92mNb Reactions Research Articles

Measurement of fission cross section for 232Th(n,x)89Rb reaction induced by neutrons around 14 MeV

In order to investigate the fission process in more detail, and to compare with the measurement of cumulative fission yields, the fission cross section of the 232Th(n,x)89Rb reaction induced by 14MeV neutron was measured using the activation technique. In our measurement the neutron flux was determined using the monitor 27Al(n,α)24Na reaction, and the neutron energies were measured by the method of cross-section ratios of 90Zr(n,2n)89Zr to 93Nb(n,2n)92mNb reactions. The cross sections were deduced as 14.0±0.9mb at En=14.7±0.3MeV and 13.2±1.0mb at En=14.1±0.3MeV.

Cross section measurements for 141Pr(n,γ)142Pr reaction at neutron energies from 13.5 to 14.8 MeV

Activation cross-sections were measured for the 141Pr(n,γ)142Pr reaction at three different neutron energies from 13.5 to 14.8 MeV. The fast neutrons were produced via the 3H(d,n)4He reaction on Pd-300 neutron generator. The natural high-purity Pr2O3 powder was used as target material. Induced gamma activities were measured by a high-resolution gamma-ray spectrometer with high-purity germanium detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The neutron fluences were determined by the cross section of 27Al(n,α)24Na reaction. The neutron energy in the measurement were by the cross section ratios of 90Zr(n,2n)89m+gZr and 93Nb(n,2n)92mNb reactions. The data for 141Pr(n,γ)142Pr reaction cross sections are reported to be 3.3 ± 0.2, 2.7 ± 0.2 and 2.2 ± 0.2 mb at 13.5 ± 0.2, 14.1 ± 0.2, and 14.8 ± 0.2 MeV incident neutron energies, respectively. Results were discussed and compared with some corresponding values found in the literature.

New integral experiments for large angle scattering cross section data benchmarking with DT neutron beam at JAEA/FNS

Abstract A new integral experiment with a deuteron–triton fusion (DT) neutron beam started in order to validate scattering cross section data. First the DT neutron beam was constructed with a collimator. The performance of the collimator system and the characteristics of the DT neutron beam were measured. Second a new integral experiment for type 316 stainless steel (SS316) was carried out with this DT neutron beam. The DT neutron beam of 3.5 cm in diameter was injected to the front surface center of an SS316 cylindrical assembly. Reaction rates of the 93Nb(n,2n)92mNb reaction in the assembly were measured with the activation foil method and were calculated with the Monte Carlo transport calculation code. The measurement points were located at three positions, on the center of the beam axis and at 15 cm and 30 cm apart from the axis. The ratio of calculation to experiment of the 93Nb(n,2n)92mNb reaction rate became smaller than 1 with the distance from the beam axis. Then, the dependency of each reaction rate on scattering angle was calculated. It was proved that at off-axis positions, where C/E is smaller than 1, 90° scattering contribute relatively larger than at on-axis positions and backward scattering made little contribution to the results in this experiment. The reasons of the discrepancy between the measured and calculated data will be investigated.

Measurements of activation cross sections for 175Lu(n, α) 172Tm, 176Lu(n, α) 173Tm and 175Lu(n, p) 175m+gYb reactions induced by neutrons around 14 MeV

The cross sections for the 175Lu(n, α) 172Tm, 176Lu(n, α) 173Tm and 175Lu(n, p) 175m+gYb reactions have been measured in the neutron energy range of 13.5–14.8 MeV using the activation technique. The first data for 175Lu(n, α) 172Tm reaction cross sections are presented. In our experiment, the fast neutrons were produced via the 3H(d, n) 4He reaction on K-400 Neutron Generator at Chinese Academy of Engineering Physics (CAEP). Induced gamma activities were measured by a high-resolution (1.69 keV at 1332 keV for 60Co) gamma-ray spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The neutron fluences were determined by the cross section of 93Nb(n, 2n) 92mNb or 27Al(n, α) 24Na reactions. The neutron energy in the measurement was by the cross section ratios of 90Zr(n, 2n) 89m+gZr and 93Nb(n, 2n) 92mNb reactions. The results were discussed and compared with experimental data found in the literature and with results of published empirical formulae.

Activation cross sections for (n, p) reactions on nickel isotopes induced by neutrons around 14 MeV

The cross sections of 58Ni(n, p) 58(m+g)Co, 60Ni(n, p) 60mCo, 61Ni(n, p) 61Co and 62Ni(n, p) 62mCo reactions induced by neutrons around 14 MeV were measured using activation technique and a coaxial HPGe γ-ray detector. The natural nickel foils of 99.9% purity were used as target materials. Fast neutrons were produced by the T(d, n) 4He reaction. 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 90Zr(n, 2n) 89Zr to 93Nb(n, 2n) 92mNb reactions. The results of this work are compared with the collected partial recent data published previously and the estimations obtained from the published empirical formula based on the statistical model with dependence on the Q-value and odd–even effect taken into consideration.

Cross-sections for formation of 178m2Hf and 179m2Hf through reactions on natural hafnium at neutron energy 14.8 ± 0.2 MeV

The cross sections for formation of metastable state of 178Hf (178m2Hf, 574.215 keV, 31 y) and 179Hf (179m2Hf, 362.55 keV, 25.05 d) through reactions induced by 14.8 ± 0.2 MeV neutrons on natural hafnium were measured for the first time. The monoenergetic neutron beam was produced via the 3H(d, n)4He reaction on ZF-300-II Intense Neutron Generator at Lanzhou University. Induced gamma activities were measured by a gamma-ray spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The neutron fluence were determined by the cross section of 93Nb(n, 2n)92mNb reaction. The neutron energy in the measurement were by the cross section ratios of 90Zr(n, 2n)89m+gZr and 93Nb(n, 2n)92mNb reactions.

Measurement of neutron-induced activation cross sections of lanthanum at 14.8 MeV

Cross-sections for (n,p), (n,α), (n,n′α), (n,t) and (n,2p) reactions have been measured on 139La isotope at the neutron energy 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Neutrons were produced via the 3H(d,n)4He reaction using a solid tritium–titanium target. The neutron fluences were determined using the monitor reaction 27Al(n,α)24Na. The neutron energy in this measurement was determined by cross section ratios for the 90Zr(n,2n)89m+gZr and 93Nb(n,2n)92mNb reactions. Data are reported for the following reactions: 139La(n,p)139Ba, 139La(n,α)136Cs, 139La(n,n′α)135mCs, 139La (n,t)137mBa, and 139La(n,2p)138Cs. The cross sections were discussed and compared with experimental data found in the literature, and with the comprehensive evaluation data in ENDF/B-VII.0, JENDL-3.3, JEFF-3.1/A, and TENDL-2008 libraries.

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**Supported by Program for Science & Technology Innovation Talents in Universities of Henan Province, China (2008 HASTIT032) and Scientific Research Start up Outlay of High-Position Talent in Pingdingshan University in Henan Province, China

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.

Measurement of cross sections for ( n, 2 n), ( n, p) and ( n, α) reactions on germanium isotopes induced by 14 MeV neutrons

Activation cross sections at the neutron energy about 14 MeV on germanium isotopes have been measured, employing the activation technique and γ-ray spectrometry. The data of the cross section are reported for the ( n, 2 n), ( n, p) and ( n, α) reactions. The neutron flux was determined using the monitor reactions 27Al ( n, α) 24Na and the neutron energies were measured by the method of cross section ratios for 90Zr ( n, 2 n) 89Zr to 93Nb ( n, 2 n) 92mNb reactions. The measured results were compared with the other measurements.

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 14 MeV

The cross sections of 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 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, a)24Na and the neutron energies were measured with the method of cross-section ratios for 90Zr(n, 2n)89Zr to 93Nb(n, 2n)92mNb reactions.

Cross-section measurement for the reactions producing short-lived nuclei induced by neutrons around 14 MeV

The cross-sections of 180W(n,2n) 179mW, 186W(n,2n) 185mW, 165Ho(n,2n) 164mHo, 64Ni(n, α) 61Fe, 165Ho(n, α) 162Tb and 51V(n,p) 51Ti reactions induced by neutrons around 14 MeV were measured using activation technique and calculated by a previously developed formula in this work. The neutron flux was determined using the monitor reactions 93Nb(n,2n) 92mNb and 27Al(n, α) 24Na, the neutron energies were measured with the method of cross-section ratios for 90Zr(n,2n) 89Zr to 93Nb(n,2n) 92mNb reactions. The results of this work are compared with data published previously.

Cross-section measurements for (n, 2n), (n, p) and (n, α) reactions on strontium isotopes at the neutron energy about 14 MeV

Cross-sections for 84Sr(n, 2n) 83Sr, 86Sr(n, 2n) 85mSr, 86Sr(n, 2n) 85Sr, 88Sr(n, 2n) 87mSr, 84Sr(n, p) 84Rb, 86Sr(n, p) 86Rb, 88Sr(n, p) 88Rb and 88Sr(n, α) 85mKr reactions have been measured at neutron energies from 13.5 to 14.6 MeV using activation technique and by means of γ-ray spectrometry. The neutron flux was determined using the monitor reaction 93Nb(n, 2n) 92mNb and the neutron energies were measured by the method of cross-section ratios for 90Zr(n, 2n) 89Zr to 93Nb (n, 2n) 92mNb reactions. The results of present work are compared with data published previously.

Cross section measurements for (n, p) and (n, 2n) reactions of rare-earth isotopes at neutron energies from 13.5 to 14.6 MeV

Cross sections for (n, p) and (n, 2n) reactions have been measured on some rare-earth isotopes at neutron energies of 13.5-14.6 MeV using activation technique. Data are reported for the following reactions:150Nd(n, 2n) 149Nd, 148Nd(n, 2n) 147Nd, 142Nd(n, 2n) 141Nd, 160Gd(n, 2n) 159Gd, 158Gd(n, p) 158Eu, 146Nd(n, p) 146Pr, 141Pr(n, p) 141Ce and 139La(n, p) 139Ba. The neutron fluences are determined by the cross sections of 27Al(n, a) 24Na and 93Nb(n, 2n) 92mNb reactions.

Cross section measurements for ( n,3 n) reactions induced by 14.8 Mev neutrons

The cross sections for 209Bi( n,3 n) 207Bi, 191Ir( n,3 n) 189Ir, 151Eu( n,3 n) 149Eu and 185Re( n,3 n) 183Re reactions were measured by the activation method. The experimental results were 12.1±1.1, 64.6±6.5, 2.7±0.4 and 66.0±5.6 mb at the neutron energy of 14.8±0.2 MeV, respectively. The neutron flux was determined by the cross section of the 27Al( n, α) 24Na reaction. The neutron energy in these measurements was determined by the method of cross section ratios for 90Zr( n,2 n) 89m+gZr and 93Nb( n,2 n) 92mNb reactions.

Calibration of the JET neutron activation system for DT operation

The neutron activation system at JET is a pneumatic transfer system capable of positioning activation samples close to the plasma. Its primary purpose is to provide a calibration for the time-dependent neutron yield monitors (fission chambers and solid state detectors). Various activation reactions with different high energy thresholds were used including Fe56(n,p) Mn56, Al27(n,α) 24Na, 93Nb(n,2n) 92mNb, and Si28(n,p) 28Al reactions. The silicon reaction, with its short half life (2.25 min), provides a prompt determination of the 14 MeV DT yield. The neutron induced γ-ray activity of the Si samples was measured using three sodium iodide scintillators, while two high purity germanium detectors were used for other foils. It was necessary to use a range of sample masses and different counting geometries in order to cover the wide range of neutron yields (1015–1019 neutrons) while avoiding excessive count rates in the detectors. The absolute full energy peak efficiency calibration of the detectors was measured taking into account the source-detector geometry, the self-attenuation of the samples and cross-talk effects. An error analysis of the neutron yield measurement was performed including uncertainties in efficiency calibration, neutron transport calculations, cross sections, and counting statistics. Cross calibrations between the different irradiation ends were carried out in DD and DT (with 1% and 10% tritium content) discharges. The effect of the plasma vertical displacement was also experimentally studied. An agreement within 10% was found between the 14 MeV neutron yields measured from Si, Fe, Al, Nb samples in DT discharges.

Activation cross sections for generation of long-lived radionuclides

Results of recent measurements of activation cross sections leading to the generation of long-lived radionuclides of importance in fusion reactor technology are summarized. The cross sections measured are109Ag(n, 2n)108mAg,151Eu(n, 2n)150mEu,153Eu(n, 2n)152Eu,159Tb(n, 2n)158Tb,179Hf(n, 2n)178m2Hf,193Ir(n, 2n)192m2Ir,209Bi(m, 2n)208Bi,94Mo(n, p)94Nb,108Cd(n, p)108mAg,137Ba(n, p)137Cs and182W(n, n' a)178m2Hf at 14 MeV. The neutron fluences are determined by the cross sections of54Fe (n, p)54Mn and93Nb(n, 2n)92mNb reactions. The neutron energies in these measurements are determined by cross section ratios for90Zr(n, 2n)89m+gZr and93Nb(n, 2n)92mNb reactions.

Activation cross sections for the element rhenium

The185Re(n,α)182Ta,187Re(n,α)184Ta,187Re(n,p)187W and187Re(n,2n)186gRe reaction cross sections included by 13.5–14.7 MeV neutrons were measured by the activition method. The neutron fluences were determined by the cross section of the27Al(n,α)24Na reaction. The neutron energies in these measurements were determined by the cross section ratios for90Zr(n,2n)89m+gZr and93Nb(n,2n)92mNb reactions.

Determination of the mean neutron energy using the Zr/Nb and the Ni method

The cross-section ratios for the 90Zr(n, 2n) 89g−mZr and 93Nb(n, 2n) 92mNb reactions as well as for the 58Ni(n, p) 58g+mCo and 58Ni(n, 2n) 57Ni reactions have been measured by the activation method for the purpose of neutron spectrometry around 14 MeV in a neutron tube having a cylindrical acceleration structure (KORONA). The results are compared with the theoretically calculated values. The superiority of the “Zr/Nb ratio” method over the “Ni-ratio” method is discussed.

Cross-Section Measurement for 109Ag(n,2n)108mAg Reaction

Cross sections for the 109Ag(n,2n)108mAg reaction are measured using an activation method relative to cross sections for the 93Nb(n, 2n)92mNb reaction in the 13.64- to 14.80-MeV neutron energy rang...

Cross sections for the 93Nb(n,2n)92mNb reaction

The cross section of the 93Nb(n,2n)92mNb reaction has been studied by use of the activation method from the threshold energy of 8.8–19.8 MeV. Measurements are relative to the known cross-section values for the reactions H(n,n)H, 32S(n,p)32p, and 27Al(n,α)24Na. The cross-section value increases smoothly with energy and reaches a maximum value of 444 ± 18 mb at about 14.5 MeV then decreases to values of 293 ± 14 mb at 19.8 MeV. An effective cross-section value for a fission neutron spectrum calculated from the results is 0.321 ± 0.019 mb. The activation of Nb as a transfer standard for 14 MeV neutrons is discussed.