共查询到20条相似文献,搜索用时 15 毫秒
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Two new di-nitrogen centers, which were labeled M2 and M3, were found together with known W7 and N4 centers in an unusual reddish-brown natural diamond. The following magnetic hyperfine interaction parameters (expressed in MHz) were determined for the two nitrogen atoms:A 1 (1) =117.95(5),A 1 (2) =A 1 (3) =84.48(5),A 2 (1) =7.1(1),A 2 (2) =A 2 (3) =6.6(1) for M2 andA 1 (1) =121.55(5),A 1 (2) =A 1 (3) =85.90(5),A 2 (1) =6.0(1),A 2 (2) =5.4(1),A 2 (3) =5.1(1) for M3. Hyperfine interaction tensors for the nitrogen atom N1 with a larger interaction have axial symmetry about the <111> direction, but those for the other nitrogen atom, N2, appear to be small, almost isotropic. Probable models of the M2 and M3 centers are suggested and discussed. 相似文献
3.
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
4.
M. Chaichian M. Hayashi K. Yamagishi 《Zeitschrift fur Physik C Particles and Fields》1983,20(3):237-241
The angular distributions of high-mass dileptons with large transverse momentum produced in longitudinally polarized hadronic collisions, hadron +hadron→(γ*,Z 1 0 ,Z 2 0 , ...)+X→l + l ?+X, are calculated in the QCD lowest order. The formulas presented in general form, are applicable to any gauge model of underlying electroweak interactions. Numerical results are obtained for the angular distributions in \(\bar p\) p-collisions at \(\sqrt s = 540GeV\) for the Weinberg-Salam,SU(2)×U(1)×U(1)′ andSU(2)×SU(2)′×U(1) models. Clearly distinguishable signals are revealed. 相似文献
5.
A. E. Stuchbery H. H. Bolotin C. E. Doran I. Morrison L. D. Wood H. Yamada 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(4):669-674
The gyromagnetic ratios of the 4 1 + , 6 1 + , and 2 2 + states in186W were measured relative to that of the 2 1 + level by means of the transient field implantation perturbedγ-ray angular distribution technique. The nuclei in the states of interest were Coulomb excited using a beam of 220-MeV63Cu projectiles and recoiled swiftly through a thin, polarized Fe foil. The present measurements yielded ratiosg(4 1 + )/g(2 1 + )=1.04±0.07,g(6 1 + )/g(2 1 + )=1.03 ±0.20 andg(2 2 + )/g(2 1 + )=0.63±0.13. The sizable disparity between the measuredg-factors of the ground- and excited-band is examined within the context of the interacting boson approximation model. 相似文献
6.
H. Haberland C. Ludewigt H. Schindler D. R. Worsnop 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(1):151-153
Beams of Ar m (H2O) 2 ? ,m=0 to 4, are passed through an electric field and separated with a quadrupole mass spectrometer. Form<=2 the signal disappears at 31±1 kV/cm. Form=3 and 4 and larger (H2O) n ? (n≧6) no field detachment is observed up to 40 kV/cm. The application of these results to the binding of excess electron in water clusters is discussed. 相似文献
7.
J. L. Goity 《Zeitschrift fur Physik C Particles and Fields》1987,34(3):341-345
We calculate theK S Emphasis>0 →γγ decay within the approach of non-linear realization of chiralS U(3)×S U(3). The branching ratio with respect to theπ + π - channel turns out to be 3.5×10?6 and therefore similar to the result gotten previously by dispersion relation techniques in a non-chiral model. We also discuss theK L 0 →γγ decay by taking into account new results onη 1-η 8 mixing from recent measurements of the η→γγ decay. 相似文献
8.
Prof. Dr. A. Scharmann K. -H. Schartner 《Zeitschrift für Physik A Hadrons and Nuclei》1969,219(1):55-69
The polarization degree of then 1 S-21 P(n=3, 5)-,n 1 D-21P(n=3, 4, 5)- andn 1 P-21 S(n=3, 4)-transitions of helium excited by proton impact has been measured in the energy range of 100 keV to 1 MeV. The results in connection with respective H 2 + - ande ?-impact values are used in a comparison with the principle statements of the 1. Born- and the Bethe-Born-approximation. The results are in a qualitative agreement with the theoretical calculations. 相似文献
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10.
B. Berg 《Zeitschrift fur Physik C Particles and Fields》1983,20(3):243-245
Using the background field technique I computeι L I /ι L S =e (0.5928(N?)/2+0.2044)/(N?2) in agreement with a calculation by Symanzik. Implications for Monte Carlo simulations are also discussed. 相似文献
11.
A. I. Reznikov S. Ya. Umanskii Yu. A. Chaikina 《Russian Journal of Physical Chemistry B, Focus on Physics》2007,1(5):465-471
An asymptotic method was used to derive analytical expressions for the matrix elements of interaction between the N2 molecule in the X 1Σ g + and A 3Σ u + electronic states and the Zn atom in the 1 S and 3 P states. Quadrupole-quadrupole, dispersion, and exchange interactions were taken into consideration. The character of the set of diabatic vibronic potential energy surfaces of the system suggests that the energy transfer in the process N2(A 3Σ u + ) + Zn(1 S) → N2(X 1Σ g + ) + Zn(3 P) may prove to be rather effective. 相似文献
12.
Using the experimentally measured values ofx=A 2(0)/A 1(0) andy=V(0)/A 1(0) and the measured ratiosR st=Γ(D s + →φl + ν l)/Γ(D ins + →φπ +) andR h=Γ(D s + →φρ +)/Γ(D s + →φπ +), we present evidence for significant nonfactorization contribution in the decay amplitude forD s + →φπ +. We analyze the role of nonfactorization inD s + →φρ + and conclude that present data onR h are consistent with factorization inD s + →φρ +. A measurement of polarization inD s + →φρ + would greatly assist our analysis. 相似文献
13.
L. K. Kostov W. Andrejtscheff L. G. Kostova A. Dewald K. O. Zell P. von Brentano 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):179-184
The lifetimes of several negative-parity states in126,130Xe and132Ba have been determined by means of the generalized centroid-shift method. The reactions124,128Te(α,2n) and122Sn(13C, 3n) have been used. Following results were obtained:T 1/2(2758 keV)=1.3±0.2 ns in126Xe,T 1/2(2060 keV)=0.20±0.10 ns,T 1/2(2104 keV)=0.50±0.10 ns,T 1/2(2376 keV)=0.30±0.10 ns andT 1/2(2973 keV)=4.6±0.4 ns in130Xe as well asT 1/2(2120 keV)=0.40 ?0.10 +0.20 ns in132Ba. A systematics of the B(E2; 7 ? 1 ?5 1 ? ) values in theN=76 nuclei is presented. Electric dipole and quadrupole transition rates are discussed in terms of octupole and quadrupole collectivity. The structure of the 5 1 ? and 7 1 ? states is considered. Nuclear reactions:124,128Te(α, 2 n ),E=26 MeV,122Sn (13C, 3n),E=53 MeV; measuredE γ I γ , γ-r.f. DeducedT 1/2, B(σL) in126,130Xe and132Ba. Ge detectors. Generalized centroid-shift analysis. 相似文献
14.
I. Alfter E. Bodenstedt B. Hamer J. van den Hoff W. Knichel H. Münning S. Piel R. Sajok J. Schüth 《Zeitschrift für Physik A Hadrons and Nuclei》1993,345(3):273-283
Theg-factors of the four lowest states of the ground state rotational band of158Dy have been determined asg(2 1 + )=+0.362(23),g(4 1 su+ )=+0.340(20),g(6 1 su+ )=+0.207(36) andg(8 1 su+ )=+0.21(11). Theg-factors of the 2+ and 4+ states were measured by the IPAC method with radioactive samples of 2.4 h158Er in external magnetic fields. To investigate the higher states, for the first time an on-line γ—γ IPAC experiment was performed with the reaction156Gd(α, 2n)158Dy by use of the static hyperfine field of DyGd. 相似文献
15.
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
16.
Peter Kumlin 《Communications in Mathematical Physics》1992,144(2):257-278
The wave and scattering operators for the equation $$\left( {\square + m^2 } \right)\varphi + \lambda \varphi ^2 = 0$$ withm>0 and λ>0 on four-dimensional Minkowski space are analytic on the space of finite-energy Cauchy data, i.e.L 2 1 (R 3)⊕L 2(R 3). 相似文献
17.
F. V. Demekhin D. V. Omel’yanenko B. M. Lagutin V. L. Sukhorukov L. Werner A. Ehresmann K. -H. Schartner H. Schmoranzer 《Russian Journal of Physical Chemistry B, Focus on Physics》2007,1(3):213-221
The dynamics of predissociation of the 2σ u ?1 (c 4Σ u ? ), v vibrational states of the O 2 + ion was studied theoretically using the method of coupled differential equations. The main equations describing the vibrational motions of nuclei in the adiabatic and diabatic approximations are given. The applicability scope of approximate methods for solving these equations was studied. The predissociation widths for the v = 0 and 1 vibrational levels were found to be Γ0 = 0.054 meV and Γ1 = 9.71 meV. This substantiated the results of recent observations of neutral fragments formed after the dissociation of the O2 molecule. About 99% of the O 2 + ions in the 2σ u ?1 (c 4Σ u ? ), v states were found to decompose to the O(1 D) + O+(4 S) dissociation products. 相似文献
18.
V. F. Kurshetsov Yu. M. Antipov A. V. Artamonov V. A. Batarin O. V. Eroshin V. Z. Kolganov A. S. Konstantinov A. P. Kozhevnikov A. E. Kushnirenko L. G. Landsberg V. M. Leontiev G. S. Lomkatsi V. V. Molchanov V. A. Mukhin A. F. Nilov D. I. Patalakha S. V. Petrenko V. T. Smolyankin D. V. Vavilov V. A. Victorov 《Physics of Atomic Nuclei》2005,68(3):439-454
A search for narrow Θ+(1540), a candidate for a pentaquark baryon with positive strangeness, has been performed in an exclusive proton-induced reaction $p + C(N) \to \Theta ^ + \bar \kappa ^0 + C(N)$ on carbon nuclei or quasifree nucleons at $E_{beam} = 70GeV(\sqrt s = 11.5GeV)$ studying nK +, pK S 0 , and pK L 0 decay channels of Θ+(1540) in four different final states of the $\Theta ^ + \bar K^0 $ system. In order to assess the quality of the identification of the final states with neutron or K L 0 , we reconstructed Λ(1520) → nK S 0 and ? → K L 0 K S 0 decays in the calibration reactions p + C(N) → Λ (1520)K ++C(N) and p+C(N) → p?+C(N). We found no evidence for a narrow pentaquark peak in any of the studied final states and decay channels. Assuming that the production characteristics of the $\Theta ^ + \bar K^0 $ system are not drastically different from those of the Λ(1520)K + and p? systems, we established upper limits on the cross-section ratios $\sigma (\Theta ^ + \bar K^0 )/\sigma (\Lambda (1520)K^ + ) < 0.02$ and $\sigma (\Theta ^ + \bar K^0 )/\sigma (p\phi ) < 0.15$ at 90% C.L. and a preliminary upper limit for the forward-hemisphere cross section $\sigma (\Theta ^ + \bar K^0 )$ nb/nucleon. 相似文献
19.
Electric monopole transitions between the 0 2 + , 0 1 + and 2 2 + , 2 1 + levels in76Se, populated in the decay of76Br, were investigated by means of conversion electrons and gammaray spectroscopy. TheK-electron intensity ratios ofE0 andE2 transitions connecting the 0 2 + level to the 0 1 + and 2 1 + levels and of theE0 andE2 components in the 2 2 + →2 1 + transition were determined. The ratioX(E0/E2) of theE0 toE2 reduced transition probabilities and, from the available lifetimes, theE0 strength parameters ρ(E0) were deduced for the two transitions. The results are compared with the predictions of current models. 相似文献