共查询到20条相似文献,搜索用时 628 毫秒
1.
C. Günther H. Hübel A. Kleinrahm R. Kulessa H. Emling P. Fuchs E. Grosse D. Schwalm H. J. Wollersheim J. Idzko H. Ower 《Zeitschrift für Physik A Hadrons and Nuclei》1981,301(2):119-123
Multiple Coulomb excitation measurements on198, 200Hg have been performed with 5MeV/amu208Pb projectiles andB(E2)-values are determined for transitions between states up to spin 8+. In198Hg a reduction of theB(E2)-value for the yrast transition 8+→6+ by a factor of 3 as compared to the rigid rotor prediction is observed, which supports the earlier proposed idea that the ground state band is crossed between the 6+ and 8+ state by a weakly interactingvi 13 2/2 rotation aligned band. In each of the two nuclei,198Hg and200Hg, a state with a possibleI π=8+ assignment is observed, which is tentatively interpreted as the 8+ member of the ground state band. 相似文献
2.
R. S. Simon F. Folkmann Ch. Briançon J. Libert J. P. Thibaud R. J. Walen S. Frauendorf 《Zeitschrift für Physik A Hadrons and Nuclei》1980,298(2):121-128
In the actinides bothi 13/2 protons andj 15/2 neutrons are close to the Fermi surface. At rapid rotation these high-j particles will unpair and align their orbital angular momentum along the axis of rotation giving rise tos-bands that cross the ground-state band. Coulomb excitation of the odd nuclei 237 93 Np (established up to the 45/2+ state) and 235 92 U (established up to the 51/2? state) provides specific information about these band crossings: From the saturating alignment of the odd high-j particle in both nuclei at intermediate rotational frequencies we find the aligned angular momentum of thei 13/2 protons-band to be 6.6? while the corresponding value for thej 15/2 neutrons-band is 5.5?. At more rapid rotation above ?ω=0.18 MeV we observe additional alignment in235U. This is ascribed to the interaction of the protons-band. From the gradual onset of the additional alignment we deduce that forZ=92 the protons-band interacts strongly with the ground-state band and from a comparison of the actual amount of alignment with the full value of 6.6? we estimate the crossing to occur around ?gw c p =0.25 MeV. 相似文献
3.
I. Bergström J. Blomqvist C. J. Herrlander C. G. Lindén 《Zeitschrift für Physik A Hadrons and Nuclei》1976,278(3):257-264
Using the204Hg(α, pn)-reaction andα-particles of energies 39–55 MeV, we have found an isomeric 3.6 min 12? state in206Tl at 2,642.9 keV which has the two-hole configurationπh 11 2/?1 vi 13 2/?1 The 12? state decays mainly by anE5 transition of energy 1,021.4 keV to a 7+ state at 1,621.5 keV whose main configuration isπs 1 2/?1 vi 13 2/?1 There is, in addition, evidence for a weak 565 keVM 4 branch to an 8+ state at 2,078 keV whose main configuration should beπh 11 2/?1 vf 5 2/?1 . The 7+ state decays by a stretched cascade ofγ-rays to states of the following values ofJ π and excitation energy: 5 ? + , 1,405.4 keV; 4?, 952.1 keV; 2?, 265.8 keV and 0?, 0 keV. The main configurations of these states areπh 11 2/?1 vp 1 2/?1 ,πd 3 2/?1 vf 5 2/?1 ,πd 3 2/?1 vp 1 2/?1 andπs 1 2/?1 vp 1 2/?1 respectively. From the nuclear masses of208Pb,207Pb,207Tl, and206Tl and the experimental excitation energies it is possible to obtain the proton hole-neutron hole interaction in206Tl. This interaction is compared with the calculations of Kuo and Herling and the discrepancies are discussed. The 12?→8+ M4 transition rate is reduced because of destructive interference between the protonh 11/2→d 3/2 and the neutroni 13/2→f 5/2 contributions. The magnitude of the reduction is accurately reproduced by the wave functions of Kuo and Herling. The 12?→7+ E5 transition rate is about twice as large as the single-holeπh 11 2/?1 πs 1 2/?1 transition rate. This deviation is fully explained by the configuration admixtures in the 7+ state, given by Kuo and Herling. 相似文献
4.
5.
M. Piiparinen R. Broda Y. Nagai P. Kleinheinz A. Pakkanen 《Zeitschrift für Physik A Hadrons and Nuclei》1981,301(3):231-235
From (p, xn) in-beamγ-ray and electron measurements aT 1/2=235(14) ns isomer at 720 keV was identified in 63 148 Eu85 and the levels populated in its decay have been characterized. The results determineI π=9+ for the isomeric state, and we assign it as the (πh 11/2 j 0 ?2 ν f 7 2/3 )9+ shell model state, analogous to the configuration of the 235 μs isomer in 63 146 Eu83. 相似文献
6.
We have performed a two-channel calculation of Cabibbo-angle favoured decays,D s + →VP. We find a satisfactory fit toS s + →φπ +,ρ 0 π + andK + \(\bar K^{ * 0} \) data from ARGUS and E-691. We have also studied Cabbibo-angle favouredD→VP decays in a coupled channel formalism. We coupleD→K *π,K ? and \(\bar K^0 \phi \) channels inI=1/2 state, andK *π andK ? channels inI=3/2 state. We leave the two channels, \(\bar K^0 \omega \) and \(\bar K^{ * 0} \eta \) out of our unitarization scheme. Particular attention is paid to the role of the weak annihilation term in these decays. 相似文献
7.
A. Alzner E. Bodenstedt B. Gemünden J. van den Hoff S. Fiel R. Sajok H. Koch Th. Schäfer R. Vianden 《Zeitschrift für Physik A Hadrons and Nuclei》1988,331(3):277-286
The followingg-factors have been derived from time integral measurements of γ-γ angular correlations in the static magnetic hyperfine field of magnetized gadolinium metal probes:156Gd:g(4 1 + )=+0.310(19)g(6 1 + )=+0.25(21)g(4 3 + , 1511 keV)=+0.809(27)158Gd:g(4 1 + )=+0.409(15). The 5.35d 156Tb sources were produced by the reaction156Gd(d, 2n)156Tb in our cyclotron. A carrier-free 150y 158Tb source was obtained from ISOLDE/CERN. In comparison with the precisely knowng-factors of the 2 1 + states,g(2 1 su+ ,156Gd) =+0.386(4) andg(2 1 + ,158Gd)=0.381(4), we observe a large reduction for the156Gd 4 1 + state whereasg increases slightly for158Gd. The half-life of the 4 1 + state of158Gd was remeasured as158Gd:T 1/2(4 1 + )=148(2) ps. A measurement of the rotation in the 4 3 + state of156Gd in external magnetic fields of various strengths up toB ext=9.5 T did not confirm the anomalous dependence of the magnetic hyperfine field in gadolinium metal on the external field, which has been reported by Persson et al. [29]. 相似文献
8.
C. G. Lindén I. Bergström J. Blomqvist C. Roulet 《Zeitschrift für Physik A Hadrons and Nuclei》1978,284(2):217-231
High-spin states in204Pb were populated in the204Hg(α,4n) reaction using α-particles in the energy region 42–51 MeV. Prompt and delayedγ-rays as well as conversion electrons were studied in addition to excitation functions, angular distributions andγ-γ coincidences. In this way a stretched cascade ofγ-rays from a level at 8125.9 keV was found to feed the previously known isomeric 9? level at 2185.7 keV. Spins and parities were established for levels up to and including a 19? level at 6098.0 keV. The levels with c= 172212; and 19? at excitation energies of 5664.3 and 6098.0 keV are likely to be due to the simplep 1 2/s-1 i 13 2/?3 andf 5 2/?1 i 13 2/?3 configurations. The agreement between calculated and experimental energies for all observed levels in the regionJ=9–19 is very good in cases where the empirical two-particle interactions used are satisfactorily well known. Above the 19? level there are three weakly populated levels at 7402.1, 7849.2 and 8125.9 keV, which are likely to haveJ≥20. None of these energies agrees with the calculated value 7695±20 keV for the 20+ state of thei 13 2/?4 configuration which has the highest angular momentum produced by the four valence neutron holes. This apparent anomaly can be understood if the yrast levels withJ≥20 have angular momentum contribution from the core. It seems likely that the states at 7402.1, 7849.2 and 8125.9 keV are due to proton core excited states of the typeπh 9/2 h 11 2/?1 ×νp 1 2/?2 i 13 2/?2 withJ π=20+ andJ π=21+ andπh 9/2 h 11 2/?1 ×νp 1 2/?1 f 5 2?1 i 13 2/?2 withJ π=22+ or 23+, respectively. The state at 8126 keV has the highest energy so far directly observed in a stretched cascade ofγ-rays from the decay of a heavy nucleus produced in (α, xn) reactions. 相似文献
9.
Absolute values of the excitation cross sections of the (0,0) bands [for O+(4 S), O+(2 P)-N2 pairs] and the (0,0), (0,1), (1,2), and (2,3) bands [for N+(3 P)-N2 pairs] of the first negative system of the N 2 + ion have been measured in collisions with nitrogen molecules of nitrogen and oxygen ions in the ground state and in a metastable state in the interval of ion energies 1–10 keV. The process of excitation of the (0,0) band of the first negative system of the N 2 + ion by oxygen ions in the metastable 2 P state is of a quasi-resonant character. The presence in the beam of ions in metastable states was monitored by measuring the excitation efficiency of the (0,0) band λ3914 Å of the N 2 + ion in different operating regimes of the highfrequency ion source. For N+ ions in the 3 P ground state, as the collision frequency is decreased the relative vibrational population of the v′=1 and v′=2 levels of the B 2Σ u + state of the N 2 + ion is observed to deviate strongly from the value calculated in the Franck-Condon model. 相似文献
10.
Paramagnetic centers of NH 3 + , Al, and HO2 · have been observed in alkali feldspars from Aichi prefecture, Japan. The quartet signal has been tentatively ascribed to NH 3 + rather than to ·CH3, although the hyperfine splitting by14N (I=1) was not observed. The averageg- andA-valuesg av=2.0033 andA av H =2.45 mT, respectively, were attributed to hydrogen. The powder spectra of Al centers stable up to 400 K were simulated by the anisotropicg factors ofg zz =2.060,g xx =2.0014,g yy=2.0021 andA=0.9 mT. Newly discovered HO2 · is stable up to 570 K. The intensities of the spectra from NH 3 + and Al centers were enhanced by gamma-ray irradiation, while that of HO2 · was not enhanced. Production efficiency,G-value (radical/100 eV) of NH 3 + has been obtained to beG=0.01. These results suggest that ESR dating of feldspars is possible. 相似文献
11.
I. Blomqvist B. Bülow A. Fredrikson B. Johnsson G. G. Jonsson K. Lindgren M. Nilsson R. Petersson O. Glomset N. Freed W. Rhodes 《Zeitschrift für Physik A Hadrons and Nuclei》1978,284(3):313-317
The lifetime of the 331.3 keV 0 2 + state in100Zr has been measured at the gas-filled recoil separator for fission products JOSEF. By observing the delayed coincidences between theβ-particles populating the level and theE0 conversion electrons from its decay into the ground state, a half-life of 3.37±0.30 ns has been obtained. From the measured lifetime and the relative intensities of the 0 2 + →0 1 + and 0 2 + →2 1 + transitions, values of 0.493±0.015 for theE0 strength parameterρ, and of 16 single particle units forB(E2,2 1 + → 0 2 + ) have been deduced. The enhanced nature of theE0 transitions suggests mixing of the 0 1 + and 0 2 + states which may be estimated by comparing the experimentalB(E2) values for the 2 1 + →0 1 + and 2 1 + →0 2 + transitions with the predictions of the asymmetric VMI model. 相似文献
12.
K. -H. Speidel V. Mertens W. Trölenberg M. Knopp H. Neuburger K. Bharuth-Ram J. Gerber 《Zeitschrift für Physik A Hadrons and Nuclei》1984,315(3):319-323
The transient field technique has been used to determine theg-factor of the 4 2 + state at 6.010MeV excitation in24Mg. The deduced value ofg=+0.5(4) is consistent with collective model expectations. Further, the equality within experimental accuracies, of the g-factors of the 2 1 + , 2 2 + , 4 1 + and 4 2 + states agrees with theoretical predictions for thisT=0 self-conjugate nucleus, in contrast to the results for20Ne. 相似文献
13.
G. de Angelis S. Lunardi D. Bazzacco J. Rico F. Terrasi M. Piiparinen A. Atac J. Nyberg 《Zeitschrift für Physik A Hadrons and Nuclei》1993,347(2):93-98
An in-beamγ-ray study performed with the114Cd(30Si,p 3n) reaction has established the structure of theN=79 nucleus140Pm. States up toI=(20)? and 5.5 MeV excitation energy have been recognized above the 5.95 m isomeric state which we identify, from the GT decay to140Nd, as the 8? member of the (πd 5 2/?1 vh 11 2/?1 ) multiplet, changing the present 7? assignment. The low energy part of the level scheme is discussed in terms of the coupling of the valence holes in respect to theZ=64,N=82 shell closure. A new 8+ isomeric state witht 1/2=1 ?0.5 +1 ns has been observed, having most likely a (πh 11/2 vh 11/2 -1 )8 configuration. 相似文献
14.
Coulomb excitation byα-particles of vibrational-like states in even-mass rare-earth nuclei is used to determine the reduced transition probabilitiesB(E2; 0 gs + →2 γ + ),B(E2; 0 gs + →2 β + ),B(E2; 2 gs + →0 β + ) andB(E2; 0 gs + →3 oct ? ) in150Nd,152, 154Sm,154, 158Gd,164Dy and166Er. TheB(Eλ; 0 gs + →I=λ)-values range from 2.4 to 6.5 single-particle units for transitions to the 2 γ + -states, 0.8 single-particle units for the 2 β + -states and from 14.1 to 21.7 single-particle units for the 3?-states. 相似文献
15.
R. Kuchta 《Zeitschrift für Physik A Hadrons and Nuclei》1988,331(3):243-253
Starting from an isospin invariant shell-model hamiltonian, we describe a method for deriving microscopically the IBM-hamiltonian appropriate to lights d-shell nuclei. The key ingredients of our approach are:a) the Belyaev-Zelevinsky-Marshalek (BZM) bosonization procedure;b) two successive unitary transformations that extract the “maximally decoupled” collective bosons with angular momentaJ=0(s ππ + ,s νν + ,s πν + ) andJ =2(d ππ + ,d νν + ,d πν + (T=0),d πν + (T=1)). The method is applied to obtain the low-energy spectra and the electron scattering form factors for the 0 1 + →2 1 + transitions in20Ne and24Mg. Good agreement with the exact shell-model results is achieved. The inclusion of proton-neutron bosons (s πν + ,d πν + (T=1),d πν + (T=0)), as well as the renormalization of boson parameters due to the non-collective degrees of freedom, are shown to play a crucial role. 相似文献
16.
Studies of the time dependencies of the number density of N 2 + , Ne+ and Ne 2 + ions have been made during the decay period of plasmas produced in neon containing various concentrations of nitrogen molecules. Reaction rate constants were obtained for N 2 + +N2+Ne→N 4 + +Ne((1.2±0.2)×10?29 cm6 sec?1) and Ne++N2→N 2 + + Ne ((2.9±0.3) × 10?12 cm3 sec?1). The ambipolar diffusion coefficient of N 2 + in neon was found to beD a p o =350±20 cm2 sec?1 Torr. 相似文献
17.
The symmetric charge-exchange reaction of fast N 2 + ions (U ion=800 eV) has been investigated by the method of laser-induced fluorescence. The distinction between the primary N 2 + ion beam and the N 2 + ions formed by charge-exchange was possible because of the different velocities of the two species which resulted in two spectral distributions separated by the Doppler-shift. Simulation techniques have been used in order to obtain rotation-vibration distributions for both the inelastically scattered fast ions and the charge-exchange products. The rotation distributions could be described by a temperature of 1,000 K for the inelastic and 300 K for the charge-exchange process. The latter process exhibits, however, a significant vibrational excitation which is attributed to the existence of a stable intermediate complex of N 4 + . The preferred geometry for the intermediate collision complex is assumed to be non-planar. 相似文献
18.
It was shown that optical bleaching of M A + color centers at 80 K in SrF2-Na crystals causes the core of an M A + -center to transform into the V a + Me + V a + configuration, in which all three point defects are arranged diagnonally in the cube cell. Reirradiation of an optically bleached crystal by x-rays generates F D centers in it: V a + Me + V a + + e ? → V a 0 Me + V a + ≡ F D. The F D → M A + transformation in SrF2-Na crystals proceeds at T = 135 K, in contrast to the F A → M A + transformations, which take place at T > 200 K. 相似文献
19.
Gerd Bergmann 《Zeitschrift für Physik B Condensed Matter》1997,102(3):381-383
It is numerically shown that the groundstate of the Friedel problem (consisting of a conduction band and a dresonance), occupied with (n+ 1) electrons, can be written as Ψ = (A a 0 * +Bd*) Π v=1 n a v * Φ0, where a 0 * represents a localized conduction electron state, d* is the Friedel resonance state and Π v=1 n a v 8 Φ0 is a Slater determinant of n single electron states a t * , (Φ0 is the vacuum state). The a i * together with a 0 * are part of a full ortho-normalized basis of the conductions band. 相似文献
20.
G. Menzen A. Wolf H. Lawin G. Lhersonneau K. Sistemich 《Zeitschrift für Physik A Hadrons and Nuclei》1985,321(4):593-598
Theg factors of the first excited 2+ levels in the neutron-rich nuclei102Mo and104Mo have been studied through the measurement of the perturbed angular correlations for theγ-γ cascades between the 0 2 + -2 1 + -0 1 + level sequences. The results of g=0.42±0.07 for102Mo and ofg= ?0.11 +0.12 for104Mo agree with the prediction of the vibrational-rotational model. In terms of IBA, with the assumption ofN π=3 for the Mo isotopes which takes into consideration a two particle, two-hole excitation across the Z=40 subshell, the proton-bosong factor is deduced to beg π=1.00±0.23. It is shown that this value provides evidence for subshell effects in100Zr. 相似文献