Tensor force manifestations in ab initio study of the 2H(d,γ)4He, 2H(d,p)3H, and 2H(d,n)3He reactions

The (2)H(d,p)(3)H, (2)H(d,n)(3)He, and (2)H(d,γ)(4)He reactions are studied at low energies in a multichannel ab initio model that takes into account the distortions of the nuclei. The internal wave functions of these nuclei are given by the stochastic variational method with the AV8' realistic interaction and a phenomenological three-body force included to reproduce the two-body thresholds. The obtained astrophysical S factors are all in very good agreement with the experiment. The most important channels for both transfer and radiative capture are identified by comparing to calculations with an effective central force. They are all found to dominate thanks to the tensor force.     

Determination of the reaction-matrix elements of the D(d,n)3He and D(d,p)3H reactions forE d ≤500 keV

All available data of the mirror fusion reactions D(d, n)³He and D(d, p)³H have been subjected to a new analysis in order to extract the matrix elements of all 16 transitions necessary for inclusion of alll2 waves. Their energy dependence was assumed to be governed solely by Coulomb penetrabilities. The Levenberg-Marquardt algorithm was used to fit all experimental data. The experimental data are reproduced satisfactorily. The results compare well with anR-matrix analysis and with refined resonating group calculations. No suppression of quintet entrance-state transitions and therefore no neutron suppression in polarized fusion can be derived from this analysis.This work was funded by the German Federal Ministers for Research and Technology (BMFT) under the contract numbers 06-OK-153 and 06-OK-272     

H2(v=3)+H2(He)碰撞中的转动能量转移

激发态Na2与H2碰撞,使H2(v=3,J=3)得到布居,在H2和He总气压为800Pa及温度为700K的条件下,利用相干反斯托克斯拉曼散射（CARS）光谱技术研究了H2(3,3)与H2(He)间转动能量转移过程。改变CARS激光束与激发Na2的激光之间的延迟时间,测量He不同摩尔配比时H2(3,J)态CARS谱强度的时间演化,得到H2(3,3)的总弛豫速率系数分别为=(21±5)×10-13cm3s-1和=(5.6±1.6)×10-13cm3s-1。测量H2(3,J)各转动态的相对CARS谱强度,由速率方程分析,得到H2(3,3)+H2→H2(3,J)+H2中,对于J=2,4,转移速率系数分别为11±4和8.2±3.1cm3s-1。在H2(3,3)+He→H2(3,J)+He中,对于J=2,4,转移速率系数分别为3.1±1.2和2.1±0.7cm3s-1。对于H2(3,3),单量子弛豫׀∆J׀=1约占该态总弛豫率的90%。     

Relativistic Description of 3He (e, e�� p)2H

The relativistic distorted-wave impulse approximation is used to describe the ³He(e, e?? p)²H process. We describe the ³He nucleus within the adiabatic hyperspherical expansion method with realistic nucleon-nucleon interactions. The overlap between the ³He and the deuteron wave functions can be accurately computed from a three-body calculation. The nucleons are described by solutions of the Dirac equation with scalar and vector (S?CV) potentials. The wave function of the outgoing proton is obtained by solving the Dirac equation with a S?CV optical potential fitted to elastic proton scattering data on the residual nucleus. Within this theoretical framework, we compute the cross section of the reaction and other observables like the transverse-longitudinal asymmetry, and compare them with the available experimental data measured at JLab.     

Measurement of the2H(d, γ)4He reaction at intermediate excitation energies

The²H(d, )⁴He differential cross section was measured at deuteron laboratory energies of 20, 24, and 28 MeV between _cm=45° and _cm=135°. AtE _d =28 MeV a complete angular distribution was determined and fitted with Legendre polynomials. The ratioR=d/d (_cm=90°)/d/d (_cm=135°) was measured for each deuteron energy.     

The nuclear structure of 126Te studied with (d,p), (d,3He) and (d,d′) reactions

At the Munich Tandem Accelerator the reactions ¹²⁵Te(d, p)¹²⁶Te, ¹²⁶Te(d, d′)¹²⁶Te and ¹²⁷I(d, ³He)¹²⁶Te were measured with deuteron energies between 24 and 28 MeV up to excitation energies of about 3.2 MeV. Using γ-lines from previous (n,γ), (n,n′γ) and (γ,γ′) experiments, a level scheme of ¹²⁶Te up to above 3 MeV was established. The results are compared with quasiparticle-phonon model calculations.     

Comparative analysis of (p,d), (d,t) and (3He, α) reactions on13C nucleus

The angular distributions of the (p, d), (d, t) and(³He, ) reactions on¹³C have been analysed within the framework of DWBA in which additional information on nuclear vertex constants was introduced. Although all these reactions seem to be similar single nucleon transfer, their mechanism is shown to be quite different and so is the information extracted thereof. While from the (p, d) reactions spectroscopic factors may be extracted unambiguously, from the (d, t) reactions it is possible to obtain directly the values of vertex constants only, which in turn are consistent with those determined by extrapolation of the experimental cross sections of the (p, d) reactions to the pole.In the case of (³He, ) reactions, however, the analysis indicates inadequacy of the DWBA concerning the calculations of central partial amplitudes. For a more reliable extraction of structural information, besides the correct normalization of peripheral amplitudes, a contribution of more complex mechanisms must be taken into account.     

Study of the 3He(4He,γ)7Be and 3H(4He,γ)7Li Reactions in an Extended Two-Cluster Model

 The ³He(⁴He, γ)⁷Be and ³H(⁴He, γ)⁷Li reactions are studied in an extended two-cluster model which contains α + h/t and ⁶Li + p/n clusterizations. We show that the inclusion of the ⁶Li + p/n channels can significantly change the zero-energy reaction cross sections, S(0), and other properties of the ⁷Be and ⁷Li nuclei, like the quadrupole moments Q. However, the results agree with the known correlation trend between S(0) and Q. Moreover, we demonstrate that the value of the zero-energy derivatives of the astrophysical S-factors are more uncertain than currently believed. Received June 17, 1999; revised February 22, 2000; accepted for publication April 17, 2000     

Stability of the H2–(He,Ne, Ar) fluid mixtures

A theory of mixtures based on a statistical mechanical perturbation scheme is used to compute the excess free energy of mixing, the excess entropy of mixing and the concentration fluctuations in the long wavelength limit as functions of composition (c) over a wide range of temperature (T = 150 to 350 K) and pressure (p = 10 MPa to 10 GPa). This has been utilized to investigate the effects of c, T and p on the solubility of H₂ (the first element of the periodic table) to He, Ne and Ar (the first three elements of the last group) and the thermodynamic stability of the mixture. The long-range correlations among the constituent species are included through the double Yukawa potential which acts as a perturbation to the hard sphere reference mixture. The non-additivity of the potentials of the constituent species is linked to the second virial coefficients which can be determined from the experimental data. Necessary corrections to the equation of state for dimerisation of H₂ molecule and quantum effects are included. At a given T = 150 K and p = 100 MPa, H₂–Ar mixture exhibits greater thermodynamic stability than H₂–Ne and H₂–Ar.     

Measurement of the astrophysical S factor for the low energy 2H(d,γ)4He reaction

The y-rays and protons from an Ed = 20 keV deuteron beam incident on a D-Ti target were measured. A branching ratio of the 2H(d,T)4He reaction versus the 2H(d,p)aH reaction of F.v/l'p = (1.06+ 0.34) x 10-7 has been obtained, and the astrophysical S factor of the 2H(d,T)aHe reaction at the center of mass energy Ecru ≈ 7 keV of (6.0+2.4) x 10-8 keV.b was deduced.     

Nuclear structure studies of 125Te with (n,γ), (d,p) and (3He,α) reactions

Levels in ¹²⁵Te were investigated in the range up to 3.3 MeV excitation energy by the (n,γ), (d,p) and (³He,α) reactions. Over 160 levels and about 360 γ-transitions were established, most for the first time. The states below 2.3 MeV with the most complete spectroscopic information were interpreted in terms of the interacting boson-fermion model (IBFM). Unitary treatment of both positive- and negative-parity states is achieved with the same model parameter close to the intermediate case between O(6) and U(5) limits. Excitation energies, electromagnetic transition rates, γ-branchings and spectroscopic factors are discussed in connection with the possible structures. A family of low-spin negative-parity states has been identified and understood by the IBFM proving their antialigned origin.     

100—300MeV~3He(π~-,n)~2H反应的微观描述

本文将G.E.Brown等研究π-核散射的Isobar模型推广应用到中能(π,N)反应的描述上,用唯象近似方法处理多体效应,探讨了非静态修正、核子关联波函数以及出射核子扭曲效应对反应微分截面的影响,计算了100-300MeV~3He(π~-,n)~2H反应角分布,所得结果与实验基本一致。     

(n,3He)的反应截面的系统学

本文研究了中、重质量核的14MeV中子的(n,~3He)反应截面的系统学特性,在对实验数据分析,评价的基础上,给出了系统学的经验公式,计算了一批核素的反应截面,同实验值符合较好,并讨论了可能的反应机制。 The systematic characters of (n, ~3He) reaction cross sections have been studied formedium and heavy mass nucleus at 14MeV. A set of the empirital parameters have been eatracted onthe bases of analyzing and evaluating available data. The (n,~3He) reaction cross sections of somenuclei have been calculated, and a good agreement with the experimental data have been obtained.Most possible reaction mechanisms are also discussed.     

The γ-Decays of 210Po-Levels from the (3He, d*γγ)-Reaction

An in-beam experiment with the subcoulomb reaction ²⁰⁹Bi(³He, d^*γγ)²¹⁰Po at 20.5 MeV was performed with two Euroball Cluster detectors in Cologne. It closed the gap between the low energy levels of the level-scheme and the high energy levels found in ²⁰⁹Bi(³He, d)²¹⁰Po and ²⁰⁸Pb(⁴He, t)²¹⁰Po particle experiments. New branchings have been found and the (³He, d^*γγ) reaction below the coulomb-barrier has been used successfully. Received: 17 December 1998 / Revised version: 27 January 1999     

3He4He与H2分子碰撞的同位素效应研究

用公认精确度较高的密耦近似方法计算了入射能量E=0.5eV时惰性气体原子3He(4He)与H2分子替代碰撞体系的转动激发碰撞截面.通过分析3He(4He)-H2碰撞体系分波截面和微分截面的差异,总结出在氦原子的同位素替代情形下3He(4He)-H2碰撞体系分波截面和微分截面随分波数增加和同位素原子质量改变的变化规律.     

3He(e,e′pp) and 3He(e,e′pn) reactions at AmPS and MAMI

This paper reports on measurements of the ³He(e,e′pp) reaction measured at AmPS and the ³He(e,e′pn) reaction measured at MAMI. The measurements were performed in similar kinematics to allow a comparison to be made between the cross sections of the two reactions. Results are shown for both reactions together with a comparison for the ³He(e,e′pp) data with continuum Faddeev calculations.     

Discovery of deeply bound π− states in the208Pb(d,3He) reaction

Narrow lines were observed around 133 MeV excitation energy in the²⁰⁸Pb(d,³He) reaction atT _d=300 MeV/u using the Fragment Separator System at GSI. They are assigned to the deeply boundπ ^??²⁰⁷Pb states with configurations of $\left( {2p} \right)_{\pi ^ - } $ (3p_1/2, 3p_3/2) _n ^?1 .     

Insights on d μ t sticking from d μ d stripping and μ,3He capture

Data from the recent PSI high statistics experiment on d μ d fusion are used to measure the stripping process in d μ d→ n+μ,³He and test current calculations of the stripping process. The PSI results in μ³He capture are also used to remove a troubling background from this measurement. Combination of these results with the old dμ t sticking analysis slightly raise and improve that result to ω_s= (0.58± 0.04)% and indicate that theory and experiment can meet if theoretical stripping is increased only at the beginning of the track. This conclusion is in accord with the new stripping calculations where excited state stripping is increased significantly. This revised version was published online in August 2006 with corrections to the Cover Date.     

配合物Eu(C5H8NO3)2(C3H5N2)2Cl3·3H2O光致发光性能

利用OPO激光激发光谱和三维荧光光谱研究了配合物Eu(C5H8NO3)2(C3H5N2)2Cl3·3H2O固体粉末在不同激发光源下的荧光特性,测试了不同浓度配合物水溶液的荧光光谱.固体荧光结果显示该配合物具有很好的荧光性能,当激发光波长为320-400nm时,产生波长分别为400-500nm、580-620nm及690-710nm的三个荧光区;当激发光波长为700-880nm时产生峰值为450nm升频转换荧光,激发光波长为700-800nm时产生峰值分别为590nm和615nm的升频转换荧光.溶液荧光结果表明在10-4-10-2mol/L浓度范围内荧光强度与溶液浓度呈正相关.对其可能的发光机制进行了探讨.     

Microscopic description of the reactions d + d → p + 3H and d + d → n + 3He at low energies

A collective adiabatic approach is used to explore the total and differential cross sections for the reactions d + d → p + ³H and d + d → n + ³He at incident-deuteron energies of up to 6 MeV. All substantially contributing partial waves of order not higher than that of G waves are taken into account. The experimental value of the difference of the cross sections for the above mirror reactions is reproduced theoretically under the assumption that nuclear forces obey the condition of isotopic invariance. The positions and amplitudes of the maxima in the calculated total cross sections virtually coincide with those of the corresponding experimental values. It is shown that, around the maxima of the cross sections under study, dominant contributions to them come from the P wave. The sensitivity of observables to the parameters of nucleon-nucleon interaction is analyzed.