrast states and a new 20.4 ns 132 isomer at 2200.2 keV in 145Gd have been observed. The isomer decays via a fast 927.3 keV E3 transition with B(E3) = 48 ± 7 W.u. Another weaker decay branch is a mixed, strongly hindered E1 + M2 + E3 transition to the vh?1112 state. We propose an octupole vf72j?2 × 3? main configuration for the isomer, analogous to the 997 keV 132+ isomer in 147Gd. The levels of 145Gd are discussed on the basis of the spherical shell model.  相似文献   

8.
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   

9.
We prove a theorem concerning the energies of the 2S and 3D states in a potential V(r) = ?g2r + Vc(r), where Vc is a non-singular confining potential. If (ddr)3(r2Vc) is positive, then the 3D state lies above the 2S state, provided
ddr1rddr2Vc+rdVcdr < 0, ?r>0.
For Vc = rα, this corresponds to 0 < α < 2.  相似文献   

10.
The systematics of particle-hole states in the 2s-1d and 1f72 shells have been analyzed in terms of the Bansal-French-Zamick weak coupling method. States considered are d?32fn72 (J = 32+), (s?d)n72 (J = 72?) and (s?d)nf272 (J = 0+and 7+), the jn components corresponding to even-even ground states.  相似文献   

11.
Excitation functions of the capture reaction 12C(p, γ0)13N have been obtained at θγ = 0° and 90° and Ep = 150–2500 keV. The results can be explained if a direct radiative capture process, E1(s and d → p), to the ground state in 13N is included in the analysis in addition to the two well-known resonances in this beam energy range [Ep = 457(12+) and 1699 (32?) keV]. The direct capture component is enhanced through interference effects with the two resonance amplitudes. From the observed direct capture cross section, a spectroscopic factor of C2S(l = 1) = 0.49 ± 0.15 has been deduced for the 12? ground state in 13N. Excitation functions for the reaction 12C(p,γ1p1)12C have been obtained at θγ = 0° and 90° and Ep = 610–2700 keV. Away from the 1699 keV resonance the capture γ-ray yield is dominated by the direct capture process E1 (p → s) to the 2366 (12+) keV unbound state. Above Ep = 1 MeV, the observed excitation functions are well reproduced by the direct capture theory to unbound states (bremsstrahlung theory). Below Ep = 1 MeV, i.e., Ep → 457 keV, the theory diverges in contrast to observation. This discrepancy is well known in bremsstrahlung theory as the “infrared problem”. From the observed direct capture cross sections at Ep ? 1 MeV, a spectroscopic factor of C2S(l = 0) = 1.02 ± 0.15 has been found for the 2366 (12+) keV unbound state. A search for direct capture transitions to the 3512 (32?)and 3547 (52+) keV unbound states resulted in upper limits of C2S(l = 1) ≦ 0.5 and C2S(l = 2) ? 1.0, respectively. The results are compared with available stripping data as well as shell-model calculations. The astrophysical aspect of the 12C(p, γ0)13N reaction also is discussed.  相似文献   

12.
Excited 72? states to which enhanced L = 0 (p, t) transitions are observed have been identified in 41Ca at 2958 keV and in 57Co at 2611 keV. A comparison of these (p, t) transitions with those to the 0+ states in 40Ca at 3353 keV and in 58Ni at 2940 keV leads to the conclusion that these states are obtained by weak-coupling of a f72 particle and hole, respectively, to the excited 0+ states of the doubly even cores. It is suggested that these cases are examples of a rather general weak-coupling phenomenon.  相似文献   

13.
The reduced M2 transition probabilities 112?172+1 in the odd-A isotopes 109–121Sn are found to reveal a specific behaviour. B(M2) values are calculated in the framework of the quasiparticlephonon model. The coupling of a quasineutron with the 2+, 3? and 2? one-phonon core excitation is taken into account. Inclusion of all one-phonon 2? states up to 24 MeV in the wave functions of the excited states 112?1and72+1 reduces the theoretical B(M2) values by 3–4 times as compared to the single-particle values. The specific B(M2) dependence on the mass number appears to be due to the pairing effect.  相似文献   

14.
High spin states in the νd52g922) multiplet in 93Mo were investigated with the 93Nb(p, n) 93Mo reaction. A new isomeric state at 2430 keV with a half-life of 3.53±0.18 ns is interpreted as the lower 172+ member of the multiplet. A number of further states have been identified. The results are compared to previous experiments and shell model calculations.  相似文献   

15.
The q2 variation of the factor ?+(q2) in the decay K+π0e+ν has been studied using a sample of even detected in the CERN 1.1 m3 heavy-liquid bubble chamber. The data are consistent with a linear development ?+(q2)=?+(0) (1+λ+q/m2π) with λ+=0.027±0.008.  相似文献   

16.
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   

17.
John Lekner 《Physica A》1982,112(3):544-556
We derive comparison identities for waves satisfying the equation d2Ψ/dz2+q2(z)Ψ=0. One of these identities is used to show that to second order in the product (wavenumber component normal to interface) × (interface thickness), the reflection amplitude is given by r=(1?2q1q2l2)(q1?q2)(q1+q2), where l is a legnth determined by the deviation of the interface profile from a step, and q1, q2 are the normal components of the wave numbers in media 1 and 2 on either side of the interface. For the continuous interfaces discussed, l is about two-fifths of the 10–90 interface thickness. The corresponding formula for the transmission amplitude is t=(1+12(q1?q2)2l2)2q1(q1+q2).  相似文献   

18.
From the angular distributions of γ-rays emitted by oriented 129gTe and 129mTe nuclei implanted in iron by isotope separator, unique spin assignments could be made for the excited states of 129I at 487.4 keV (52+), 696.0 keV (112+), 729.6 keV (92+), 768.9 keV (72+), 1050.4 keV (72+) and 1111.8 keV (52+). In addition, E2/M1 amplitude ratios for the following 129I γ-rays (energies are in keV) are derived: δ(459.6) = ?(0.076+0.037?0.148); δ(487.4) = 0.50+0.17?0.10 or δ? = 0.35+0.15?0.09; δ(556.7) = 0.06±0.02 or δ? = ?(0.10±0.02); δ(624.4) = 0.10±0.26 or δ? > 0.4; the 696.0 keV γ-ray is pure E2; δ(729.6) = ?(0.34±0.06) or δ?1 = 0.55±0.05; δ(741.1) = ?(0.27±0.10) or δ?1 = ?(0.43±0.12); δ(817.2) = 0.46±0.04 or δ?1 =0.20±0.03 if Iπ (845 keV) = 72+; δ(1022.6) = ?(0.02 ±0.02) or δ?1 = ?(0.23±0.02); δ(1084) = 0.56 +0.04?0.14; δ(1111.8) = 0.06±0.05 or δ?1 = ?(0.08±0.05). The anisotropy of the 531.8 keV γ-ray excludes 12+ as a possible spin assignment for the 559.6 keV level, so that no 12+ level is fed in the decay from 129Te. Anisotropies for the 209, 250.7, 278.4 and 281.1 keV γ-rays are also measured. Comparison of the level scheme is made with theoretical predictions from both the pairing-plus-quadrupole model and the intermediate coupling unified model.  相似文献   

19.
Discharges through mixtures of helium and neon show two band groups near 4250 and 4100 Å as first observed by Druyvesteyn. These bands, assigned to the HeNe+ ion by Tanaka, Yoshino, and Freeman, have been studied under high resolution and have been fairly completely analyzed. The upper state of the transition is a very weakly bound state resulting from He+(2S) + Ne(1S0). There are two lower states resulting from the two components of Ne+(2P) + He(1S0). The upper of these two (2Π12) is also very weakly bound while the lower of the two, the 2Σ+ ground state, has a dissociation energy of 0.69 eV and an re value of 1.30 Å. All bands in both band groups show four branches designated Rff, Qef, Qfe, and Pee. From their analysis the rotational constants in the various vibrational levels of the three electronic states have been determined. While no spin splitting in the B2Σ+ state has been found the ground state X2Σ shows a very large spin splitting and the A22Π12 state a very large Ω-type doubling. The vibrational numberings in all these states were established by the study of the spectrum of 3HeNe+. At the same time the hyperfine structure observed in all lines of 3HeNe+ confirmed the nature of the upper state B2Σ+ as resulting from He+ + Ne, i.e., by charge exchange from the ground state. The 2Π12 component of the 2Π state has not been observed, presumably because of low intensity.  相似文献   

20.
Excitation functions for the 24Mg(p, γ)25Al capture reaction have been obtained for the beam energy range Ep = 0.2–2.3 MeV. The analysis of these data revealed the presence of the direct capture process to the low-lying states in 25Al at Ex(Jπ) = 0(52+), 452(12+), 945(32+), 2485(12+) and 3062 keV (32?). The presence of the weaker direct capture transitions is manifested through interference effects on the tails of the two broad resonances at Ep = 823 and 1623 keV. The deduced spectroscopic factors for these final states in 25Al are compared with the corresponding values from stripping data as well as model calculations. An astrophysical S-factor of S(0) ≈ 30 keV· b for this reaction has been obtained.  相似文献   

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