K-shell ionization by protons for Cr, Cu, In and by alpha-particles for Cr, Cu

K-shell ionization cross sections have been determined for Cr, Cu and In at proton bombardment in the energy region from 0.9 to 2.5 MeV. The same cross sections were determined for Cr and Cu at alpha bombardment in the 0.9–4.0 MeV region. The experimental results are compared with five different theoretical calculations.     

Electrodisintegration of C,Cu and Ag by electrons and positrons

Absolute cross sections for the electrodisintegration of ¹²C, ⁶³Cu and ¹⁰⁷Ag by electrons and positrons have been measured in the energy range from 20 to 30 MeV. The cross sections have been determined from the induced activities. The measured cross-section ratio σ⁻/σ⁺ is not equal to 1 and increases with Z. This is in contradiction to the Born-approximation calculations of the virtual-photon spectrum.     

The interaction of 605 MeV 63Cu with 197Au

Binary coincident fragments from the ⁶³Cu + ¹⁹⁷Au reaction at a copper energy of 605 MeV have been studied. Fragment energies were measured and fragment masses determined by a kinematic method. Three types of event are defined by suitable adjacent limits in the mass versus total kinetic energy event space. The angular distributions of cross section, average total kinetic energy and average mass have been determined for each event region. Total cross sections determined in the present experiment are compared to those found at lower bombarding energies. Further information on the sequential fission process has been obtained from measurements of yields of radioactive isotopes resulting from bombardment ofthin and thick targets of Au by 605 MeV Cu ions.     

中子与52Cr反应截面的理论分析

根据中子与天然核Cr及其同位素反应的总截面,去弹性散射截面和弹性散射角分布的实验数据,获得了入射中子能量从1MeV—250MeV的一组普适中子与Cr及其同位素反应的光学模型势参数.应用光学模型,扭曲波玻恩近似理论,宽度涨落修正的Hauser-Feshbach理论,和预平衡反应的激子模型,计算和分析了中子与⁵²Cr反应的所有截面、角分布、能谱和双微分截面.理论计算与实验数据进行了分析比较.     

Search for the density effect in inner-shell lonization by ultra relativistic electron impact

We have extended the measurements ofK-andL-shell ionization cross sections by electron impact into the ultra relativistic energy region, 0.9≦E≦2.0 GeV, in order to search for a saturation of the cross section. This phenomenon, which is due to the polarization of the target medium, is called density effect. It is predicted to occur at several hundred MeV impact energy and preferentially for lowZ target elements. Theoretical calculations are presented, based on the one-photon-exchange approximation. The absolute measurements of theK-andL-shell cross sections for Ni(K), Cu(K), Ag(K, L) and Au(L) performed at the 2.5 GeV electron synchrotron of the Bonn University, however, exhibit that the cross sections show no saturation but are still increasing. Furthermore, from theK X-ray yields, obtained at 0.9 and 2.0 GeV by bombarding the lowZ elements S, Ca, Mn, Ni and Ge, we obtain for the corresponding cross section ratio σ _K (2GeV)/σ _K (0.9GeV)=1.08±0.01 on the average. TheK X-ray yield of a composite Ca — Mn target amounts to $$[\sigma _K (Ca;2.0GeV)/\sigma _K (Mn;2.0GeV)]/[\sigma _K (Ca;0.9GeV/\sigma _K (Mn;0.9GeV)] = 0.99 \pm 0.02.$$ . All three results are in disagreement with theory. This severe discrepancy is discussed but the origin for it is not yet understood.     

Inner-shell ionization ofZ=25–32 elements by 5-48 MeV32S ions

TheK-shell ionization cross sections of Mn, Ni, Cu, Zn and Ge under³²S bombardment have been measured in the energy range from 5 to 48 MeV. The cross sections are compared with available theories based on a direct Coulomb ionization mechanism and with the predictions of theK-vacancy sharing process. This last process can reasonably account for the measured cross sections at high bombarding energies. The energy shifts of theK _α- andK _β-lines and theK _α/K _β-intensity ratios have also been measured. This information is used to deduce the defect configuration of the atoms. The mechanisms responsible for the multiple vacancy production are discussed.     

Triton-emission cross sections with 30 MeV d(Be) break-up neutrons

Triton-emission cross sections were measured for Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ag, Ta, Tl, Pb and Bi with a 30 MeV d(Be) break-up neutron spectrum characterized by a multiple-foil activation technique. The accumulated tritium was separated by vacuum extraction and measured by low-level gas-phase β^? counting. The systematic trend in the cross sections is somewhat similar to that in the 53 MeV d(Be) break-up neutron spectrum; apart from some initial decrease as a function of Z, the cross section is almost constant over the entire range of Z = 22 to 83. The magnitudes of the cross sections lie between those with 14 MeV neutrons and 53 MeV d(Be) break-up neutrons. Hauser-Feshbach calculations show that the statistical model describes the triton-emission cross sections for nuclei in the (2s, ld) shell within a factor of 2; for the heavier nuclei, however, the calculated cross sections are much smaller than the experimental values.     

Study by track detectors of the 580-MeV photofission of U,Au, Te,Ag, Se,Cu and Cr

The fission of U, Au, Te, Ag, Se, Cu and Cr induced by photons with a maximum energy of 580 MeV has been investigated using mica and glass track detectors in a sandwich configuration. Cross sections for U, Au, Te and Ag fission have been obtained which are in fair agreement with existing data for charged-particle induced fission, but are substantially lower than previous photofission results, obtained by other authors for Te and Ag targets.     

Evaporation residue cross sections from the fusion of52Cr+110Pd

Evaporation residue cross sections for the fusion of⁵²Cr and¹¹⁰Pd were studied at four energies close to the barrier (up toE _CM ?E _B =26 MeV). The cross sections were analysed using a multiple-chance fission/evaporation calculation. Agreement with the data is obtained with a fission barrier reduced by 40 to 20%, depending on incident energy.     

Mass measurement and spectroscopy of57Cu with the58Ni(14N,15C)-reaction

The mass of⁵⁷Cu has been measured with the⁵⁸Ni(¹⁴N,¹⁵C)-reaction at 150 MeV incident energy with theQ 3D-spectrometer. The reaction has been selected after a careful inspection of the DWBA-expression for the cross section with respect to the highest weighting factors for spins andl-transfer. Cross sections of several μb/sr have been obtained. TheQ-value has been measured to beQ ₀=?19.90 (4) MeV and the⁵⁷Cu mass excess is ?47 340 (40) keV. Four lines of excited states have been observed up to 5.7 MeV. These states have a structure of single particle character, since⁵⁷Cu consists of a doubly closed core with N=Z=28 and a proton outside, and states up to the 2d 5-shell are observed.     

Observation of deuteron D-state and compound nucleus effects in (d,p) reactions on 46Ti and 52Cr with a polarized deuteron beam

The cross section and the vector and tensor analyzing powers have been measured for ⁴⁶Ti(d, p)⁴⁷Ti at deuteron energies of 6 and 10 MeV and ⁵²Cr(d, p)⁵³Cr at 6 MeV. Transitions were observed to the states at E_x=0.159, 1.549 and 1.793 MeV in ⁴⁷Ti and the states at E_x=0.0, 0.564, 1.006 and 2.321 MeV in ⁵³Cr. In addition, the cross sections and vector analyzing powers for deuteron elastic scattering were measured for the same targets and deuteron energies and compared to optical model calculations. The choice of optical parameters for the DWBA analysis of the (d, p) reactions is discussed. Calculations made with the DWBA method show that the deuteron D-state must be included to reproduce even qualitatively the (d, p) tensor analyzing power measurements. The j-dependence of the tensor analyzing power T₂₂ is discussed. The validity of the local energy approximation (which was used to incorporate the deuteron D-state into the DWBA calculations) is evaluated by comparison to finite range calculations. The contribution of compound nucleus reactions to the measured cross sections and analyzing powers was investigated. In order to determine the compound cross section, the Ericson fluctuations in excitation functions of cross section and vector analyzing power were measured from 5 to 7 MeV on each target. The formulas used to calculate the polarization observables from the Hauser-Feshbach theory are presented.     

Al,Ti,Cu,Mo原子的K壳层电离截面的理论计算

 电子离子碰撞过程是模拟激光等离子体的超热电子的能谱和产额的主要过程之一。基于相对论性的电子离子碰撞的K壳层的电离截面理论,计算了Al,Ti,Cu,Mo原子的K壳层的电子离子碰撞截面,结果和最近的文献实验数值和其它理论数值进行了比较,计算结果可用来模拟激光等离子体的超热电子能谱和产额。     

Total nuclear photon absorption cross sections for some light elements

Absolute nuclear photon absorption cross sections have been measured for the elements Li, Be, C, O, Al, Si and Ca from 10 MeV up to photon energies beyond the meson production threshold. Magnetic Compton spectrometers and a bremsstrahlung spectrum with fixed end-point energy were used. The cross sections show structure in the region of the giant resonance and fall off smoothly towards higher energies. In the giant resonance region recent 1p-1h calculations are in poor agreement with these measurements except for one calculation for carbon, which included low lying excited states of the residual mass-11 system. The cross section in the intermediate region (40 to 140 MeV) can be described by the quasideuteron model with the density of deuteron-like structures taken as 8 NZ/A. The moments of the measured cross sections are compared with sum rule predictions. The integrated cross sections from 10 MeV up to the meson production threshold (140 MeV) exceed the classical dipole sum by a factor of 1.4 to 2.     

Investigation of giant-dipole-resonance decay in the (<Emphasis Type="Italic">γ, n</Emphasis>) reactions on <Superscript>52</Superscript>Cr and <Superscript>51</Superscript>V nuclei

The cross sections for the emission of fast neutrons (? _n > 3.7 MeV) in the reactions ⁵²Cr(γ, n)⁵¹Cr and ⁵¹V(γ, n)⁵⁰V at incident-photon energies in the range between 16.0 and 25.8 MeV were studied. The neutron energy spectra were measured at the bremsstrahlung-photon endpoint energies of 18.5, 21.0, and 23.0 MeV for the ⁵²Cr and ⁵¹V nuclei and at the bremsstrahlung-photon energy of 25.5 MeV for the ⁵¹V nucleus. Special features of giant-dipole-resonance decay that are associated with the existence of a structure in photoneutron cross sections and spectra are discussed.     

Reaction and fission cross-sections of 750 A·MeV238U ions on Pb,Cu and Al-targets

Charge-loss and fission cross-sections of²³⁸U at 750 A·MeV were measured on Al, Cu and Pb targets. The charge-loss rate was obtained by the attenuation method. Fission was selected by detecting the pair of highly ionizing fragments. Since the neutron-loss cross sections were measured in a parallel experiment for the same projectiles, all cross sections contributing to²³⁸U collisions on nuclei are available now as function of the target mass number and can be compared with current models.     

Description of Differential Cross Sections for <Superscript>63</Superscript>Cu + <Emphasis Type="Italic">p</Emphasis> Nuclear Reactions Induced by High-Energy Cosmic-Ray Protons

The results of calculation of ⁶³Cu + p differential cross sections at incident-proton energies between 10 and 200 MeV and a comparative analysis of these results are presented as a continuation of the earlier work of our group on developing methods for calculating the contribution of nuclear reactions to radiative effects arising in the onboard spacecraft electronics under the action of high-energy cosmic-ray protons on ⁶³Cu nuclei (generation of single-event upsets) and as a supplement to the earlier calculations performed on the basis of the TАLYS code in order to determine elastic- and inelastic-scattering cross sections and charge, mass, and energy distributions of recoil nuclei (heavy products of the ⁶³Cu + p nuclear reaction). The influence of various mechanisms of the angular distributions of particles emitted in the ⁶³Cu + p nuclear reaction is also discussed.     

Investigation of some low-lying states in Pb by inelastic electron scattering

Differential cross sections for inelastic electron scattering from ²⁰⁸Pb have been measured in the momentum-transfer range from 0.48 fm⁻¹ to 1.54 fm⁻¹. The cross sections for the excitation of the 3⁻ level at 2.6 MeV cannot be reproduced with a modified liquid-drop model using a two- or three-parameter Fermi distribution, but are instead consistent with a phenomenological distribution which consists of two Gaussian functions multiplied with r^L−1. The value obtained for the reduced transition probability B (0.624±0.04 b³) is somewhat different from that determined in earlier electron scattering experiments. The cross sections for the excitation of the two 5⁻ levels at 3.2 and 3.7 MeV exhibit a striking difference in that the ratios of the cross section in the two first diffraction maxima are different by a factor of 2.5. The cross sections for the excitation of the level at 3.2 MeV can be reproduced with the modified liquid-drop model using a three-parameter Fermi distribution. The value for B is determined to be 0.053±0.014 b⁵. The excitation of the level at 3.7 MeV cannot be described by this model. There are strong indications that the transition charge here consists of two regions with opposite sign.     

6.8MeV质子对Cr,Co,Ni,Cu,Zn的弹性散射

本实验测量了6.8MeV质子对Cr,Co,Ni,Cu和Zn的弹性散射角分布。在其微分截面σ_e(θ)与库仑散射微分截面σ_R(θ)之比对θ的作图中显示:这几种元素A相近,也有大体相似的角分布曲线;其极大极小位置可以用kR′sinθ_m/2=常数表之,显示出核的粗糙结构的特征。但在大角度处,这几种质量数A相近的核,其(σ_e(θ))/(σ_R(θ))值却有显著的差异,而且偶z核的(σ_e(     

ELASTIC SCATTERING OF FAST NEUTRONS FROM Fe,Cu AND Pb

Using time of flight technique the elastic differential cross sections were measured for neutrons from natural Fe, Cu, and Pb in the energy range 1.10 to 1.40 MeV.The effect of neutron attenuation and multiple scattering in the sample is corrected by extrapolation of the experimental results. The correction of scattering angles due to the finite source-sample-detector geometry is also considered. The measured elastic differential cross sections are expressed by Legendre polynomial expansions, from which the total cross sections are obtained.The Optical-Model Calculations are carried out which show a reasonable consistency with the measured values.