共查询到20条相似文献,搜索用时 218 毫秒
1.
Yu.N. Lobach A.D. Efimov A.A. Pasternak 《The European Physical Journal A - Hadrons and Nuclei》1999,6(2):131-140
Lifetimes of excited states in 110Cd have been measured by the Doppler shift attenuation method in the reaction (α,2nγ) at E
α= 25 MeV. Lifetime values for 8 states and lifetime limits for 3 states were obtained. The band structures of 110Cd have been interpreted in terms of a modified version of the interacting boson model (IBM + 2 q.p.). The calculations explain
well the excitation energies and electromagnetic transition probabilities up to J
π= 16+, except for the 10+
1 state. The structural features are discussed in terms of collective and two quasiparticle excitations.
Received: 20 March 1999 / Revised version: 28 May 1999 相似文献
2.
We discuss the quasi-adiabatic approximations to the three-body wave-function in breakup processes and clarify the assumptions
underlying the model. This suggests alternative approximation schemes. Using different theoretical three-body models, calculated
angular distributions of differential cross sections for the 11Be(p,d) reaction are presented, for which new preliminary data have been reported at 35 MeV. We show that calculations are sensitive
to the inclusion of deuteron breakup and to the breakup model used, particularly if absolute spectroscopic information on
the 0+ and 2+
10Be core-state parentages is deduced. There is also considerable sensitivity to the model employed in calculations of the relative
cross sections of the two states.
Received January 19, 1999; revised April 16, 1999; accepted for publication February 28, 2000 相似文献
3.
V. V. Varlamov B. S. Ishkhanov V. N. Orlin V. A. Chetvertkova 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(6):833-841
A combined analysis of experimental data on total and partial photoneutron reaction cross sections, obtained using bremsstrahlung
γ-radiation and quasi-monoenergetic annihilation photon beams, was performed for nine Sn isotopes. The partial reactions σeval(γ, nX) and σeval(γ, 2nX) cross sections were evaluated using an approach free of the shortcomings of experimental neutron multiplicity sorting methods.
This approach involves calculations within the photonuclear reaction model, based on Fermi gas densities and considering the
effects of nucleus deformation, the isospin splitting of its giant dipole resonance (GDR), and experimental data on the total
photoneutron cross sections σexp(γ, xn) = σexp(γ, nX) + 2σexp(γ, 2nX) = σexp(γ, n) + σexp(γ, np) + … + 2σexp(γ, 2n) + 2σexp(γ, 2np) + …. The evaluated σeval(γ, nX) and σeval(γ, 2nX) reactions cross sections were obtained using the introduced transition multiplicity functions F
theor = σtheor(γ, 2nX)/σtheor(γ, xn) = σtheor(γ, 2nX)/[σtheor(γ, nX) + 2σtheor(γ, 2nX) + …]; and σeval.(γ, 2nX) = F
theor.σexp.(γ, xn) = σeval(γ, nX) = (1 − 2F
theor)σexp(γ, xn). The evaluated partial reaction cross sections were used to assess the total photoneutron reaction cross sections σeval(γ, sn) = σeval(γ, nX) + σeval(γ, 2nX) + … as functions of the mass number A. The GDR features of 112, 114, 116, 117, 118, 119, 120, 122, 124Sn isotopes were studied and are discussed here. 相似文献
4.
T. Shizuma T. Ishii H. Makii T. Hayakawa S. Shigematsu M. Matsuda E. Ideguchi Y. Zheng M. Liu T. Morikawa P. M. Walker M. Oi 《The European Physical Journal A - Hadrons and Nuclei》2006,30(2):391-396
Excited states in neutron-rich 188W have been populated using a 186W(18O,16O) reaction. In-beam γ-rays were measured in coincidence with scattered particles detected by a high-resolution ΔE-E Si telescope. In this experiment, the ground-state band has been identified up to I
π = 8+. The γ band, the K
π = 2- octupole band, and a 2-quasiparticle state were also observed. The results are compared with predictions of self-consistent
HFB cranking calculations and blocked-BCS multi-quasiparticle calculations. 相似文献
5.
J.H. Ha J.C. Kim C.S. Lee J.Y. Huh C.-B. Moon Y. Gono S. Mitarai T. Morikawa M. Shibata H. Watanabe M. Miyake E. Komatsu A. Odahara E. Ideguchi X.H. Zhou 《The European Physical Journal A - Hadrons and Nuclei》1998,1(3):247-248
High-spin states of odd-odd 168Lu were observed up to 18ħ for the first time using the 159Tb(13C, 4nγ)168Lu reaction at E
13C= 58.5 MeV. γ-γ coincidence, E
γ singles, excitation function, and the DCO ratios were measured. Two rotational bands with signature splitting were populated,
among which the lower-energy band is identified as π 7/2+[404] ⊗ν 5/2+[642] in view of alignment and energy systematics.
Received: 27 October 1997 相似文献
6.
7.
We have investigated the heaviest one-neutron halo candidate, the 19C nucleus. Few-body model calculations of cross-section angular distributions for the 19C(p,d)18C reaction together with test calculations carried out for the 17C(p,d)16C reaction at a low incident energy are presented for different possible halo-neutron configurations. We show that there is
a clear distinction in particular between l
n
= 0 and l
n
= 2 halo transfers. The sensitivity of the cross sections to the assumed 19C single-neutron separation energy is discussed.
Received October 13, 1999; revised November 25, 1999; accepted for publication April 29, 2000 相似文献
8.
B. V. Danilin N. B. Shul’gina S. N. Ershov J. S. Vaagen RNBT Collaboration 《Physics of Atomic Nuclei》2009,72(8):1272-1284
Hyperspherical-harmonics method to investigate the lightest nuclei having three-cluster structure is discussed together with
recent experiments. Properties of bound states and methods to explore three-body continuum are presented. The challenges created
by large neutron excess and halo phenomena are highlighted. Astrophysical aspects of the 7Li + n → 8Li + γ reaction and the solar-boron-neutrinos problem are analyzed. Three-cluster structure of highly excited states in 8Be is shown to be responsible for extreme isospin mixing. Progress in studies of 6He- and 11Li-induced inclusive and exclusive nuclear reactions is demonstrated, providing information on the nature of continuum structures
of Borromean nuclei.
The text was submitted by the authors in English. 相似文献
9.
I. V. Glavanakov P. Grabmayr Yu. F. Krechetov A. N. Tabachenko 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(6):747-749
Experimental research on positive-pion photoproduction on the oxygen nucleus in the 16O(γ, π+p) reaction at high recoil momenta of the residual nuclear system was performed. The yield for the 16O(γ, π+p) reaction was analyzed using a model that takes Δ-isobar configurations in nuclei ground states into account, together with
the earlier-measured yield of the12C(γ, π+p) reaction. The estimated number of isobars per nucleon N
Δ = 0.012 ± 0.005 was obtained for the 12C nucleus, and 16O N
Δ = 0.018 ± 0.004 was obtained for the 16O nucleus. 相似文献
10.
Wen-Xin Qin 《Communications in Mathematical Physics》2012,311(2):513-538
In this paper we are mainly concerned with existence and modulation of uniform sliding states for particle chains with damping
γ and external driving force F. If the on-site potential vanishes, then for each F > 0 there exist trivial uniform sliding states x
n
(t) = n
ω + ν
t + α for which the particles are uniformly spaced with spacing ω > 0, the sliding velocity of each particle is ν = F/γ, and the phase α is arbitrary. If the particle chain with convex interaction potential is placed in a periodic on-site potential,
we show under some conditions the existence of modulated uniform sliding states of the form
xn(t)=nw+nt+a+u(nw+nt+a),x_n(t)=n\omega+\nu t+\alpha+u(n\omega+\nu t+\alpha), 相似文献
11.
V. V. Anisovich L. G. Dakhno M. A. Matveev V. A. Nikonov A. V. Sarantsev 《Physics of Atomic Nuclei》2007,70(2):364-381
Earlier by the authors (Yad. Fiz. 70, 68 (2007)), the bƃ states were treated in the framework of the spectral integral equation, together with simultaneous calculations of radiative
decays of the considered bottomonia. In the present paper, such a study is carried out for the charmonium
states. We reconstruct the interaction in the c-c sector on the basis of the data for the charmonium levels with J
PC = 0−+, 1−−, 0++, 1++, 2++, 1+− and radiative transitions ψ(2S) → γχ
c0(1P), γχ
c1(1P), γχ
c2(1P), γχ
c(1S) and χ
c0(1P), χ
c1(1P), χ
c2(1P) → γJ/ψ. The c-c levels and their wave functions are calculated for the radial excitations with n ≤ 6. Also, we determine the c-c component of the photon wave function using the e
+
e
−-annihilation data: e
+
e
− → J/ψ(3097), ψ(3686), ψ(3770), ψ(4040), ψ(4160), ψ(4415) and perform the calculations of the partial widths of the two-photon decays for the n = 1 states η
c0(1S), χ
c0(1P), χ
c2(1P) → γγ and n = 2 states η
c0(2S) → γγ, χ
c0(2P) → γγ. We discuss the status of the recently observed c-c states X(3872) and Y(3941): according to our results, the X(3872) can be either χ
c1(2P) or η
c2(1D), while Y(3941) is χ
c2(2P).
The text was submitted by the authors in English. 相似文献
12.
D. Rudolph C. Baktash M.J. Brinkman M. Devlin H.-Q. Jin D.R. LaFosse L.L. Riedinger D.G. Sarantites C.-H. Yu 《The European Physical Journal A - Hadrons and Nuclei》1999,4(2):115-145
High-spin states of nuclei near doubly magic 56Ni were studied with the reaction 28Si(36Ar,xpynzα) at 136 MeV beam energy. The Gammasphere array in conjunction with the 4π charged-particle detector array Microball and
neutron detectors were used to detect γ rays in coincidence with evaporated light particles. The resulting extensive decay
schemes of 54Fe, 54,55Co, 56,57Ni, and 58Cu are compared to shell model calculations in the fp shell.
Received: 19 September 1998 / Revised version: 27 November 1998 相似文献
13.
A. Gasparyan J. Haidenbauer C. Hanhart K. Miyagawa 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):61-67
The prospects of utilizing the strangeness production reaction γd→K
+
Λn for the determination of the Λn low-energy scattering parameters are investigated. The spin observables that need to be measured in order to isolate the
Λn singlet (1
S
0) and triplet (3
S
1) states are identified. Possible kinematical regions where the extraction of the Λn scattering lengths might be feasible are discussed. 相似文献
14.
The principles of construction and the results of testing of a system for measuring P-odd asymmetries in nuclear reactions with polarized cold neutrons by the integrated method of recording events at the neutron
polarization switching frequency above the fundamental frequencies of the reactor power fluctuation spectrum are presented.
It is shown experimentally that if the signal under investigation is characterized by the spectral density of power decreasing
with increasing frequency, switching of the equipment at a higher frequency decreases the measuring error. The dependence
of the error of measurements of P-odd asymmetry in the emission of γ quanta in the 10B(n, α)7Li* ⟹ γ ⟹ 7Li(g.s.) reaction on the neutron polarization switching frequency is derived. The system described here is implemented experimentally
for the first time. 相似文献
15.
A. S. Frolova S. S. Semikh S. V. Rozov E. A. Yakushev 《Physics of Particles and Nuclei Letters》2011,8(7):786-788
The purpose of the work is to evaluate the neutron background from an additional neutron source, the (α, n) reaction on 13C, in the polyethylene neutron shielding of the EDELWEISS-II experiment on the search for weakly interacting cold matter particles.
The characteristic length of radon diffusion into polyethylene is obtained, the neutron energy spectrum is constructed, and
the neutron flux from the (α, n) reaction is evaluated. 相似文献
16.
V. V. Anisovich L. G. Dakhno M. A. Matveev V. A. Nikonov A. V. Sarantsev 《Physics of Atomic Nuclei》2007,70(1):63-92
In the framework of the spectral integral equation, we consider the
states and their radiative transitions. We reconstruct the
interaction on the basis of data for the levels of the bottomonium states with J
PC = 0−+, 1−−, 0++, 1++, 2++ as well as the data for the radiative transitions γ (3S) → γχbJ(2P) and γ(2S) → γχbJ(1P) with J = 0, 1, 2. We calculate bottomonium levels with the radial quantum numbers n ≤ 6, their wave functions, and corresponding radiative transitions. The ratios Br[χbJ(2P) → γγ(2S)]/Br[χbJ(2P) → γγ(1S)] for J = 0, 1, 2 are found to be in agreement with data. We determine the
component of the photon wave function using the data for the e
+
e
− annihilation, e
+
e
− → γ(9460), γ(10 023), γ(10 036), γ(10 580), γ(10 865), γ(11 019), and predict partial widths of the two-photon decays ηb0 → γγ, χb0 → γγ, χb2 → γγ for the radial excitation states below the
threshold (n ≤ 3).
The text was submitted by the authors in English. 相似文献
17.
I. Peter W. von Oertzen H.G. Bohlen A. Gadea B. Gebauer J. Gerl M. Kaspar I. Kozhoukharov T. Kröll M. Rejmund C. Schlegel S. Thummerer H.J. Wollersheim 《The European Physical Journal A - Hadrons and Nuclei》1999,4(4):313-317
One and two neutron transfer has been measured in the heaviest asymmetric nuclear system with semi magic nuclei showing superfluid
properties, in 206Pb+118Sn collisions at an energy well below the Coulomb barrier with scattering orbits covering the largest angles. Particle-γ coincidence
techniques using 5 Euroball-Cluster detectors (EB) combined in a set-up with the Heidelberg-Darmstadt NaI-Crystal Ball (CB)
have been used. Transfer channels are identified with EB via their known γ-decays of the lowest excited states. Using the
unique feature of the set-up with the CB, transfer to well defined final states with known quantum numbers (without feeding)
are selected using the high efficiency multiplicity filter of the CB (no second γ-ray). The data are analysed using the semiclassical approach and transfer probabilities are obtained. The enhancement
for the two-neutron transfer populating the low lying superfluid 2+ state in 120Sn (and 116Sn), while the Pb-branch is in the groundstate is deduced by comparison with the strongest single neutron transfer transition.
Large enhancements (EF ≃ 103) are observed. This is the first direct measurement of enhancement for a heavy nuclear binary system with experimentally
separated levels suggesting a strong contribution from superfluid pair transfer.
Received: 18 December 1998 / Revised version: 23 February 1999 相似文献
18.
The 3He(4He, γ)7Be and 3H(4He, γ)7Li reactions are studied in an extended two-cluster model which contains α + h/t and 6Li + p/n clusterizations. We show that the inclusion of the 6Li + p/n channels can significantly change the zero-energy reaction cross sections, S(0), and other properties of the 7Be and 7Li nuclei, like the quadrupole moments Q. However, the results agree with the known correlation trend between S(0) and Q. Moreover, we demonstrate that the value of the zero-energy derivatives of the astrophysical S-factors are more uncertain than currently believed.
Received June 17, 1999; revised February 22, 2000; accepted for publication April 17, 2000 相似文献
19.
V. S. Belyaev A. P. Matafonov S. M. Ribakov V. P. Krainov V. S. Lisitsa V. P. Andrianov G. N. Ignat’ev A. S. Rusetskiy 《Laser Physics》2011,21(8):1398-1403
The experimental results on the initiation of various (γ, n) and (p, n) nuclear reactions in the picosecond laser plasma are presented. It is demonstrated that the following (γ, n) and (p, n) nuclear reactions can be initiated at a laser intensity of 2 × 1018 W/cm2 with the threshold energies of γ-quanta ranging from 1.67 to 7.56 MeV and the threshold energies of protons ranging from 1.88 to 5 MeV: 9Be(γ, n)2α, 181Ta(γ, n)180Ta, 7Li(p, n)7Be, 63Cu(p, n)63Zn, 48Ti(p, n)48V. The method based on the detection of fast neutrons using the 3He counters is employed for the measurement of the number
of the initiated (γ, n) and (p, n) nuclear reactions. The measured yield of the (γ, n) and (p, n) nuclear reactions ranges from 5 × 101 to 105 reactions per laser pulse. 相似文献
20.
N. Itagaki S. Okabe K. Ikeda I. Tanihata 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):43-47
The structure of Be and C isotopes are investigated based on the molecular-orbit (MO) model. The low-lying states are characterized
by several configurations of valence neutrons, which are constructed as combinations of basic orbits. In 10Be, all of the observed positive-parity bands and the negative-parity bands are described within the model. The second 0+ state of 10Be has a large α-α cluster structure, and this is characterized by a (1/2+
σ)2 configuration. An enlargement of the α-α distance due to two-valence neutrons along the α-α axis makes their wave function
smooth and reduces the kinetic energy drastically. Furthermore, the contribution of the spin-orbit interaction due to coupling
between the S
z = 0 and the S
z = 1 configurations, is important. In the ground state of 12Be, the calculated energy exhibits similar characteristics, that the remarkable α clustering and the contribution of the spin-orbit
interaction make the binding of the state with (3/2-
π)2(1/2+
σ)2 configuration properly stronger in comparison with the closed p-shell (3/2-
π)2(1/2-
π)2 configuration. This is related to the breaking of the N = 8 (closed p-shell) neutron magic number. Also, the molecule-like structure of the C isotopes is investigated using a microscopic α+α+α+n+n+ . . . model. The combination of the valence neutrons in the π- and the σ-orbit is promising to stabilize the linear-chain state
against the breathing and bending modes, and it is found that the excited states of 16C are the most promising candidates for such structure.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
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