Measurement of the 158Sm mass excess by the (18O, 20Ne) reaction

A Q- value of 4.046 ±0.102 MeV has been determined for the two protons transfer reaction ¹⁶⁰Gd(¹⁸O, ²⁰Ne) ¹⁵⁸Sm at 98.95 MeV. This result yields a first experimental measured value of ? 65.738 ± 0.102 MeV for the mass excess of ¹⁵⁸Sm, the nucleus far from stability. The result is compared with current theoretical predictions.     

Measurement of the 11B(11B, 10Be)12C proton transfer reaction at low energies

Differential cross sections for the ¹¹B(¹¹B,¹⁰Be)¹²C proton transfer reaction leading to the ¹⁰Be(g.sO+¹²C(4.43 MeV) $\text{(Q = 0.289}\text{MeV}\text{)}\text{and}{}^{10}\text{(3.37}\text{MeV}\text{) +}{}^{12}\text{C}\text{(g.s.) (Q = 1.36}\text{Me V}\text{)}$ final channels have been measured at E_c.m. = 5.5 MeV by coincident detection of the ¹⁰Be and ¹²C nuclei. The integrated cross sections for the ¹⁰Be + ¹²C(4.43 MeV) channel have been obtained for incident energies between E_c.m. = 2.66 and 3.64 MeV from the yields of the 4.43 MeV γ-ray emitted in the ¹²C 4.43 MeV → g.s. transition. The cross-section magnitudes compare well with the DWBA calculations. The sub-barrier transfer cross sections exhibit an unusual energy dependence: their ratio to the total reaction cross section is decreasing with decreasing incident energy.     

High-lying excited states in ~(10)Be from the ~9Be(~9Be,~(10)Be)~8Be reaction

A transfer-reaction experiment of ~9Be(~9Be,~(10)Be)~8Be was performed at a beam energy of 45 Me V.Excited states in ~(10)Be up to 18.80 Me V are produced using missing mass and invariant mass methods.Most of the observed high-lying resonant states,reconstructed from theα+~6He and t+~7Li decay channels,agree with the previously reported results.In addition,two new resonances at 15.6 and 18.8 Me V are identified from the present measurement.The 18.55 Me V state is found to decay into both the t + ~7Lig:s: and t + ~7Li?(0.478 MeV) channels, with a relative branching ratio of 0:93 ± 0:33. Further theoretical investigations are encouraged to interpret this new information on cluster structure in neutron-rich light nuclei.     

9Be + 12C, 9Be + 16O,9Be + 19F reactions at energies below the barrier

The ¹⁶O + ⁹Be reactions have been studied from E_c.m. = 2.0 MeV to 5.1 MeV, an energy near the top of the Coulomb barrier. The cross section for the neutron transfer reaction ⁹Be(¹⁶O,¹⁷O¹ (0.87 MeV))⁸Be has been measured over this range by detecting the prompt 0.87 MeV γ-rays. The total fusion cross section has been determined from E_c.m. = 2.8 to 5.1 MeV by observing individual γ-ray transitions in the evaporation residues with a Ge(Li) detector, and then summing the separate yields. Direct processes are found to dominate the reaction yield below E_c.m. = 4 MeV. A comparison of the energy dependence of the fusion cross section for this reaction and the ¹²C + ¹³C reaction, which proceeds via the formation of the same compound nucleus, ²⁵Mg, reveals differences at sub-barrier energies. Optical model and incoming-wave boundary condition calculations are presented. Data have also been obtained for the near optimum Q-value neutron-transfer reactions ⁹Be(¹²C, ¹³C¹)⁸Be and ⁹Be(¹⁹F, ²⁰F)⁸Be, and these are discussed in terms of a simple model of sub-barrier direct reactions.     

On the knock-out mechanism for the12C(P,α)9B reaction

Using a multiwire proportional counter with CH₄ and Ar as counting gases, theK-fluorescence yield of chlorine was determined to beω _K=0.101±0.004, and theK-fluorescence yield of bromine was found to beω _K=0.626±0.012. The respective sources were³⁷Ar and⁸¹Kr, the latter produced by a (n, γ)-reaction from⁸⁰Kr. The ω_K-value of chlorine correlates with the theoretical computation of Walters and Bhalla [1], compared to that of bromine, which seems to confirm the theory of Kostroun et al. [18].     

Spectroscopic Measurement in 9He and 12Be

Spectroscopy for neutron-rich nuclei ⁹He and ¹²Be has been performed by means of heavy-ion double charge exchange (HIDCX) (¹⁸O, ¹⁸Ne) reaction on stable target nuclei ⁹Be and ¹²C, respectively. Several clear peaks in ¹²Be at low excitation energy region even above neutron separation energy have been observed in one-shot measurement, whereas no prominent signals of ⁹He have been observed owing to the small cross section. It is shown that the HIDCX reaction is a new powerful spectroscopic tool for study of unstable neutron-rich nuclei.     

Angular correlation measurements in the Be9(d,p, γ)Be10 reaction

Thep-γ angular correlations in the Be⁹(d, p, γ)Be¹⁰ reaction have been measured in the reaction plane atE _d =1.3, 1.5, 1.9, 2.3 and 2.45 MeV for proton anglesθ _p =35°, 80° and 120°. The anisotropy of the angular correlations measured forθ _p =35° is independent of deuteron energy. A systematic shift of the symmetry axis from the recoil direction has been observed. The shift is 20.5° at E_d=2.45 MeV. The anisotropy decreases with increasing proton angle and vanishes atθ _p =120°.     

Mechanism of the 12C(11B,15N)8Be reaction and 8Be + 15N optical-model potential

Angular distributions of the ¹²C( ¹¹B, ¹⁵N) ⁸Be reaction were measured at the energy E_lab(¹¹B) = 49 MeV for the transitions to the ground and 2.94 MeV (2⁺) excited state of ⁸Be and to the ground and 5.270 MeV (5/2⁺) + 5.299 MeV (1/2⁺), 6.324 MeV (3/2^-), 7.155 MeV (5/2⁺) + 7.301 MeV (3/2⁺), 7.567 MeV (7/2⁺) excited states of ¹⁵N. The data were analyzed by the coupled-reaction-channel method. The elastic, inelastic scattering and one- and two-step transfers were included in the coupling scheme. The data of the ¹²C( ¹¹B, ⁸Be) ¹⁵N reaction at E_cm = 9.4-17.8 MeV known from the literature, were also included in the analysis. The mechanism of the ¹²C( ¹¹B, ¹⁵N) ⁸Be reaction and the optical-model potential parameters for the ¹⁵N + ⁸Be channel were deduced. The energy dependence of the optical-model parameters for the ¹⁵N + ⁸Be channel was obtained.     

Neutron polarizations from the9Be(d,n)10B and11B(d,n)12C reactions

Neutron polarization angular distributions were measured for the⁹Be(d,n)¹⁰B and¹¹B(d,n)¹²C reactions for deuteron energies of 5.47 and 5.34 MeV, respectively. Using neutron time-of-flight techniques, polarizations to eight states in¹⁰B and to six states in¹²C have been measured. Neutron polarization energy excitation functions for both reactions were measured for deuteron energies from 3.0 to 5.5 MeV in 0.25 MeV steps at 30° (lab). Distorted wave method calculations carried out to compare theoretical calculations against experimental results were not in good agreement with the data.     

Be(d,n)反应中子源能谱测量及应用

 利用中子飞行时间技术和BC501A液体闪烁探测器的粒子分辨特性,测量了0°方向、20 MeV氘束轰击厚金属铍靶反应产生的中子源能谱,测量的中子能谱范围为0.7～25.0 MeV。在60°方向放置芪晶体闪烁探测器,由刻度好的BC501A液体闪烁探测器归一校正后,用于中子源强度监测。利用Be(d, n) 反应中子源,采用单粒子灵敏度标定方法,实验标定了0.75~15.75 MeV能量范围内的薄膜闪烁探测器中子能量响应曲线,实验结果与蒙特卡罗模拟计算结果在8%的不确定度范围内一致。     

Be(d,n)反应中子源能谱测量及应用

利用中子飞行时间技术和BC501A液体闪烁探测器的粒子分辨特性,测量了0°方向、20 MeV氘束轰击厚金属铍靶反应产生的中子源能谱,测量的中子能谱范围为0.7～25.0 MeV。在60°方向放置芪晶体闪烁探测器,由刻度好的BC501A液体闪烁探测器归一校正后,用于中子源强度监测。利用Be(d, n) 反应中子源,采用单粒子灵敏度标定方法,实验标定了0.75~15.75 MeV能量范围内的薄膜闪烁探测器中子能量响应曲线,实验结果与蒙特卡罗模拟计算结果在8%的不确定度范围内一致。     

Polarisation und differentieller Wirkungsquerschnitt der Neutronen aus der Reaktion9Be(α,n)12C

The differential cross section and the angular distribution of the polarization of neutrons from the reaction⁹Be(α, n) leading to the ground state of¹²C have been determined at 1.75 and 1.96 MeV energy of theα-particles. The polarization was measured by left-right asymmetry induced by elastic scattering from⁴He. From Blatt, Biedenharn and Simon, Welton theory analysis a set of spectroscopic data has been obtained for five states of the compound nucleus¹³C.     

Neutron-neutron scattering length in the reaction9Be (n,nn)8Be at 10.3 MeV

In a kinematically complete experiment on⁹Be(n, nn)⁸Be_gs at 10.3 MeV, the absolute differential cross section of then-n FSI configuration at _lab=30° has been measured. It was our particular object to determine the singlet scattering length of then-n interaction via its final-state interaction being embedded in a multi-nucleon background. An extended and thorough analysis yielded¹ a _nn =–16.5±1.0 fm which is consistent with the results of the most recent and most precise kinematically complete measurements with three hadrons in the final state. These, however, altogether contradict the values deduced from ^– dnn.     

Heavy cluster knockout reaction (16)O((12)C,2(12)C)(4)He and the nature of the (12)C-(12)C interaction potential

The heavy cluster knockout reaction (16)O((12)C,2(12)C)(4)He performed for the first time, reveals the true nature of the (12)C-(12)C interaction. The observed cross section is enhanced by almost 2 orders of magnitude over the conventional zero range distorted wave impulse approximation (DWIA) predictions. An attractive (12)C-(12)C optical potential, as obtained in the folding model, does not explain the enhanced cross section in the finite range (FR) DWIA framework. The inclusion of a hard core of fairly long range ～3.65 fm explains the data. The present investigation of (16)O((12)C,2(12)C)(4)He along with the (12)C-(12)C elastic scattering also proves beyond doubt that the folding model's deep attractive heavy ion potentials are unsuitable to describe the highly overlapping heavy ions. The application of FR-DWIA opens up new avenues to use the heavy core knockout for the detailed investigation of heavy as well as Borromean halo nuclei.     

Spectroscopy of9He with the (13C,13O)-reaction on9Be

First results of the double-charge-exchange reaction⁹Be(¹³C,¹³O)⁹He, E_Lab=380 MeV, are presented. The ground state and an excited state at 3.8 MeV are clearly seen. A preliminary value of the⁹He mass excess is obtained: 41.5±0.6 MeV. Spectra of of the⁹Be(¹³C,¹⁴O) He-reaction have been measured with high resolution. The ground state transition appears as a pronounced sharp peak, but no other narrow peaks are observed.     

Measurement of the mass of110Pd and114Pd using the (14C,16O) reaction

A measurement of the mass excess of¹¹⁰Pd and¹¹⁴Pd has been made by detecting emergent¹⁶O ions in aQ3D magnetic spectrometer using the¹¹²Cd(¹⁴C,¹⁶O)¹¹⁰Pd and¹¹⁶Cd(¹⁴C,¹⁶O)¹¹⁴Pd reactions at 60 MeV. The results are compared with theoretical predictions.