The (n, 2n) excitation functions for93Nb and103Rh with special respect to the isomeric states in92Nb and102Rh

By means of the activation technique the excitation functions for the reactions⁹³Nb(n,2n)^92mNb(10.15d),¹⁰³Rh(n,2n)^102mRh(2.9y), and¹⁰³Rh(n,2n)^102gRh(206d) were measured with an average total uncertainty of about ±8% between 10 and 20 MeV neutron energy. In addition the total⁹³Nb(n, 2n) cross-section was compared with the⁵⁹Co(n, 2n) cross-section at 16.8 MeV by direct neutron detection using the time-of-flight technique. The results are compared with statistical theory, especially with theoretical expectations for the isomeric cross-section ratios, which are only in reasonable agreement with the experiment if one assumes a ground state spinI _g=5 for⁹²Nb andI _g=2 for¹⁰²Rh.     

Measurements of activation cross-sections for 165Ho(n,2n)164gHo and 180W(n,2n)179gW reactions induced by neutrons around 14 MeV

The cross-sections of ¹⁶⁵Ho(n,2n)^164gHo and ¹⁸⁰W(n,2n)^179gW reactions induced by neutrons around 14 MeV were measured using activation technique and calculated by a previously developed formulas, in which the neutron flux was determined using the monitor reaction ⁹³Nb(n,2n)^92mNb. Because both of the excited and ground states were produced in each of the two reactions, one formula was introduced to take out the effect from excited state. Comparison between this work and old data were given.     

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.     

Cross-sections for the formation of isomeric pair Ge through (n, 2n), (n, p) and (n, α) reactions measured over 13.73 MeV to 14.77 MeV and calculated from near threshold to 20 MeV neutron energies

The cross-sections for formation of isomeric pair, ⁷⁵Ge^m(σ_m) and ⁷⁵Ge^g(σ_g), through ⁷⁶Ge(n, 2n), ⁷⁵As(n, p) and ⁷⁸Se(n, α) reactions were measured at 13.73 MeV, 14.42 MeV and 14.77 MeV neutrons and also estimated using EMPIRE-II and TALYS codes over neutron energies from near threshold to 20 MeV. For each (n, 2n), (n, p) and (n, α) reaction, the cross-section initially increases with neutron energy, but starts decreasing as the neutron energy exceeds the respective threshold of (n, 3n), (n, pn) and (n, αn) reactions. The higher values of σ_m relative to σ_g reveal that the transitions of the excited ⁷⁵Ge from higher energy levels to metastable state (7⁺/2) are favored as compared to unstable ground state (1⁻/2). The present values of cross sections for formation of ⁷⁵Ge^m,g through (n, 2n) and (n, α) reactions are lower, and that of (n, p) reaction are higher compared to most of the corresponding literature cross-sections.     

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 measurements for (n, 2n) reactions on stannum isotopes in the neutron energy range of 13.5 to 14.6 MeV

Cross-sections for (n, 2n) reactions have been measured on stannum isotopes at the neutron energies of 13.5 to 14.6 MeV using the activation technique. Data are reported for the following reactions:112Sn(n, 2n)111Sn, 118Sn(n, 2n)117Sn and 124Sn(n, 2n)123mSn. The neutron fluences were determined using the monitor reaction 93Nb(n, 2n)92mNb or 27Al(n, α)24Na. The results of present work were compared with data published previously.     

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.     

A study of the93Nb levels populated via the (n,n′ γ) reaction

De-excitation γ-rays from levels in⁹³Nb up to 2203 keV were observed following inelastic neutron scattering at incident energies between 0.6 and 2.575 MeV. The energy level and decay modes of⁹³Nb are deduced. Spin and parity assignments are based on the comparison of the experimental (n, n′) cross sections with calculated cross sections using Hauser-Feshbach theory corrected for level-width fluctuation corrections. The low-lying levels of⁹³Nb have been studied within the framework of the vibration-particle model to account for their energy and spin assignments, as well as the reduced transition probabilities measured in Coulomb excitation experiments.     

Cumulative fission yield measurements with 14.7 MeV neutrons on 238U

The fission yield data in the 14 MeV energy neutron induced fission of ²³⁸U play an important role in decay heat calculations and generation-IV reactor designs. In order to accurately measure fission product yields (FPYs) of ²³⁸U induced by 14 MeV neutrons, the cumulative yields of fission products ranging from ⁹²Sr to ¹⁴⁷Nd in the ²³⁸U(n, f) reaction with a 14.7 MeV neutron were determined using an off-line γ-ray spectrometric technique. The 14.7 MeV quasi-monoenergetic neutron beam was provided by the K-400 D-T neutron generator at China Academy of Engineering Physics (CAEP). Fission products were measured by a low background high purity germanium gamma spectrometer. The neutron flux was obtained from the ⁹³Nb (n, 2n)^92mNb reaction, and the mean neutron energy was calculated using the cross-section ratios for the ⁹⁰Zr(n, 2n)⁸⁹Zr and ⁹³Nb(n, 2n)^92mNb reactions. With a series of corrections, high precision cumulative yields of 20 fission products were obtained. Our FPYs for the ²³⁸U(n, f) reaction at 14.7 MeV were compared with the existing experimental nuclear reaction data and evaluated nuclear data, respectively. The results will be helpful in the design of a generation-IV reactor and the construction of evaluated fission yield databases.     

Cross-section measurement for Ni(n,x)58(m+g)Co,Ni(n,x)60mCo,Ni(n,x)61Co and Ni(n,x)62mCo reactions induced by neutrons around 14MeV

The cross sections of Ni(n,x)58(m+g)CO,Ni(n,x)80mCo,Ni(n,x)61Co and Ni(n,x)62mCo reactions induced by neutrons around [14]MeV were measured in this work and calculated by a previously developed formula in this work.The neutron flux was determined using the monitor reaction 27Al(n,α)24Na and the neutron energies were measured with the method of cross-section ratios for 89Zr(n,2n)89Zr to 93Nb(n,2n)92mNbreactions.     

The Zr(d,n)Nb and Zr(d,n)Nb reactions

The (d, n) reaction on ⁹⁰Zr and ⁹⁶Zr has been studied at 12 MeV deuteron bombarding energy using the neutron time-of-flight technique with an overall neutron time resolution of 1.9 ns. Angular distributions of neutron groups leading to states in ⁹¹Nb and ⁹⁷Nb were measured in the angular range between 15° and 60°. The measured cross sections were analyzed in the framework of the distorted-wave theory of stripping reactions to deduce l-values and proton spectroscopic factors of states in the residual nuclei. The results are compared with the corresponding data available from (³He, d) studies. The fractionation of the single-particle proton states and their centroid energies are determined.     

Isomeric cross sections for the (n, 2n) reaction on 82Se, 81Br,and 45Sc at 15.1 MeV

Activation techniques have been used to measure the cross sections at 15.1 MeV neutron energy for the following reactions: ⁸²Se(n, 2n)^81m+gSe, ⁸¹Br(n, 2n)^80m+gBr, and ⁴⁵Sc(n, 2n) ^44m+gSc. Isomeric cross-section ratios were evaluated by applying the method of least squares to the time behavior of γ-ray activity following the ground-state decay of each isomeric pair. The absolute cross section σ_m for the formation of the metastable state was measured by the mixed-powder method with the ²⁷Al(n, α)²⁴Na reaction as the monitor. The cross section σ_g for the formation of the ground state was then determined by using the isomeric cross-section ratio. The sum of σ_m and σ_g for each reaction is compared with the theoretical value obtained from calculations based on the statistical model for the formation of a compound nucleus and its subsequent emission of neutrons.     

Wirkungsquerschnitte und Isomerenverhältnis für die Reaktionen89Y(α, 3n)90g Nb und89Y(α, 3n)90m Nb

Absolute cross-sections and isomeric cross-section ratios have been measured for the reactions⁸⁹Y(α, 3n)^{90g, 90m} Nb. The energy of the α-particles was varied between 34 and 54 MeV. The experimental isomeric ratios are compared with statistical-model calculations.     

Study of energy levels of 92Nb observed in the 92Zr(p,n) reaction

The energy levels of ⁹²Nb were observed in the ⁹²Zr(p, n) reaction by use of the neutron time-of-flight technique. Limits on the spins and parities of the ⁹²Nb levels were placed by observing the enhancement in the relative yield of the final states at an isobaric analog resonance and by the measurement of the relative yield off resonance. The measured enhancements and off-resonance yields are compared with values calculated using the statistical compoundnucleus model. Comparison of results from the two methods is used to obtain spin-parity assignments for nine energy levels lying between 976 and 1739 keV in ⁹²Nb.     

New cross-section measurements for the (n, 2n), (n, p), and (n, α) reactions on bromine in the 14 MeV region with detailed uncertainty quantification

Measurement of the cross-sections of the ⁷⁹Br(n, 2n)⁷⁸Br, ⁸¹Br(n, p)^81mSe, ⁸¹Br(n, α)⁷⁸As, and ⁷⁹Br(n, α)⁷⁶As reactions was performed at specific neutron energies, precisely, 13.5±0.2, 14.1±0.2, 14.4±0.2, and 14.8±0.2 MeV, relative to the standard ⁹³Nb(n, 2n)^92mNb and ²⁷Al(n, α)²⁴Na reference reactions using offline γ-ray spectrometry and neutron activation. Monoenergetic neutrons were generated at the China Academy of Engineering Physics via a ³H(d, n)⁴He reaction using the K-400 Neutron Generator equipped with a solid ³H-Ti based target. The activity of the reaction produce was obtained using a high-purity germanium detector. The cross-sections of the (n, 2n), (n, p), and (n, α) reactions on the bromine isotopes were measured in the 13–15 MeV neutron energy range. The covariance analysis approach was employed for a thorough inspection of any uncertainties within the measured cross-section data. A discussion and comparison of the observed outcome were carried out with previously published data, especially with the results of the JENDL-4.0, JEFF-3.3, TENDL-2019, and ENDF/B-VIII.0 data libraries, along with the theoretical excitation function curve derived by employing the TALYS-1.95 program. Improved cross-section restrictions for the investigated processes in the 13–15 MeV neutron energy range will be obtained using the current findings, which will help to raise the caliber of associated databases. Furthermore, the parameters of relevant nuclear reaction models can be verified using this data.     

Energy levels in 93Mo populated by the 93Nb(p,nγ) reaction

Energy levels of ⁹³Mo have been investigated by means of the ⁹³Nb(p, nγ)⁹³Mo reaction. The excitation functions of the level de-excitation γ-rays were measured with a Ge(Li) detector under proton bombardment in the energy range 3.0 to 5.0 Me V. A detailed γ-ray decay scheme which includes 69 levels and 123 γ-ray lines was constructed from the threshold energies for 64 γ-rays and the γ-ray excitation functions around five isobaric analogue resonances in the ⁹³Nb(p, nγ) reaction. Spin-parity values for 59 levels and favourable values for 8 levels were assigned from the analysis of relative neutron yields via the isobaric analogue resonances of the parent odd-odd nucleus ⁹⁴Nb. The results of the present experiment are compared with shell-model calculations.     

14MeV中子引起的Pb(n,x)203Hg, W(n,x)182Ta和W(n,x)183Ta的核反应截面测量

利用活化方法测量了14MeV中子引起的Pb(n,x)²⁰³Hg,W(n,x)¹⁸²Ta和W(n,x)¹⁸³Ta的反应截面.中子注量由监督反应⁹³Nb(n,2n)^92mNb给出,中子能量利用⁹⁰Zr(n,2n)^89m+gZr和⁹³Nb(n,2n)^92mNb反应的截面比来确定.     

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.     

High spin states in95Tc populated in the93Nb(α, 2nγ) reaction

The⁹³Nb(α, 2nγ)⁹⁵Tc reaction has been studied at a bombarding energy of 22.5 MeV using Ge(Li)-detectors. Gamma singles spectra, gamma-gamma coincidences, excitation functions and gamma angular distribution have been obtained. A level scheme has been constructed. Spin and parity assignments up to 29/2⁺ are given.     

A formula used to subtract the effect of gamma-ray of the others to that of measured reaction in measurement of cross section of nuclear reaction and its application

Abstract According to the regulation of growing and decay of artificial radioactive nuclide, a formula used to subtract the effect of characteristic γ-ray of the others to that of measured reaction was deduced. And then the cross sections of 120Te (n, 2n)119mTe reaction induced by neutrons around 14 MeV were measured by activation relative to the 93Nb (n, 2n)92mNb. In the process of the cross sections measured to be calculated, it was subtracted that the effect of characteristic γ-ray of 126Te (n, p)126Sb to that of measured 120Te (n, 2n)119mTe reaction using the formula deduced. The experimental results were (689±37) and (750±41) mb at the neutron energies of (13.5±0.3) and (14.6±0.3) MeV, respectively. Measurements were carried out by γ-detection using a coaxial HPGe detector. As samples, spectroscopically pure tellurium powder has been used. The fast neutrons were produced by the T(d, n)4He reaction. The neutron energies in these measurements were determined by the method of cross-section ratios between 90Zr (n, 2n) 89m+gZr and 93Nb (n, 2n) 92mNb reactions.