Predictions for cross sections of light proton-rich isotopes in the ~(40)Ca + ~9Be reaction

The cross sections for Z=10–19 with isotopes T_z=-3/2 to-5 in the 140A Me V~(40)Ca+~9Be projectile fragmentation reaction have been predicted.An empirical formula based on the correlation between the cross section and average binding energy of an isotope has been adopted to predict the cross section.The binding energies in the AME16,WS4,and the theoretical prediction by the spherical relativistic continuum Hartree-Bogoliubov theory have been used.Meanwhile,the fracs parametrization and the modified statistical abrasion-ablation model are also used to predict the cross sections for the proton-rich isotopes.The predicted cross sections for the T_z=-3 isotopes are close to 10~(-10)mb,which hopefully can be studied experimentally.In addition,based on the predicted cross sections,Z=14 is suggested to be a new magic number in the light proton-rich nuclei with T_z-3/2,for which the phenomenon is much more evident than it is from the average binding energy per nucleon.     

Experimental determination of one-and two-neutron separation energies for neutron-rich copper isotopes

A method is proposed to determine the one-neutron S_n or two-neutron S_(2n) separation energy of neutronrich isotopes.Relationships between S_n(S_(2n)) and isotopic cross sections have been deduced from an empirical formula,i.e.,the cross section of an isotope exponentially depends on the average binding energy per nucleon B/A.The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64 A Me V ~(86)Kr+~9Be reaction.S_n,S_(2n),and B/A for the very neutron-rich ~(77,78,79)Cu isotopes are determined from the proposed correlations.It is also proposed that the correlations between S_n,S_(2n) and isotopic cross sections can be used to find the location of neutron drip line isotopes.     

Cross-section prediction for isotopes near neutron drip line in ~(70, 80)Zn projectile fragmentation reactions

The cross sections for ~(59,60)Ca, recently measured in the 345 A MeV ~(70)Zn+~9 Be reaction,were estimated using the FRACS parametrization and an empirical formula,which are in good agreement.The FRACS parametrization and the empirical formula are combined to predict the cross sections for extreme calcium isotopes ~(66,70)Ca in the~(70,80)Zn+~9 Be reactions at the incident energies of ~(60,80),and 345 A MeV.The dependence of emperical formula parameters on the reaction system,as well as the incident energy,are discussed.The results indicate that ~(66,70)Ca can be discovered in reactions of ~(60,80)A MeV ~(80)Zn+~9 Be.The predicted binding energy for extreme neutron-rich isotopes by the spherical relativistic continuum Hartree-Bogoliubov theory was adopted in the calculation.Hence,the planned Beijing Isotope-Separation-On Line Neutron-Rich Beam Facility(BISOL),which is a third generation radioactive ion beam facility,could provide the opportunity to discover ~(66,70) Ca and neighboring neutron-drip line nuclei.     

Probing Temperature from Intermediate Mass Fragment by Isobaric Yield Ratio in Heavy-Ion Collisions

A probe to extract the temperature(T_(iyr)) from intermediate-mass fragment has been proposed using the isobaric yield ratio(IYR) difference based on the modified Fisher model.By analyzing the isobaric cross section in the measured 140 A MeV~(40,48)Ca+~9Be reactions,the Tiyr can well fit the IYR difference for the large mass fragments.Because of the fragments are produced in different colliding regions,it is also suggested to select the fragments according to different mechanisms when using TIYR.     

Discovery and cross-section measurement of 58 new fission products in projectile-fission of 750 · A MeV 238U

The projectile fission of uranium at relativistic energy impinging on a Be target was investigated with the fragment separator, FRS, in order to produce and identify new isotopes and to measure their production yields. Fifty eight new fragments have been observed with a neutron excess of (N - Z)/Z reaching 0.8 and cross sections as small as 0.3 nb.     

Fusion reactions around the barrier for Be+~(238)U

Fusion-evaporation cross sections of ~(238)U (~9Be,5n)~(242)Cm are measured over a wide energy range around the Coulomb barrier.These measured cross sections are compared with model calculations using two codes,namely HIVAP2 and KEWPIE2.HIVAP2 calculations overestimate the measured fusion-evaporation cross sections by a factor of approximately 3.In KEWPIE2 calculations,two approaches,namely the Wentzel-Kramers-Brillouin(WKB) approximation and the empirical barrier-distribution (EBD) method,are used for the capture probability;both of them properly describe the measured cross sections.Additionally,fusion cross sections of ~(7,9)Be+~(238)U measured in two experiments are applied to constrain model calculations further through three codes,i.e.,HIVAP2,KEWPIE2,and CCFULL.Parameters in these codes are also examined by comparison with measured fusion cross sections.All the comparisons indicate that the KEWPIE2 calculations using the WKB approximation agree well with the measured cross sections of both fusion reactions ~(7,9)Be+~(238)U and the fusion-evaporation reaction ~(238)U (~9Be,5n)~(242)Cm.Calculations using the fusion code CCFULL are also in good agreement with the measured fusion cross sections of ~(7,9)Be+~(238)U.     

Scaling of charge-changing interaction cross sections and point-proton radii of neutron-rich carbon isotopes

Charge-changing cross sections σ(cc) of stable and unstable nuclei ((9-11)Be, (14-16)C, and (16-18)O) on a carbon target were investigated at 300 MeV/nucleon. A phenomenological analysis based on the Glauber theory indicates an approximate, but universal, scaling of σ(cc) over a wide range of A/Z. This allows the determination of the density distributions of protons tightly bound in the nuclei. An application to (16)C, which is considered to be an anomalously deformed nucleus, indicates a systematic evolution of proton root-mean-square radii and has revealed for the first time a neutron skin effect in carbon isotopes. Being complementary to isotope-shift and electron-scattering experiments, the present method can open up a new approach to explore the structure of exotic nuclei.     

A scaling phenomenon for the cross section of fragment produced in projectile fragmentation reactions

A scaling phenomenon has been found for the cross section of a fragment, which is defined as a "square" cross section(SCS).This phenomenon can unify the cross sections of fragments in projectile fragmentation(PF) reactions. An empirical formula is proposed to calculate SCSfor a fragment with parameters determined by an extensive investigation of measured reactions ranging from Fermi energies to relativistic energies. The scaling phenomenon of SCShas been verified using different techniques,showing that the scaling of SCSgenerally exists in PF reactions. The concept of SCS, which can be assumed as a standard value for a fragment, is shown to accurately predict the cross sections of isotopes in PF reactions with incident energies ranging from tens of A MeV to approximately 1000 A MeV.     

Quenching of neutron spectroscopic factors of radioactive carbon isotopes with knockout reactions within a wide energy range

The quenching factors of one-neutron spectroscopic factors,which are ratios of theoretical to experimental one-neutron removal cross sections,are studied for the carbon isotopes ~(15-19)C,with ~(12)C and ~9Be targets within incident energies from around 50 to 900 MeV/nucleon.The resulting values of quenching factors do not show strong energy dependence within such an energy range.The average values of the these quenching factors agree well with the systematics in [J.A.Tostevin and A.Gade,Phys.Rev.C,90 057602(2014)],which was established for a large set of radioactive nuclei with different masses below 305 MeV/nucleon.     

质子数Z 分别位于Ru 之上和之下的A~(100~126) 丰中子原子核三轴形变在原子核形状变迁和共存中的重要作用(英文)

基于Ru (Z = 44) 丰中子同位素中存在最大三轴形变的理论预言和实验证据,综述了近年来Rh (Z = 45),Pd (Z =46), Ag (Z =47), Cd (Z =48)(质子数Z 位于Ru,Z =44 之上)及Zr (Z =40), Nb (Z =41), Mo (Z =42),Tc (Z =43)(质子数Z 位于Ru,Z =44 之下) 的A~ (100~126) 丰中子同位素中关于三轴形变的形状变迁和形状共存系统性研究的重要进展。252Cf 自发裂变瞬发 射线-- 三重符合、特别是新建立的--- 四重符合数据的系统观测和研究,在Ru, Pd, Cd 和Nb 丰中子同位素中显著扩展或首次观测到了一系列能带,为这个核区原子核形状的研究提供了新的、重要的实验数据。联系此前报道的有关进展,使用PES, TRS, PSM, CCCSM 和SCTAC 理论模型计算拟合新的实验数据,在该核区沿同中素和同位素链,并随自旋和激发能变化各自由度,跟踪原子核形状渐进变化,获得了新的系统性研究成果,显著扩展和深化了人们对原子核形状变迁和形状共存的认知。对于Ru 及其上的Rh (Z = 45), Pd (Z = 46), Ag (Z = 47) 和Cd (Z = 48) 丰中子同位素的研究表明:Rh 丰中子核具有比最大值稍小的三轴形变,γ = 28°,并在103{106Rh 同位素链上鉴别出了手征对称破缺;在三轴形变核112Ru和114Pd(N = 68)中发现了三轴原子核的摆动运动,该摆动运动也可能在114Ru (N = 70)中存在;观察到了从具有最大三轴形变的110,112Ru 中手征破缺到稍小三轴形变的112,114,116Pd 中扰动的手征破缺的过渡;在较软的Ag 核中观察到了丰富的谱学结构,在104,105Ag 中鉴别出了可能的手征对称破缺,在较重的115,117Ag 中提出了趋于三轴形变的软度;具有小形变的Cd核的能级结构被解释为准粒子耦合、准转动和软三轴形变;最近的库伦激发的研究提供了Z = 50, N = 82满壳附近122,124,126Cd 核中出现核集体性的实验和理论证据;上述研究成果展现出从Ru中的最大三轴形变(γ=30°,三轴形变极小增益为0.67 MeV), 经具有大三轴形变的Rh核γ=28°),到Pd核中的稍小、但稳定于中等自旋到高自旋区的三轴形变(γ~41°,三轴形变极小增益为0.32 MeV),再经Ag核中的软度,最后到具有很小形变、但仍出现集体性质、包括软三轴形变的Cd核的过渡。对于Pd核转动带交叉系统性的研究揭示了其第一带交叉(νh_11/2)2 中子转动顺排的上行驱动,和第二带交叉(πg_9/2)2质子转动顺排的下行驱动效应,成功地解释了114Pd 中的三轴摆动运动,并给出了110-118Pd同位素链中理论早已预言、而比早期理论预言更为完整准确的形状渐进变迁和形状共存的图像。根据该核区的系统研究,发现最大三轴形变出现在112Ru,而在相邻的偶Z(Pd)同位素链,三轴形变极小的中心在114Pd, 两者均为N = 68。上述系统性研究沿相邻的Ru和Pd偶Z同位素链,在N =68同中素中鉴别出最大三轴形变,均比理论预言的108Ru 和110Pd 多4个中子。在Z值位于Ru (Z = 44) 之下的Zr (Z = 40), Nb (Z = 41), Mo (Z = 42) and Tc (Z = 43) 丰中子同位素中,Y和Zr核具有很强的轴对称四极形变,而在较重的Zr同位素中出现了自由度;较重的Nb核(A = 104~106) 基态具有中等程度的软三轴形变和强四极形变,随着自旋和激发能的增加,过渡到接近于轴对称的强四极形变;而较轻的Nb核(A≤103) 基态均接近轴对称形状;在Nb同位素链上基态由球形到强四极形变的形状突变发生在100Nb(N = 59),在100-106Nb同位素链中基态的软三轴形变随中子数增加而增加;在Nb核中还观察到关于软三轴形变的形状共存;Mo核具有大的三轴形变,观察到了振动和手征对称破缺;Tc核具有比最大值稍小的三轴形变,γ=26°,并观察到了手征对称破缺。质子数Z从41到48的A~(100~126)丰中子同位素,特别是Pd和Nb 同位素,呈现出关于三轴形变的过渡特征。This paper reviews the systematic investigations and understanding for the shape transitions and coexistence with regard to triaxial deformations in A s 100 to 126 neutron-rich Rh (Z = 45), Pd (Z = 46), Ag (Z = 47), Cd (Z = 48) and Zr (Z = 40), Nb (Z = 41), Mo (Z = 42), Tc (Z = 43) isotopes with Z beyond and below Ru (Z = 44), respectively, in Ru the maximal triaxial deformation having been predicted and deduced. The recent measurements and studies of prompt triple- and four-fold, γ-γ-γ and γ-γ-γ-γ, coincidence data from the spontaneous fission of 252Cf using Gammasphere have yielded considerable expansion and extension or first observation of the bands in Ru, Pd, Cd, and Nb isotopes,which provided important data for the studies of nuclear shapes in this region. Combined with previous investigations, recent systematic studies of the new data well reproduced by PES, TRS, PSM, CCCSM and SCTAC model calculations have traced shape changes along the isotonic and isotopic chains, respectively,and with changing excitations/spins as well, significantly expanding our knowledge of shape transitions/coexistence in nuclei.For the neutron-rich Ru and beyond, Rh, Pd, Ag and Cd isotopes, triaxial deformations γ= 28°,slightly smaller than the maximal value, were deduced in Rh (Z = 45) isotopes, with chiral symmetry breaking proposed in 103-106Rh; onset of wobbling motions were identified in 112Ru and 114Pd (N =68),and probably also in 114Ru (N =70); evolution from chiral symmetry breaking in 110,112Ru with maximal triaxial deformations to disturbed chirality in 112,114,116Pd with less pronounced triaxial deformations was proposed; rich nuclear structure was proposed in soft Ag isotopes with possible chiral doubling structure suggested in 104,105Ag, and softness towards triaxial deformation proposed in heavier 115,117Ag;quasi-particle couplings, quasi-rotations and soft triaxiality were suggested in Cd (Z =48) isotopes with small deformations; onset of collectivity was recently suggested in 122,124,126Cd in the vicinity of Z =50 and N = 82 closed shells by studies of Coulomb excitations; shape evolutions from maximal triaxial deformations in Ru (γ=30°, with triaxial minimum energy gain of 0.67 MeV), through Rh with large triaxial deformations ( γ=28°), to less pronounced triaxiality in Pd (with triaxial minimum energy gain of 0.32 MeV), then soft triaxiality in Ag, and finally to slightly deformed Cd isotopes but with emergence of collectivity and soft triaxiality were proposed. The systematic studies of the band crossings in Pd revealed up-rising drivings of the first band crossings caused by (νh_11/2)2 and down-sloping drivings of the second band crossings by (πg_9/2)2, explained the onset of wobbling motions in 114Pd,and showed a long-sought picture of shape evolution and coexistence in the Pd isotopic chain which is more complete but complex than earlier predictions. Based on the systematic studies in the mass region,maximal triaxial deformation is found to be reached in 112Ru and less-pronounced triaxiality centered at 114Pd, both for N =68, four neutrons more than predicted in earlier theoretical calculations.In the neutron-rich Zr (Z =40), Nb (Z =41), Mo (Z =42) and Tc (Z =43) isotopes with Z just below Ru, large quadrupole deformations of axially symmetric shapes were deduced in Y and Zr isotopes, with emergence of the degree of freedom having been suggested for heavier Zr isotopes; medium triaxial deformations were deduced for the ground states of heavier (A > 104) Nb isotopes, and, with increasing excitations and spins, evolution from medium triaxial deformations with strong quadrupole deformations at ground states to nearly axially-symmetric shapes were deduced; light Nb isotopes (A6103) have near axially-symmetric shapes with strong quadrupole deformations; combining with the identification of onset of strong quadrupole deformation at 100Nb in the Nb isotopic chain, an increase of soft triaxiality with increasing neutron number was proposed in 100-106Nb. Shape coexistence with regard to soft triaxiality is also proposed in Nb isotopes; large triaxial deformations, vibrations and chiral doublets were proposed in Mo isotopes; chiral doubling and large triaxial deformations (γ ~26°) slightly smaller than the maximal triaxiality were suggested in Tc isotopes.The neutron-rich nuclei with Z ranging from 41 through 48 and A ~100 to 126, especially the Pd and Nb isotopes are thus found to be transitional nuclei with regard to triaxiality.     

用电子散射对S核和Si核同位素的进一步研究

用相对论平均场计算了^26,28,30,32S和^22,24,26,28Si的结合能, 均方根半径, 质子皮厚度, 单粒子能级等. 两套参数TM2和NL-SH的计算结果与实验值比较符合. 用平均场与相对论Eikonal近似结合计算出³²S和²⁸Si的形状因子和微分截面的结果, 与实验值也符合得较好. 进一步研究了S和Si的同位素链的基本性质和电子散射, 讨论了电子散射的电荷形状因子对电荷密度变化的敏感性. 电荷形状因子在下一代电子--不稳定原子核对撞机上可以测量, 这将能精确测量不稳定核的电荷半径和电荷密度分布, 本文计算的结果可供未来实验参考.     

Cross sections for evaporation residue production near theN=126 shell closure

In fusion reactions of⁴⁰Ar with isotopes of Ho, Tm, Yb, Lu, Hf and Ta, cross sections for the production of proton-rich evaporation-residues near the 126 neutron shell were measured. This first comprehensive study of very fissile spherical residues reveals a surprisingly low stabilizing influence of the sphericalN=126 shell on the survival probability. The experimental results are compared with evaporation calculations. Conclusions for the production of superheavy nuclei are drawn.     

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.     

Size-dependent electron-impact detachment of internally cold Cn- and Aln- clusters

The cross sections for electron detachment of internally cold Cn- and Aln- clusters were measured using an electrostatic ion beam trap fitted with an internal electron target. The measured electron-impact detachment cross sections for the Cn- (n = 1-9) clusters exhibit even-odd oscillations reflecting the binding energy trend, namely, higher cross sections for weaker binding. Surprisingly, however, these cross sections increase on the average with cluster size, n, in spite of the increase in electron binding. In contrast, the Aln- (n = 2-5) clusters follow the known scaling laws for electron detachment. We suggest that the size-dependent polarizability of these clusters is responsible for the observed behavior.     

The axial-vector strength in the proton-rich argon isotopes

The proton-rich isotopes³²Ar-³⁵Ar represent the first sequence for which the superallowed Gamow-Teller strength is known out toZ? N=4. The results are compared with two sets of predictions from large shell-model calculations, which give systematically different quenching factors, on the average 0.54 and 0.89. Possible reasons for this are discussed. A comparison is also made with the Gamow-Teller strength of proton-rich isotopes of neighbouring elements.     

Probing the structure of exotic nuclei by transfer reactions

Low energy single nucleon transfer reactions are proposed as a tool to investigate the structure of nuclei far off stability. Experimental concepts and conditions are discussed, in particular high resolution γ-ray spectroscopy after single nucleon pickup reactions. Nuclear structure is described by Skyrme Hartree-Fock calculations including pairing. As representative examples, binding energies, radii and wave functions for Mg and Sn isotopes are calculated. In the neutron deficient Mg isotopes a proton skin is found. At the neutron driplines the Mg and Sn isotopes develop extended neutron skins. The nuclear structure results are used in DWBA and EFR-DWBA transfer calculations. Single nucleon transfer reactions of ^32,36Mg and exotic Sn beams on targets ranging from ²H to ²⁴Mg in inverse kinematics are explored. The one-nucleon transfer cross sections decrease strongly for high-Z targets. An impact parameter analysis shows that the transfer process is selective on the tails of the wave functions. The largest cross sections are obtained for ²H and ⁹Be targets at incident energies of E _lab = 2-5 MeV/u. The energy-momentum dependence is closely related to the special properties of wave functions of weakly bound states. Two-neutron (p,t) stripping reactions are studied for a ⁶He projectile. A strong competition of sequential and direct processes is found at low energies. Received: 1 October 1997 / Revised version: 25 November 1997     

Simple approximation of cross sections for nuclear reactions involving Z = 3–12, 14 nuclei

A compact cross section data base is obtained for almost 5000 nonresonance nuclear reactions involving stable and unstable Be, B, C, N, O, F, Ne, Na, Mg, and Si isotopes. The calculations are performed using the Sãn Paulo potential and the barrier penetration formalism. The calculated cross sections are approximated by simple analytical formulas. The results are necessary for simulating nuclear burning in neutron stars.     

缺中子Np新核素的α衰变研究

合成远离稳定线的新核素、探索原子核存在的极限是目前核物理研究的重要课题。在中子壳N=126的最丰质子一侧,极端缺中子的超铀核素处于质子滴线和中子壳的交叉位置,合成和研究该核区核素对研究N=126壳结构的演化性质具有重要意义。基于兰州重离子加速器上的充气反冲核谱仪装置(SHANS),利用36,40Ar+185,187Re熔合蒸发反应,合成了极缺中子的219,220,223,224Np新核素,在中子壳N=126附近首次建立了Np同位素链的$ \alpha$衰变系统性,获得了N=126壳效应在Np同位素链中依然存在的实验证据。依据单质子分离能的系统性分析,确定了Np同位素链中质子滴线的位置,219Np也成为目前已知的最重的质子滴线外核素。此外,基于实验测量的反应截面,并与理论模型的计算结果相比较,讨论了进一步合成该核区其它新核素218,221,222Np的可行性。     

基态S和D原子的低能弹性碰撞及SD(X~2Ⅱ)自由基的准确相互作用势与分子常数

使用Gaussian03程序包提供的CCSD(T)理论及Duning等的相关一致基cc-pVnz和aug-cc-pVnZ(n=2,3,4,5),对SD(X~2Ⅱ)自由基的平衡核间距、谐振频率及相互作用势进行了计算,并拟合出了相应的光谱常数.在CCSD(T)/aug-cc-pV5Z理论水平下,光谱常数D_0,D_e,D_e,R_e,ω_e.a_e,B_o及B_e的值分别为3.65730 eV,3.77669 eV,0.13424 cm~(-1),1938.372 cm~(-1),0.09919 cm~(-1),4.88585 cm~(-1)和4.8872 cm~(-1),均与已有的实验结果相符很好.利用在CCSD(T)/aug-cc-pv5Z理论水平下获得的相互作用势,在绝热近似下通过数值求解双原子分子核运动的径向薛定谔方程,找到了J=0时SD(X~2Ⅱ)自由基的全部23个振动态,完整地求出了每一振动态的振动能级及相应的经典转折点、惯性转动常数和离心畸变常数;在1.0×10~(-11)-1.0×10~(-4)a.u.的碰撞能区内通过数值求解原子.原子散射的径向薛定谔方程,研究了基态S原子和基态D原子沿sD(X~2Ⅱ)相互作用势的弹性碰撞,计算了这一弹性碰撞的总截面和各分波截面,分析了各分波截面对总截面的影响.结果表明:总截面的形状主要由S分波截面决定,尽管直到l=4的各分波截面均有形状共振存在,但由于其强度都较弱,全部被湮没在较强的总弹性截面中.

Abstract：

The equilibrium internuclear separations, harmonic frequencies and interaction potentials have been calculated by employing the CCSD(T) theory in combination with the series of the correlation-consistent basis sets, cc-pVnZ and aug-ce-pVnZ (n = 2, 3, 4, 5), of Dunning and co-workers. The potential energy curves are all fitted to the Murrell-Sorbie functions, which are used to determine the spectroscopic parameters. At the CCSD(T)/aug-cc-pV5Z level of theory, the values of D_0, D_e, R_e, w_e, a_e,B_0 are 3.65730 eV, 3.77669 eV, 0.13424 cm~(-1), 1938.372 cm~(-1), 0.09919 cm~(-1) , 4.88585 cm~(-1) and 4.8872 cm~(-1), respectively, which conform almost perfectly with the available measurements. With the analytic interaction potential obtained at the CCSD(T)/aug-cc-pV5Z level of theory, a total of 23 vibrational states has been predicted for the first time when the rotational quantum number J is set to equal zero (J = 0) by solving the radial Schrodinger equation of nuclear motion. The complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are reproduced from the SD (X~2Ⅱ) potential when J = 0. The total and various partial-wave cross sections are calculated for the elastic collisions between the ground-state S and D atoms at energies from 1.0 × 10~(11) to 1.0 × 10~(-4) a.u. when the two atoms approach each other along the SD(X~2Ⅱ) interaction potential. No shape resonances can be found in the total elastic cross sections. The results show that the shape of the total elastic cross sections is mainly dominated by the s-partial wave at very low temperatures. Because of the weakness of the shape resonances coming from various partial waves, they are all covered up by the strong total elastic cross sections.     

Cross sections for the production of berylium isotopes from the 880 MeV alpha-particle bombardment of carbon

The cross sections for the production of ⁹Be and ¹⁰Be from the 880 MeV α-particle bombardment of carbon have been measured to be 10.6 ± 1.7 and 6.5 ± 1.4 mb. These values are essentially twice the high-energy proton cross sections. It is shown that the effect of the interstellar helium on the distribution of berylium isotopes in cosmic rays is thus less important than had been anticipated.