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1.

Amand Faessler K.R. Sandhya Devi A. Barroso 《Nuclear Physics A》1977,286(1):101-114

Backbending in (at least the first half of) the rare earth nuclei seems to be determined by the alignment of an

i_{132}

neutron pair. This is supported by the disappearance of backbending due to the blocking of an

i_{132}

level by an odd neutron for example in ¹⁶⁵Yb. Contrary to expectations backbending disappears also by adding an odd

h_{92}

,proton to ₇₀¹⁶⁶Yb in ₇₁¹⁶⁷Lu for this state (but is present if the odd proton is in the

g_{72}

level). A theory is presented which explains the odd neutron and the odd proton nuclei. It turns out that the odd proton in ¹⁶⁷Lu serves only as a type of catalyst for the alignment of an

i_{132}

neutron pair. The odd proton changes the deformation and moves the Fermi surface nearer (

g_{72}

) or farther away (

h_{92}

) from the nearest

i_{132}

neutron level. In one case one finds backbending and in the other case no backbending in ¹⁶⁷Lu. 相似文献

2.

VAMPIR calculations for ¹²⁸Ba and ¹³⁰Ce: Two mechanisms of backbending

K.W. Schmid F. Grümmer E. Hammarén Amand Faessler 《Nuclear Physics A》1985,436(3):417-437

Hartree-Fock-Bogoliubov calculations with spin and number projection before the variation (VAMPIR) are performed for the nuclei ¹²⁸Ba and ¹³⁰Ce using a slightly renormalized Brueckner G-matrix as effective interaction in a rather large single-particle basis. The results are compared to those of Hartree-Fock-Bogoliubov calculations with projection after the variation, those of multiconfiguration calculations (MONSTER) and to experiment. In both nuclei the VAMPIR and the MONSTER approaches turn out to be of about the same quality and agree rather well with the experimental data. Analysis of the VAMPIR mean fields reveals that two somewhat different mechanisms are responsible for the backbending observed in the yrast bands of the two nuclei. While in ¹³⁰Ce the well-known alignment of two high-j quasiparticles (proton

h_{112}

) is found, in ¹²⁸Ba first a neutron pair is scattered from the

h_{112}

to the

g_{72}

orbit, and then the larger alignment energy of the less occupied neutron

h_{112}

states produces the backbend. This latter effect is in agreement with the predictions of a simple model presented by us some years ago. 相似文献

3.

Level structure of ¹⁰⁰Tc

J.A. Pinston W. Mampe R. Roussille K. Schreckenbach D. Heck H.G. Börner H.R. Koch S. Andre D. Barneoud 《Nuclear Physics A》1979,321(1):25-44

Gamma and electron spectra following thermal neutron capture on ⁹⁹Tc have been studied with a bent-crystal spectrometer, Ge(Li) and Si(Li) detectors and a magnetic spectrometer. Prompt and delayed γ-γ coincidences with Ge(Li) detectors have been performed. A level scheme is proposed for ¹⁰⁰Tc comprising 21 excited states up to 640 keV. The binding energy of the last neutron in ¹⁰⁰Tc was deduced. For most levels, spin and parity values were assigned. Two isometric transitions of respective half-lives 10.2 and 4.6 μs have been identified using the ¹⁰⁰Mo(d, 2n)¹⁰⁰Tc reaction with a pulsed beam of deuterons. From the comparison of the present (n, γ) study and the collaborative study of the ⁹⁹Tc(d, p) reaction, several members of the multiplets

π g_{92} ν g_{72}

,

π g_{92} ν g_{52}

,

π g_{92} ν s_{12}

and

π p_{12} ν d_{52}

have been identified. 相似文献

4.

g-Factors of high-spin isomers in ¹⁹⁴Hg and ¹⁹⁶Hg

R. Kroth S.K. Bhattacherjee C. Günther M. Guttormsen K. Hardt H. Hübel A. Kleinrahm 《Physics letters. [Part B]》1980,97(2):197-199

The g-factors of the 10⁺ isomeric states in ¹⁹⁴Hg and ¹⁹⁶Hg have been measured using the in beam IPAD method. The results

g(^{194} Hg) = ?0.24(4)

and

g(^{196} Hg) = ?0.18(9)

are in agreement with the value expected for an (

i_{1} 32

^?2) neutron satructure and clearly contradict the previous assignment as (

h_{112}^{?2}

) proton configurations. Cranking model calculations show that the neutron excitation energies in the rotating frame agree satisfactorily with the experimental energies and that the proton excitations are expected ≈2 MeV above the experimental yrast line 相似文献

5.

Spectroscopy of high-spin states in ²¹⁷Ra

N. Roy D.J. Decman H. Kluge K.H. Maier A. Maj C. Mittag J. Fernandez-Niello H. Puchta F. Riess 《Nuclear Physics A》1984,426(2):379-398

相似文献

6.

The γ-decay of the

1 g_{92}

and 2p inner-hole states in ¹¹¹Sn via the ¹¹²Sn(³He, αγ) reaction at 32 MeV

F. Azaiez S. Fortier S. Galès E. Hourani J.M. Maison J. Kumpulainen J.P. Schapira 《Nuclear Physics A》1985,444(3):373-401

The γ-decay of the deeply-bound hole states in ¹¹¹Sn has been investigated at 32 MeV incident energy by means of the ¹¹²Sn(³He, αγ) reaction. The α-particles emitted near 0° were detected in a Si counter located at the image plan of the superconducting solenoidal spectrometer SOLENO. The γ-rays in coincidence with the α-particles were detected by two Ge(Li) detectors located at 90° and 142° with respect to the beam direction, respectively. Energies, spins and decay schemes have been established for the low-lying states up to 2.5 MeV excitation energy in ¹¹¹Sn. The γ-decay of the broad bump, located around 4.2 MeV and previously attributed to neutron pick-up from the inner

1 g_{92}, 2 p_{12}, and 2 p_{32}

neutron. Subshells, reveals the importance of quasiparticle-phonon m the spreading mechanism of the inner-hole strengths. The

1 g_{92}

and 2p strength functions have been deduced from the α-decay of the enhanced structures (3 ≦ E_x≦ 8 MeV). They are compared to the ones measured in previous inclusive neutron pick-up experiments and to those calculated in the framework of the quasiparticle-phonon nuclear model. 相似文献

7.

Radii of single-proton states in isotopes of tin

A. Warwick R. Chapman J.L. Durell J.N. Mo 《Physics letters. [Part B]》1979,87(4):335-338

Sub-Coulomb (t, α) reactions have been employed in the determination of the rms radii of the

1 g_{92}

,

2 p_{12}

and

2 p_{32}

proton orbits in ^{112,116,118,120,124}Sn. The experimental values are compared to the results of Hartree-Fock calculations. 相似文献

8.

Experimental and shell-model studies of the reactions ⁹¹Zr(d,p)⁹²Zr and ⁹⁰Zr(t,p)⁹²Zr

S.S. Ipson K.C. McLean W. Booth J.G.B. Haigh R.N. Glover 《Nuclear Physics A》1975,253(1):189-215

The results of high-resolution studies of the ⁹¹Zr(d, p) reaction at E_d = 12 MeV and the ⁹⁰Zr(t, p) reaction at E_t = 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

2 d_{52}

,

3 s_{12}

,

2 d_{32}

,

1 g_{72}

and

1 h_{112}

orbits and a proton space comprising the

1 g_{92}

and

2 p_{12}

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

9.

The proton shell closure at 14C

R.R. Sercely R.J. Peterson P.A. Smith E.R. Flynn 《Nuclear Physics A》1979,324(1):53-62

Data for the ¹⁴C(³He, d)¹⁵N and ¹⁴C(t, ⁴He)¹³B reactions are compared to DWBA calculations to measure the spectroscopic factors for

p_{12} and p_{32}

proton transitions. Good fits are found for the stripping data, as well as to similar stripping data on ¹²C. These results lower the previous value for proton

p_{32}

hole strength in ¹⁴C by a factor of two, indicating that the neutron closure of the p-shell has provided a very good proton closed shell at ¹⁴C. Stripping results to low-lying positive parity states in ¹⁵N are interpreted within a Nilsson scheme, which reproduces the experimental results, but which requires a large deformation for the s-d orbitals. 相似文献

10.

Proton-neutron excitations in the high-spin states of ⁹⁵Tc

G. Winter F. Dönau L. Funke P. Kemnitz E. Will 《Nuclear Physics A》1977,291(2):401-412

The high-spin states of ⁹⁵Tc have been studied in the reaction ⁹³Nb(α, 2n)⁹⁵Tc using inbeam spectroscopy of both γ-rays and conversion electrons. A new sequence of negative-parity states extending up to angular momentum

I = 292

was found to exist within an excitation energy interval of 4.1 MeV. The positive-parity states are in remarkable agreement with the predictions of a simplified shell-model approach on the basis of coupled excitations of

g_{92}

proton and

d_{52}^{?}

as well as

g_{72}

neutron configurations. A similar analysis for the negative-parity states shows qualitative agreement with the experimental results. 相似文献

11.

The level structure of ⁹⁰Mo

F.W.N. De Boer C.A. Fields L.E. Samuelson J. Sau 《Nuclear Physics A》1982,388(2):303-316

High-spin states of the N = 48 nucleus ⁹⁰Mo have been studied using the 33 MeV ⁹⁰Zr(³He, 3nγ) reaction. A previously unknown level structure above the 8⁺ isomer and several new lower-lying levels have been identified. The results are discussed in terms of shell-model calculations which allow four protons in the

2 p_{12} and 1 g_{92}

subshells and two neutron holes in the

1 f_{52}, 2 p_{32}, 2 p_{12}, or 1 g_{92}

orbitals. 相似文献

12.

Lifetimes and g-factors of the 6− and 7− isomers in 66Ga and 68Ga

A. Filevich A. Ceballos M.A.J. Mariscotti P. Thieberger E. Der Mateosian 《Nuclear Physics A》1978,295(3):513-524

The 6^? and 7^? isomeric states in ⁶⁶Ga and ⁶⁸Ga at 1440.9 and 1229.6 keV, respectively, have been populated with the (¹³C, 2np) and (¹⁵N, n2p) reactions on natural Fe. The half-lives of these states have been measured to be

T_{12} (6^{?},^{66} Ga) = 57.3 ± 1.2 ns

and

T_{12} (7^{?},^{68} Ga) = 64 ± 2 ns

. Using previous data on the hyperfine field of Ga in Fe, the g-factors of these states have been determined by means of the TDPAD method. The results are

g(6^{?},^{66} Ga) = 0.129 ± 0.003

and

g(7^{?},^{68} Ga) = 0.105 ± 0.003

. These values are in very good agreement with the independent particle model if one assumes the

{π f_{52}, ν g_{92}}_{6^{?},7^{?}}

and

{π p_{32}, ν g_{92}}_{6^{?}}

configurations and uses the empirical proton and neutron g-factors from odd-A neighboring nuclei instead of the Schmidt values. The large disagreements with experiment when Schmidt values are used show that core polarization effects are important in these nuclei. 相似文献

13.

E2 core polarization for sd-shell single-particle states calculated with a skyrme-type interaction

H. Sagawa B.A. Brown 《Nuclear Physics A》1984,430(1):84-98

We have studied the core-polarization effect on the 1s0d-shell single-particle electromagnetic quadrupole transitions due to coupling with the quadrupole giant resonances. The self-consistent Hartree-Fock + RPA method is applied for the calculations of the single-particle wave functions and the response functions of the giant resonances. The particle-vibration-coupling model is used to calculate the core-polarization effect in the vicinity of ¹⁶O and ⁴⁰Ca. The effective coupling hamiltonian is determined by the SGII Skyrme-type interaction which is used in the HF + RPA and particle-vibration-coupling calculation. The results are discussed for the proton and neutron effective charges and for the longitudinal and transverse form factor for the

0 d_{32}^{?1} → 1 s_{12}^{?1}

pro single-particle transition in ³⁹K. Good agreement with recent longitudinal data for this transition is obtained. 相似文献

14.

The structure of 209Bi: (I). Microscopic structure from analog resonances

T.P. Cleary Nelson Stein P.R. Maurenzig 《Nuclear Physics A》1974,232(2):287-310

Excitation functions for the ²⁰⁹Bi(p, p′) reaction have been measured for incident proton energies from 14.0 to 15.5 MeV to study the population of states in ²⁰⁹Bi via decay of the isobaric analog resonances in the compound nucleus ²¹⁰Po. The analogs correspond to parent states in the lowest one MeV of excitation in ²¹⁰Bi. Strong resonances are observed in the excitation functions for twenty proton groups corresponding to levels between 2.75 and 3.65 MeV in ²⁰⁹Bi. From these results, levels which possess microscopic 2p-1h structure involving the

h_{92}^{π}, g_{92}^{ν} and p_{12}^{?1_{ν}}

orbitals are identified and their ²¹⁰Bi parentage determined. The resonant scattering results together with other direct inelastic scattering data allow the spins and parities for many of the levels to be deduced. The results of a microscopic calculation, in which empirical two-body matrix elements are employed to describe the interactions between the

h_{92}^{π}, g_{92}^{ν} and p_{12}^{?1_{ν}}

orbitals, are also reported and compared with the experimental results for levels in ²⁰⁹Bi. The excellent agreement between theory and experiment demonstrates that the general character of these levels can be understood microscopically in terms of their 2p-1h structure. 相似文献

15.

Dipole moments and spin rotations of the neutron

Norman F. Ramsey 《Physics Reports》1978,43(10):409-421

A recently completed neutron beam experiment is described which sets the limit on μ_E the neutron electric dipole moment of

| μ_{E} e |<3×10^{?24} cm

. A new experiment with bottled cold neutrons has been started and should eventually provide much lower limit. The original apparatus has recently been used to measure the ratio

gm_{n} μ_{p}

of the magnetic moment of the neutron to that of proton with the result

μ_{n} μ_{p} = ?0.68497945(17)

. A new apparatus is being planned to measure the parity violating small rotation of the neutron spin due to the weak interaction when the neutron passes through a material such as Bi or Sn. A still larger rotation may be studied when the molecules of the medium are optically active (cork screw shaped). 相似文献

16.

Neutron-proton shell model multiplets in ⁸⁸Y and ⁹⁰Y from a study of the (α, nγ) reaction

H.W. Baer R.L. Bunting J.E. Glenn J.J. Kraushaar 《Nuclear Physics A》1974,218(2):355-371

The non-selective nature of the (α, nγ) reaction has been used to complement information from charged-particle reactions on the level structure of ⁸⁸Y and ⁹⁰Y. The γ-ray spectra were recorded with a 25 cm³ Ge(Li) detector at 90° to the beam using primarily targets of ⁸⁵Rb₂CO₃ and ⁸⁷Rb₂CO₃ and α-particle energies of 11.8, 12.2 and 13.0 MeV. The resulting transitions were accommodated in level schemes that involved primarily the following shell model configurations:

(π p_{12})^{1} (ν g_{92})^{?1}

,

(π g_{92})^{?1} (ν g_{92})^{1}

,

(π p_{12})^{1} (ν p_{12})^{?1}

,

(π f_{52})^{?1} (ν g_{92})^{?1}

in ⁸⁸Y and

(π p_{12})^{1} (ν d_{52})^{1}

,

π g (_{92})^{1} (ν d_{52})^{1}

,

(π p_{12})^{1} (ν s_{12)})^{1}

in ⁹⁰Y. 相似文献

17.

Study of the germanium isotopes with the (p,t) reaction

G.C. Ball R. Fournier J. Kroon T.H. Hsu B. Hird 《Nuclear Physics A》1974,231(2):334-348

The levels of ^{70, 71, 72, 74}Ge have been investigated with the (p, t) reaction at 20 MeV. Strong transitions to the ground state and to the 2₁⁺ and 3₁^? collective levels were observed for all even isotopes. A comparison of the experimental angular distributions with those calculated assuming a closed ⁷⁰Ge core indicates that only ≈ 15% of the observed ground state L = 0 transition strength comes from

(1 g_{92})^{2} and (2 p_{12})^{2}

pick up. The excitation energies and L-transfers obtained in the present work are found to be in generally good agreement with previous data. 相似文献

18.

Generalized neutron particle-hole states in an extended unified model

K. Heyde M. Waroquier H. Vincx P.J. Brussaard 《Nuclear Physics A》1974,234(1):216-252

Negative-parity levels in the doubly even N = 82, Z nuclei, with 3.0 MeV ? E_x? 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.

2 d_{32}^{?1},3 s_{S_{12}}^{?1},2 d_{52}^{?1},1 g_{72}^{?1}

) are coupled to the low-lying levels (E_x ? 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 ?E_x ? 6.0 MeV. 相似文献

19.

The g-factor difference for the 6₁⁺ and 8₈⁺ states in ²¹⁰Po

C.V.K. Baba D.B. Fossan T. Faestermann F. Feilitzsch P. Kienle C. Signorini 《Physics letters. [Part B]》1973,43(6):483-486

The difference in g-factors for the 6₁⁺ and 8₁⁺

(πh_{92}^{2})

states in ²¹⁰Po has been measured as

(g_{6} ? g_{8}) g_{8} = 2.0 ± 0.7%

. This result represents a small violation of additivity. A value of g₈ = 0.909 ± 0.011, independent of g₆, was also obtained. 相似文献

20.

Shell-model study of ⁴⁴Ti using a pairing-plus-surface-tensor interaction

D. Banerjee 《Nuclear Physics A》1974,236(1):67-76

相似文献