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1.
High spin states of 57Co have been studied via prompt γ-ray spectroscopy in the reactions 48Ti(12C, p2n) and 54Fe(α, p) at 26–48 MeV and 12–24 MeV, respectively. The energies and decay modes of these levels were determined from the analysis of γ-ray singles and γ-γ coincidence spectra, excitation functions, angular distributions and correlations. The relevant lifetimes were measured by the Doppler-shift attenuation method. The new levels established in this work are at 4037, 4814 and 5918 keV with the most probable Jπ assignment of 152?, if 172? and 192?, respectively. The previously known level at 2524 keV was assigned to have Jπ = 132?. These together with the known 92?(1224 keV) and 112?(1690 keV) levels constitute the yrast states of 57Co. The measured lifetimes of the above six levels are (in order of increasing energies) 0.085±0.030, 0.32±0.10, 0.16±0.06, 0.10?0.07+0.06, 1.5?0.54 and 0.17?0.07+0.08 ps, respectively. Comparisons with some theoretical calculations are presented.  相似文献   

2.
Three enhancements are observed in the final state ω°π+π+π++π?π? selected from the channel pp → 3π+? π° 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 KK)I=1 effect seen around the same mass in other reactions.  相似文献   

3.
Quark masses     
In quark gluon theory with very small bare masses, -ψMψ, spontaneous breakdown of chiral symmetry generates sizable masses Mu, Md, Ms, … We find (Mu + Md) /2 ≈ mp/ √6 ≈ 312 MeV, and Ms ≈ 432 MeV. Scalar densities have well determined non-zero vaccum expectations 〈0|ua|0〉 ≡ 〈0|ψ(x) (λa/2)ψ(x)/0〉 ≈ ?π2Ma, i.e〈0? uo/vb0〉 ≈ 8 × 10?3 (GeV)3 at an SU(3) breaking of the vacuum c′ ≡ 〈0|u8|〉/〈0|uo|0〉 ≈ ? 16%  相似文献   

4.
High resolution spectra of the ν3 band of methane, 12CH4, were recorded by using a “third generation vacuum Fourier interferometer”; a large pressure range (from 0.009 to 10 Torr) with a sample path fixed at eight meters was used, enabling observation of transitions with intensity ratios as low as 110 000. More than 350 forbidden transitions of the ν3 band, including about 125 transitions of the Q+ branch, were unambiguously identified. Of the 277 transitions retained for computations, one-hundred have 11 ≤ J ≤ 16. From combination difference relations using pairs of transitions having the same upper state energy level (forbidden-allowed and forbidden-forbidden pairs were used), 276 independent differences between ground state energy levels could be determined with uncertainties of about 0.001 cm?1.These data yielded the following values for the ground state structure constants of 12CH4 along with their standard deviations (in cm?1): βohc=5.2410356±0.0000096, γohc=(?1±0.00074) 10?4, πohc=(5.78±0.18) 10?9, ?ohc=(?1.4485±0.0023) 10?6, ?ohc=(1.768±0.126) 10?10, ξohc=(?1.602±0.067) 10?11, Thus, for the first time, the scalar constant π0 has been evaluated and ir values have been obtained for the two tetrahedral constants ?0 and ξ0; furthermore, these values are in very good agreement with the ones recently determined from radiofrequency data, i.e., in cm?1: ?ohc=(?1.45061±0.00014) 10?6, ?ohc=(1.7634±0.0068) 10?10, ξohc=(?1.5432±0.0040) 10?11 From these values, the 276 differences can be reproduced with an overall rms deviation equal to 0.0009 cm?1.Finally, the ground state energies of 12CH4 have been calculated for J ≤ 16.  相似文献   

5.
The dark conductivity of crystalline DCH contacted with a J2 saturated 0.5 n NaJ electrolytic solution is found to be determined by field-driven, 3eversible doping by J?/J?3 ions penetrating the crystal at negative bias. The maximum conductivity is about 10?3 (Ω cm)?1 at a doping level of ≈ 10?3 mol per base mole DCH.  相似文献   

6.
Predissociations in the y1Πg and x1Σg? Rydberg states of N2 (configurations u?14pσ and u?13pπ, respectively) and their likely causes, are discussed. Peaking of rotational intensity at unusually low J values, without sharp breaking off, is interpreted as due to case c? or case ci predissociation. Λ doubling in the y state, attributed to interactions with the x1Σg? state and with another, 1Σ+, state of the same electron configuration as x, is analyzed. From this analysis the location of the (unobserved) 1Σg+ state, here labeled x′, is obtained. It is concluded that the predissociation in the Π+ levels of the y state is an indirect one mediated by the interaction with x′ coupled with predissociation of x′ by a 3Σg? state dissociating to 4S + 2P atoms: combined, however, with perturbation of the y state by the k1Πg Rydberg state (configuration g?14dπ), whose Π+ levels are completely predissociated.  相似文献   

7.
This letter reports a study of 117 opposite-sign and 41 like-sign dimuons, in a wide-band neutrino exposure of Gargamelle at CERN SPS. No signal is found in the μ?μ? channel. The μ?μ+ channel is found to be dominated by D-meson production and decay. There is evidence in these events for missing energy which may be interpreted as an unseen neutrino. The V0 multiplicities, K0/event=0.53?0.20+0.25and Λ/event=0.03?0.04+0.06 show only evidence for charmed meson production. Information on the D-meson fragmentation function is presented. In a specific model, a rate σ?μ+)σ(μ?)=(0.72±0.14×10?2 is found, independent of the energy. An investigation of these events for visible D-decays sets a limit on the life-time τD<0.8 ×10?12s at 90% C.L.  相似文献   

8.
Compound nucleus states in 5Li and 5He have been investigated with the 3He(d,p)pt and 3H(d,n)pt three-particle reactions. The observed Jπ=32? states (EX≈20 MeV) can be understood, in analogy to the ground states of the A=5 system, by coupling a p32 nucleon to the first 0+ excited state of 4He.  相似文献   

9.
The possibility of neutron triplet pairing and superfluidity in neutron star matter is investigated, and the energy gap and corresponding critical temperature is calculated or estimated as a function of Fermi momentum or density. The calculations are performed for a “one-pion-exchange gaussian” potential, and compared with the results for neutron and proton singlet pairing and superfluidity calculated earlier.The results indicate that neutron superfluidity, corresponding specifically to 3P2 state pairing, may exist in a high-density shell in the nuclear-matter region of a neutron star, i.e. for 1.6 × 1014g/cm3 < ρ < 1.4 × 1015g/cm3, and the maximum self-consistent energy gap is Δ01kF ≈ 0.6 MeV and Δ03(kF) ≈ 0.1 MeV for an effective mass m1 ≈ 0.75 and kF ≈ 2.1 fm?1, i.e. for a mas ? ≈ 5.2 × 1014g/cm3. For m1 = 1.0 we get correspondingly Δ01(kF) ≈ 3.3 MeV and Δ03(kF) ≈ 0.6 MeV for kF ≈ 2.2 fm?1.  相似文献   

10.
Forty Ω? events have been observed in a large (133 events/βb) experiment at 4.2 GeV/c incident K? momentum. Thirty nine of the events come from the three-body reaction K?p→Ω?K+K0. The Ω? is mainly produced in the forward hemisphere (direction of the incident K?). The lifetime is measured to be τ = (0.75 +0.14?0.11 × 10?10 sec substantially less than the Particle Data Group value of (1.3 ?0.3+0.2) × 10?10 sec. The mass is determined to be 1671.7 ± 0.6 MeV, in good agreement with other determinations. The decay asymmetry parameter α (for the decay mode Ω? → ΛK?) is found to be ?0.2 ± 0.4.  相似文献   

11.
The quadrupole interaction frequencies ω0 = 3eQ1Vzz41(21-1) h? in the 5? state of 118Sn have been measured by time differential perturbed angular correlation technique in Sn, Sb and (95% Sn+5% Sb) environments. The ω0 for 116Sn was determined in Sn environment only. With the help of the known electric field gradient 1) of Sn in a Sn lattice the quadrupole moments have been deduced as Q(5?, 118Sn) = ±0.10(4) b and Q(5?, 116Sn) = ±0.165(60) b. These values together with the known2) quadrupole moment of the analogous 5? state in 120Sn are interpreted in terms of the pure single-particle model. The data exhibit the expected strong systematic variation of QI with the number of particles in the h112. subshell which is being filled with 1, 3 and 5 neutrons in 116Sn, 118Sn, and 120Sn, respectively.  相似文献   

12.
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   

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 σπA2(s) ≈ 2σπω(s) ≈ 4σππ(s) ≈ 9(m?2/s)3σμμ for large s.  相似文献   

14.
Laser-induced fluorescence excitation has been used to measure Stark splittings of selected lines in the A?1A2-X?1A1 and a?3A2-X?1A2 band systems of H2CS in electric fields up to 13 kV/cm. The derived excited state a-axis dipole moments are 0.820 ± 0.007 D for the 41 level of the 1A2 state; 0.838 ± 0.008 D for the zeroth vibrational level of 1A2; and 0.534 ± 0.015 D for the zeroth vibrational level of the 3A2 state. These results are compared with the corresponding values of H2CO, and interpreted in terms of the changing localization of the π and π1 orbitals accompanying electronic excitation.  相似文献   

15.
The branching ratio Λ(KS0→π+π?γ)Λ(KS0→π+π?) has been determined to be (2.68±0.15)×10?3 for photon energies Eγ1 greater than 50 MeV in the KS0 rest frame. The decay KS0π+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 Eγ1 > 50 MeV.  相似文献   

16.
We studied the energy width and the width in reciprocal space Δq of the central mode of SrTiO3 above Tc. At Tc+4° we observed an energy width of about 6×10?7 eV. If the measured Δq is interpreted by a correlation length Δq?1 = ξ = ξ0??23 we obtain ξ0 = 75 A?.  相似文献   

17.
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 σ(π?)σ(π+) 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 〈rn212?〈rp212=0.03(3) fm.  相似文献   

18.
A high-accuracy investigation of the level scheme of 47V has been performed using the 46Ti(p, γ)47V reaction. The γ-decay schemes of the strong (p, γ) resonances at Ep = 1546, 1549, 1565 and 1572 keV lead to 17 new energy levels in 47V with excitation energies between 2.7 and 5.1 MeV. From the (p,γ) angular distributions mixing ratios of the primary γ-transitions and Jπ values of the resonances and of many states populated in the γ-decay have been determined. The total width of the Ep = 1549, 1565 and 1572 keV resonances for γ-decay are found to be Γγ = 0.12, 0.15 and 0.03 eV, respectively. The Q-value of the 46Ti(p,γ)47V reaction is found to be 5168.6 keV. The two resonances at Ep = 1549 and 1565 keV, which have Jπ = 32?, are interpreted as fine structure components of the analogue state of the E1 = 2.545 MeV Jπ = 32? level in 47Ti while the (72) resonance at Ep = 1546 keV might correspond to the E1 = 2.615 MeV72? parent state in 47Ti. The analogue-antianalogue M1 transition strength of the split 32? analogue state is 0.01 single-particle units and fits well into our systematics of IAS → AIAS transitions in fp-shell nuclei.  相似文献   

19.
The reactions 72, 74, 76Ge(3He, d) were investigated at Elab = 23 MeV with a multigap and a Q3D magnetic spectrograph. Some 30 new levels up to E1 ≈ 4 MeV have been found. The level schemes of the odd As isotopes 73, 75, 77As up to E1 ≈ 4 MeV seem to be rather independent of the neutron number. The good agreement of the low-lying level structure with the Coriolis-coupling model including a pairing force was verified and the vacancies of low-lying shell model states were extracted and compared with the simple pairing theory.  相似文献   

20.
Medium resolution infrared grating spectra of gaseous ketene, H2CCO were recorded between 1000 and 400 cm?1, both at instrument temperature (40°C) and with cooling (?40°C). Interferometric Fourier spectra were also measured at ?70°C with resolution 0.22 cm?1 between 450 and 330 cm?1. The K structure of the fundamentals ν5, ν6, ν8, and ν9 was assigned. These fundamentals are coupled by a-axis Coriolis interactions. These couplings were analysed on the symmetric top basis for setting up the perturbation matrix and by utilizing the K-dependent Coriolis shifts of levels. A preliminary analysis of the Coriolis intensity anomalies was also undertaken.Band center values from combination differences are ν50 = 587.30 (27) and ν60 = 528.36 (39) cm?1. Synthetic spectra indicate the band origins of ν8 and ν9 to be close to 977.8 and 439.0 cm?1, respectively. Estimates of Coriolis coupling constants obtained from synthetic spectra are ζ58a = + 0.33 (5), ζ68a = + 0.714 (20), ζ59a = ? 0.774 (20), and ζ69a = ? 0.30 (2). Approximate ratios of unperturbed vibrational transition moments obtained from spectral simulations are M80:±iM50:±iM60:M90 ≈ +2:?9:+10:+0.5.  相似文献   

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