共查询到20条相似文献,搜索用时 31 毫秒
1.
G. Mairle G.J. Wagner P. Grabmayr K.T. Knöpfle H. Riedesel K. Schindler V. Bechtold L. Friedrich P. Ziegler 《Nuclear Physics A》1982,382(2):173-184
The reactions have been investigated at Ed = 52 MeV. Vector analyzing powers as large as 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
2.
J. Gasser 《Annals of Physics》1981,136(1):62-112
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 . We find that the quark mass ratios must lie in the range and . 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
3.
K. Moriyasu T. Burnett D. Holmgren H.J. Lubatti D. Rees G. Swider B. Yuldashiev K. Dziunikowska A. Eskreys K. Eskreys A. Gula D. Kisielewska H. Rudnicka P. Stopa W. Ko R.L. Lander J.S. Pearson D. Pellett A. Zieminski 《Nuclear Physics B》1978,137(4):377-389
Double-scattering effects are studied in π?d interactions at 360 GeV/c. The partial cross sections are presented. The double-scattering probability per πd collision is found to be . We have extracted the partial cross section XN of the double-scattering plus interference contributions, and find that XN obeys KNO scaling. The data are compared with various theoretical predictions. 相似文献
4.
The results of a vibrational and rotational analysis of the banded transition in are presented. Only three of the six vibrational modes are active in the spectrum with , , and . The spin forbidden transition gains intensity primarily by a mixing of the and states. This is confirmed by a rotational analysis of the 000 band of both isotopes. The rotational analysis shows that the coupling in the state is near Hund's case b and that the spin constants are nearly 10 times greater than those observed for CH2O. A calculation shows that this difference is due to the greater spin orbit coupling of S in CH2S and to the smaller energy differences between the , , , and the states. The r0 structure calculated from the rotational constants is , , βHCH = 119.6°, and α (out of plane) = 16.0°. A simultaneous fit of the vibrational levels in ν′4 of CH2S and CD2S to a double minimum potential function yielded a barrier to molecular inversion of 13 cm?1 and an equilibrium out-of-plane angle of 15°. 相似文献
5.
Michał Praszałowicz 《Physics letters. [Part B]》1985,158(3):264-269
We find that the realistic baryon mass spectrum in the SU(3) Skyrme model with massive 0? mesons can be obtained only for Fπ < 70 MeV. We fit mΛ and and obtain baryon masses within the limits of ± 16% of the experimental val ues, but at the expense of very low ifFπ=46.32 MeV. 相似文献
6.
The relativistic generalization of the Thomas-Fermi model of the atom is derived. It approaches the usual nonrelativistic equation in the limit Z ? Zcrit, where Z is the total number of electrons of the atom and and α is the fine structure constant. The new equation leads to the breakdown of scaling laws and to the appearance of a critical charge, purely as a consequence of relativistic effects. These results are compared and contrasted with those corresponding to N self-gravitating degenerate relativistic fermions, which for give rise to the concept of a critical mass against gravitational collapse. Here m is the mass of the fermion and is the Planck mass. 相似文献
7.
The magnetic hyperfine splitting vM=|gμNBHF/h| of 196mAu (jπ=12?; configuration ¦(π(; 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 and isomeric states in the neighbouring odd Pt, Au and Hg nuclei the structure of the 12? state is discussed. 相似文献
8.
H. Braun M. Cornelssen H.-U. Martyn O. Erriquez S. Natali F. Romano D. Bertrand M. Csejthey-Barth J. Lemonne P. Renton P. Vilain D.C. Cundy T.I. Pedersen D. Waldren 《Physics letters. [Part B]》1973,47(2):185-188
The q2 variation of the factor 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 with λ+=0.027±0.008. 相似文献
9.
S. Cochavi S. Gilad M.A. Moinester J. Alster M. Buenerd P. Martin 《Nuclear Physics A》1974,233(1):73-80
The 91Zr(d, 3He) reaction was studied at a deuteron energy of 28 MeV. Angular distributions were measured from 13° to 47°; lp values were extracted for the prominent lines of 90Y. The lp values and transition strengths were determined by DWBA analysis. The angular distributions for the doublet (g.s. and 0.20 MeV state) exhibit the characteristic l = 1 shape. States at 1.42, 1.57, 1.64 and 1.81 MeV were also populated strongly in the (d, 3He) reaction; the 1.42, 1.57 and 1.81 MeV levels contain l= 1 transition strength and are most likely members of the multiplet. The 2.03 MeV state has a characteristic l = 3 angular distribution and is suggested to be the only member of the sextet to be unambiguously observed in this study, most probably the 5? or 4? member. The members of the sextet were populated weakly (less than 100 μb/sr) in this reaction. 相似文献
10.
P. Benkheiri J. Boucrot B. Bouquet P. Briandet B. DAlmagne C.Dang Vu B. Eisenstein A. Ferrer P. Fleury B. Grossetête G. Irwin A. Jacholkowski A. Lahellec H. Nguyen P. Petroff F. Richard P. Rivet G. De Rosny H. Yoshida 《Physics letters. [Part B]》1977,68(5):483-486
From the study of the reaction using a fast proton (pF) trigger device in the CERN Omega spectrometer, we find evidence for two narrow states produced mainly in association with a Δ° (1232) and a N° (1520). The statistical significance of each peak is greater than 6 standard deviations. Masses and natural widths of these resonances are respectively M = 2020 ± 3 MeV, Λ1 = 24 ± 12 MeV and M2 = 2204 ± 5 MeV, Λ2 = 16?16+20 MeV. Our data are consistent with a small production of the narrow ~ 1935 MeV resonance already reported. Production cross sections for these new resonances are given. 相似文献
11.
12.
Negative-parity levels in the doubly even N = 82, Z nuclei, with 3.0 MeV ? Ex? 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. ) are coupled to the low-lying levels (Ex ? 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 ?Ex ? 6.0 MeV. 相似文献
13.
The threshold behaviour of pion production presented in our earlier work is successfully compared with the new SPEAR data. By using duality and sum rules we derive FT(π+)(x) ≈ FL(π+)(x) ≈ FT(π0)(x) ? FL(π0)(x) for x near 1. An accompanying results is for large s. 相似文献
14.
S. Iversen H. Nann A. Obst Kamal K. Seth N. Tanaka C.L. Morris H.A. Thiessen K. Boyer W. Cottingame C. Fred Moore R.L. Boudrie D. Dehnhard 《Physics letters. [Part B]》1979,82(1):51-54
π+ and π? elastic and inelastic scattering from 18O have been measured at T(π)=164 MeV. Consistent with the results at 230 MeV, it is found that the ratio for the 21+ state is 1.86(16), while for the 31? state it is 0.89(6). These results are interpreted as indicating differences in neutron and proton deformations characterizing the 21+ transition and partial neutron blocking for the 31? transition. Optical model analysis of elastic scattering leads to the conclusion that . 相似文献
15.
The time dependence of microwave absorption was measured for the J = 2-1 and J = 3-2 transitions of OCS under on- and off-resonant conditions utilizing Stark and source modulation, respectively. The two effective pressure parameters obtained under the two conditions, which correspond to and , respectively, according to the Bloch equation, are different beyond experimental error; the difference is 0.94 ± 0.38 (2.5σ) MHz/Torr for J = 2?1. This difference was also determined to be 1.19 ± 0.30 MHz/Torr from the dependence of the nutation frequency on the microwave power. 相似文献
16.
Three enhancements are observed in the final state ω°π+π+π++π?π? selected from the channel at 715 MeV/c: one in ω°π± at 1040 MeV (~ ≈ 55MeV) ω°π+π?, respectively near 1315 MeV (~ ≈ 100 MeV) and 1405 MeV (~ ≈ 40 MeV). The first two effects are strongly correlated and are interpreted in terms of a sequential decay A°2 through a new object, the B1. The second (ωππ) enhancement seems to be an ?°?° effect below threshold and is attributed to a pionic decay of the effect seen around the same mass in other reactions. 相似文献
17.
H. Taureg G. Zech F. Dydak F.L. Navarria P. Steffen J. Steinberger H. Wahl E.G.H. Williams C. Geweniger K. Kleinknecht 《Physics letters. [Part B]》1976,65(1):92-96
The branching ratio has been determined to be (2.68±0.15)×10?3 for photon energies greater than 50 MeV in the KS0 rest frame. The decay KS0→π+π?γ is found to be dominated by the internal bremsstrahlung transition. The branching rato of a possible direct transition is found to be less than 0.06 × 10?3 at 90% confidence level for . 相似文献
18.
The reaction 12C(7Li, t)16O has been studied at with the LASL tandem accelerator and QDDD magnetic spectrometer. Angular distributions to levels with Ex < 11 MeV have been obtained from 0° to 90°, including 0°. The results have been analyzed with finite-range distorted-wave Born approximation theory. The α-particle spectroscopic factors and reduced widths obtained are compared with those calculated with group theory (SU(3)) and other models. The analysis of data for the 7.1 and 9.6 MeV Jπ = 1? levels, which are of great importance in stellar helium buring, yields a ratio, R, of dimensionless reduced α-widths . The observed line width of the 9.6 MeV level (Γc.m. = 390 ± 60 keV) is less than the accepted value (Γc.m. = 510 ± 60 keV) and implies θ2a(9.6 MeV) ≈ 0.6. These results as well as data for the 6.92 MeV Jπ = 2+ and 10.35 MeV Jπ = 4+ “α-cluster” states indicate 0.09 < θ2a(7.1 MeV) < 0.33 with a mean value θ2a(7.1 MeV) = 0.14 ± 0.04. The implication for stellar helium burning is discussed. 相似文献
19.
Robert W. Field Richard A. Gottscho E. Miescher 《Journal of Molecular Spectroscopy》1975,58(3):394-413
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 B′2Δ (v = 1) levels. No level shifts larger than the detection limit of 0.1 cm?1 are observed at the crossings near and ; 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 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 and which connect states belonging to the configurations , , and . 相似文献
20.
The cross-channel isospin amplitude is measured in the single reaction γn → ?0(pπ?) at 7.5 GeV assuming the ?0 dominance model. A low-mass enhancement is found for in the range of m(pπ?) of ~1.2 to ~1.7 GeV. The reaction strongly violates s-channel helicity conservation but is consistent with t-channel helicity conservation. The features are found to be very similar to those obtained in previous analyses of πp → π(Nπ) reactions. 相似文献