A QED description of relativistic Coulomb excitation in heavy ion collisions

A quantum electrodynamical treatment of Coulomb excitation in relativistic heavy ion collisions is presented. It is shown that a subtle interplay between quantum and relativistic kinematical effects induced by the nuclear recoil due to excitation generates a qualitatively different prediction (under certain kinematical conditions) from the corresponding prediction of conventional theories. The present formalism is applied to the clear fission problem and the results seem to solve the puzzle associated with this process for some time.     

Exploring relativistic many-body recoil effects in highly charged ions

The relativistic recoil effect has been the object of experimental investigations using highly charged ions at the Heidelberg electron beam ion trap. Its scaling with the nuclear charge Z boosts its contribution to a measurable level in the magnetic-dipole (M1) transitions of B- and Be-like Ar ions. The isotope shifts of 36Ar versus 40Ar have been detected with sub-ppm accuracy, and the recoil effect contribution was extracted from the 1s(2)2s(2)2p 2P(1/2) - 2P(3/2) transition in Ar13+ and the 1s(2)2s2p 3P1-3P2 transition in Ar14+. The experimental isotope shifts of 0.00123(6) nm (Ar13+) and 0.00120(10) nm (Ar14+) are in agreement with our present predictions of 0.00123(5) nm (Ar13+) and 0.00122(5) nm (Ar14+) based on the total relativistic recoil operator, confirming that a thorough understanding of correlated relativistic electron dynamics is necessary even in a region of intermediate nuclear charges.     

Doubly inelastic collisions with relativistic heavy ions and target recoil momentum spectroscopy

We consider relativistic collisions of heavy hydrogenlike ions with hydrogen and helium atoms in which the ion-atom interaction causes both colliding particles to change their internal states. Concentrating on the study of the longitudinal momentum spectrum of the atomic recoil ions, we discuss the role of relativistic and higher order effects, predict a surprisingly strong influence of the projectile's electron on the momentum transfer, and show that the important information about the doubly inelastic collisions could be obtained in experiment merely by measuring the recoil momentum spectrum.     

A relativized quark model for radiative baryon transitions

In this paper we investigate the electromagnetic form factors of baryons and their resonances using the framework of a relativized constituent quark model. Beyond the usual single-quark transition ansatz, we incorporate relativistic corrections which are welldetermined by the intrinsic interaction and confinement forces between the quarks. Furthermore we separate off for the compound three-quark system the relativistic center-of-mass motion by an approximately Lorentz-invariant approach. In this way for the first time recoil effects could be explicity studied. Using the harmonic oscillator wavefunctions with the configuration mixing as derived in the Isgur-Karl model, after restoring gauge invariance our relativized interaction hamiltonian can be used to calculate the transversely and longitudinally polarized photon transition form factors of the baryons.     

Electronic recoil effects in high-energy photoelectron spectroscopy

It is shown that the recoil energy imparted to the residual ion by the outgoing fast photoelectron leads to noticeable modifications of X-ray excited photoelectron spectra of molecules containing light atoms. The vibrational band envelopes may differ considerably from those predicted by the Franck-Condon principle. Al Kα excited valence electron bands are shown to exhibit, in addition to the translational recoil energy of the molecule, energy shifts of up to several tenth of an eV due to recoil-induced vibrational and rotational excitation. This effect has to be kept in mind when ionization potentials are determined from ESCA spectra. The recoil-induced vibrational and rotational excitation depends on the orbital quantum numbers of the ionized electron. Simple formulae for the shift of the centroid and the broadening of the band due to recoil effects are given for the special case of diatomic molecules.     

Electron-nucleon interaction in quasi-free scattering: (II). Non-relativistic Hamiltonian through fourth order

The interaction of non-relativistic nucleons with relativistic electrons can be expressed by a Hamiltonian expanded in a power series of the recoil nucleon velocity. In this paper third- and fourth-order terms are calculated. Free electron-nucleon-scattering and quasi-free electron scattering on ¹²C are studied and results through various orders are compared with the relativistic formulae. A different off-shell behaviour of the relativistic approach is found, which is independent of the higher-order terms and seems responsible for the different results of knock-out reactions.     

Determining Nuclear Form factor for Detection of Dark Matter in Relativistic Mean Field Theory

In this work, we derive the nuclear form factor for the spin-independent collision between the WIMPs and nucleus in terms of the relativistic mean field (RMF) theory. Comparison with the traditional form factors which are commonly used in literature is given and it is found that our results are slightly above that of the 2PF model by 4% to 8%, but deviate from the Helm form factor by 15% to 25% for the whole recoil energy spectrum of 0 ∽ 100keV. Moreover, taking Xe and Ge as examples, we show the dependenceof the form factor on the recoil energy.     

相对论重离子反应的热化过程

本文从相对论BUU理论出发研究了1GeV/n能区重离子反应全局(global)和局域(local)平衡性质,计算表明在该能区平均场对反应动力学过程仍有相当的作用;对有限核系统的反应动力学过程的时间演化的研究表明,有限核系统无论全局的还是局域的平衡均未能达到完全平衡,因而对有限核系统重离子反应基于完全热平衡概念的适用性值得怀疑.     

Radiative corrections for level widths in light muonic atoms

The corrections, which are associated with electron vacuum polarization, for the radiation level widths and line intensities in light muonic atoms are examined. The total level widths, with allowance for the finite size of the nuclei, relativistic effects, and recoil are found. Zh. éksp. Teor. Fiz. 112, 805–817 (September 1997)     

用负温度高能离子束的相对论多普勒效应实现从红外到X射线连续调谐激光器

利用负温度高能离子束的相对论多普勒效应,可能实现从红外到X射线连续调谐激光器。调谐范围△ν_T=2ν₀βγ。离子束从零到c调速时,激光频率为0—∞。本文给出了激光参数的相对论变换式,计算了负温度相对论离子束激光器的增益、阈值和输出特性,提出了用激光束对相对论离子束进行共振激发的方法,并讨论了He⁺离子束及Ar⁺离子束激光器的设计参数。 关键词：     

Recoil corrections to muonic atom energy levels

The relativistic correction due to nuclear recoil is calculated for a distributed nuclear charge using the effective potential model of Grotch and Yennie. For the lowest states the results differ substantially from the well-known point nucleus values and disagree somewhat with the recent calculation of Fricke.     

Polarization transfer in the 4He(e-->,e'p-->)3H reaction up to Q2=2.6 (GeV/c)2

We have measured the proton recoil polarization in the 4He(e-->,e(')p-->)4H reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.     

Peculiarities of induced radiation and controlled dechanneling of relativistic particles in crystals under the Cherenkov—Vavilov extreme condition

Peculiarities of induced radiation and absorption of hard electromagnetic radiation are considered on the basis of the channeling of relativistic particles in crystals under the Vavilov—Cherenkov extreme condition. It is shown that the consistent inclusion of quantum recoil in the relativistic region makes it possible to produce a number of anomalous effects having no analogs in optics. In particular, it is predicted that it is possible to simultaneously cool the beam of fast particles during radiation and absorption and to create a tandem laser for which successive radiation of quasicharacteristic-radiation quanta at the normal and anomalous Doppler effect leads to the restoration of the initial state of the quantum system and to the multiple repetition of the radiation cycle. It is shown that the main difficulties preventing these effects from being produced directly in the X-and gamma-ray spectral regions are related to the necessity to use media with positive dispersion. It is considered that such dispersion can be produced by changing the effective susceptibility of the medium in the case of radiation diffraction.     

Ion acoustic solitary waves in weakly relativistic plasma with nonthermal electron, positron and warm ion

The Korteweg-de Vries equation for a weakly relativistic ion acoustic wave propagating in oollisionless plasma containing nonthermal electron, positron and warm ion is derived. The effects of the ion temperature, nonthermal parameter and relativistic effect on the amplitude, width and energy of soliton are studied.     

Electro-magnetic nucleon form factors and their spectral functions in soliton models

It is demonstrated that in simple soliton models essential features of the electro-magnetic nucleon form factors observed over three orders of magnitude in momentum transfer t are naturally reproduced. The analysis shows that three basic ingredients are required: an extended object, partial coupling to vector mesons, and relativistic recoil corrections. We use for the extended object the standard skyrmion, one vector meson propagator for both isospin channels, and the relativistic boost to the Breit frame. Continuation to time-like t leads to quite stable results for the spectral functions in the regime from the 2- or 3-pion threshold to about two rho masses. Especially the onset of the continuous part of the spectral functions at threshold can be reliably determined and there are strong analogies to the results imposed on dispersion theoretic approaches by the unitarity constraint.     

Status of the SHIPTRAP Project: A Capture and Storage Facility for Heavy Radionuclides fromSHIP

The ion trap facility SHIPTRAP is being set up to deliver very clean and cool beams of singly-charged recoil ions produced at the SHIP velocity filter at GSI Darmstadt. SHIPTRAP consists of a gas cell for stopping and thermalizing high-energy recoil ions from SHIP, an rf ion guide for extraction of the ions from the gas cell, a linear rf trap for accumulation and bunching of the ions, and a Penning trap for isobaric purification. The progress in testing the rf ion guide is reported. A transmission of about 93(5)% was achieved. This revised version was published online in July 2006 with corrections to the Cover Date.     

The contribution ofK-electron capture for the production of highly charged Ne recoil ions by 156 MeV bromine impact

The recoil ion production cross sections in 2MeV/amu Br ⁿ⁺+Ne⁰→Br ^n′++Ne ^q+ were measured using a projectile ion — recoil ion coincidence technique where the final charge states of both collisions partners were detected simultaneously. Multiple ionization was found to be the dominant process for the production of low charge state recoil ions whereas the production of highly charged recoil ions is accompanied by electron capture from the Nek-shell. The derived ratio of single to double Ne-k electron capture probabilities indicates deviations from a binomial statistics distribution.     

Electro-magnetic nucleon form factors and their spectral functions in soliton models

It is demonstrated that in simple soliton models essential features of the electro-magnetic nucleon form factors observed over three orders of magnitude in momentum transfert are naturally reproduced. The analysis shows that three basic ingredients are required: an extended object, partial coupling to vector mesons, and relativistic recoil corrections. We use for the extended object the standard skyrmion, one vector meson propagator for both isospin channels, and the relativistic boost to the Breit frame. Continuation to time-liket leads to quite stable results for the spectral functions in the regime from the 2- or 3-pion threshold to about two rho masses. Especially the onset of the continuous part of the spectral functions at threshold can be reliably determined and there are strong analogies to the results imposed on dispersion theoretic approaches by the unitarity constraint.     

Nuclear structure effects in the isotope shift with halo nuclei

Corrections to atomic energy levels due to nuclear structure effects are discussed. These are the finite nuclear size combined with relativistic and recoil corrections, and the nuclear polarizability. Good understanding of these effects is necessary for interpretation of high-precision measurements of the isotope shifts with neutron-rich nuclei ^6,8He, ¹¹Li and ¹¹Be. The summary of the results of the accurate atomic structure calculations is presented also.     

Anomalous thresholds and the Isgur-Wise function

The original de Rafael-Taron bound on the slope of the Isgur-Wise function at zero recoil is known to be violated in QCD by singularities appearing in an unphysical region. To be consistent, quark models must have corresponding singularity structures. In an existing relativistic quark-loop model, the meson-quark-antiquark vertex is such that the required singularity is an anomalous threshold. We also discuss the implications of another anomalous threshold, whose location is determined by quark masses alone.