On the smoothness of the symbol of multidimensional singular integral operators

Пустьf — характерист ика, аΦ — соответству ющий символ n-мерного сингу лярного интегрального опера тора, которые являютс я однородными функция ми нулевой степени вR ⁿ,n≧2, с нулевыми средни ми значениями на един ичной сфереS ^n?1 пространств аR ⁿ . В статье установлива ются связи между хара ктеристикойf и символом? в термин ах наилучших равномерн ых приближений полин омами по сферическим гармони кам и сферических равномерных модулей непрерывности, котор ые позволяют установить связь так же в терминах пространст вW ^r H ^w (S ^n?1). Доказывается, ч то установленные резул ьтаты в терминах пространствW ^r H ^w (S ^n?1) неу лучшаемые.     

The effective charge effect in partially stripped ion-helium collisions

The double and single ionization cross section ratios of helium by partially stripped carbon, oxygen and fluorine ions are measured for projectile charge states ranging from +1 to +4 and impact energies from 1.5 MeV to 7.5 MeV. The effective charge effect in partially stripped ion-helium collisions is studied. It is found that the effective charge q_eff increases as the impinging energy increases and q _eff shows a modest dependence upon the projectile charge state in the present energy range. The projectile charge state, projectile energy, projectile and target electronic state dependences of the effective charge effect may be explained using orbital interpenetrating.     

Structural study of 12 MeV electron irradiated polypropylene by X-ray diffraction

12 MeV electron beams with different doses of 4, 8, 16 and 32 Mrad from LINAC designed by Nanjing University have been used to irradiate polypropylene films and their structures studied by X-ray diffraction afterwards. We have found that the electron irradiation does not change the total crystallinity of polypropylene but greatly inflences its crystal structure with increase of phase and decrease of phase as irradiation dose increases (within 16 Mrad). However, it is unexpected that the structure of irradiated sample with 32 Mrad are similar to that of the control sample. This behavior has also been observed in positron annihilation lifetime measurements.     

用Бернштейн多项式通近 可微函数的渐近表达

本文研究用BepaiuTefta多项式逼近可微函数·改进了现有结果，建立了一个含有点态因子的渐近等式;     

Measurements of high pT light fragments at CM 90° in 800 A MEV C + C collisions

The spectra of high-p_T fragments have been measured at CM 90° in 800 A MeV C + C collisions for p_T up to 1.8 GeV/c (proton), 2.5 GeV/c (deuteron) and 2.8 GeV/c (triton) at the Bevalac. Invariant cross sections were measured down to eight orders of magnitude lower than those for production of low momentum protons. The proton spectrum shows a significant deviation from the Boltzmann shape in the high-energy region. The spectra of deuterons and tritons are explained well by, respectively, squaring and cubing the observed proton spectra.     

146Ce核的八级形变带和准γ带

通过测量²⁵²Cf自发裂变所产生的瞬发γ射线, 对¹⁴⁶Ce核的高自旋结构进行了重新研究, 结果更新了以前报道的能级纲图, 把八级形变集体带扩展到更高的自旋, 并且重新构建了可能的准γ带结构. 此外, 用反射不对称壳模型(RASM)对¹⁴⁶Ce核的八级形变带进行了计算, 低自旋处的计算结果与实验数据符合得很好.     

Gamma rays from dark matter annihilation in the Draco and observability at ARGO

The CACTUS experiment recently observed a gamma ray excess above 50 GeV from the direction of the Draco dwarf spheroidal galaxy. Considering that Draco is dark matter dominated, the gamma rays may be generated through dark matter annihilation in the Draco halo. In the framework of the minimal supersymmetric extension of the standard model we explore the parameter space to account for the gamma ray signals at CACTUS. We find that the neutralino mass is constrained to be approximately in the range between 100 GeV∼400 GeV and a sharp central cuspy of the dark halo profile in Draco is necessary to explain the CACTUS results. We then discuss further constraints on the supersymmetric parameter space by observations at the ground-based ARGO detector. It is found that the parameter space can be strongly constrained by ARGO if no excess from Draco is observed above 100 GeV.     

Bimodal fission in binary and ternary spontaneous fission of 252Cf

The hot bimodal fission of ²⁵²Cf is reexamined with new high-statistics data. We constructed a γ-γ-γ coincidence cube for binary fission and LCP-gated γ-γ matrix for ternary fission. By identifying the secondary fission fragments from their γ-ray transitions, we measured the yields for various fission splits. The normal neutron yield distribution is found to be Gaussian for Xe-Ru. However, the binary fission split of Ba-Mo is found to exhibit a bimodal neutron distribution with the “hot mode” corresponding to ≈3.1% of the total yield. In α ternary fission, the first measurements of yields for specific fission splits are presented. The Te-α-Ru and Xe-α-Mo neutron yields fit well with a single mode, but the Ba-α-Zr split shows evidence for an enhanced hot mode with an intensity of ≈13.8% of the normal mode. The text was submitted by the authors in English.     

Collective bands in 104,106,108Mo

We have used our analysis of γ-γ-γ data (5.7 × 10¹¹ triples and higher folds) taken with Gammasphere from prompt γ rays emitted in the spontaneous fission of ²⁵²Cf to study the collective bands in ^104,106,108Mo. The one-phonon and two-phonon γ-vibrational bands and known two-quasiparticle bands in neutron-rich ^104,106Mo were extended to higher spins. The one-and two-phonon γ-vibrational bands have remarkably close energies for transitions from the same spin states and identical moments of inertia. Several new bands are observed and are proposed as quasiparticle bands in ^104,106Mo, along with the first β-type vibrational band in ¹⁰⁶Mo. The quasiparticle bands have essentially constant moments of inertia near the rigid-body value that indicate blocking of the pairing interaction. Candidates for chiral doublet bands in ¹⁰⁶Mo are strong. These are the first reported chiral vibrational bands in an even-even nucleus. The text was submitted by the authors in English.     

The LPCTrap experiment: measurement of the β–ν angular correlation in 6He using a transparent Paul trap

We report on the status of the LPCTrap experiment, devoted to measure the β–ν angular correlation in the pure Gamow–Teller decay of ⁶He. This measurement is motivated by the search for the presence of tensor type contributions to the weak interaction. The ⁶He ions are confined in a novel transparent Paul trap. The β particles and the recoil ions are detected in coincidence to deduce the angular correlation parameter. The commissioning run performed in 2005 has given the proof of principle of this experiment. Up to 10⁵ coincidences were recorded during a second run in 2006.