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1.
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   

2.
Mössbauer-effect studies yield the following nuclear parameters: In 155Gd, Q(86)/Q(0) = 0.087 ± 0.006, Q(105)/Q(0) = 1.00 ± 0.03. In 156Gd, g(89) = 0.386 ± 0.004, 156Q(89)/155Q(0) = ?1.51 ± 0.02. In157Gd, Q(64)/Q(0) = 1.80 ± 0.03 and g(64) = ?0.185 ± 0.005. The value of g(89) is in very good agreement with the theoretical value.  相似文献   

3.
The inclusive production of K?1(890) and K?1(1420) is studied in K??p interactions at 10 and 16 GeV/c. At 10 GeV/c an enhancement in the (K?0π?) mass distribution is found at 1.74 GeV, but no clear signal is seen at 16 GeV/c. The fraction of K0's coming from decay of the K1(890) orK1(1420) is large, being (50 ± 6)% and (45 ± 5)% at 10 and 16 GeV/c, respectively. The inclusive cross sections for K1?(890) and K10(890) production are almost constant with energy from 8 to 32 GeV/c with values of 3.5 and 3.3 mb, respectively. The K1(890) production cross section is studied as a function of transverse and longitudinal variables and found to derive mainly from fragmentation of the incident K? meson. The spectra of K0's resulting from the decay of K1(890) are studied.  相似文献   

4.
Results on K1(890) production in K?p → NKπ reactions at 16 GeV/c are presented. Total cross sections, differential cross sections and density matrix elements are determined. It is found that: (i) The cross section for K1?(890) p is consistent with containing two components, one due to natural parity exchange, falling slowly with increasing energy, the other, due to unnatural parity exchange, vanishing rapidly with increasing energy. For K1o(890)n, the cross section decreases steadily as the energy increases. (ii) Natural spin-parity exchange dominates in the K1?(890) p channel, the unnatural exchange contribution being approximately (5±4)%. In K1o(890)n, natural spin-parity exchange is only about (30±10)%. (iii) The reacton K?pK1?(890)p is dominated (95±5)% by isoscalar exchange. (iv) The effective trajectory involved in the I = 0 natural parity exchange is consistent with the ω-f trajectory. (v) Interference terms between exchanges with positive (f, πo,…) and negative (?o, ω,…) C-conjugation amount to (23±12) μb at 16 GeV/c.  相似文献   

5.
The first results are reported on the Pn values obtained with the recoil focussing parabolatype mass separator for unslowed fission products Lohengrin installed at the Grenoble high flux reactor. The mass chains studied were 90, 91, 93, 94, 95, 99, 134, 137, 138 and 139. Both the neutron and the β activities were measured simultaneously. The technique used to measure the neutron and the β activities and the method of analyzing the experimental data are discussed in detail. The present work led to: (i) three new periods corresponding to the new isotopes of selenium (91Se, T12 = 0.27±0.05 sec), strontium (99Sr, 0.6±0.2 sec) and telurium (138Te, 1.3±0.3 sec); (ii) accurate periods of 99Y(T12 = 1.45±0.22 sec) and134Sn (0.7±0.2 sec); (iii) four new delayed neutron precursors consisting of 91Se, 94Kr, 99Sr and 138Te; (iv) six new Pn values corresponding to the precursors 91Se (Pn = (21±10)%), 94Kr ((5.7±2.2)%), 99Sr ((3.4±2.4)%), 99Y ((1.2±0.8)%), 134Sn ((17±13)%) and138Te ((6.3±2.1)%); (v) a precise Pn value of the precursor 137Te ((2.5±0.5)%); (vi) a redetermination of the Pn values of the precursors 90, 91Br, 93Kr, 93, 94, 95Rb and 137, 138, 139I. The results of this work are discussed and compared with the existing data. The low level sensitivity of the present detection system is determined to be Pn(m)Yq(m) ? 0.4 × 10?6n/f (where Yq(m) is the cumulative yield for the mass m and the ionic charge q).  相似文献   

6.
The results of integral precession measurements are reported for 32+ and 52+ excited states in 123,125Te. The measurements were made using the ion implantation perturbed angular correlation technique by recoiling the excited nuclei into polarized iron. The measured mean lifetimes and g-factors are: 123Te (440 keV, 32+) τ = 39±4 ps, g = 0.34 ± 0.06; (505 keV, 52+) τ = 26±3 ps, g = 0.04±0.025; and 125Te(443 keV, 32+) ρ = 27±3.3 ps, g = 0.39±0.06; (464 keV, 52+) g = 0.12±0.04. The results are compared with theoretical predictions.  相似文献   

7.
The46Ti(p, n)46V reaction threshold has been measured as 8007.7 ± 1.8 keV, equivalent to an energy release of 6030.6 ± 1.8 keV in the beta decay46V+)46Ti. The 46V half-life has been measured as 422.28 + 0.23 ms. The corresponding ft value is reasonably consistent with those of other superallowed Fermi decays.  相似文献   

8.
Using a target prepared by on-line isotope separation, thermal neutron capture in 84Rb (Iπ = 2?) has been shown to induce proton emission to the ground state (0+) and first excited state (2+) of 84Kr. The branching ratio was measured as Γp(0+)Γp(2+) = 4.7 ± 0.7, favouring a 32? assignment of the capturing state without excluding 52?, and the (nth, p) cross section as 12 ± 2 b. The energy available for the process was determined to be 3.45 ± 0.01 MeV, in agreement with other mass data in the region.  相似文献   

9.
The chemiluminescence spectrum of atomic Pb reacting with O3 under single-collision conditions includes a series of 55 bands in the regions 450–850 nm. A vibrational analysis is obtained which shows emission is to the ground state of PbO from excited electronic states not previously analyzed. Forty-nine of the bands are assigned to the a(1)-X(0+) transition and the remaining six are tentatively identified as the forbidden b(0?)-X(0+) transition. Both the a and b states are believed to be Hund's case (c) components of the 3Σ+ states arising from the configuration σ2π3π1. The vibrational parameters of the a state are ν4 = 16 029 ± 8, ωe = 478.7 ± 1.9, and ωexe = 2.292 ± 0.128 cm?1, where the uncertainties represent two standard deviations of the least-squares fit. Emission is also observed from the PbO B state produced in the reaction of metastable Pb atoms with O3. Using pulsed laser excitation, an attempt is made to determine radiative lifetimes. We find for the PbO A(0+) state τ = 3.74 ± 0.3 μsec, and for the PbO B(1) state τ = 2.58 ± 0.3 μsec, while for the a(1) state τ is estimated to be greater than 10 μsec. From the vibrational analysis, energy conservation arguments place a lower limits to the ground state dissociation energy of D00(PbO) ≥ 3.74 ± 0.03 eV (86.2 ± 0.7 kcal/mole). For the Pb + O3 reaction we find less than 1% of the products are PbO1 molecules that emit in the visible. Correlations are made with the low-lying states of other Group IV chalconides based on the assignment of the PbO a 3Σ+(1) state and the correspondence between the low-lying triplet states of PbO and CO.  相似文献   

10.
We report the first observation of the decay ?′→?π+π?l+l?π+π?. The 7 events seen yield a branching ratio B(?′→+π?)=(19±8)%. A consistent value of B=(26±13)% is obtained from the charged multiplicities of the ?′ and ? decays. Using these values we deduce Γtot(?′)=(31+10?8) keV and Bee(?′)=(1.8±0.5)%. Furthermore we estimate Γ(?′→gg?)=(10±5) keV in agreement with QCD predictions using vector gluons while one would expect 100 keV with scalar gluons.  相似文献   

11.
Hyperfine structure of the (0, 0, 1) - (1, 0, 1) transition of methanol has been investigated by beam absorption and of the (J, 1, 3?) → (J, 1, 3+) transitions for J = 2, 3, and 6 by beam-maser spectroscopy. The best-fit results for the spin-rotation and spin-spin coupling constants CJKτ±(i) and DJKτ±(i), respectively, are in kHz1: C101(1) = 2.4(10), C101(2) = ?0.6(10), D101(1) = ?13.8(9), D101(2) = 7.0(9), C213?(1) = ?5.0(10), C213?(2) = ?5.5(10) and (CJ13?(2) - CJ13+(2)) = 0.98(9).  相似文献   

12.
The inclusive production of Λ, KS0, Σ±(1385) and K(892) in π?p interactions at 6 GeV/c has been studied. The observed cross sections are: σ(Λ)=0.94±0.06 mb, σ(KS0)=0.98±0.06 mb, σ(Σ+(1385))=60±7 μb, σ(Σ?(1385))=90±9 μb, σ(K1+(892))=216±28 μb and σ(K1?(892))=41±8 μb, respectively. The inclusive spectra of these particles are presented as functions of squared transverse momentum and Feynman scaling variable x. The polarization of Λ has also been investigated. It is found from a comparison with higher-energy data that the inclusive cross sections for Σ±(1385) and the production ratios Σ±(1385)/Λ in π?p at 6 GeV/c have not reached the high-energy limiting values.  相似文献   

13.
14.
The F2(2) ← F1(2) and F2(2) ← F1(1) transitions of the J = 7 levels of the ground state of CH4 have been observed by infrared-radio frequency double resonance using the 3.39 μ HeNe laser line. The transition frequencies are 423.02 ± 0.02 MHz and 1246.55 ± 0.02 MHz, respectively. Using these frequencies and the splitting of the E and F2 levels of the J = 2 state calculated from the molecular beam magnetic resonance spectra of Ozier, the centrifugal distortion constants are derived to be Dt = 132933 ± 10 Hz, H4t = ? 16.65 ± 0.2 Hz, and H6t = 10 ± 1 Hz. The J = 15 E(1)E(2) microwave transition is predicted as 14150 ± 9 MHz.  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.
A forward dispersion relation cannot be applied to charged particle scattering amplitudes unless the influence of the Coulomb interaction is explicitly considered. Earlier studies have shown how Coulomb effects can be taken into account when direct (s-channel or bound-state) poles are investigated. In this paper we extend the Coulomb modification to include I = 0 exchange (u-channel) processes as well. We then apply a forward dispersion relation to empirical d + α, p + d and n + d elastic scattering amplitudes which contain both direct and exchange poles with and without Coulomb effects. We obtain detailed and model-independent information on the following vertices: 6Li-α-d (S- and D-state) 4He-d-d, 3He-d-p, 3H-d-n and d-p-n. From the coupling constants we calculate the asymptotic normalization (spectroscopic factors) C21 of the corresponding cluster wave functions, which become: C20(6Li, αd) = 4.62 ± 0.23, C22(6Li, αd) = (1 ± 6) × 10?4, C20(α, dd) < 2, C20(3He, dp) = 3.5 ± 0.4, C20(3H, dn) = 2.6 ± 0.3 and C20(d, np) = 1.66 ± 0.1.  相似文献   

17.
Lifetimes of low-lying states in 19F were measured using the Doppler-shift attenuation method through the 15N(α, γ)19F reaction. Values of τm = 3700 ± 700 fs (1.35 MeV), 140 ± 15 (1.46), 19 ± 7 (4.00) and 63 ± 19 (4.03) were obtained for the lowest 52?, 32?, 72? and 92? members, respectively, of the Kπ = 12? rotational band and 5 ± 3 fs (1.55 MeV) and 370 ± 25 (2.78) for the 32+ and 92+ members of the Kπ = 12+ ground-state band. For the Doppler-shift attenuation analysis correction factors of the nuclear and electronic stopping powers were determined by measuring the Doppler-shift attenuation and γ-ray line shape of the 2.78 → 0.20 MeV transition and range values of 100, 200. 300 and 370 keV 19F nuclei in tantalum. All calculations were done with Monte Carlo methods. The transition strengths are discussed in terms of different theoretical predictions.  相似文献   

18.
A gas ΔE ? ER telescope has been used to measure charge yields and their correlations with kinetic energies for 229Th and 232U. Even-charge yields are enhanced compared with odd-charge yields for both fissioning systems; this enhancement increases for events with higher kinetic energy. The mean odd-even effect δpis = (40±4)% for229Th; it is (21 ± 3)% for232U-the same as for233U((22.1±2.1)%) and235U((23.7±0.7)%). The energy-integrated δp and δp for different energy windows, vary strongly as a function of charge (Z) due to the underlying shells. The δp averaged over Z increases fast with kinetic energy, contrary to the existing results for 233U and 235U, where δp flattens off at low energies. For both systems, the most probable kinetic energy ē shows a strong odd-even stagger; the mean odd-even effect on energy, δEKo?e, is 1.4 ± 0.3 MeV for229Th, and 1.7±0.4 MeV for232U the latter is about twice the value for 233U (0.95 ± 0.09 MeV) and235U (0.7 MeV). These results are discussed in terms of the existing models.  相似文献   

19.
The interaction of electrons and polar-optical phonons is investigated for CdTe and InP in cylotron resonance (CR) emission and absorption experiments. Under hot electron conditions three different Landau level transitions are observed. From the positions of the fundamental transition and the CR line splittings the nonparabolicity and the polaron contribution to the effective mass are analysed using a variational approach for the polaron shifts. The bare band edge masses and the polaron coupling constants are determined to be m10=0.0900±0.0005, α=0.35+-0.03 for CdTe and m10=0.0765±0.0005, α=0.15±0.01 for InP.  相似文献   

20.
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   

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