共查询到20条相似文献,搜索用时 15 毫秒
1.
《Nuclear Physics A》1999,645(3):331-375
Levels in 125Te were investigated in the range up to 3.3 MeV excitation energy by the (n,γ), (d,p) and (3He,α) reactions. Over 160 levels and about 360 γ-transitions were established, most for the first time. The states below 2.3 MeV with the most complete spectroscopic information were interpreted in terms of the interacting boson-fermion model (IBFM). Unitary treatment of both positive- and negative-parity states is achieved with the same model parameter close to the intermediate case between O(6) and U(5) limits. Excitation energies, electromagnetic transition rates, γ-branchings and spectroscopic factors are discussed in connection with the possible structures. A family of low-spin negative-parity states has been identified and understood by the IBFM proving their antialigned origin. 相似文献
2.
《Nuclear Physics A》1997,625(3):598-620
At the Munich Tandem Accelerator the reactions 125Te(d, p)126Te, 126Te(d, d′)126Te and 127I(d, 3He)126Te were measured with deuteron energies between 24 and 28 MeV up to excitation energies of about 3.2 MeV. Using γ-lines from previous (n,γ), (n,n′γ) and (γ,γ′) experiments, a level scheme of 126Te up to above 3 MeV was established. The results are compared with quasiparticle-phonon model calculations. 相似文献
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4.
N. G. Goncharova F. A. Zhivopistsev K. V. Shitikova 《Czechoslovak Journal of Physics》1981,31(4):367-382
The complication effects in the highly-excited state structure (impurity of the complex configurations of the 2p2h type) of the (, n), (e, e) and (–, ) nuclear reactions with the40Ca nucleus have been studied in terms of the ph-approximation including the following effects: (a) the presence of states of the two particles — two holes type, (b) rigidity loss by nucleus in excited state. 相似文献
5.
《Nuclear Physics A》1986,460(3):501-528
The γ-ray spectrum emitted after thermal neutron capture in 86Sr was studied at the ILL high flux reactor with pair- and intrinsic Ge spectrometers. 759 transitions were assigned to the reaction 86Sr(n, γ)87Sr and 385 of them were placed into a 87Sr level scheme of 80 levels. This represents 90% of the observed intensity. The level energies were determined with a precision of better than 20 ppm; the neutron binding energy was determined to be 8428.16 (17)keV. In a second set of experiments high resolution particle spectra of the reactions 86Sr(d, p)87Sr and 88Sr(d, t)87Si were recorded at 20 MeV deuteron energy with the München Q3D spectrometer. These data were used to establish newly found levels and to differentiate between primary and secondary transitions in the (n, γ) data. The observed level densities and primary transition strengths are compared with statistical models. 相似文献
6.
V. V. Varlamov B. S. Ishkhanov V. N. Orlin N. N. Peskov M. E. Stepanov 《Physics of Atomic Nuclei》2013,76(11):1403-1414
Systematic discrepancies between the results of various experiments devoted to determining cross sections for total and partial photoneutron reactions are analyzed by using objective criteria of reliability of data in terms of the transitional photoneutron-multiplicity function F i = σ(γ, in)/σ(γ, xn), whose values for i = 1, 2, 3, ... cannot exceed by definition 1.00, 0.50, 0.33, ..., respectively. It was found that the majority of experimental data on the cross sections obtained for (γ, n), (γ, 2n), and (γ, 3n) reactions with the aid of methods of photoneutron multiplicity sorting do not meet objective criteria (in particular, F 2 > 0.50 for a vast body of data). New data on the cross sections for partial reactions on 181Ta and 208Pb nuclei were obtained within a new experimental-theoretical method that was proposed for the evaluation of cross sections for partial reactions and in which the experimental neutron yield cross section σ expt(γ, xn) = σ(γ, n) + 2σ(γ, 2n) + 3σ(γ, 3n) + ..., which is free from problems associated with determining neutron multiplicities, is used simultaneously with the functions F i theor calculated within a combined model of photonuclear reactions. 相似文献
7.
S. R. Palvanov 《Physics of Atomic Nuclei》2014,77(1):35-38
The induced-activity method was used to measure the isomeric ratio of the yields of the (γ, n), (n, 2n), and (γ, 2n) reactions on the 113In nucleus. The energy dependence of the isomeric ratios of the yields of the photonuclear reactions 113In(γ, n)112m,g In and 113In(γ, 2n)111m,g In is studied in the energy range of 12–35 MeV. 相似文献
8.
《Nuclear Physics A》1987,473(1):129-159
The γ-ray spectrum emitted after thermal neutron capture in 87Sr was studied at the ILL high flux reactor with pair- and intrinsic Ge-spectrometers. 661 transitions were assigned to the reaction 87Sr(n, γ)88Sr and 205 of them were placed into a 88Sr level scheme of 47 levels. This represents 88% of the observed intensity. The level energies were determined with a precision of better than 20 ppm; the neutron binding energy was determined as 11 112.69 (22) keV. To aid the analysis high resolution particle spectra of the reaction 87Sr(d, p)88Sr were measured at 20 MeV deuteron energy with the Munich Q3D spectrometer. 85 states were observed with this reaction. The data helped to establish newly found levels and to differentiate between primary and secondary transitions in the (n, γ) data. The observed level densities and primary transition strengths are compared with statistical model predictions and non-statistical effects are discussed. 相似文献
9.
Tran Duc Thiep Truong Thi An Nguyen Tuan Khai Nguyen The Vinh Phan Viet Cuong A. G. Belov O. D. Maslov 《Physics of Particles and Nuclei Letters》2009,6(2):126-133
We have determined the isomeric ratios in photonuclear reactions 116Cd(γ, n)115m, g
Cd, 138Ce(γ, n)137m, g
Ce, 153Eu(γ, n)152m, g
Eu, 96Mo(γ, p)95m, g
Nb, 118Sn(γ, p)117m, g
In, 89Y(γ, 2n)87m, g
Y, 106Cd(γ, np)104m, g
Ag, and 112Sn(γ, np)110m, g
In induced by bremsstrahlungs with end-point energies in the Giant Dipole Resonance (GDR) region. The targets were irradiated
at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research,
Dubna. Gamma spectra of irradiated samples were measured with a spectroscopic system consisting of 8192-channel analyzer and
high-energy resolution (180 keV at gamma ray 1332 keV of 60Co) semiconductor detector CANBERRA. The results were discussed and compared with those of other authors.
The article is published in the original. 相似文献
10.
《Physics letters. [Part B]》1987,191(3):227-231
Calculations of charge-exchange processes in the final state of the quasi-elastic (e, e′N) reaction have been performed employing the Lane formalism. The Lane equations were decoupled by means of a transformation to the isospin representation. It is found that charge exchange has a small effect on the (e, e′p) cross section, but may play an appreciable role in the (e, e′n) reaction. 相似文献
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12.
A. S. Kachan I. V. Kurguz V. M. Mischenko S. N. Utenkov 《Bulletin of the Russian Academy of Sciences: Physics》2014,78(7):591-600
The excitation functions of 40Ar(p,p′γ)40Ar and 40Ar(p,γ)41K reactions are measured in the E p = 1.0–3.0 eV range of accelerated protons. The excitation function in the E p > 2.6 MeV range of accelerated protons is measured for the first time. The strengths of all (more than 200) measured resonance states are calculated. 相似文献
13.
The ratios of the cross sections for the formation of the ground and isomeric states in reactions on107Ag,109Ag, and113In are calculated based on the assumption that at low energies the (, n) reaction proceeds via a) formation of the compound nucleus, b) evaporation of a neutron, and c) cascade -transitions. The number of cascade -quanta and the distribution of the excitation energy between the -quanta and the neutron is not postulated beforehand (as is usually done), but is calculated based on the statistical theory. By comparing with experiment, the parameter of the spin-dependence of the density of nuclear states is found. It is shown that the average number of -quanta in the cascade increases approximately linearly with the energy of the particles. The energy spectrum of the -quanta in the (, n) reaction is calculated. The distribution of -quanta has a maximum at low energies (1 MeV), which, as the energy of the primary particles is increased, moves slowly into the higher energy range while broadening at the same time.Translated from Izvestiya Vysshykh Uchebnykh Zavedenii, Fizika, No. 8, pp. 77–81, August, 1984. 相似文献
14.
E. Navrátil 《Czechoslovak Journal of Physics》1962,12(10):734-737
The Courant model for direct photonuclear reactions is modified by using the wave functions of a shell model with spin-orbital bond. It is shown that the introduction of spin-orbital interaction does not influence the cross-section. The changes caused by the spin-orbital bond are apparent only on the angular distribution, which has the Courant forma+bsin2
, but with a different value ofb/a, i.e. the anisotropy coefficient. New selection lawsj j, j j±1 are found. The introduction of spin-orbital interaction permits the negative value of the anisotropy coefficient, found in some experimental papers, to be explained in a natural way.
Excerpt from diploma work done at Faculty of Technical and Nuclear Physics in Prague.
In conclusion the author thanks lecturer J. Kvasnica for the choice of subject and valuable remarks. 相似文献
- - (, n) (, )
: - . , . , - , , a+bsin2 , , b/a, . . . j j, j j±1. - , .
Excerpt from diploma work done at Faculty of Technical and Nuclear Physics in Prague.
In conclusion the author thanks lecturer J. Kvasnica for the choice of subject and valuable remarks. 相似文献
15.
I. R. Gulamov A. A. Karakhodzhaev A. M. Mukhamedzhanov G. K. Nie E. A. Pak R. Yarmukhamedov V. Burjan J. Cejpek V. Kroha J. Křemének M. Kurka 《Czechoslovak Journal of Physics》1990,40(8):875-894
The angular distributions of the (p, d), (d, t) and(3He, ) reactions on13C have been analysed within the framework of DWBA in which additional information on nuclear vertex constants was introduced. Although all these reactions seem to be similar single nucleon transfer, their mechanism is shown to be quite different and so is the information extracted thereof. While from the (p, d) reactions spectroscopic factors may be extracted unambiguously, from the (d, t) reactions it is possible to obtain directly the values of vertex constants only, which in turn are consistent with those determined by extrapolation of the experimental cross sections of the (p, d) reactions to the pole.In the case of (3He, ) reactions, however, the analysis indicates inadequacy of the DWBA concerning the calculations of central partial amplitudes. For a more reliable extraction of structural information, besides the correct normalization of peripheral amplitudes, a contribution of more complex mechanisms must be taken into account. 相似文献
16.
The measurement of parity-violating (PV) observables in few-nucleon system can shed light on our current understanding of the weak interaction between nucleons.Theoretical models describe the nucleonnucleon weak interaction at low energies use a series of undetermined parameters.Two parity violating measurements have been considered: the capture of polarized slow neutrons on hydrogen (n + p → d + γ) at Los Alamos National Laboratory for first phase and Oka Ridge National Laboratory for second phase and the helicity dependence of the deuteron photodisintegration cross section using circularly polarized photons (γ + d → n + p) at Shanghai Institute of Applied Physics.The goal of both experiments is to constraint the weak meson-nucleon couplings to a precision of 1 ×10^-8 .The introduction of both experiments is presented. 相似文献
17.
《Nuclear Physics A》1987,473(3):471-493
γ-ray and γγ-coincidence spectra of the 110Cd(p, nγ)110In reaction were measured with Ge(Li), Ge(LEPS), and Ge(HP) spectrometers at 6 MeV bombarding proton energy. Energies (Eγ) and relative intensities (Iγ) of 95 110In transitions (including 70 new ones) have been determined. The electron spectrum of the reaction was measured with a combined magnetic plus Si(Li) spectrometer at Ep = 6 MeV. Internal conversion coefficients of 41 transitions in 110In have been determined for the first time. The angular distribution of γ-rays was measured at 5.2, 5.6, and 6 MeV bombarding proton energies. A new, more complete level scheme of 110In has been deduced. On the basis of the internal conversion coefficients of transitions, Hauser-Feshbach analysis of (p, n) reaction cross sections, γ-ray angular distribution (and other) results unambiguous spin and parity assignments were made to 11 excited 110In levels. The energies of several 110In proton-neutron multiplets were calculated on the basis of the parabolic rule derived from the cluster-vibration model. The comparison of experimental and theoretical results provided identification of about 20 p-n multiplet states in 110In. 相似文献
18.
An irradiation of 238U with a beam of reactor fast neutrons permits revealing about 550 gamma transitions associated with the respective (n, n′γ) reaction and with fission fragments. The use of all known data on gamma radiation from fission fragments makes it possible to identify gamma transitions belonging to 238U with a high probability. The scheme of levels and gamma transitions is composed for 238U. New levels (including those of spin-parity J π = 0+) at excitation energies below 2 MeV are proposed. The low-lying levels in the rotational band for two-phonon octupole excitations are determined. It is found that a hybrid state is formed upon the crossing of this band and the band based on two-quasiparticle excitations. This hybrid state must involve excitations of both types. A small value of the rotational-band parameter in the isomer of energy 2559.0(4) keV is explained by the contribution to this state from two-quasiparticle configurations belonging to the 1k 17/2 subshell. The same circumstance may also be responsible for an enhanced yield of ternary fission for this isomer. 相似文献
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The (2)H(d,p)(3)H, (2)H(d,n)(3)He, and (2)H(d,γ)(4)He reactions are studied at low energies in a multichannel ab initio model that takes into account the distortions of the nuclei. The internal wave functions of these nuclei are given by the stochastic variational method with the AV8' realistic interaction and a phenomenological three-body force included to reproduce the two-body thresholds. The obtained astrophysical S factors are all in very good agreement with the experiment. The most important channels for both transfer and radiative capture are identified by comparing to calculations with an effective central force. They are all found to dominate thanks to the tensor force. 相似文献