Dissociative ionization cross sections of CO2 at electron impact energy of 5 keV

The dissociative ionization of CO2 induced by 5 keV electrons in two-body and three-body dissociative channels of CO2＋2 and CO3＋2 is identified by the ion-ion coincidence- method using a momentum imaging spectrometer. The partial ionization cross sections （PICSs） of different ionic fragments are measured and the results generally agree with the calculations made by a semi-empirical approach. Furthermore, the PICSs of the dissociative channels are also obtained by carefully considering the detection efficiency of the micro-channel plates and the total transmission efficiency of the time of flight system.     

Second-order Born calculation of coplanar symmetric(e, 2e) process on Mg

The second-order distorted wave Born aPl6roximation （DWBA） method is employed to investigate the triple differen- tial cross sections （TDCS） of coplanar doubly symmetric （e, 2e） collisions for magnesium at excess energies of 6 eV-20 eV. Comparing with the standard first-order DWBA calculations, the inclusion of the second-order Born term in the scattering amplitude improves the degree of agreement with experiments, especially for backward scattering region of TDCS. This indicates that the present second-order Born term is capable to give a reasonable correction to DWBA model in studying coplanar symmetric （e, 2e） problems of two-valence-electron target in low energy range.     

Polarization effect in （e, 2e） reaction process for Ar （3s） in coplanar asymmetric geometry

The （e, 2e） triple differential cross sections （TDCSs） of Ar （3s） are calculated by using distorted-wave Born approx- imation under coplanar asymmetric geometry. The incident electron energy is 113.5 eV, and the scattering electron angle 01 is -15~. The ejected electron energy is set at 10 eV, 7.5 eV, 5 eV, and 2 eV, respectively. The polarization effects have been discussed and the polarization potential Vpol changing from a second-order to a fourth-order term has been analyzed. Our calculated TDCSs have been compared with reported experimental and theoretical results, and the calculated TDCSs of polarization potential up to the fourth order could give a good fit with experimental results in the binary region, but fail to predict the correct recoil-to-binary ratio in most cases.     

Theoretical analysis on fully differential cross sections for C~(6+)impact ionization of helium

Fully differential cross sections （FDCS） are calculated within a four-body model for single ionization of helium by C6＋ impact at the incident energy of 100 MeV/a.u. （atomic unit）. The results are compared with experimental data and other theoretical predictions. It is shown that our results are in very good agreement with experiment for three small momentum transfers in the scattering plane; however, some significant discrepancies are still present at the largest momentum transfer in both the scattering plane and the perpendicular plane. In actuality, the problem has not been explained by the theory during the last decade. Accordingly, the contributions of different scattering amplitudes to FDCS are analyzed. It is found that for the largest momentum transfer the cross section arising from a destructive interference of the three amplitudes is much smaller than the experimental data. However, the cross section due to the constructive interference of two scattering amplitudes between projectile-ionized electron interaction and projectile-passive electron interaction almost approaches the experimental data.     

Evaluation of the 1077 keV γ-ray emission probability from 6SGa decay

6SGa decays to the excited states of aSzn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011, JIANG Li-Yang deduced a new value for 1077 keV γ-ray emission probability by measuring the 69Ga（n,2n） 6SGa reaction cross section. The new value is about 20% lower than values obtained from previous absolute measurements and evaluations. In this paper, the discrepancies among the measurements and evaluations are analyzed carefully and the new values are re-recommended. Our recommended value for the emission probability of 1077 keV γ-ray is （2.72±0.16）%.     

双核模型下超重核117的生成截面研究

Within the framework of the dinuclear system model, the capture of two colliding nuclei, and the formation and de-excitation process of a compound nucleus are described by using an empirical coupled channel model, solving the master equation numerically and the statistical evaporation model, respectively. In the process of heavy-ion capture and fusion to synthesize superheavy nuclei, the barrier distribution function is introduced and averaging collision orientations are considered. Based on this model, the production cross sections of the cold fusion system ^76-82Se＋^209Bi and the hot fusion systems ^55Mn＋^238U, ^51V＋^244pu, ^59Co＋^232Th, ^48Ca＋^247-249Bk and ^45Sc＋^246-248Cm are calculated. The isotopic dependence of the largest production cross sections is analyzed briefly, and the optimal projectile-target combination and excitation energy of the 1n-4n evaporation channels are proposed. It is shown that the hot fusion systems ^48Ca＋^247-249Bk in the 3n evaporation channels and ^45Sc＋248Cm in the 2n-4n channels are optimal for synthesizing the superheavy element 117.     

Stereodynamics of the O（^3p） with H： （D2） （v = O,j =O） reaction

Quasi-classical trajectory theory is used to study the reaction of O（3p） with H2 （D2） based on the ground 3A″ potential energy surface （PES）. The reaction cross section of the reaction O＋H2→＋OH＋H is in excellent agreement with the previous result. Vector correlations, product rotational alignment parameters （P2（j′. k）） and several polarizeddependent differential cross sections are further calculated for the reaction. The product polarization distribution exhibits different characteristics that can be ascribed to different motion paths on the PES, arising from various collision energies or mass factors.     

Translational,vibrational, rotational enhancements and alignments of reactions H＋CIF （v = 0-5, j ： 0,3,6,9） 〉HCI＋F and HF＋CI,at EreI ： 0.5-20 kcal/mol

Quasi-classical trajectory calculations of the title reactions H ＋ C1F （v = 0-5, j = 0, 3,6, 9） -＋ HCl ＋ F and H ＋ C1F （v = 0-5, j =0, 3, 6, 9） → HF ＋ C1 at Erel = 0.5 kcal/mol-20 kcal/mol on ground potential energy surface DHTSN of 1 2AI [M. E Deskevich, M. Y. Hayes, K. Takahashi, R. T. Skodje and D. J. Nesbitt, J. Chem. Phys. 124, 224303 （2006）] are performed. Potential energy surfaces derived from DHTSN for the title reactions are obtained, and compared with that of DHTSN for the reaction F ＋ HC1 -＋ HF ＋ C1. Both potential energy surfaces have an early barrier pattern. Integral cross sections and alignments of product molecules HC1 and HF dependent on the internal energy states v and j of reactant molecule C1F are obtained and compared. Translational, vibrational, and rotational energy specific translational enhancements of the reactant molecule CIF of the title reactions are found. Reaction mechanisms of the title reactions according to the respective potential energy contours are further found and explained. Reasons of simultaneous translational and vibrational enhancements are clarified.     

用光学极限的Glauber模型结合相对论平均场对8Li和8B的半径的研究

We study the reaction cross sections （σR） and root-mean-square （RMS） radii of ^8Li and ^8B, the halo-like nuclei, with stable target ^12C, ^27Al and ^9Be within the standard optical-limit Glauber model, using densities obtained from relativistic mean-field （RMF） formalisms and other types of distributions. It is found that the experimental σR can be reproduced well at high energy. The RMS radius and Ar extracted by RMF- theory and harmonic oscillator distribution are compared. larger than those of SLi. In addition, we analyze in detail the We find that the RMS radius and Ar of SB are relationship between σR and density distribution.     

Roles of Isospin in Evaporation Residue Cross Section as a Probe of Nuclear Dissipation

The influence of isospin on the excess of evaporation residue cross section over its standard statistical-model value for nuclei ^194pb, ^200Pb, and ^206pb is studied via a Langevin equation coupled with a statistical decay model. The magnitude of this excess for a low-isospin fissioning nucleus is shown to be larger and its dependence on the nuclear viscosity coefficient to be stronger than those of a high-isospin fissioning nucleus. These results suggest that to obtain a more accurate information of viscosity coefficient inside the saddle point by measuring evaporation residue cross sections, we had better choose those compound systems with small isospin.     

Influence of Isotope Substitution Helium Atom on Partial Cross Sections in He-HF Collisions

Close-coupling equation and anisotropic potential developed in our previous research are applied to HE-SHe （4He, 6He, 8He,10He） collision system, and partial cross sections （PCSs） at the incident energy of 40 me V are calculated. By analyzing the differences of these PCSs, change rules of PCSs with the increase of partial wave number, and with the change of the mass of isotope substitution helium atom are obtained. The results show that excitation PCSs converge faster than elastic PCSs for collision energy and each of systems considered here. Also excitation PCSs converge more rapidly for high-excited states. Tail effect is present only in elastic scattering and low-excited states but not in high- excited states. With the increase of the mass of isotope substitution helium atom, converging speed of elastic, total inelastic, and state-to-state excitation PCS slows down, and the maxima of these PCSs undergoes a regular change.     

Production of the neutral top-pion πt^0 in association with a high-pw jet at the LHC＊

In the framework of the topcolor-assisted technicolor （TC2） model, we study the production of the neutral top-pion πt^0 in association with a high-pw jet at the LHC, which proceeds via the partonic processes gg→πt^0g, gq →πt^0q, qq→πt^0g, gb（b）→πt^0b（b）, and bb→πt^0g. We find that it is very challenging to detect the neutral top-pion πt^0 via the process pp → πt^0 ＋jet ＋ X＋ tt＋jet ＋X, while the possible signatures of πt^0 might be detected via the process pp→πt^0 ＋jet ＋ X→（tc＋tc）＋jet＋X at the LHC.     

Measurement of the pion form factor for Mππ^2 between 0.1 and 0.85 GeV2 with the KLOE detector

The KLOE experiment at the φ-factory DAФPNE has measured the pion form factor in the range between 0.1 〈 Mππ^2 〈 0.85 GeV^2 using events taken at √s = 1 GeV with a photon emitted at large polar angles in the initial state. This measurement extends the Mππ^2 region covered by KLOE ISR measurements of the pion form factor down to the two pion production threshold. The value obtained in this measurement of the dipion contribution to the muon anomalous magnetic moment of △αμ^ππ= （478.5±2-0stat±4.8syst±2.9theo）·10^-10 further confirms the discrepancy between the Standard Model evaluation for αμ and the experimental value measured by the （g-2） collaboration at BNL.     

Electron-Helium Atom Collisions in the Presence of a Bichromatic Laser Field

The differential cross section （DCS） for electron-helium atom collisions in the presence of a bichromatic CO2 laser field is investigated as a function of the scattering angle θ by employing first-Born approximation （FBA） with a simple screening electric potential. We discuss in detail the influence of the scattering geometry, the photon energy and the number of photons exchanged on the DCSs. These illustrate that the three factors have important effects on the elastic scattering and the screening electric potential is effective.     

Angular dependence of multiple-bit upset response in static random access memories under heavy ion irradiation

Experimental evidence is presented relevant to the angular dependences of multiple-bit upset (MBU) rates and patterns in static random access memories (SRAMs) under heavy ion irradiation. The single event upset (SEU) cross sections under tilted ion strikes are overestimated by 23.9% 84.6%, compared with under normally incident ion with the equivalent linear energy transfer (LET) value of ～ 41 MeV/(mg/cm 2 ), which can be partially explained by the fact that the MBU rate for tilted ions of 30 is 8.5%-9.8% higher than for normally incident ions. While at a lower LET of ～ 9.5 MeV/(mg/cm 2 ), no clear discrepancy is observed. Moreover, since the ion trajectories at normal and tilted incidences are different, the predominant double-bit upset (DBU) patterns measured are different in both conditions. Those differences depend on the LET values of heavy ions and devices under test. Thus, effective LET method should be used carefully in ground-based testing of single event effects (SEE) sensitivity, especially in MBU-sensitive devices.     

Electron impact ionization of neon and neonic ions under distorted-wave Born approximation

The （e, 2e） triple differential cross sections of 2s orbitals of neon and neonic ions （Z = 11-14） are calculated using a distorted-wave Born approximation under coplanar asymmetric geometry. The calculated results show that, with the increase in the nuclear charge number Z, the amplitude of triple differential cross sections decreases. The angle difference between the binary peak position and the direction of momentum transfer gradually increases with the increase in the nuclear charge Z, and a new structure appears at an ejected angle 90° 〈 θ2 〈 120°. Three kinds of collision processes are proposed to illustrate the formation mechanism of such collision peaks.     

Associated production of a neutral top-Higgs with a heavy-quark pair in the γγ collisions at ILC

We have studied the associated production processes of a neutral top-Higgs in the topcolor assisted technicolor model with a pair of heavy quarks in γγ collisions at the International Linear Collider （ILC）. We find that the cross section for ttht in γγ collisions is at the level of a few fb with the c.m. energy √s=1000 GeV, which is consistent with the results of the cross section of ttH in the standard model and the cross section of tth in the minimal supersymmetric standard model. It should be clear that hundreds of to thousands of ht per year can be produced at the ILC. This process of γγ→ttht is really interesting in testing the standard model and searching the signs of technicolor.     

Measurement of R at VEPP-2000

The new e^＋e^- storage ring, VEPP-2000, is being commissioned at Budker Institute of Nuclear Physics, Novosibirsk. Measurement of the total cross section e^＋e^- → hadrons in the whole VEPP-2000 energy range is one of the main goals of the new experiments. We discuss the goals of the measurement and the expected systematic errors.     

Single Production of Top Quark via e-γ Collision in Left-Right Twin Higgs Model

In the context of the left-right twin Higgs （LRTH） model, we fist study single production of the standard model （SM） top quark via e-γ collisions. We find that the corrections of the LRTH model to the cross section of the process e-γ→vebt might be observed only for f ≤750 GeV and the heavy top quark mass scale M ≥500 GeV in future high energy linear e^＋e^- collider （LC） experiment with the center-of-mass （CM） energy √s = 500 GeV and a yearly integrated luminosity of ￡ = 100 fb^-1. We also consider single production of the heavy top quark T via e-γ collisions. Our numerical results show that the possible signals of the heavy top quark T might be observed via the decay channel T →Ф^＋b→tbb in future LC experiment with √s = 3 TeV and ￡ = 500 fb^-1.     

Microscopic Three-Body Force Effect on Nucleon-Nucleon Cross Sections in Symmetric Nuclear Matter

We provide a microscopic calculation of neutron-proton and proton-proton cross sections in symmetric nuclear matter at various densities, using the Brueckner Hartree-Fock approximation scheme with the Argonne Va4 potential including the contribution of microscopic three-body force. We investigate separately the effects of three-body force on the effective mass and on the scattering amplitude. In the present calculation, the rearrangement contribution of three-body force is considered, which will reduce the neutron and proton effective mass, and depress the amplitude of cross section. The effect of three body force is shown to be repulsive, especially in high densities and large momenta, which will suppress the cross section markedly.