首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 453 毫秒
1.
Excited Jπ=0+ states in 40Ca have been identified by the observation of L=0 angular distributions in the 38Ar(τ, n) 40Ca reaction. Strong transitions are observed to the ground state, the known 2p–2h at 9.38 (T=1) and 11.98 MeV (T=2), and to states at 8.28 and 10.65 MeV. The strongest excited-state transition is to the 8.28 MeV state, which we identify as the 2p–2h T=0 state. The Jπ=0+ state at 7.30 MeV which has been suggested as the 2p–2h T=0 state is not observed.  相似文献   

2.
Shell model calculations ofJ=2+,S=0 andS=1 states indicate that the spin flip quadrupole strength is much more fragmented than itsS=0 analog, at least in light nuclei. A sum rule technique is then used to study the coexistence betweenS=0 andS=1 states; it illustrates why theS=0 strength is fairly immune to changes in the noncentral part of the nuclear interaction. In16O, someE2 spin flip strength is predicted to lie in the 40 MeV region where it could be located by inelastic electron and pion scattering experiments.  相似文献   

3.
Theg-factor of theJ π=21/2+ isomeric state in111In (T 1/2=13.3 ns) and of theJ π=6+ isomeric state in112Sn (T 1/2=13.7 ns) were measured using the spin rotation method. The result obtained for theJ π=21/2+ level in111In,g=+0.47 (2), indicates that this state has an almost pure ((πg 9/2)?1 νg 7/2 νd 5/2) shell model configuration. The experimental valueg=+0.04 (3) for theJ π=6+ isomer in112Sn agrees with the theoretical value calculated within the frame of the BCS model.  相似文献   

4.
《Physics letters. [Part B]》1988,201(4):568-572
In a new experiment we have obtained 3006 new events in the reaction πpφφn, approximately doubling the statistics which now total 6658. A refined partial wave analysis of the φφ system again reveals three resonances (gT, gT′, gT′') with IGJPC=0+2++. The absence of the OZI suppression, and the observation of only three JPC=2++ states (gT, gT′, gT′') which comprise virtually all the cross section are unusual characteristics of the data. The large φφn signal occurs over a mostly structureless and incoherent φK+Kn background. All these unusual characteristics are well explained if these states are produced by 1–3 glueballs (multigluon resonances).  相似文献   

5.
《Physics letters. [Part B]》1988,215(3):469-472
Complete in- and out-of-plane fission fragment angular correlations for 238U have been measured in (e, e′f) coincidence experiments for momentum transfers qeff=0.20 and 0.28 fm and excitation energies ω=5.5–15 MeV. A combined analysis with previously extracted E1 and E2/E0 multipole strength distributions yields strength distributions for all 6 near barrier fission channels (Jπ, K) = (0+, 0), (1, 0), (1, 1), (2+, 0), (2+, 1), and (2+, 2) up to ≈8 MeV. An estim ate of the respective fission barriers, deduced from the increase of the fission cross sections, is given.  相似文献   

6.
We have searched for the giant magnetic dipole resonance in 90Zr and an associated state in 208Pb. Among the experimental techniques employed in this search was the detection of inelastically scattered protons in coincidence with ground-state de-excitation γ-rays, No state in 90Zr up to an excitation of 10.5 MeV or in 208Pb between 5.0 to 6.0 MeV was observed with the desired characteristics. In 90Zr, heretofore unidentified levels at 5.51, 5.89 and 6.42 MeV were determined to have Jπ = 1?. In 208Pb Jπ = 1? states were observed at 5.29, 5.51 and 5.94 MeV. The implications of our observations are discussed.  相似文献   

7.
The energies and spectroscopic factors ofJ π=5/2+ states of nucleus91Nb excited via a reaction transferring a proton to the 2d 5/2 orbit of90Zr target state have been calculated. Effective two-body interaction used has been extracted from the experimentally observed two-body energies of (1g 9 2/?1 (n) 2d 5/2(n)), (1g 9 2/?1 (n) 1g 9/2(p)) and (1g 9/2(p)-2d 9/2(n)) multiplets in90Zr,90Nb and92Nb nuclei respectively. Most of the calculated energies and the strengths ofJ π=5/2+ levels have reasonably good counterparts in the experimental spectrum, however the calculation shows about 17% strength lying at 6.8 MeV, without having a confirmed counterpart in the observed level scheme. The reduced transition strengthsB(M1) forM l transitions from 5/2? T>(11/2) state to the various components of 5/2+ T<(=9/2) state have also been reported; but the corresponding experimental values are not available. The main feature of the reduced transition strengths is that theM1 transition to the state at 3.69 MeV is inhibited whereas that to the state at 6.79 MeV is enhanced, the relevant core-configuration, interfering destructively in the former case and constructively in the latter.  相似文献   

8.
The 17O(p, p)17O and 17O(p, α0)14N reactions have been studied in the energy range Ep = 0.5–1.33 MeV. Excitation functions for elastic scattering measured at several angles give lp values for six resonances and Jπ; T values of 3+; 1 and 2+; 1 for the states at 6.16 and 6.28 MeV, respectively. From both reactions, Jπ limitations were found for six resonant levels. The 17O(p, α0)14N reaction also yields information on T-assignments and level formation parameters. Experimental results are discussed in terms of shell-model configurations.  相似文献   

9.
The d(π+, π)T+++ and the d(π, π+) T reactions were studied at an incident pion energy of 260 MeV. Outgoing negative pions were detected at 35° and 55° in the first reaction, and the positive pions at 45° in the second. Indications for structures corresponding to a (π+pp) system with a mass of 2003.0±1.0 MeV and a (πnn) system with a mass of 200.1±1.5 MeV were observed with marginal statistical significance. Upper limits for the cross sections are obtained.  相似文献   

10.
Studies via the 16O(3He, pγ)18F, 14N(α,γ)18F and 17O(p, γ)18F reactions have resulted in new Jπ assignments for 11 states or negative parity: Ex(keV) (Jπ) = 3791(3?), 4226(2(?)), 4398(4?), 4860(1(?)), 5502(3(?)), 5785(2?), 6097(4?), 6108(1(?), 2(?), 3(?)), 6241(3?, T = 1), 6643(2?, T = 1) and 6878(3(t-), 4?). The 6241 keV state is probably isospin mixed. New information for 5 states of positive parity has also been obtained: Ex(keV) (Jπ) = 3838(2+), 4115(3+), 4652(4+, T = 1), 4753((0+), T = 1) and 4964(2+, T = 1). Mean lives, branching and mixing ratios are reported for all states. The results for the negative-parity states are discussed in the framework of the various models available. The states at Ex = 1080(0?), 2100(2?) and 4398(4?) keV are interpreted as the first three members of a Kπ = 0? rotational band.  相似文献   

11.
《Nuclear Physics A》1986,451(4):741-750
Angular distributions for scattering from 6Li with π+ and π beams were measured at 100, 180 and 240 MeV incident energy. Elastic (Jp = 1+, T = 0) and inelastic (Jp = 3+, T = 0, Ex = 2.19 MeV) data were obtained over large angular ranges. The elastic results are compared to calculations within the αnp cluster model.  相似文献   

12.
The resonance reaction25Mg(p, γ)26Al in the energy rangeE p =300–400 keV was used to populate high-lying bound states in the self-conjugate nucleus26Al. The existence of three resonances atE p =304, 316 and 388 keV was verified, the spins of the ones at 316 and 388 keV were found to be 3? and 2+, respectively. The spin of the bound level at 4,547 keV level was fixed to beJ π=2+. Several strong isovector Ml transitions were observed, which led toT=1 assignments for the levels atE x =4,191, 4,547, 4,599, 5,141 and 5,542 keV. The results for excitation energies and values ofJ π,T together with previous experimental and theoretical data on26Al and the neighboring |T z |=1 nuclei26Mg and26Si are discussed in the framework of the isospin model.  相似文献   

13.
In the present work one- and two-channel approaches using the expansion of the effective-range function K(E) in powers of energy E are applied to obtain the asymptotic normalization coefficients (ANCs) and vertex constants (VCs) for the d + α system. The coefficients of the K(E) expansion are found by fitting the d α phase shifts. By analytic continuation of K(E) thus obtained to the corresponding poles the ANCs and VCs for D wave d α resonances with J π = 1+, 2+, 3+ are calculated for the first time. The 1+-resonance and the bound state of 6Li (J π = 1+) are considered jointly in the two-channel (S + D) effective-range approach and the ANCs and VCs for the ground 6Li state are found.  相似文献   

14.
The56Fe(d,p)57Fe reaction has been studied at an incident energy of about 10 MeV. The ground state doublet of57Fe has been resolved using the Heidelberg Q 3 D magnetic spectrograph and the Minnesota split-pole spectrograph. The ratio of the spectroscopic strengths (2J+1)S for the transitions to the first excited state at 14.4 keV excitation energy (J π=3/2?) and the ground state (J π=1/2?) has been determined to be 5.80±0.5. This number is of special interest with respect to a possible deformation of the nucleus57Fe and in connection with the corresponding analogue resonances in57Co.  相似文献   

15.
The coupled-channels formalism, which has been previously applied successfully to interpret the negative-parity resonances in4He, has now been extended to the positiveparity 2?ω resonances in this system. The 1p-1h approach has been modified to include coupling to the 2p-2h configurations, which also belong to 2 excitations, by using the effective operator formalism. The effect of the Pauli term in thes-wave channel is examined and is found to be important in reproducing the 0+,T=0 resonance energy and width. Resonances with spins up toJ π=3+ have been studied, and the agreement with available data is satisfactory. In particular, from the good fit to the asymmetry coefficientβ(E), one establishes the presence of a 2+,T=0 resonance around 35-MeV excitation in the system.  相似文献   

16.
《Physics letters. [Part B]》1986,168(4):321-325
A specific ansatz for higher baryon numbers yields B=2 configurations which lead to bound T=0, JP=0+ and slightly unbound T=0, JP=1+ solitons after quantization of the rotational motion. Due to the small size of the resulting soliton it is difficult to interpret the T=0, JP=1+ state as a deuteron.  相似文献   

17.
Tritons from the reaction139La(d, t)138La atE d=16 MeV were analyzed at eleven reaction angles from 22 ° to 90 ° with a broad-range magnetic spectrograph. TheQ-value of the reaction is ?2522±5 keV. The nine lowest-lying states in138La are interpreted in terms of the shell model configurations (πg 7/2)?1 (vd 3/2)?1, (πg 7/2)?1 (vs 1/2)?1 and (πg 7/2)?2 (πd 5/2)?1(vd 3/2)?1. Seven levels in the energy range of 700–1300 keV are populated byl=5 transitions and are interpreted as coming from the (πg 7/2)?1(vh 11/2)?1 configuration. The ground state of138La is shown to haveJ π=5+. Therefore, beta decay by unique second-forbidden transitions to the 2+ one-phonon states of138Ce and138Ba must be inferred in spite of unusually high logft values of 19.2 and 18.5, respectively.  相似文献   

18.
Using the reaction175Lu(19F, 6n) theg-factor of the188Hg isomeric state (J π=12+,T 1/2=135 ns) has been measured with the TDPAD method. The experimental value g=?0.168(10) supports the interpretation of an almost pure (vi13/2)?2 configuration for this isomer.  相似文献   

19.
The resonance in the12C+12C system atE c.m.=19.3 MeV has been studied in the neutron and proton decay channels. From(p, γ), (n, p) and (n, γ) coincidence measurements high spin states could be localized inA=23 nuclei, in23Mg up to possibly 21/2+. These states were resonantly populated. The present data favorJ π=17/2+ for the 9.61 MeV state in23Mg and therefore also for the probable parent state at 9.81 MeV in23Na. AJ π=12+ assignment to the resonance is supported and evidence was found that the resonant excitation of the lowest 15/2+ and 17/2+ states in mass 23 nuclei is caused by a change of the intrinsic structure of the Yrast levels aroundJ π=15/2+ towards larger deformation.  相似文献   

20.
《Nuclear Physics A》1997,617(2):195-210
We describe the Jπ = 0+, 2+, 4+, … ground state bands of 222,224,226Ra, using a model in which these bands are treated as a 14C cluster orbiting the appropriate Pb core. For each isotope, we obtain good agreement with the measured half-life for the 14C decay of the 0+ ground state, as well as with the excitation energies and in-band E2 decays of other states of the ground state band. We also propose extensions of the model to deal with the observed low-lying Jπ = 1, 3, 5, … bands, their in-band E2 decays, and the E1 and E3 transitions connecting to the ground state bands.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号