Cross section determination of^(27)Al(n,2n)^(26)Al reaction induced by 14-MeV neutrons uniting with D-T neutron activation and AMS techniques

Aluminum is the primary structural material in nuclear engineering,and its cross section induced by 14-MeV neutrons is of great significance.To address the issue of insufficient accuracy for the^(27)Al(n,2n)^(26)Al reaction cross section,the activation method and accelerator mass spectrometry(AMS)technique were used to determine the^(27)Al(n,2n)^(26)Al cross section,which could be used as a D-T plasma ion temperature monitor in fusion reactors.At the China Academy of Engineering Physics,neutron activation was performed using a K-400 neutron generator produced by the T(d,n)4He reaction.The^(26)Al∕^(27)Al isotope ratios were measured using the newly installed GYIG 1 MV AMS at the Institute of Geochemistry,Chinese Academy of Sciences.The neutron flux was monitored by measuring the activity of 92mNb produced by the 93Nb(n,2n)92mNb reaction.The measured results were compared with available data in the experimental nuclear reaction database,and the measured values showed a reasonable degree of consistency with partially available literature data.The newly acquired cross-sectional data at 12 neutron energy points through systematic measurements clarified the divergence,which has two different growth trends from the existing experimental values.The obtained results are also compared with the corresponding evaluated database,and the newly calculated excitation functions with TALYS−1.95 and EMPIRE−3.2 codes,the agreement with CENDL−3.2,TENDL-2021 and EMPIRE−3.2 results are generally acceptable.A substantial improvement in the knowledge of the^(27)Al(n,2n)^(26)Al reaction excitation function was obtained in the present work,which will lay the foundation for the diagnosis of the fusion ion temperature,testing of the nuclear physics model,evaluation of nuclear data,etc.

Measurements of the^(128)Te(n,2n)^(127m,g)Te reaction cross sections and isomeric cross section ratio of^(127m,g)Te at the neutron energy of 14 MeV

In this study,measurements of the^(128)Te(n,2n)^(127m,g)Te reaction cross sections and the computation of the isomeric cross section ratio were performed around the neutron energy of 13−15 MeV.We used aγ-ray spectrometric technique to conduct the measurements.The neutron energy was produced by the^(3)H(d,n)^(4)He reaction.For the^(128)Te(n,2n)^(127m,g)Te reaction,the excited state,ground state,total cross section,and isomeric cross section ratio were determined using the TALYS-1.96 code,a theoretical nuclear model that allows for variations in density options.The initial experimental data,assessed nuclear data,and theoretical calculations based on the TALYS-1.96 algorithm were compared with the measurement results.The new data produced by this study are essential for validating nuclear models and establishing parameters for nuclear reactions.

Measurement of ^(232)Th(n,2n)^(231)Th reaction cross-sections at neutron energies of 14.1 MeV and 14.8 MeV using neutron activation method

In this study, the activation cross-sections were measured for ^(232)Th(n,2n)^(231)Th reactions at neutron energies of 14.1 and 14.8 MeV, which were produced by a neutron generator through a T(d,n)~4He reaction. Induced gamma-ray activities were measured using a low background gamma ray spectrometer equipped with a high resolution HPGe detector. In the cross-section calculations, corrections were made regarding the effects of gamma-ray attenuation, dead-time, fluctuation of the neutron flux, and low energy neutrons. The measured cross-sections were compared with the literature data, evaluation data(ENDF-B/VII.1, JENDL-4.0 and CENDL-3.1), and the results of the model calculation(TALYS1.6).

Measurement of^(134)Xe(n,2n)^(133m),gXe reaction cross sections in 14‑MeV region with detailed uncertainty quantification

A lead-shielded HPGe detector and offlineγ-ray spectra of the residual product were used to measure the cross section(CS)and ratios of isomeric CS(σm/σg)in^(134)Xe(n,2n)^(133m),gXe reactions at different energies(13.5 MeV,13.8 MeV,14.1 MeV,14.4 MeV,14.8 MeV)relative to the^(93)Nb(n,2n)^(92)mNb reaction CS.The target was high-purity natural Xe gas under high pressure.The T(d,n)4He reaction produces neutrons.TALYS code(version 1.95)for nuclear reactions was used for calculations,with default parameters and nuclear level density models.The uncertainties in the measured CS data were thoroughly analyzed using the covariance analysis method.The results were compared with theoretical values,evaluation data,and previous experimental findings.CS data of the 134Xe(n,2n)133mXe and 134Xe(n,2n)133gXe reactions and the corresponding isomeric CS ratios at 13.5 MeV,13.8 MeV,and 14.1 MeV neutron energies are reported for the first time.This research advances our knowledge of pre-equilibrium emission in the(n,2n)reaction channel by resolving inconsistencies in the Xe data.

Cross-section measurement of(n,2n) reactions for Nd isotopes induced by 14 MeV neutrons

Cross-sections of the(n,2n) reactions for neodymium(Nd) isotopes induced by 14 MeV neutrons were measured in this work by using the activation and relative methods. The measured cross-sections of the ^(150)Nd(n,2n)^(149)Nd,^(148)Nd(n,2n)^(147)Nd, and ^(142)Nd(n,2 n)^(141)Nd reactions were 1854 ± 81, 1789 ± 119, and 1559 ± 98 mb, respectively, at a neutron energy of 14.2 ± 0.2 MeV,and 1485 ± 74, 1726 ± 85, and 1670 ± 119 mb, respectively, at 14.9 ± 0.2 MeV. The results were compared with the experimental values from the reported literature, with the evaluated data from the ENDF/B-VII.1, CENDL-3.1, and JENDL-4.0 libraries, and with the curves calculated by the Talys-1.8 code.

Formation cross sections of nuclei with (n,2n) reactions

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Erratum to “Absolute Measurement of Cross Sections of ^(27)Al(n,α)^(24)Na and ^(56)Fe(n,p)^(56)Mn Reactions at E_n=14.6 MeV”

The publisher regrets that some misprints appeared in the formula for the correction factork on page 343.It is reprinted correctly as the following:k=n(1-e-λ（t1-t0）/n)/eλ（t1-t0）-1·(sum from i=1 to n Naieiλ（l1-l0）/n)/sum from i=1 to n Nai

Ab initio Calculations of Electron-Impact Excitation Cross Sections for N_2 Molecule

One of the great difficulties in understanding nitrogen plasma elementary processes is the lack of an available database of the cross-sections of electron-impact excitations and radiations. Ab initio calculations of vibrational excitation cross sections for electron collisions with nitrogen molecules in low-lying states using similarity function approach, such as a-a＇, a-w, B-B＇ and B-W transition systems, are reported here for the first time. In the meantime, the average excitation energies of neighboring levels of these systems have been calculated. In order to obtain the cross sections, accurate spectroscopic constants and transition dipole moments have been investigated. Potential energy curves and other electronic transition dipole moments for the low-lying states of N2 have been re-evaluated using complete active space self-consistent field （CASSCF） approach with aug-cc-pVqZ basis set. The calculated cross-sections could provide a database for studying the elementary processes and the properties in N2 plasma.

Empirical Neutron Cross Section Formulae for (n, p) and (n, d) Reactions of He-3 Target

In this work, new cross section formulae for (n, p) and (n, d) reactions of He-3 have been investigated as a function of incident neutron energy. The new Empirical formulae were produced by using the least squares method to the experimental cross sections data, which were taken from Experimental Nuclear Reaction Data EXFOR Database Version of 2021. Several functions were examined to choose the best one that fits the data. Statistical hypothesis testing was used to insure how well the suggested equations fit the set of data. Two statistical indicators were used for each case for goodness-of-fit. Very high compatibility was found between the empirical values and the experimental data for both reactions.

THE (n, 2n) CROSS-SECTION FOR Na—23 BETWEEN E_n=13.3—18.5 MeV

The （n,2n） cross- section for 23Na have been measured by the activation method in the energy range of En=13.3—18.5 MeV. Monoenergetic neutrons were obtained from T（d,n） 4He reaction at Ed=2.3 MeV. The induced specific activities were detected by a coincidence counting setup. For comparison, the other measured, evaluated and calculated data from En=12—20 MeV are also given.

Systematics of Isomeric Cross Section Ratio for(n,t)Reaction at 14.6 MeV

On the basis of Hauser-Feshbach theory and some approximations,parametrized formulae of isomeric cross section ratio including two adjustableparameters for(n,t)reaction at 14.6MeV are derived.By fitting these formulae to theavailable measured data,parameters are obtained and the systematic behaviour of theisomeric cross section ratio are studied.The isomeric cross section ratio predicted by thepresent work is in good agreement with the limited measured data.

Stereodynamics of the O(~3P) with H_2(D_2) (ν=0,j=0) reaction

Quasi-classical trajectory theory is used to study the reaction of O（3p） with H2 （D2） based on the ground 3A″ potential energy surface （PES）. The reaction cross section of the reaction O＋H2→＋OH＋H is in excellent agreement with the previous result. Vector correlations, product rotational alignment parameters （P2（j′. k）） and several polarizeddependent differential cross sections are further calculated for the reaction. The product polarization distribution exhibits different characteristics that can be ascribed to different motion paths on the PES, arising from various collision energies or mass factors.

Polarization effect in(e,2e) reaction process for Ar(3s) in coplanar asymmetric geometry

The （e, 2e） triple differential cross sections （TDCSs） of Ar （3s） are calculated by using distorted-wave Born approx- imation under coplanar asymmetric geometry. The incident electron energy is 113.5 eV, and the scattering electron angle 01 is -15~. The ejected electron energy is set at 10 eV, 7.5 eV, 5 eV, and 2 eV, respectively. The polarization effects have been discussed and the polarization potential Vpol changing from a second-order to a fourth-order term has been analyzed. Our calculated TDCSs have been compared with reported experimental and theoretical results, and the calculated TDCSs of polarization potential up to the fourth order could give a good fit with experimental results in the binary region, but fail to predict the correct recoil-to-binary ratio in most cases.

The radial correlation of atomic electrons in (e,2e) reaction

We perform a research of the influence of atomic electrons correlation to some characteristics of the (e,2e) process on helium. The Hilleraas type J-matrix approach was used for numerical calculations.

Mechanism analysis of reaction S+(2D)+H2(X1Σg^+) → SH+(X3Σ-) + H(2S) based on the quantum state-to-state dynamics

We present a state-to-state dynamical calculation on the reaction S++ H2→ SH+ +H based on an accurate X2 A″ potential surface. Some reaction properties, such as reaction probability, integral cross sections, product distribution, etc.,are found to be those with characteristics of an indirect reaction. The oscillating structures appearing in reaction probability versus collision energy are considered to be the consequence of the deep potential well in the reaction. The comparison of the present total integral cross sections with the previous quasi-classical trajectory results shows that the quantum effect is more important at low collision energies. In addition, the quantum number inversion in the rotational distribution of the product is regarded as the result of the heavy–light–light mass combination, which is not effective for the vibrational excitation. For the collision energies considered, the product differential cross sections of the title reaction are mainly concentrated in the forward and backward regions, which suggests that there is a long-life intermediate complex in the reaction process.

State-to-state quantum dynamics of N(2D) ＋ HD (v =0, j = 0) reaction

The N（2D） ＋ HD （v = 0, j = 0） reaction has been studied by a quantum time-dependent wave packet approach with a second-order split operator on the potential energy surface of Li et al. （Li Y, Yuan J, Chen M, Ma F and Sun M J. Comput. Chem. 34 1686）. The rovibrationally resolved reaction probability, vibrationally integral cross section, and differential cross section of the NH ＋ D and ND ＋ H channel are investigated at the state-to-state level of theory. The experimental data of the thermal rate constant of two output channels is very scare, but the sum of the two output channels is in excellent agreement with the experimental data which was reported by Umemoto et al. It may imply that the thermal rate constants of the two output channels are accurate and reliable.

State-to-state quantum dynamics of the N(~4S)+H_2(X^1Σ^+) → NH(X^3Σ^-)+H(~2S) reaction and its reaction mechanism analysis

Quantum state-to-state dynamics of the N(4S) + H-2(X1+Σ) → NH(X3Σ) + H(2S) reaction is reported in an accurate novel potential energy surface constructed by Zhai et al.(2011 J. Chem. Phys. 135 104314). The time-dependent wave packet method, which is implemented on graphics processing units, is used to calculate the differential cross sections. The influences of the collision energy on the product state-resolved integral cross sections and total differential cross sections are calculated and discussed. It is found that the products NH are predominated by the backward scattering due to the small impact parameter collisions, with only minor components being forward and sideways scattered, and have an inverted rotational distribution and no inversion in vibrational distributions; both rebound and stripping mechanisms exist in the case of high collision energies.

Calculation of production cross sections of γ-rays from thermal-neutron captures

The calculation methods of production cross sections of γ-rays for thermal-neutron captures are briefly presented. The check of intensity balance is made. The examples are given to illustrate its application.

A Facile Synthesis of N-alkyl-4'-methyl-1,1'-biphenyl-2-sulfona-mide via Linking DoM Reaction with Suzuki Reaction

Six N-alkyl-4＇-methyl-1,1＇-biphenyl-2-sulfonamides were synthesized facilely and efficiently from low cost and readily available benzenesulfonyl chloride and C1-C4 fatty amines via linking DoM reaction with Suzuki reaction.The structures of the new compounds synthesized were confirmed by elemental analysis,IR,1H NMR and MS.This new method makes a feature of low cost and readily available starting material,fewer steps,mild condition,easiness to operate and higher yield.

^(176)Hf(n,2n)^(175)Hf和^(185)Re(n,2n)^(184)Re^(m,g)反应截面研究

用中国原子能科学研究院HI－13串列加速器、高压倍加器和北京大学4．5MV静电加速器分别获得能量为10～12、14和18MeV的中子，测量了(176)Hf（n，2n）和(185)Re（n，2n）的反应截面，并与现有的实验数据作了比较，初步搞清了分歧的主要原因和激发函数的走向。用中国核数据中心UNF理论程序和系统学程序计算了激发函数曲线形状并与国际数据库ENDF／B－6、JEF－2、JENDL－3、ADL－3和ENDL／A的推荐值在绝对值和曲线走向方面进行了比较，并给出推荐曲线。