Transfer reactions induced by 12C ON 18O and 26Mg AT 46 MeV

It is argued that a recent claim that there is an error of a factor of two in the Law- Campbell theory of K-electron shake-off in β^? decay is wrong.     

Fragmentation of stable and neutron-rich 12-16C into boron fragments at approximately 240 MeV/nucleon

The elemental fragmentation cross sections of boron fragments produced by stable and neutron-rich^12-16C beams with a carbon target were systematically measured at an incident beam energy of approximately 240 MeV/nucleon.The measured cross sections were found to increase as the projectile mass number increases.The observed feature is explained qualitatively based on the abrasion-ablation two-stage reaction model and is compared quantitatively with predictions from various reaction models,including empirical and statistical models.All models agree with the measured cross sections within a factor of 2.     

Three particle reactions observed from 10Ne + 12C at 160 MeV

Coincidences between light particles (Z ? 4) and heavy ions (A ? 9) have been measured for the ²⁰Ne + ¹²C reaction at $\text{E}{}_{\mathrm{<mtext>lab</mtext>}}\text{(}{}^{20}\text{Ne}\text{) = 160}\text{MeV}$. α, ¹⁶O events from the ¹²C(²⁰Ne, α¹⁶O)¹²C reaction and α, ²⁰Ne events from ¹²C(²⁰Ne, α²⁰Ne)⁸Be have been found. Energy distributions and angular correlations of these events are consistent with α-decay from the intermediate nuclei ²⁰Ne and ²⁴Mg formed by inelastic scattering and α-transfer in a first reaction step.     

Study of the reactions 12C(d,d)12C and 12C(d,p)13C across the resonance at Ed = 2.71 MeV

The second order processes in particle transfer reactions are tested by measuring the resonance structure of the 3⁺ state of ¹⁴N at 12.61 MeV for some outgoing channels of the ¹²C + d reaction.     

用12C离子模拟质子引起的单粒子效应

在理论分析的基础上 ,提出了一种利用兰州重离子加速器提供的高能12C离子模拟质子引起单粒子效应的途径 .在保证核反应机制是引起单粒子效应主要机制的前提下,用高能12C离子可以模拟质子在功率金属 -氧化物 -半导体场效应晶体管中引起的单粒子烧毁以及单粒子栅极击穿 ,获得质子单粒子效应的饱和截面 ,定性研究质子单粒子效应的角度效应 ,还可以作为高能质子单粒子效应实验前的预备实验 .该方法拓展了兰州重离子加速器加速的轻的重离子在单粒子效应实验研究方面的应用 ,对现阶段国内开展质子单粒子效应实验研究具有重要意义. The mechanisms for proton and heavy ion induced single event effect (SEE) are discussed and a method to simulate proton induced SSEE (PSEE) with high energy 12 C is proposed in this paper. The experiments which can be done by using this method include single event burnout (SEB) and single event gate rupture in power MOSFET, single event upset (SEU) and single event transient (SET) in less sensitive device and angle effect. The experimets with high energy ...     

Energy dependence of multinucleon transfer reactions induced by 20Ne on 12C

The energy dependence of up to five nucleon transfer reactions induced by ²⁰Ne on ¹²C has been measured in the energy range 150 to 294 MeV. Good agreement is found between the experiment and both DWBA and semiclassical calculations.     

Charge-exchange reaction on 12C with 217 MeV 3He particles

Differential cross sections for the (³He, t) charge-exchange reaction have been measured on a ¹²C target with 217 MeV ³He particles. High energy tritons were detected using a thick Ge(Li) crystal (43 mm) and a 4 mm Si(Li) detector in an E-ΔE telescope. Microscopic DWBA calculations have been carried out, using the rather well known wave functions of the ¹²C levels from Gillet and Vinh-Mau. The sensitivity of this reaction to the different terms of the two-body effective interaction is discussed. A comparison of the (³He, t) and (³He, ³He') reactions populating analog final states is also presented. The two-step mechanisms (³He,α)(α, t) and (³He, d)(d, t) are introduced for the first two levels 1⁺(g.s.) and 2⁺(0.969 MeV) and the results emphasize the importance of such processes at high energy.     

Three-nucleon transfer on 12C: The 12C(α, p)15N reaction at 96.8 MeV

Angular distributions of protons from the ¹²C(α, p)¹⁵N reaction have been measured over the angular range from 10–70° at an α-particle bombarding energy of 96.8 MeV. Well defined particle groups are observed up to an excitation energy of 18 MeV in ¹⁵N. The relatively small number of states excited implies a selectivity both in the reaction mechanism and in structure effects. DWBA calculations using a semi-microscopic three-nucleon form factor have been performed using several different sets of wave functions. Good agreement in the ratio σ_exp/σ_th is obtained for most states using the ¹⁵N wave functions of de Meijer. The strongest state in the (α, p) spectrum is observed at 15.397 MeV in ¹⁵N and DWBA calculations give good agreement for a $\text{13}\text{2}{}^{\mathrm{+}}$ assignment. This state has been observed only in other three-nucleon transfer reactions involving heavy ions. The recent discovery of a $\text{9}\text{2}{}^{\mathrm{+}}$ state at 10.693 MeV in a p+¹⁴C resonance measurement is supported by our analysis.     

Scattering and reactions of 14C + 14C and 14C + 14C

We have studied elastic scattering, inelastic scattering and several transfer channels of the systems ¹⁴C + ¹⁴C and ¹⁴C + ¹²C over a wide range of energies up to E_c.m. = 35 eMeV and 32 MeV, respectively. The reaction channels were identified by means of kinematic coincidences between solid-state detectors, γγ coincidences were measured to determine cross sections for mutual inelastic scattering of ¹⁴C + ¹⁴C.Pronounced regular gross structures, similar to those found for ¹⁶O + ¹⁶O, are observed in the elastic excitation function of ¹⁴C + ¹⁴C at θ_c.m. = 90°, The angular distributions measured at the energies of the maxima and an optical-model analysis suggest that one or a few surface partial waves dominate the scattering behaviour. Correlated structure of narrower width is found in the inelastic channels and, to a lesser degree, in the transfer channels which appear with rather small cross sections.In ¹⁴C + ¹²C elastic scattering the gross structures are strongly fragmented, in contrast to ¹⁴C + ¹⁴C but similar to ¹²C + ¹²C. While the ¹²C(2⁺) excitation is very weak, the observed strengths of the ¹⁴C(3^?) excitation and of neutron transfer point to a substantial role of these channels as coupling partners to the elastic configuration and to their influence on the elastic scattering behaviour. A correlated intermediate structure is observed near 23.5 MeV, where a dominance of l = 18 is suggested by the elastic scattering angular distribution. This unexpectedly high l-value exceeds l_graz at this energy by at least two units of ?.     

Time-dependent Hartree-Fock calculations for 14N + 12C reactions

We present Time-Dependent Hartree-Fock calculations for the massasymmetric system ¹⁴N + ¹²C in the range 20 ? E_cm ? 114. A simplified effective interaction of the Skyrme form has been used and the orbital angular motion of the ions has been treated in the rotating frame approximation. The overall magnitude of the calculated fusion cross-section is in agreement with experiment. The calculated differential cross section for direct inelastic reaction products is proportional to ${}^1\text{sin θ}$. This is in contrast to the exponential decrease observed experimentally.     

The sub-Coulomb 12C + 12C resonances in a microscopic 12C+12C,α+20Ne, 8Be+16O cluster basis

The low-J resonances in the Coulomb barrier region of the ¹² C+¹²C system are investigated in the framework of a microscopic cluster model basis including ¹²C+¹²C, α+ ²⁰Ne, and su8 Be+ ¹⁶O fragment decompositions. Calculations are carried out in an orthogonality condition model approximation in which Pauli-forbidden components are properly excluded from the basis but in which the interaction among cluster fragments is approximated by a local potential, obtained from a gaussian NN interaction by a folding procedure leading to both spherical and Q · Q terms. Only minor adjustments of overall strength and fall-off parameters are introduced to gain a consistent picture of the low-energy spectrum in the separate rearrangement channels. The basis includes cluster relative motion excitations with oscillator quanta from 12 to 20 and is not quite rich enough to give a detailed quantitative comparison between theory and experiment. Predicted excitation energies are too high by ~ 3 MeV and predicted ¹²C partial widths are too small to indicate a well-developed surface-peaked molecular character; but it does appear possible to identify a 5 MeV region as the potential seat of the 0⁺, 2⁺, 4⁺ resonances. The number and approximate spacing of the resonance fine structure components are in agreement with experiment.     

Microscopic investigation of the 12C + 12C interaction

The ¹²C + ¹²C system is studied in the framework of the generator coordinate method. Each ¹²C nucleus is described by a closed $\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ subshell. Phase shifts and resonances are determined for several effective two-body interactions involving a spin-orbit term. The existence and properties of simple local equivalent potentials for the ¹²C + ¹²C collision are discussed. The ¹²C + ¹²C system is too light to be well described by potentials independent of the angular momentum or weakly dependent on it.     

Intermediate resonance of inelastic 12C + 12C scattering

The intermediate resonances observed in the inelastic ¹²C + ¹²C cross sections to the single and mutual 2₁⁺(4.43 MeV) excitations and the single 3₁^? (9.64 MeV) excitation are studied by the coupled-channel method with the use of the coupling interaction derived by the folding procedure between ¹²C and ¹²C. It is shown that the model is successful in reproducing the gross structures of the inelastic cross sections and especially the correlated resonance energies of the inelastic channels. The inelastic resonances are shown to be due to the molecular resonances in an adiabatic potential between two ¹²C, which reproduces correctly the coupled channel resonances.     

Mass 2 and 3 cluster structure study with quasi-free reactions induced by 58 MeV protons on 9Be, 12C and 14N

Cross sections for (p, pd) and (p,p³He) reactions at 58 MeV have been measured for ⁹Be, ¹²C and ¹⁴N targets. An energy resolution of about 400 keV permitted identification of several excited states in the different residual nuclei. The experimental results are presented and analysed in the framework of the distorted-wave impulse approximation. Spectroscopic and mechanism information is discussed. Some additional quasi-free reactions involving t, ³He and α structure of ⁹Be have been observed and are also reported.     

Systematics of back angle 12C scattering — the 12C + 20Ne and 12C + 24Mg systems

The back angle scattering of ²⁰Ne and ²⁴Mg ions from ¹²C display structured excitation functions and oscillatory angular distributions. These measurements bridge the gap between the previously studied ¹²C + ¹⁶O and ¹²C + ²⁸Si systems.     

12C(12C, 8Be)16O angular distributions and excitation functions between 35 and 69 MeV bombarding energy

An array of eight detectors has been developed for identifying the particle unstable ⁸Be nucleus from nuclear reactions with high detection efficiency. Absolute cross sections have been measured for the reaction ¹²C(¹²C, ⁸Be_g.s.)¹⁶O to the ground state and to several excited states in ¹⁶O. Excitation functions at seven angles from 15° to 45° (lab) in 5° steps have been measured for bombarding energies between E¹²_C(lab) = 35 and 69 MeV. Excitation functions were obtained for the following states in the residual nucleus ¹⁶O which were found to be strongly populated: g.s.(0⁺); 6.1 MeV (0⁺, 3^?); 6.9 MeV (2⁺); 10.4 MeV (4⁺); 11.1 MeV (4⁺); 14.7 MeV (6⁺,…) and 16.3 MeV (6⁺,…). The energy range is covered in 250 keV (c.m.) steps; at certain energy ranges in ¹²⁵ keV or 50keV steps. All excitation functions exhibit a strong energy dependence of the cross section; pronounced gross structures with superimposed fine structures, similar to those observed for ¹²C+¹²C elastic and inelastic scattering at these energies, are observed. At 19.3 MeV, where resonant structures were observed in the reactions ¹²C(¹²C, p)²³Na, ¹²C(¹²C, n)²³Mg and ¹²C(¹²C, d)²²Na, no resonance is found for the reaction studied here. At 60, 61 and 63 MeV angular distributions have been measured in 1° and 2.5°(lab) angular steps. The excitation functions have been analyzed in terms of Ericson fluctuations and cross-correlation functions.     

Statistical fluctuations and compound elastic scattering for 12C(12C, 12C)12C and 16O(16O, 16O)16O

The difference between the observed fluctuations in the elastic excitation functions for carbon-carbon and oxygen-oxygen scattering, just above the Coulomb barrier, is interpreted in terms of the compound nucleus model.     

Spins of resonances in the 12C + 12C system

By measuring angular distributions we have assigned J^π = 6⁺ to a resonance at E_c.m. = 7.50 ±0.05 MeV in the ¹²C + ¹²C system.     

Spin determination of the 12C + 12C resonance at Ec.m. = 6.25 MeV

The J^π value of the ¹²C + ¹²C resonance at E_c.m. = 6.25 MeV has been determined to be 2⁺. This is in contrast to several theoretical predictions which give J^π = 0⁺. In addition, J^π values of several sub-Coulomb resonances of the ¹²C + ¹²C reaction have been determined for the first time.     

46.8MeV的p+12C非弹性散射

在Glauber多重散射理论框架下，使用跃迁密度方法和三种N湮没势，计算了46.8MeV的反质子在¹²C上的非弹性散射微分截面. 理论曲线与实验数据符合得较好. 关键词： Glauber理论 反质子 非弹性散射 湮没势 跃迁密度