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1.
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   

2.
Beta-delayed γ-rays have been observed from the decay of 72Kr12 = 16.7 ± 0.6 s). A decay scheme is proposed based on γ-γ and β+-γ coincidence measurements. The total decay energy was measured to be QEC = 5057 ± 135 keV. The value is compared with mass predictions.  相似文献   

3.
Levels of 184W populated in the decay of 8.7 h 184Ta have been studied by a variety of experimental techniques. As a result of β and γ-ray energy and intensity determinations and extensive β-γ and γ-γ coincidence measurements, a detailed 184Ta decay scheme accommodating more than 99.5% of the decay intensity has been established. Intense β-ray groups of end-point energies 1165±26 and 1123±26 keV populate levels in 184W at 1699 and 1746 keV, which de-excite predominantly to the 8.3 μs isomeric level at 1285 keV, recently identified as the 12?[510]ν?112+ [615]ν Kπ = 5? band origin. The 1699 keV level also de-excites to members of a 12?[510]ν?72 [503]ν Kπ = 3+ band based at 1425 keV. New information about the properties of the γ-vibrational and K = 2 octupole bands in 184W is presented and the possible configurations of the levels directly populated in the β? decay are discussed. The configuration 72+[404]π ?32? [512]ν Kπ = 5? is indicated for the 184Ta ground state.  相似文献   

4.
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   

5.
The γ-ray decay spectrum of 82 s 59Cu produced by the 58Ni(p, γ) 59Cu reaction has been studied with a 40 cm3 Ge(Li) detector. The number of γ-rays now known for this decay has more than doubled. Additional direct β+ branches to the 1679.7(52?), 2414.8(32?) and 2681 keV states of 59Ni have been identified with log ft values of 5.5, 5.5 and 6.0, respectively. A major change is the reassignment of the 1340.4 keV γ-ray to a 1679.7 → 339.3 keV transition. A limit of log ft ≧ 6.9 is given for the direct feeding of the 1337(72?) keV state, together with limits for direct population of other energetically available states. The new weak γ-ray branches found for the 878.0, 1301.5 and 1679.7 keV levels are in excellent agreement with the recent theoretical calculations of Glaudemans et al.  相似文献   

6.
Excitation functions for the 54Fe(p, γ)55Co reaction have been recorded in the energy region Ep = 1100–1760 keV. The decay schemes and branching ratios of ten resonances have been investigated. Angular distributions of primary γ-rays have been measured for three resonances to establish resonance spins. Resonance strengths for six resonances and gamma widths for three resonances have been determined. The isobaric analogues of the ground (Jπ = 72?) and 1919 keVJπ = 32?) states of the parent nucleus 55Fe have been identified at 4722 and 6712 keV respectively in 55Co. The Coulomb displacement energies of the observed analogue pairs (0–4722 keV) and (1919–6712 keV) have been obtained. The strengths of the possible analogue-antianalogue transitions for the proton capture state at Ep = 1679 keV have also been determined.  相似文献   

7.
The energy levels of 97Ru have been studied through the decay of 31.1 min 97gRh and 44.3 min 97mRh using Ge(Li), Si(Li), Nal, plastic and anthracene detectors in singles and in coincidence experiments. A total of 139 γ-rays were observed. Ninety-eight γ-rays have been placed into the decay schemes involving 38 excited levels in 97Ru. The level energy of 97mRh was determined to be 258.6 keV. The spin and parity of 97gRh and 97mRh are assigned as 92+and12?, respectively. The fraction of decay of the isomer by the isomeric transition was measured with the Si(Li) detector, and αk values were determined for strong transitions. The half-life of the 188.6 keV, 32+ state in 97Ru was determined as 0.23 ± 0.02 ns by delayed e-γ coincidence measurements. The nuclear structure of low-lying levels is compared with similar levels in other odd-mass nuclei (N = 53) isotones and Ru isotopes).  相似文献   

8.
We have carried out measurements on the decay of 119In isomers and the 118Sn(n, γ) reaction to supplement Coulomb excitation measurements on 119Sn. In addition to the 311.39 keV isomeric transition in 119In, we observed 13 γ-rays in 119Sn from the decay of the 2 min and 18 min 119In isomers. These γ-rays have been incorporated into a level scheme of 119Sn with levels at 0, 23.867, 89.54, 787.01, 920.5, 921.4, 1089.5, 1187.76, 1249.67, 1304.44 and 1354 keV. Conclusive evidence for the existence of a 920.5–921.4 keV, 32+-52+ level doublet was obtained from capture γ-ray measurements of resonance energy neutrons.  相似文献   

9.
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   

10.
We present a microscopically-founded potential model for the 13N(p, γ)14O reaction at energies of astrophysical interest. The model is shown to reproduce the 13C(p, γ)14Ocross section very well. The 13N(p, γ)14O reaction is dominated by the first excited J = 1? resonance in 14O. For this resonance we find a proton width of Γc.m. = 40.1 keV and a photon width of Γγ = 1.50 eV.  相似文献   

11.
Excitation curves for the 21Ne(p, γ)22Na, 21Ne(p, p′γ)21Ne and21Ne(p, p)21Ne reactions have been obtained for Ep = 0.4–1.6 MeV. Neon gas enriched to 92 % in 21Ne was recirculated in a differentially pumped gas target system. The fifteen previously reported (p, γ) resonances were established and nineteen new (p, γ) resonances found. Anomalies in the elastic scattering yield were observed for fourteen resonances. The reported state at Ex = 7278 ± 7 keV in 22Na was resolved into a doublet separated by 1 keV. All unbound states in 22Na, observed previously in other reactions, have been confirmed as resonance states in the energy range covered, with the exception of the Ex = 7942 ± 7 keV state. The new Ep = 663, 694, 1235, 1432 and 1543 keV resonances correspond to new unbound states in 22Na. Excitation energies, γ-ray decay schemes, resonance widths and strengths as well as limits on Jπ assignments are reported for all the resonances. From the Coulomb excitation of the Ex = 350 keV, first excited state in 21Ne a value of B(E2) = 0.014 ± 0.002 e2 · b2 is deduced. The astrophysical as well as the nuclear structure implications of the present results are discussed.  相似文献   

12.
The electron capture decay schemes of 245Bk and 246Bk have been investigated by measuring the γ-ray and conversion-electron spectra of mass-separated 245Bk and 246Bk samples. The γ-ray spectra were measured with a 25 cm3 Ge(Li) spectrometer and the conversion-electron spectra were measured with a cooled Si (Li) detector. Multipolarities of most of the transitions in 245Cm and 246Cm were deduced. The half-lives of 245Bk and 246Bk were determined by following the decay of the 252.85 and 798.7 keV photopeaks and were found to be 4.90 ± 0.03 d and 1.80 ± 0.02 d, respectively. The α/(α+EC) ratio for the 245Bk decay was measured to be (1.2 ± 0.1) × 10?3. On the basis of the present investigation the following non-rotational states were identified in 245Cm: 72+ [624], 0; 52+[622], 252.85; 12+ 355.95; 32? vibrational, 633.65; and 12+[620], 740.95 keV. The 32? state at 633.65 keV is int as a Kπ = 2? phonon coupled to the i72+[624] single-particle state. Our measurements of 246Bk γ-ray and conversion-electron energies and intensities confirm previous level assignments in 246Cm.  相似文献   

13.
The yield curve of the reaction 34S(p, γ)35Cl has been measured over the energy range Ep = 1.95–2.91 MeV. Proton energies and strengths of 84 resonances are given. The decay schemes of 38 selected resonances have been studied, and for these branching ratios and spin limits are presented. The proton energy of the well known Jπ = 72? analogue resonance has been measured as Ep = 1211.45 ± 0.09 keV. The reaction Q-value is Q = 6371.6 ± 0.4 keV.  相似文献   

14.
The 20Ne(p, γ)21Na capture reaction has been studied in the energy range Ep = 0.37–2.10 MeV. Direct-capture transitions to the 332 (52+) and 2425 keV (12+) states have been found with spectroscopic factors of C2S(1d) = 0.77±0.13 and C2S(2s) = 0.90±0.12, respectively. The high-energy tail of the 2425 keV state, bound by 7 keV against proton decay, has also been observed in the above energy range as a subthreshold resonance. The excitation function for this tail is consistent with a single-level Breit-Wigner shape for a γ-width of Γγ = 0.31±0.07 eV at Ex = 2425 keV. The extrapolation of these data to stellar energies gives an astrophysical S-factor of S(0) = 3500 keV · b. Two new resonances at Ep = 384±5 and 417± 5 keV have been observed with strengths of ωγ = 0.11±0.02 and 0.06±0.01 meV, corresponding to the known states at Ex(Jπ) = 2798 (12?) and 2829 keV (presumably 92+), respectively. For the known Ep = 1830 keV resonance, a strength of ωγ = 1.0± 0.3 eV and a total width of Γ = 180± 15 keV were found. Branching ratios as well as transition strengths have been obtained for these three states. The Q-value for the 20Ne(p, γ)21Na reaction (Q = 2432.3 ± 0.5 keV) as well as excitation energies for many low-lying states in 21Na have been measured. No evidence was found for the existence of the state reported at Ex = 4308±4 keV.In the case of 22Ne(p, γ)23Na, direct-capture transitions to six final bound states have been observed revealing sizeable spectroscopic factors for these states. The astrophysical S-factor extrapolated from these data to stellar energies, is S(0) = 67 ± 12 keV · b.The astrophysical as well as the nuclear structure aspects of the present results are discussed.  相似文献   

15.
The anisotropies of the 177, 326, and 503 keV γ-transitions between negative parity states of 131Xe have been remeasured in the decay of oriented 131I nuclei. In addition the linear polarization of the 503 keV radiation has been determined with a Compton polarimeter consisting of two Ge(Li) detectors. A combined analysis of the reported experiment and earlier internal conversion and angular distribution data yields the unique assignments 92?and72? for the levels at 341 and 667 keV. The E2M1 mixing ratios of the 177 and 326 keV transitions are δ(177) = ?4.5 ± 1.5 and δ(326) = ?4.4 ± 1.6. The intensity of the L = 2 component in the first forbidden β-decay to the 667 keV level is at most 60 %.  相似文献   

16.
Energy levels of 85Rb and 87Rb have been studied via de-excitation γ-rays following Coulomb excitation with 35Cl ions. In addition to the known negative-parity states at 151.2 keV and 868.2 keV in 85Rb, two states at 281.0 keV and 731.8 keV have been found with fourγ-ray transitions of 129.8, 281.0, 450.8 and 731.8 keV. Only one Coulomb excited state at 402.6 keV in 87Rb has been observed. The B(E2↑) values (in units e2 · b2) have been determined as 0.0035±0.0004 (151.2 keV), 0.0016±0.0002 (281.0 keV), 0.0101 ±0.0010 (731.8 keV), and 0.036±0.004 (868.2 keV) for the states in 85Rb, and as 0.0054±0.0006 (402.6 keV) for the state in 87Rb. The mean lifetimes of the 731.8 keV and 868.2 keV states have been measured by the Doppler shift attenuation method as 6.4±0.7 psec and 4.2±0.5 psec respectively. Angular distribution measurements allow unique spin and parity assignments of 12? and 32? to the 281.0 keV and 731.8 keV levels respectively. The spin and parity of the 868.2 keV level has been restricted to 52? or 72?.  相似文献   

17.
The γ-ray spectrum emitted after thermal neutron capture in 40K has been studied at the ILL high flux reactor with curved crystal Bragg, pair and Ge(Li) spectometers. 585 transitions were assigned to the reaction 40K(n, γ)41K and 490 of them were placed into a 41K level scheme; 68 new states are proposed. On the basis of γ-ray branches to states with established spin and parity, many new spin-parity assignments were made. The level energies up to 4 MeV were measured with a precision of 8–50 eV relative to the 411.8 keV 198Au standard, those above 4 MeV with a precision of 50–100 eV. The spin of the capture state was found to be I = 72; the neutron binding energy was determined to EB = 10095.25(10) keV. The level density of Iπ = 52±, 72±, 92± states was analyzed in terms of the constant-temperature Fermi gas model. It was shown that in this spin window the level scheme is almost complete up to an excitation energy of 5 MeV.  相似文献   

18.
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   

19.
The decays of neutron-deficient 15 s 99Ag and 124 s 99gAg nuclides have been investigated at the Leuven Isotope Separator on-line facility. Sources were produced by the 92Mo(14N, 2p5n) and natZr(14N, xn) reactions. Positron, conversion electron, X- and γ-ray singles spectra together with γ-γ coincidence measurements have been performed on mass-separated samples. The 12? isomeric level in 99)Ag decays with a 163.6 keV isomeric transition to a 72+ level at 342.6 keV. Of the 106 γ-rays observed in the β+EC decay of the 99Ag ground state, 68 γ-rays (92 % of the γ-ray intensity) have been placed in a proposed level scheme. The relative variation of the Jπ = 92+and12? levels in odd-mass Ag isotopes has been calculated using a residual proton-neutron delta interaction. The occurrence of decoupled bands in the odd Pd isotopes is discussed. Detailed calculations for 99Pd have been carried out in the framework of the Nilsson model (strong-coupling wave functions) using a strong Coriolis band mixing. Energy spectra for high-spin states, wave functions and low-lying non-yrast levels (below Ex = 1 MeV) are also discussed.  相似文献   

20.
Yield curves of the reaction 36S(p, γ)37Cl have been measured over the range Ep = 500–2000 keV with a highly enriched (81%) 36S target. Proton energies, with a precision of typically 0.3 keV, and strengths are presented for the nearly 200 observed resonances. Several previously reported resonances, among which the well-known Jπ = 72?, Ep = 1887 keV analogue resonance, are proven to be multiplets.At 75 selected resonances in the ranges Ep = 500–1200 and 1800–2000 keV the decay schemes have been studied. These measurements also provide rather detailed information on the γ-ray branching ratios of more than 50 bound states of which the majority has not been observed previously. Precision excitation energies have been determined; for the levels with Ex < 5 MeV the median uncertainty amounts to 30 ppm. The reaction Q-value is Q = 8386.34 ± 0.23 keV.These precision data invalidate several previous spin and parity assignments to low-lying bound states of 37Cl. They also provide a basis for the lifetime measurements and spin and parity assignments to be discussed in the following paper.  相似文献   

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