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1.
Differential cross sections were measured for 50Ti(p, p) at four angles for Ep = 1.83 to 2.97 MeV, with an overall energy resolution of about 350 eV. Spins, parities and total widths were extracted for 212 levels. An energy region near Ep = 1.37 MeV was also examined in order to study the analogue of the ground state of 5Ti. Coulomb energies and spectroscopic factors were determined for the analogues of the ground and first excited states of 51Ti. The latter analogue was highly fragmented. The s-wave spacing and width distributions were analyzed and the number of missing levels estimated. The s12 and p12 proton strength functions were determined.  相似文献   

2.
Neutron pick-up cross sections and vector analyzing powers have been measured for the reaction 55Mn(d, t)54Mn at 17 MeV. The mixture of p12 to p32 transfer to the low-lying ln = 1 states has been found. Evidence of the f72 hole nature of several strong ln = 3 states above 1 MeV has been obtained.  相似文献   

3.
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   

4.
Excitation functions of the capture reaction 12C(p, γ0)13N have been obtained at θγ = 0° and 90° and Ep = 150–2500 keV. The results can be explained if a direct radiative capture process, E1(s and d → p), to the ground state in 13N is included in the analysis in addition to the two well-known resonances in this beam energy range [Ep = 457(12+) and 1699 (32?) keV]. The direct capture component is enhanced through interference effects with the two resonance amplitudes. From the observed direct capture cross section, a spectroscopic factor of C2S(l = 1) = 0.49 ± 0.15 has been deduced for the 12? ground state in 13N. Excitation functions for the reaction 12C(p,γ1p1)12C have been obtained at θγ = 0° and 90° and Ep = 610–2700 keV. Away from the 1699 keV resonance the capture γ-ray yield is dominated by the direct capture process E1 (p → s) to the 2366 (12+) keV unbound state. Above Ep = 1 MeV, the observed excitation functions are well reproduced by the direct capture theory to unbound states (bremsstrahlung theory). Below Ep = 1 MeV, i.e., Ep → 457 keV, the theory diverges in contrast to observation. This discrepancy is well known in bremsstrahlung theory as the “infrared problem”. From the observed direct capture cross sections at Ep ? 1 MeV, a spectroscopic factor of C2S(l = 0) = 1.02 ± 0.15 has been found for the 2366 (12+) keV unbound state. A search for direct capture transitions to the 3512 (32?)and 3547 (52+) keV unbound states resulted in upper limits of C2S(l = 1) ≦ 0.5 and C2S(l = 2) ? 1.0, respectively. The results are compared with available stripping data as well as shell-model calculations. The astrophysical aspect of the 12C(p, γ0)13N reaction also is discussed.  相似文献   

5.
The rotational spectrum of the SF radical in the 2Π12 state was observed by using a source-modulation microwave spectrometer with a 1-m-long discharge cell. The SF radical was generated directly in the cell by a dc discharge in an OCSCF4 mixture. A previous measurement of the microwave spectrum in the 2Π32 state was also extended to higher-J transitions. The least-squares analysis of all the observed spectral lines gave the B0 rotational constant and the D0 centrifugal distortion constant to be 16 576.9140(46) and 0.02924(10) MHz, respectively, where the values in parentheses denote 2.5 times the standard deviations. The Λ-doubling constant pv was found to be extremely small, 3.409(44) MHz, and it was presumed that contributions of 2Σ+ and 2Σ? states to the Λ doubling cancel each other. All the four fluorine hyperfine coupling constants were also determined, from which the spin density on the F atom was calculated to be 0.13.  相似文献   

6.
The fundamental bands of the CF radical in the X2Π12 and X2Π32 electronic states were observed by using an infrared tunable diode laser as a source. Zeeman modulation could be used in detecting lines not only in the 2Π32 state, but also in 2Π12, because the CF radical deviates considerably from Hund's case (a). From the least-squares analysis of the observed spectra, the following molecular constants were obtained: Be = 1.416 704 (37) cm?1, αe = 0.018 419 (50) cm?1, re = 1.271 977 (17) A?, De = 6.68 (15) × 10?6cm?1, p0 = 0.008 580 (21) cm?1, p1 = 0.008 52 (11) cm?1, and ν0 = 1286.1281 (5) cm?1, with three standard errors in parentheses.  相似文献   

7.
Accurate SCF computations are reported on the Rydberg states of N2 of electron configurations ---1πu3u, ---1πu3u, and ---3σg2πg, also on the valence states of the configuration ---1πu3g. The Rydberg state calculations supplement those of Lefebvre-Brion and Moser. A comparison is made between the ---1πu3u states and the parallel set of states of the u3g configuration. This comparison shows a sharp difference in the 1Σ+ states of the two configurations, the 1Σ+ state being very high in the latter but relatively low in the former configuration. Recknagel coefficients are given for the several states of the two configurations; as expected, these are much smaller for the u3u configuration. Also, the 1Δ state is relatively lower for the latter configuration.  相似文献   

8.
The lifetimes of 14 excited states in 91Nb and lower bounds for 5 additional states were measured with the Doppler-shift attenuation method, utilizing the 91Zr(p, nγ)91Nb reaction. By using calibrated F(τ) curves, the uncertainty of the stopping power was reduced to about 15 %. Multipole mixing ratios were determined for several transitions from the γ-ray angular distributions. The experimental data on γ-ray transition probabilities were compared with theoretical values. These were calculated using shell-model wave functions based on a 88Sr core and active protons in the 2p12and 1g92orbitals. For the negative-parity states also excitations of protons from the 2p32and 1f52 orbitals were taken into account.  相似文献   

9.
The 58Ni(τ, α)57Ni reaction has been studied at 25 MeV incident energy. Angular distributions have been measured from 5° to 50° with a split-pole spectrometer up to 13.5 MeV excitation energy. A local zero-range DWBA analysis has been carried out, allowing l-assignments for about eighty levels, most of them previously unknown. An isospin-dependent potential has been used in the calculation of the neutron form factor for both T<and T> states, and the C2S values deduced using this procedure are compared to those obtained with the usual separation energy method. Analog states of eleven 57Co levels have been identified and the eventuality for isospin mixing in 57Ni has been discussed. A sum rule analysis has been carried out and energy centroids of hole states have been determined. About 60% of the 1d52and 2s12T< strengths and the full 1d32 and 1f72 hole strengths are observed. It is shown that the two excess neutrons in the 58Ni ground state mainly populate the 2p32, 1f52and 2p12 orbitals, whereas the occupancy number of the 1g92 subshell is found to be smaller than 0.1%. Some non-pickup angular distributions have also been observed and a CRC analysis assuming two-step processes in the (τ, α) reaction and weak-coupling wave functions for final states has been attempted. Assignments of Jπ values are proposed for four 57Ni levels, based on this analysis.  相似文献   

10.
The reactions 17O(d, t) 16O and 17O(d, τ)16N have been investigated at Ed = 52 MeV. Energy spectra of tritons and τ-particles have been measured simultaneously up to excitation energies of 22 MeV in 16O and 10 MeV in 16N, respectively. Spectroscopic factors have been obtained by a DWBA analysis of the measured angular distributions. From the comparison of the t- and τ-spectra analog (T = 1) states in 16O could be identified and the distribution of T = 0 and T = 1 spectroscopic strengths could be deduced. Nearly the total 1p12 and 1p32 hole strengths have been found and the 1d521p12?1and 1d521p32?1 particle-hole multiplets could be located both for T = 0 and T = 1. The average residual interactions in both shell-model configurations turned out to be strikingly different.  相似文献   

11.
From a study of (p,t) reactions on 31P and 30Si it is suggested that in 29P the states with Jπ=121+ and 122+, the pair 322+, 521+, and the pair 723+, 921+ are related by weak coupling of a s12 proton with the states 01+, 02+, 21+ and 41+ respectively of 28Si. Completely atypical L = 2 angular distributions have been obtained for the 321+ and 522+ states in 29P and it is suggested that this is due to contribution by two-step processes.  相似文献   

12.
The results of high-resolution studies of the 91Zr(d, p) reaction at Ed = 12 MeV and the 90Zr(t, p) reaction at Et = 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 2d52, 3s12, 2d32, 1g72 and 1h112 orbits and a proton space comprising the 1g92 and 2p12 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   

13.
The reactions 34S(d,p)35S and 36S(d,p)37S were studied at the incident deuteron energy of 12.3 MeV. Proton groups were analysed using a multi-angle magnetic spectrograph with the resolving power EΔE ≈ 1400. Precise Q-values corresponding to 13 states of 35S up to the excitation energy of 7483 keV and 22 states of 37S up to the excitation energy of 6406 keV are presented. The ground-state transition Q-value for the reaction 36S(d,p)37S was found to be 2079.12 ± 0.13 keV. Angular distributions of proton groups corresponding to 6 states in 35S and to 11 states in 37S were analysed using DWBA calculations. Transferred orbital angular momenta and spectroscopic factors were deduced. Summed spectroscopic strengths show that substantial parts of single-particle strengths for 1f72, 2p32and 2p12 in both reactions are exhausted b observed transitions.  相似文献   

14.
The doubly odd nucleus 140Pr has been investigated by means of the 141Pr(d, t)140Pr and 140Ce(p, nγ)140Pr reactions. Twenty-eight levels, up to 1300 keV excitation, were observed in the pickup study. DWBA analysis was used to determine l-values and spectroscopic factors for all but a few which are very weakly populated. Gamma-ray angular distributions, measured at Ep = 4.78 MeV for the five strongest γ-rays, show appreciable nuclear alignment and demonstrate the feasibility of such experiments in this mass region. Taken together, the two studies have permitted the identification of the 12 levels expected from the low-lying (π2d52ν2d32?1), (π2d52ν3s12?1), (π1g72ν2d32?1) and (π1g72ν3s12?1) configurations. Tenta assignments for the strong odd-parity states are suggested on the basis of their spectroscopic factors.  相似文献   

15.
The (τ, α) reaction on 48Ca, 50Ti, 52Cr and 54Fe target nuclei has been studied at 25 MeV incident energy. Angular distributions have been measured from 5° to 40° with a split-pole spectrometer in a large range of excitation energy. A local zero-range DWBA analysis has been carried out, using an isospin-dependent potential for the calculation of the neutron form factor, in order to get a coherent set of spectroscopic factors for both T> and T< levels in different nuclei. Assignments of l-values have been done for a large number of levels, most of them previously unknown, and energy centroids of hole states have been determined. Spectroscopic factors in 39Ca, 47Ti, 49, 52, 53Cr have also been obtained for strongly excited states. A sum rule analysis has been carried out for the N = 27 nuclei: the 1d32and 2s12T< hole strengths are generally fully exhausted by the observed levels, whereas only a fraction of the 1d52 strength has been evidenced. The 1f72, 1d32and 2s12 analog states have been observed in all nuclei; in 53Fe, the 1d32and 2s12 analog states appear to be split in several components. In addition, a CRC analysis has been carried out for some levels with angular distributions not accounted for by a direct pick-up process. These levels are tentatively identified with states resulting from the coupling of one f72 neutron hole with excited states of the target nucleus. In particular, the 52?and92? members of the [2+ ? f72?1] configuration have been identified in each final nucleus. Unambiguous Jπ assignments are made; and the two-step (τ, α) reaction therefo e appears as a useful spectroscopic tool, especially for investigating high spin states.  相似文献   

16.
The transverse spin pair correlation function pxn=<SxmSxm+n>=<SxmSxm+n> is calculated exactly in the thermodynamic limit of the system described by the one-dimensional, isotropic, spin-12, XY Hamiltonian
H=?2Jl=1N(SxlSxl+1+SylSyl+1)
. It is found that at absolute zero temperature (T = 0), the correlation function ρxn for n ≥ 0 is given by
ρx2p=142π2pΠj=1p?14j24j2?12p?2jif n=2p
,
ρx2p+1142π2p+1Πj=1p4j24j2?12p+2jif n=2p+1
, where the plus sign applies when J is positive and the minus sign applies when J is negative. From these the asymptotic behavior as n → ∞ of |?xn| at T = 0 is derived to be xn| ~ an with a = 0.147088?. For finite temperatures, ρxn is calculated numerically. By using the results for ?xn, the transverse inverse correlation length and the wavenumber dependent transverse spin pair correlation function are also calculated exactly.  相似文献   

17.
From the study of the reaction π?p→pFppπ? using a fast proton (pF) trigger device in the CERN Omega spectrometer, we find evidence for two narrow pp 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 pp resonances are given.  相似文献   

18.
The phenomenological predictions of the SO(10) supersymmetric grand unified model (SO(10) SGUM) for the mass scales M1, M2, weak angle ifsin2θw, quark-leptons mass ratios mbmτ, mtmb, mτmντ and proton lifetime τp are estimated by using renormalization group analysis at one-loop level. In contrast with SU(5) SGUM, we find that the SO(10) SGUM still has problems with τp but not with sin2θw and mbmτ, which may suggest that supersymmetry would be bro at a mass scale ?107GeV.  相似文献   

19.
The excitation functions of 208Pb(p, p0)208Pb have been measured in the energy range Ep = 14.2 to 17.4 MeV in 50 keV steps at θlab = 120°, 140° and 160°. The isobaric analog resonances of the parent states in 209Pb up to Ex = 2.5 MeV and the optical-model background were fit simultaneously at all energies and angles. The spreading widths and the values of a parameter β2, which measures the isospin purity of the IAR, were determined for the g92, i112, j152, d52, and s12 resonances. An average value of the isospin purity of β2 = 66% was found.  相似文献   

20.
An investigation of the γ-decay of the 1g92 analogue state in 59Cu has been performed using the 58Ni(p, γ)59Cu reaction. The (p, γ) excitation function has been taken in the range Ep = 3450–3650 keV. The decay schemes of the (p, γ) resonances at Ep = 3483, 3532 and 3547 keV, measured with Ge(Li) detectors, lead to eight new levels in 59Cu with excitation energies between 1.8 and 4.7 MeV and to spin assignments of several states. The spins of the first two resonances are found to be (12, 32) and (52). The spin of the Ep = 3547 keV resonan is, from angular distributions, uniquely determined to be Jπ = 92+ and this state is found to be the unfragmented analogue state of the E1 = 3.062 MeV, Jπ = 92+ parent state in 59Ni. The measured complete decay scheme of this resonance shows that its isovector M1 decay is in disagreement with all existing theoretical predictions.  相似文献   

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