Measurement of Some (n,2N) Reaction Cross Sections for Producing Long Half-Life Residues

Measurement of (n,2n) reaction cross sections for some nuclides,whose residues have long half-lives,is described.The activation method relative to the ⁹³Nb(n,2n)^92mNb reaction cross section was used.The cross sections of the ¹⁵¹Eu(n,2n)^150mEu、¹⁵³Eu(n,2n)¹⁵²Eu、¹⁵⁹Tb(n,2n)¹⁵⁸Tb and ¹⁰⁹Ag(n,2n)^108mAg reactions in the neutron energy range of 13.50—14.80MeV were measured.The neutron energies in this experiment were determined by means of the method of cross section ratios for ⁹⁰Zr(n,2n)^89m+gZr and ⁹³Nb(n,2n)^92mNb reactions.The results obtained were compared with other existing data.     

DETERMINATION OF THE AVERAGE NEUTRON ENERGY USING CROSS SECTION RATIO OF 58Ni(n,p)58m+gCo and 58Ni(n,2n)57Ni REACTIONS

The method of determination for average neutron energy from D-T reaction by using two silicon semiconductor detectors and the cross section ratios of ⁵⁸Ni(n,p)^58m+gCo and ⁵⁸Ni(n,2n)⁵⁷Ni reactions is described.The plot of the cross section ratio against the neutron energy has been obtained.The results have been compared with existing data.     

Theoretical Analysis of Double Differential Cross Sections for n+ 238U Reaction

Based on the new measurements of total, nonelastic, elastic cross section and elastic scattering angular distributions for n+U reactions, a set of neutron optical model potential parameters is obtained in the region of incident neutron energy from 0.1 to 20 MeV. The cross sections, angular distributions, energy spectra and double differential cross sections are calculated and analyzed by optical model, nuclear fission theory, distorted wave Born approximation theory, coupled channel theory, the unified Hauser-Feshbach theory, as well as exciton model. The results indicate that our theoretical model can reasonably analysis n+ ²³⁸U reaction data with neutron energy lower than 20 MeV.     

Cross sections for the (n,n′), (n,p) and (n, 2n) reactions on 107Ag and 109Ag isotopes

The cross sections for (n, n′), (n, p) and (n, 2n) reactions on the target nuclei ¹⁰⁷Ag and ¹⁰⁹Ag were measured by the activation technique in the neutron energy range 13 to 18 MeV. The results are interpreted in terms of the compound nucleus and precompound emission models.     

Theoretical Calculations and Analysis of n+208Pb Reaction for Intermediate Energy Neutron

Based on experimental data of total, nonelastic, elastic cross section and elastic scattering angular distributions for n+Pb reactions, a set of neutron optical model potential parameters is obtained in the region of incident neutron energy from 1—300 MeV. The cross sections, angular distributions and energy spectra are calculated and analyzed by optical model, distorted wave Born approximation theory, Hauser-Feshbach theory, exciton model and cascade mechanism inside nuclear. The results indicate that the cross sections can be given for n+ ²⁰⁸Pb reactions which are all in good agreement with experimental data.     

RESEARCH ON THE 88Y(n,2n) REACTION CROSS SECTION

The cross sections of the neutron induced (n,2n) reaction an the unstable target nucleus ⁸⁸Y in the energy range from 10.3 to 17.4MeV are obtained from the measurement of the ⁸⁷Sr (d,2n) reaction.This work is based on the hypothesis that the formation of the Compound nucleus is independent of its decay.The results are compared with our calculated results and the experimental data and calculated result of Prestwood and his co-worker.The comparison indicates that this work is worthy for further study.     

Fast Neutron Capture Cross Section of Natural Molybdenum

The radiative capture cross sections of natural Mo relative to the ¹⁹⁷Au (n,γ) were measured in the 0.7—1.4MeV neutron energy range,using a large liquid scintillator detector and the time-of-flight method.In the 0.01—2.0MeV neutron energy range,the theoretical calculation of (n,γ) reaction cross section for Mo was performed.The result of calculation is compared with the experimental data.     

Measurement of Cross Sections for Pb(n,x)203Hg,W(n,x)182Ta and W(n,x)183Ta Reactions Induced by 14 MeV Neutrons

The cross sections for Pb(n,x)²⁰³Hg,W(n,x)^l82Ta and W(n,x)¹⁸³Ta reactions have been measured by the activation method. The neutron fluences were determined by the cross sections of ⁹³Nb (n,2n)^92mNb reaction. The neutron energies in the measurements were determined by the cross section ratios of Zr(n,2n)^89m+gZr and Nb(n,2n)^92mNb reactions.     

Measurement of Reaction Cross Section for 17C and Finite-Range Glauber Model Analysis

We have measured the reaction cross section σ_R of ¹⁷C on the carbon target at the intermediate energy of 97A MeV by using transmission method.finite-range Glauber model has been employed to investigate the density distribution of ¹⁷C by fitting the present result and the previous result of interaction cross section σ_I.By contrast with the result from the analysis of σ_I,a tail in the neutron density distribution of ¹⁷C is found necessary to interpret the present result.Considering the configuration of the valence neutron,a dominant 1d_5/2(77±21%)occupancy is found,which is in agreement with results of momentum distribution measurements.     

13.5—14·6 MeV能区中子引起的89Y39（n，2n）88Y39反应截面的测量

用^93Nb（n,2n）^92mNb和^90Zr（n,2n）^89m＋gZr截面比法测定中子能量,以^93Nb（n,2n）^92mNb反应截面作中子注量标准,用活化法测量了13．5-14．6MeV中子引起的^89Y（n,2n）^88Y的反应截面值。由（13．5±0．3）,（14.1±0．2）,（14.6±0．3）MeV中子引起的^89Y（n,2n）^88Y反应截面值分别为（759±42）,（835±42）和（958±53）mb。Cross section for （n, 2n） reaction on Yttrium have been measured at energy of 14 MeV neutrons from H（d, n）He by using activation technique. The ^93Nb（n, 2n）^92mNb reaction was used to monitor the neutron fluence, HPGe detector was used to detect the γ-rays. The cross section of ^89Y （n, 2n）^88Y reaction are 759 ± 42, 835 ±42, 958 ±53 mb for neutron energy 13.5 ±0.3, 14.1±0.2, 14.6 ±0.3 MeV, respectively.     

CROSS SECTION MEASUREMENT FOR THE REACTION 56Fe（n,p）56Mn

The cross section measurement for the reaction ⁵⁶Fe（n, p）⁵⁶Mn was made using the activation method from 12 MeV to 18 MeV. The absolute cross section was determined at 14.61±0.20 MeV, the value obtained was 108.0±2.7mb. The associated particle method was used to determine the absolute neutron flux and compared with the recoil proton telescope. The agreement between both methods appeared to be within 1—2%. The resulting ⁵⁶Mn activity was measured by using a φ10×7.6cm NaI （Tl） scintillation counter. The counting efficiency of the counter was achieved by means of a standard ⁵⁶Mn source calibrated by the 4πβ-γ coincidence method. The result measured was compared with existing data.     

Cross Section Measurements for (n,d*)(n,t) and (n,n'α) Reactions

Cross sections for some (n,d*),(n,t) and (n,n'α)reactions have been measured by using the activation method relative to cross sections of ²⁷Al(n,α)²⁴Na or ⁹³Nb(n,2n)^92mNb reactions in neutron energies around 14MeV.In this paper some of the published cross section data have also been listed and compared with our results.The neutron energies were determined by the method of cross section ratios for the reactions of ⁹⁰Zr(n,2n) ^89m+gZr and ⁹³Nb(n,2n)^92mNb.     

ISOMERIC CROSS SECTION RATIO IN THE 197Au(n,2n)196Au REACTION

Isomeric cross section ratio for the ¹⁹⁷Au (n, 2n) reaction at 15 MeV is measured by the activation method. Using the Huizenga and Vandenbosch method, the isomeric ratio is calculated for the reaction. From the comparison of the measured and theoretically calculated isomeric ratio, the values of the spin cut-off factor and nuclear moment of inertia are determined.     

Cross sections for the (n, 2n) reaction on 102Pd, 110Pd, 112Cd and 192Os

The cross sections for the (n, 2n) reaction on the target nuclei ¹⁰²Pd, ¹¹⁰Pd, ¹¹²Cd and ¹⁹²Os and the cross section of the (n, 3n) reaction on ¹⁹²Os were measured by the activation method in the neutron energy range ¹³ to 18 MeV. The results are discussed in terms of the compound nucleus and the precompound emission models.     

Temperatures and Excitation Energies of Hot Nuclei in Reactions of 40Ar+natAg,209Bi at MeV/u

Coincidence measurements of fission fragment and light charged particle have been perfotrmed for the reactions of ⁴⁰Ar+^natAg,²⁰⁹Bi at E/A=25MeV using 4 PPAC and 11 sets of ΔE-E telescopes.Angular correlations of fission fragment were ploted as a function of the folding angle between the two detected fission fragments.The linear momentum transfer distributions were derived by measuring angular correlations.The backward spectra of light particles detected in coincidence with fission fragments having different average〈LMT〉are analyzed with Maxwell distribution.After some corrections the initial temperatures of the hot nuclei are determined from the energy spectra.The excitation energies corresponding to the different average〈LMT〉are obtained considering the reaction Q values and pre-equilibrum emission.In the central collision of the ⁴⁰Ar+^natAg,²⁰⁹Bi reactions,excitation energies are measured to be about 4.2MeV/u,2.4MeV/u and temperatures about 6.1MeV,5.5MeV,respecdvely.In semi-central collision,excitaionen energies are measured to be about 3.5MeV/u,1.9MeV/u and temperatures about 5.8MeV,4.8MeV respectively.     

The Cross Section Measurement for the Reactions of 48,46Ti(n,p) 48,46Sc 50Ti(n,α) 47Ca and 58Ni (n,2n) 57Ni 58Ni(n,p)58m+gCo

The cross sections for the ⁵⁰Ti(n,α)⁴⁷Ca,⁴⁶Ti(n,p)⁴⁶Sc、⁴⁸Ti(n,p)⁴⁸Sc and ⁵⁸Ni(n,2n)⁵⁷Ni ⁵⁸Ni(n,p)^58m+gCo reactions have been measured by using the activation method relative to the cross sections of the ²⁷Al(n,α)²⁴Na reaction in the neutron energy range of 13.50—14.81MeV.The neutron energies were determined by the cross section ratios of the ⁹⁰Zr(n,2N) ^89m+gZr and ⁹³Nb (n,2n) ^92mNb reactions.The results obtained are compared with the published and to be published data of several authors.     

Origins of Intermediate Mass Fragments for 40Ar+natAg Reaction at 30 MeV/u

The energy spectra of intermediate-mass fragments (IMF) (3≤Z≤16) have been measured from 6° to 110° for ⁴⁰Ar+^natAg reachon at 30 MeV/u. The energy spectra were analyzed by the moving source model. The natUres of the projechle-like source, target-like source and mid-rapidity source as well as the evolution with angle and nuclear charge were discussed. Two intermediate mass fragments, measured by correlation method in forward angles, come from two sources. One comes from projectile-like source, and other one mainly comes from intermediate source respectively.     

Dispersion Optical Model Analysis of the Neutron Cross Section Anomalv for 16O

The optical model of ¹⁶O is studied based on the dispetsion relation theory at neutron energy up to 20MeV.The total cross section anomaly is removed essendally at low energies for ¹⁶O.     

New band structures in 107Ag

High spin states in ¹⁰⁷Ag are studied via the ¹⁰⁰Mo(¹¹B, 4n)¹⁰⁷Ag reaction at an incident beam energy of 60 MeV. Prompt γ-γ coincidence and DCO ratios are measured by the detector arrays in CIAE. The level scheme has been updated and a new negative band belonging to ¹⁰⁷Ag is identified. The new negative side band has been constructed and its configuration is tentatively assigned to πg_9/2 νh_11/2(g_7/2/d_5/2).     

The Reaction Cross Section and Neutron Removal Cross Sections of 17C

The reaction cross section, together with the one-, two- and three neutron removal cross sections, of ¹⁷C with the energy of 79A MeV on carbon target were measured using the radioactive beam line RIPS of RIKEN. The reaction cross section and the one-neutron removal cross section were analyzed within the frame of Glauber model. Both the analyses favor the dominant configuration of a ¹⁶C core (2⁺) plus a d_5/2 valence neutron for ¹⁷C. The work for the neutron-rich carbon isotope on the reaction cross section σ_R and the interaction cross section σ_I on ^{12C target are summarized.}