共查询到20条相似文献,搜索用时 15 毫秒
1.
H. Toki 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):177-180
We critically review the present relativistic mean-field theory from the viewpoint of missing pions. We introduce the interesting
experimental data on pionic states taken at RCNP. These data seem to suggest the occurrence of pion condensation in the nuclear
surface. Qualitative discussion is made on the consequence of surface pion condensation on Gamow-Teller transitions and spin
response functions and others. The radioactive ion beams are the tools of studying the unstable nuclei, which have extended
nuclear surfaces. We shall start with radioactive ion beams the nuclear surface science, which includes the surface pion condensation
as the important ingredient in addition to spin-orbit splitting and surface pairing.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
2.
P. Strasser T. Matsuzaki K. Nagamine 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):197-202
X-ray spectroscopy of muonic atoms is an important tool to obtain information on the nuclear charge distribution of nuclei.
It has been successfully used for many years to study stable isotopes in condensed or gaseous states. A new method has been
proposed to extend muonic atom X-ray spectroscopy to the use of radioactive isotope beams to form muonic atoms with unstable
nuclei. This new method allows studies of the nuclear properties and nuclear sizes of unstable atoms by means of the muonic
X-ray method at facilities where both negative muon and radioactive nuclear beams would be available. Progress of a feasibility
study at RIKEN-RAL muon facility is also reported.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
3.
B.Z. Kopeliovich A.V. Tarasov O.O. Voskresenskaya 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):345-356
The Born approximation, one photon exchange, used for DIS (deep inelastic scattering) is subject to virtual radiative corrections
which are related to the long-range Coulomb forces. They may be sizeable for heavy nuclei since Zα is not a small parameter. So far, these corrections are known only for two processes, elastic scattering and bremsstrahlung
on the Coulomb field of a point-like target. While the former amplitude acquires only a phase, in the latter case also the
cross-section is modified. Although the problem of Coulomb corrections for DIS on nuclei is extremely difficult, it should
be challenged rather than “swept under the carpet”. The importance of these radiative corrections is questioned in the present
paper. We show that, in the simplest case of a constant hadronic current, the Coulomb corrections provide a phase to the Born
amplitude, therefore the cross-section remains the same. Inclusion of more realistic hadronic dynamics changes this conclusion.
The example of coherent production of vector mesons off nuclei reveals large effects. So far a little progress has been made
deriving lepton wave functions in the Coulomb field of an extended target. Employing available results based on the first-order
approximation in Zα, we conclude that the Coulomb corrections are still important for heavy nuclei. We also consider an alternative approach
for extended nuclear targets, the eikonal approximation, which we demonstrate to reproduce the known exact results for Coulomb
corrections. Calculating electroproduction of vector mesons, we again arrive at a large deviation from the Born approximation.
We conclude that one should accept with caution the experimental results for nuclear effects in DIS based on analyses done
in the Born approximation.
Received: 16 May 2001 / Accepted: 4 July 2001 相似文献
4.
A model for scalar quarks and gluons that successfully gives rise to a ln s behavior in high-energy qq scattering and which contains a non-trivial three-gluon vertex is used to study collision theory with the following aspects:
i) A three-body interaction simulating QCD is present and ii) particle production and annihilation occur naturally. In this
paper, the collision term in the model is examined in detail in the quasiparticle approximation. The construction of cross-sections
in which self-energy terms are ordered according to a coupling constant expansion is undertaken. It is shown explicitly which
terms of second order are required to obtain the scattering amplitudes that are two body in nature. Additional ordering in
the number of colors shows that quark loop diagrams are suppressed and gluon production or scattering processes dominate.
It is also shown that a consistent calculation of the scattering graphs at the two-loop level also simultaneously yields terms
that renormalize one-loop level graphs. This can then be extended to arbitrary m↦n processes. We examine the constraint equation briefly, discussing the appearance of a width. The issue of pinch singularities
is also addressed, and examples of the elimination of such singularities in equilibrium are given explicitly.
Received: 7 November 2001 / Accepted: 12 June 2001 相似文献
5.
J.-S. Graulich R. Coszach P. Leleux 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):221-225
Experimental methods in nuclear astrophysics experiments with radioactive beams are described, and evaluated. The importance
of performing the (p, p) elastic scattering in parallel to a (p, α) or a (p, γ) reaction is emphasized.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
6.
D. O. Odero 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):3-8
The time-dependent treatment of positron-hydrogen scattering for a zero total angular momentum has been presented. The initial
wavefunction of the positron-hydrogen scattering system has been expanded in terms of three dimensional dynamical wave functions
to include all higher angular momenta by solving a set of three coupled differential equations. This wavefunction is then
time evolved using Taylor series expansion of the evolution operator. The excitation probabilities are monitored as the wavefunction
propagates until there is no more change in the probabilities. The positron impact excitation cross-sections extracted from
the final wavefunction are compared with the available results of converged close coupling approach.
Received 23 July 2001 and Received in final form 25 November 2001 相似文献
7.
V.S. Gerdjikov G.G. Grahovski N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):243-248
The class of nonlinear evolution equations (NLEE) - gauge equivalent to the N-wave equations related to the simple Lie algebra are derived and analyzed. They are written in terms of (x, t) ∈ satisfying r = rank nonlinear constraints. The corresponding Lax pairs and the time evolution of the scattering data are found. The Zakharov-Shabat
dressing method is appropriately modified to construct their soliton solutions.
Received 20 October 2001 / Received in final form 30 April 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
8.
T. Otsuka Y. Utsuno R. Fujimoto B.A. Brown M. Honma T. Mizusaki 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):69-74
Two recent developments of the nuclear shell model are presented. One is a breakthrough in computational feasibility owing
to the Monte Carlo Shell Model (MCSM). By the MCSM, the structure of low-lying states can be studied with realistic interactions
for a wide, nearly unlimited basically, variety of nuclei. The magic numbers are the key concept of the shell model, and are
shown to be different in exotic nuclei from those of stable nuclei. Its novel origin and robustness will be discussed.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
9.
B. Pasquini M. Gorchtein D. Drechsel A. Metz M. Vanderhaeghen 《The European Physical Journal A - Hadrons and Nuclei》2001,11(2):185-208
We present in detail a dispersion relation formalism for virtual Compton scattering (VCS) off the proton from threshold into
the Δ(1232)-resonance region. Such a formalism can be used as a tool to extract the generalized polarizabilities of the proton
from both unpolarized and polarized VCS observables over a larger energy range. We present calculations for existing and forthcoming
VCS experiments and demonstrate that the VCS observables in the energy region between pion production threshold and the Δ(1232)-resonance
show an enhanced sensitivity to the generalized polarizabilities.
Received: 14 March 2001 / Accepted: 18 June 2001 相似文献
10.
M.N. Harakeh 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):169-175
First-generation radioactive ion-beam facilities have already been in operation for some time. Advanced facilities that will
deliver high-intensity radioactive nuclear beams ranging in energy from below the Coulomb barrier to up to several hundred
MeV per nucleon (MeV/u) are either starting operation, or under construction or in the planning stage. In this paper the perspectives
of using radioactive nuclear beams to study giant resonances in nuclei far from the valley of stability are explored. In particular,
emphasis will be made on information on certain nuclear properties that can be gained from such studies.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
11.
A. Ralko T.T. Truong 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):335-338
We discuss the occurrence and properties of exact singular anyonic wave functions describing stationary states of two identical
charged particles moving on a plane and under the influence of a perpendicular uniform magnetic field.
Received 25 September 2001 / Received in final form 4 December 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: truong@u-cergy.fr 相似文献
12.
M. Di Toro V. Baran M. Colonna V. Greco S. Maccarone M. Cabibbo 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):155-161
In the reaction dynamics of intermediate-energy radioactive beams we can probe highly asymmetric nuclear matter in compressed
as well as dilute phases. In this report some predictions are presented, based on analytical results as well as on reaction
simulations. We suggest a series of experiments with RIB aimed to shed light on isospin properties of nuclear interactions
in the medium.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
13.
F. Muller P. Fontaine M. Delsanti L. Belloni J. Yang Y.J. Chen J.W. Mays P. Lesieur M. Tirrell P. Guenoun 《The European physical journal. E, Soft matter》2001,6(2):109-115
The counterion distribution within a spherical polyelectrolyte sparse brush was measured by small-angle X-ray scattering using
contrast variation with different counterions by means of ion dialysis. The brush was made by self-association of charged
diblock copolymers. Thanks to the contrast variation method, we were able to separate the signal due to the monomers and the
signal due to the counterions. At a small length scale, it is demonstrated that the system behaves as independent charged
rods whose counterion distribution follows the Poisson-Boltzmann model.
Received 14 February 2001 and Received in final form 2 May 2001 相似文献
14.
R. Lefort B. Toudic J. Etrillard F. Guillaume P. Bourges R. Currat T. Breczewski 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(1):51-57
The diffraction pattern of n-alkane/urea inclusion compounds is known to contain a broad diffuse scattering related to the
molecular form factor of the alkane species, indicating individual rotational and/or translational disorder of these molecules.
Inelastic coherent neutron scattering reveals for the first time the entirely dynamical character of the alkane molecular
disorder around room temperature. This observation fully agrees with a recent model of the coherent scattering cross section
of totally uncorrelated motions. In the ordered phase this diffuse scattering remains, but elastic, and very low energy molecular
vibrational modes are evidenced. These observations are discussed in relation with previous incoherent neutron scattering
results.
Received 9 February 2001 and Received in final form 1st August 2001 相似文献
15.
A generalized Newton–Sabatier inversion method which permits extraction from scattering data of central and spin-orbit potentials
is presented. The inversion method originally developed by Sabatier and further elaborated by Hooshyar and Richardson, has
been reformulated to lead to physically reasonable solutions and to allow for its numerical implementation. Numerical problems
due to the occurrence of singularities in the transformation kernel are discussed and a successful application using schematic
scattering data is reported.
Received: 30 April 1997 / Revised version: 20 October 1997 相似文献
16.
Behavior of the hadron potential at large distances and properties of the hadron spin-flip amplitude
The impact of the form of the hadron potential at large distances on the behavior of the hadron spin-flip amplitude at small
angles is examined. The t-dependence of the spin-flip amplitude of high-energy hadron elastic scattering is analyzed under different assumptions on
the hadron interaction. It is shown that the long tail of the nonGaussian form of the hadron potential of the hadron interaction
in the impact parameter representation leads to a large value of the slope of the spin-flip amplitude (without the kinematical
factor ) as compared with the slope of the spin-nonflip amplitude. This effect can explain the form of the differential cross-section
and the analyzing power at small transfer momenta. The methods for the definition of the spin-dependent part of the hadron
scattering amplitude are presented. A possibility to investigate the structure of the hadron spin-flip amplitude from the
accurate measure of the differential cross-section and the spin correlation parameters is shown.
Received: 14 December 2001 / Accepted: 17 January 2002 相似文献
17.
18.
H. Iwasaki T. Motobayashi H. Akiyoshi Y. Ando N. Fukuda H. Fujiwara Zs. Fülöp K. I. Hahn Y. Higurashi M. Hirai I. Hisanaga N. Iwasa T. Kijima A. Mengoni T. Minemura T. Nakamura M. Notani S. Ozawa H. Sagawa H. Sakurai S. Shimoura S. Takeuchi T. Teranishi Y. Yanagisawa M. Ishihara 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):55-58
Experimental studies on in-beam γ-ray spectroscopy using a 12Be radioactive beam are presented. Inelastic scattering of the neutron-rich 12Be nucleus on 208Pb, 12C, and (CH2)n targets has been studied by measuring de-excitation γ-rays in coincidence with scattered particles. The level schemes and
transition probabilities are determined for low-lying excited states in 12Be. The present paper presents a brief review of the spectroscopic results, which may be associated with the N = 8 shell quenching near the drip line.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
19.
T. Ishii M. Asai A. Makishima I. Hossain P. Kleinheinz M. Ogawa M. Matsuda S. Ichikawa 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):15-19
Nuclei in the neutron-rich Ni region have been studied by γ-ray spectroscopy. Gamma-rays emitted from isomers, with T
1/2 > 1 ns, produced in heavy-ion deep-inelastic collisions were measured with an isomer-scope. The nuclear structure of the
doubly magic 68Ni and its neighbor 69,71Cu is discussed on the basis of the shell model. Future experiments for more neutron-rich Ni nuclei are also viewed.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
20.
Thick skin in neutron/proton-rich sodium isotopes 总被引:2,自引:0,他引:2
Y.K. Gambhir A. Bhagwat N. Van Giai P. Schuck 《The European Physical Journal A - Hadrons and Nuclei》2001,11(2):155-160
Nucleon (both neutron and proton) density distributions of the chain of sodium isotopes are calculated using a semi-phenomenological
model of nuclear density which incorporates correctly the asymptotic behaviour and the behaviour near the centre. The experimental
charge root-mean-square radii and the single neutron and proton separation energies, required as input, are used. The calculated
interaction cross-sections using these densities in the Glauber model agree well with the experiment. The calculated neutron
rms radii r
n and the nuclear skin thickness ( r
n - r
p) closely agree with the corresponding experimental values and also are consistent with the Relativistic Hartree-Bogoliubov
(RHB) calculations.
Received: 24 April 2001 / Accepted: 28 June 2001 相似文献