Influence of relaxation effects on probabilities of the 2s2p35S2－2s22p2 3P1，2 intercombination transitions in NII

Transition probabilities of the 2s2p^3 {}^5S_2－2s^22p^2 {}^3P_{1,2} intercombination transitions in NII have been calculated by using a large-scale multiconfiguration Dirac－Fock method. In the calculation the most important effects of relativity, correlation, and relaxation are considered. From the calculated transition probabilities, the lifetime of the 2s2p^3 {}^5S_2 metastable state is derived. The result is in excellent agreement with the latest experimental result. In the meantime the influence of anomalously strong relaxation effects on probabilities of the 2s2p^3 {}^5S_2－2s^22p^2 {}^3P_{1,2} lines in NII have been found.     

Study of n=2,Δn=0 transition of Be-, B-, C-, N- and O-like sequence in the beam--foil spectrum of titanium

The foil-excited the spectrum of highly stripped titanium ions between 12-40 nm has been studied. Titanium ions of 80 and 120 MeV were provided by the HI-13 tandem accelerator at the China Institute of Atomic Energy. GIM-957 XUV-VUV monochromator was refocused to get highly-resolved spectra. Our experimental results and the published spectral data of laser-produced plasma show agreement in nearly all cases within ±0.03 nm. The spectra contained some weak or strong lines previously unclassified. These spectral lines mainly belong to 2s2p^2 for TiXVⅢ, 2p^3 for TiXVIII, 2s2p^3 for TiXVII, 2p^6 4p for Ti XII and 2p^6 3d for Ti XII transitions.     

Dielectronic recombination of Co-like tantalum

Ab initio calculation of the total dielectronic recombination (DR) rate coefficient from the ground state of Co-like tantalum is performed using the relativistic distorted-wave approximation with configuration interaction. The contributions to the total DR rate coefficients are explicitly calculated from the complexes of Ni-like tantalum: 3s²3p⁶3d_3/2³ 3d_5/2⁶ n'l', 3s²3p⁵3d¹⁰n'l', 3s3p⁶3d¹⁰n'l', 3s²3p⁶3d⁸4ln'l', 3s²3p⁵3d⁹4ln'l' and 3s3p⁶3d⁹4ln'l' with n' ≤ 25, and 3s²3p⁶3d⁸5ln'l' with n' ≤ 9. The l' and n' dependences of partial DR rate coefficients are investigated. The contributions from higher n'complexes are evaluated by a level-by-level extrapolation method. The total DR rate coefficients mainly come from the complex series 3s²3p⁶3d⁸4ln'l', 3s²3p⁵3d⁹4ln'l' and are fitted to an empirical formula with high accuracy. Comparison of the present results with those of other works shows that the previously published data underestimate significantly the DR rates of Co-like tantalum.     

A novel type of ultra fast and ultra soft recovery SiGe/Si heterojunction power diode with an ideal ohmic contact

A novel type of p^+(SiGe)－n^-－n^+ heterojunction switching power diode with high-speed capability is presented to overcome the drawbacks of existing power diodes. The improvement is achieved by using a p^+－n^+ mosaic layer as a substitute for the n^+ region in the conventional p^+(SiGe)－n^-－n^+ diode to realize an `ideal ohmic' contact for electrons and holes simultaneously. Compared with conventional p^+(SiGe)－n^-－n^+ diodes, the ideal ohmic contact p^+(SiGe)－n^-－n^+ diodes have about one third of the reverse recovery time and a half of peak reverse recovery current. Furthermore, the softness factor increases nearly two times and the leakage current decreases 1－2 orders of magnitude. These improvements are achieved without resorting special process step to lower the carrier lifetime and thus the devices could be easily integrated into power ICs. The Ge percentage content of p^+(SiGe) layer is an important parameter for the optimal device design.     

Relativistic computation of intercombinational transition probabilities

Expressions have been obtained on the basis of S-matrix theory for the computation of electrical multipole transition probabilities in a relativistic approximation in a multielectron atom in first-order field perturbation theory. Also considered are corrections corresponding to simultaneously taking account of the external field and the interelectron interactions. Results of computing the wavelengths and probabilities of intercombinational transitions in multicharge ions between the configurations 1s 2p-1s² for 4 ≤ Z ≤28 and 1s² \(2s^n 1 2p^{n_2 } - 1s^2 2s^{n_1 \pm 1} 2 p^{n_2 \pm 1} \) for20 ≤ Z ≤ 30 are presented. The data obtained can be used to interpret soft x radiation originating in transitions observed in the solar corona and high-temperature plasma laboratories.     

Near threshold photodetachment cross section of negative atomic oxygen ions

A 40-target state close-coupling calculation for the photodetachment cross section of negative atomic oxygen near threshold is carried out with core－valence electron correlation by using the R-matrix method. It was shown that after considering the excitations of two electrons from the 2s shell, the electron affinity of O^- (2s^22p^5{}^2P°) agrees with the experimental result much better than that just considering the excitations of electrons only from the 2p shell as well as only one electron from the 2s shell. Total cross section as well as the main contribution of the ionization channels to the partial cross section are illustrated to show the structure near threshold clearly.     

On the freund-witten adelic formula for Veneziano amplitudes

On the basis of the analysis of the adele group (Tate's formula), a regularization for the divergent infinite product ofp-adic Г-functions $$\Gamma _p (\alpha ) = \frac{{1 - p^{\alpha - 1} }}{{[ - p^{ - \alpha } }}$$ is proposed, and the adelic formula is proved $$reg\coprod\limits_{p = 2}^\infty {\Gamma _p (\alpha )} = \frac{{\zeta (\alpha )}}{{\zeta (1 - \alpha )}}$$ whereζ(α) is the Riemannζ-function.     

Hyperfine structure and isotope shifts in near-infrared transitions of atomic nitrogen

We have obtained Doppler-free spectra of transitions in the → 2p²(³P) and → multiplets of atomic nitrogen using saturated absorption spectroscopy. These multiplets consist of respectively of seven and eight transitions, and have center of gravity wavelengths of 821 nm and 869 nm. Values for the hyperfine structure coupling constants of all the upper and lower states for these multiplets were obtained for both ¹⁴N and ¹⁵N. Isotope shifts of three transitions in each multiplet were also measured, and a significant J-dependence to the shifts was observed.     

Single-Spin Asymmetries in Inclusive and Exclusive Processes

Single-spin asymmetries provide important tools for investigating the structure of the hadron. We present two examples of inclusive and exclusive processes:      

Theoretical studies on dielectronic recombination of neonlike gold and its effects on plasma ionization balance and radiation energy

The dielectronic recombination (DR) of neonlike gold ions is investigated employing the flexible atomic code based on the relativistic configuration interaction method, and its influence on the ionization balance and radiation energy in high-temperature plasma is also studied. The total resonance strength for LMM configuration complex is in a good agreement with the experimental measurement and other theoretical works. The DR rate coefficients are calculated and compared with the three-body recombination and radiative recombination rate coefficients. The DR process is the dominant recombination mechanism of Ne-like gold ions for plasma with temperature T_e≥6.5 keV and density n_e≤2×10²² cm^-3, which is close to the condition of X-ray conversion region in the inertial confinement fusion. Moreover, the DR satellite spectra of LMM, LMN and LMO resonances are simulated, and compared with the intensities of the corresponding resonance lines induced by the electron impact excitation. The intensity ratio of the satellite line 3D’ [(2p⁵_3/23d_3/23d_5/2)_J=5/2[(2p^{5}_{3/2}3d_{3/2}3d_{5/2})_{J=5/2}–(2p⁶3d_3/2) _J=3/2](2p^{6}3d_{3/2})_{ J=3/2}] and the resonance line 3D [(2p⁵_3/23d_5/2)_J=1[(2p^{5}_{3/2}3d_{5/2})_{J=1}–(2p⁶)_J=0](2p^{6})_{J=0}] is given, which can be applied for diagnostics of plasma temperature.     

On the Mourre estimates for Floquet Hamiltonians

Letters in Mathematical Physics - In the spectral and scattering theory for a Schrödinger operator with a time-periodic potential $$H(t)=p^2/2+V(t,x)$$ , the Floquet Hamiltonian $$K=-i\partial...     

Fermion family recurrences in the Dyson–Schwinger formalism

We study the multiple solutions of the truncated propagator Dyson–Schwinger equation for a simple fermion theory with Yukawa coupling to a scalar field. Upon increasing the coupling constant g, other parameters being fixed, more than one non-perturbative solution breaking chiral symmetry becomes possible and we find these numerically. These “recurrences” appear as a mechanism to generate different fermion generations as quanta of the same fundamental field in an interacting field theory, without assuming any composite structure. The number of recurrences or flavors is reduced to the question of the value of the Yukawa coupling, and it has no special profound significance in the standard model. The resulting mass function can have one or more nodes and the measurement that potentially detects them can be thought of as a collider-based test of the virtual dispersion relation for the charged lepton member of each family. This requires the three independent measurements of the charged lepton’s energy, three-momentum and off-shellness. We illustrate how this can be achieved for the (more difficult) case of the tau lepton. PACS 12.15.Ff; 11.30.Rd     

Some surprises of quantum measurements and states

The problem of physical reality and measurability of observables is discussed on the example of phenomena revealed by the author. The essence of the phenomena is as follows. After measurement of the coordinate, the variance of the momentum can be smaller than the initial one and depends on the result of the coordinate measurement even if the coordinate and the momentum are uncorrelated. This refers to any pair of conjugate observables, in particular, to the number of quanta and the phase. In a state with a minimum product of uncertainties of the coordinate and the momentum, the mean value of the observable ${{\left\{ {\hat x^2 ,\hat p^2 } \right\}} \mathord{\left/ {\vphantom {{\left\{ {\hat x^2 ,\hat p^2 } \right\}} 2}} \right. \kern-0em} 2}The problem of physical reality and measurability of observables is discussed on the example of phenomena revealed by the author. The essence of the phenomena is as follows. After measurement of the coordinate, the variance of the momentum can be smaller than the initial one and depends on the result of the coordinate measurement even if the coordinate and the momentum are uncorrelated. This refers to any pair of conjugate observables, in particular, to the number of quanta and the phase. In a state with a minimum product of uncertainties of the coordinate and the momentum, the mean value of the observable , which corresponds to the classical product of the squares of the coordinate and the momentum, is negative. __________ Translated from Optika i Spektroskopiya, Vol. 96, No. 5, 2004, pp. 747–750. Original Russian Text Copyright ? 2004 by Vorontsov.     

Study of the CdS crystal evaporation kinetics by laser step atomic photoionization

Laser resonant multistep atomic photoionization is employed to measure evaporation rates and saturated vapor pressures of cadmium sulfide and pure cadmium in temperature ranges of 585–950 and 350–535 K, respectively. It is shown that CdS thermally dissociates into Cd atoms and S₂ molecules. The photoionization of cadmium atoms follows the scheme

$5s^1 S_0 \xrightarrow{{\lambda _1 = 326.1nm}}5p^3 P_1 \xrightarrow{{\lambda _2 = 479.9nm}}6s^3 S_1 \xrightarrow{{\lambda _3 = 488.1nm}}17p^3 P_2 + (\varepsilon = 12kV/cm) \to Cd^ + + e^ - .$

.

The minimal pressure of pure cadmium is found to be 10^?11 mm Hg.     

<Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis>3</Subscript> decays and CKM unitarity

We present a detailed numerical study of the K_e3 decays to in chiral perturbation theory with virtual photons and leptons. We describe the extraction of the CKM matrix element |V_us| from the experimental K_e3 decay parameters. We propose a consistency check of the K ⁺ _e3 and K⁰_e3 data that is largely insensitive to the dominating theoretical uncertainties, in particular the contributions of . Our analysis is highly relevant in view of the recent high statistics measurement of the K ⁺ _e3 branching ratio by E865 at Brookhaven which does not indicate any significant deviation from CKM unitarity but rather a discrepancy with the present K⁰_e3 data.Received: 22 January 2004, Published online: 30 April 2004Work supported in part by IHP-RTN, Contract No. HPRN-CT2002-00311 (EURIDICE) and by Acciones Integradas, Project No. 19/2003 (Austria), HU2002-0044 (MCYT, Spain)     

Ultraviolet spectra of Mg in liquid helium

Emission and absorption spectra of Mg atoms implanted in liquid helium have been observed in the ultraviolet region. We have presented a model of exciplex formation of Mg-He₁₀ and found that this model is more suitable for understanding the dynamics in the 3s3p ¹P? 3s^2 1S3s3p^{\:1}P\rightarrow 3s^{2\:1}S transition than the bubble model.     

Optical double resonance and zero field level crossing spectroscopy applied to the 5p 3 6s 5 S 2 level in the Te-I spectrum

As a first application of optical double resonance and zero field level crossing spectroscopy to the elements of the sixth group in the periodic table of the atoms, the 5p ³6s ⁵ S ₂ level in the Te-I spectrum was investigated using natural tellurium in a high temperature quartz cell. For the electronic Landé-factor and the natural radiative lifetime the following values were obtained: $$g_J \left( {5p^3 6s^5 S_2 } \right) = - 1.9657\left( {12} \right),\tau \left( {5p^3 6s^5 S_2 } \right) = 71.8\left( {2.2} \right)ns.$$      

Ti,N共掺杂4H-SiC复合增强缓冲层生长及其对PiN二极管正向性能稳定性的改善

"双极型退化"现象严重阻碍了4H-SiC双极型器件如PiN二极管等的产品化,其微观机理是电子-空穴复合条件下层错由基面位错处的扩展.为遏制"双极型退化"现象,不仅要消除漂移层中的基面位错,还需要通过生长复合增强缓冲层的方法阻止少子空穴到达含高密度基面位错片段的外延层/衬底界面.本文采用钛、氮共掺杂的方式进行缓冲层的生长...     

Einstein, Wigner and Feynman: From E=mc 2 to Feynman’s decoherence via Wigner’s little groups

The 20th-century physics starts with Einstein and ends with Feynman. Einstein introduced the Lorentz-covariant world with E=mc ². Feynman observed that fast-moving hadrons consist of partons which interact incoherently with external signals. If quarks and partons are the same entities observed in different Lorentz frames, the question then is why partons are incoherent while quarks are coherent. This is the most puzzling question Feynman left for us to solve. In this report, we discuss Wigner’s role in settling this question. Einstein’s E=mc ², which takes the form $E = \sqrt {m^2 + p^2 } $ , unifies the energy-momentum relations for massive and massless particles, but it does not take into account internal space-time structure of relativistic particles. It is pointed out Wigner’s 1939 paper on the inhomogeneous Lorentz group defines particle spin and gauge degrees of freedom in the Lorentz-covariant world. Within the Wigner framework, it is shown possible to construct the internal space-time structure for hadrons in the quark model. It is then shown that the quark model and the parton model are two different manifestations of the same covariant entity. It is shown therefore that the lack of coherence in Feynman’s parton picture is an effect of the Lorentz covariance.     

Closing in on the radiative weak chiral couplings

We point out that, given the current experimental status of radiative kaon decays, a subclass of the \(\mathcal{O} (p^4)\) counterterms of the weak chiral lagrangian can be determined in closed form. This involves in a decisive way the decay \(K^\pm \rightarrow \pi ^\pm \pi ^0 l^+ l^-\), currently being measured at CERN by the NA48/2 and NA62 collaborations. We show that consistency with other radiative kaon decay measurements leads to a rather clean prediction for the \(\mathcal{{O}}(p^4)\) weak couplings entering this decay mode. This results in a characteristic pattern for the interference Dalitz plot, susceptible to be tested already with the limited statistics available at NA48/2. We also provide the first analysis of \(K_S\rightarrow \pi ^+\pi ^-\gamma ^*\), which will be measured by LHCb and will help reduce (together with the related \(K_L\) decay) the experimental uncertainty on the radiative weak chiral couplings. A precise experimental determination of the \(\mathcal{{O}}(p^4)\) weak couplings is important in order to assess the validity of the existing theoretical models in a conclusive way. We briefly comment on the current theoretical situation and discuss the merits of the different theoretical approaches.