Thermal neutron cross-section and resonance integral of the Mo(n,γ)Mo reaction

We measured the thermal neutron cross-section and the resonance integral of the ⁹⁸Mo(n,γ)⁹⁹ Mo reaction by the activation method using a ¹⁹⁷Au(n,γ)¹⁹⁸ Au monitor reaction as a single comparator. The high-purity natural Mo and Au metallic foils with and without a cadmium shield case of 0.5 mm thickness were irradiated in a neutron field of the Pohang neutron facility. The induced activities in the activated foils were measured with a calibrated p-type high-purity Ge detector. The necessary correction factors for the γ-ray attenuation (F_g), the thermal neutron self-shielding (G_th) and the resonance neutron self-shielding (G_epi) effects, and the epithermal neutron spectrum shape factor (α) were taken into account. In addition, for the ⁹⁹Mo activity measurements, the correction for true coincidence summing effects was also taken into account. The thermal neutron cross-section for the ⁹⁸Mo(n,γ)⁹⁹Mo reaction has been determined to be 0.136 ± 0.007 barn, relative to the reference value of 98.65 ± 0.09 barn for the ¹⁹⁷Au(n,γ)¹⁹⁸ Au reaction. The present result is, in general, in good agreement with most of the experimental data and the recently evaluated values of ENDF/B-VII.0, JENDL-3.3, and JEF-2.2 by 5.1% (1σ). By assuming the cadmium cut-off energy of 0.55 eV, the resonance integral for the ⁹⁸Mo(n,γ)⁹⁹Mo reaction is 7.02 ± 0.62 barn, which is determined relative to the reference values of 1550 ± 28 barn for the ¹⁹⁷Au(n,γ)¹⁹⁸Au reaction. The present resonance integral value is in general good agreement with the previously reported data by 8.8% (1σ).     

~(71)Ga(n,γ)~(72)Ga和~(180)Hf(n,γ)~(181)Hf反应截面的测量与评价

为解决目前71 Ga(n,γ)72 Ga反应和180 Hf(n,γ)181 Hf反应截面实验数据的分歧,在中国原子能科学研究院的600kV高压倍加器和5SDH-2串列加速器上用活化法在0.5～3MeV能区内测量了这两个反应在4个能点的反应截面。并对国内外0.01～4MeV范围内的实验数据进行了修正和评价,最终给出了这两个反应在此能区范围内的推荐值。     

~(176)Hf(n,2n)~(175)Hf反应截面测量

采用相对测量技术,以活化法对13.4～14.8MeV范围内的176Hf(n,2n)175Hf反应截面进行了测量。样品固定在距离D-T中子源20cm处的圆环的不同位置上进行中子辐照,采用93Nb(n,2n)92Nbm作为监测反应,活化产物采用高纯锗探测器进行了测量,所得14MeV附近的176Hf(n,2n)175Hf反应截面实验值为(2100±85)mb,对实验结果与公开文献值和ENDF/B6.8评价库数据进行了比对。     

Activation Cross Section Measurment for te ~(180)Hf(n,γ)~(181)Hf Reaction

Introduction D. L. Smith and E. T. Cheng have reviewed the contemporary nuclear data needs and status for fusion-reactor technology. Activation cross sections were found to be unsatisfactory in 83 of 153 reaction reviewed. ~(180)Hf(n,γ)~(181)Hf cross sections are also desired for the fusion-reactor technology. Some experimental data for this reaction from 3 kev to 4 MeV are reported in the literatures. This reaction is considered as inadequate for the present in this review. To evaluate these experimental data, it is necessary to re-measure the cross sections for this reaction.     

Cross Section for ~(176)Hf(n,2n)~(175)Hf Reaction

Measurements of neutron cross section of ~(176)Hf(n,2n)~(175)Hf are reported. In the experiment, the D(d,n)~3He and T(d,n)~4He reactions were served as the neutron sources, in neutron energy ranged of 10～12 MeV, about 14 MeV and 18 MeV. The neutron flux was monitored with the ~(93)Nb(n,2n)~(92m)Nb reaction and BF_3 long counter or ~(238)U fission chamber. Details of this experiment were described and the results were compared with ENDF/B-6, JEF-2, JENDL-3, ADL-3 and the data from literature.     

Thermal neutron capture cross sections for the Sm(n,γ)Sm and Sm(n,γ)Sm reactions at 0.0536 eV energy

The neutron capture cross sections for the ¹⁵²Sm(n,γ)¹⁵³Sm and ¹⁵⁴Sm(n,γ)¹⁵⁵Sm reactions at 0.0536 eV neutron energy were measured using an activation technique based on the TRIGA Mark-II research reactor, relative to the reference reaction ¹⁹⁷Au(n,γ)¹⁹⁸Au. The activity was measured nondestructively using gamma-ray spectroscopy. Our measured values at this neutron energy are the first ones and are compared with 1/v based evaluated cross sections reported in the ENDF/B-VII and JENDL-3.3 libraries. The measured value for the ¹⁵²Sm(n,γ)¹⁵³Sm reaction is 0.28% lower than JENDL-3.3 and 0.48% higher than ENDF/B-VII. Our value for the production of ¹⁵⁵Sm is about 3% and 2.3% higher than the evaluated value with ENDF/B-VII and JENDL-3.3 at 0.0536 eV, respectively.     

Measurement of thermal neutron cross-section and resonance integral for the Ho(n,γ)Ho reaction using electron linac-based neutron source

The thermal neutron cross-section and the resonance integral of the ¹⁶⁵Ho(n,γ)^166gHo reaction have been measured by the activation method using a ¹⁹⁷Au(n,γ)¹⁹⁸Au monitor reaction as a single comparator. The high-purity natural Ho and Au foils with and without a cadmium shield case of 0.5 mm thickness were irradiated in a neutron field of the Pohang neutron facility. The induced activities in the activated foils were measured with a calibrated p-type high-purity Ge detector. The correction factors for the γ-ray attenuation (F_g), the thermal neutron self-shielding (G_th), the resonance neutron self-shielding (G_epi) effects, and the epithermal neutron spectrum shape factor (α) were taken into account. The thermal neutron cross-section for the ¹⁶⁵Ho(n,γ)^166gHo reaction has been determined to be 59.7 ± 2.5 barn, relative to the reference value of 98.65 ± 0.09 barn for the ¹⁹⁷Au(n,γ)¹⁹⁸Au reaction. By assuming the cadmium cut-off energy of 0.55 eV, the resonance integral for the ¹⁶⁵Ho(n,γ)^166gHo reaction is 671 ± 47 barn, which is determined relative to the reference value of 1550 ± 28 barn for the ¹⁹⁷Au(n,γ)¹⁹⁸Au reaction. The present results are, in general, good agreement with most of the previously reported data within uncertainty limits.     

Evaluation and Calculation of Activation Cross Sections for ~(151,153)Eu(n,2n), (n,3n), (n,γ) and (n,x) Reactions below 20 MeV

Eu is a rare-earth element. Its activation cross section is important for nuclear science and technology applications. However, there are some discrepancies in several evaluated nuclear data libraries. The cross section for ~(151,153)Eu(n,2n) reactions were one of the Coordinate Research Programs of IAEA on activation cross sections     

Evaluation and Calculation of Activation Cross Sections for ~(169)Tm(n,2n), (n,3n), (n,γ) and (n,x) Reactions Below 20 MeV

Introduction ~(169)Tm is a rare-earth element. Its activation cross sections are a good indicator for nuclear science and technology applications. However, there are no evaluated data in several nuclear data libraries. The activation cross sections for ~(169)Tm(n,2n), (n,3n), (n,γ) and some emission charged particle (n,x) reactions below 20 MeV were evaluated and calculated on the basis of experimental and theoretical data.     

Evaluation and Calculation of Activation Cross Sections for ~(158,159)Tb(n,2n), (n,3n), (n,γ) and (n,x) Reactions Below 20 MeV

Introduction ~(159)Tb is a rare-earth element. Its activation cross section is a good indicator for nuclear science and technology applications. However, the evaluated data are very scarce in several nuclear data libraries. The cross section for ~(159)Tb(n,2n)~(158)Tb reaction was one of the Coordinate Research Program of IAEA on activation cross     

Evaluation of Activation Cross Sections for (n,2n) and (n,γ) Reactions on ~(63, 65, Nat)Cu

Copper is a very important structure material in nuclear fusion engineering. The neutron activation cross section are very useful in fusion research and other applications such as radiation safety, environmental, material damage and neutron dosimetry. More efforts are required to identify and resolve the differences and discrepancies in the existing activation cross sections from different laboratories. The natural copper consists of two stable isotopes, i.e. ~(63)Cu, ~(65)Cu. The reaction Q-Values and abundances are listed in Table 1.     

Systematics of (n,2n) and (n,3n) Reaction Cross Sections

The systematics of(n,2n)and(n,3n)cross sections have been studied bymeans of the evaporation model including preequilibrium emission.A set of empi-rical parameters has been extracted on the bases of analysing and fitting the     

Measurement of thermal neutron cross-section and resonance integral for the Yb(n,γ)Yb reaction by the cadmium ratio method

The thermal-neutron cross-section and the resonance integral for the ¹⁷⁴Yb(n,γ)¹⁷⁵Yb reaction were measured by the activation method using a ⁵⁵Mn monitor as single comparator. Analytical grade MnO₂ and Yb₂O₃ powder samples with and without a cylindrical 1 mm Cd shield box were irradiated in an isotropic neutron field obtained from three ²⁴¹Am-Be neutron sources. The gamma-ray spectra from the activated samples were measured with a calibrated n-type high-purity Ge detector. The experimental results were corrected for the correction factors calculated for thermal and epithermal neutron self-shielding effects, epithermal neutron spectrum shape and gamma-ray self attenuation. Thus, the thermal neutron cross-section for the ¹⁷⁴Yb(n,γ)¹⁷⁵Yb reaction is found to be 126.5 ± 6.6 b, relative to that of the ⁵⁵Mn monitor. The resonance integral value for the ¹⁷⁴Yb(n,γ)¹⁷⁵Yb reaction is found to be 59.6 ± 8.5 b, at cadmium cut-off energy of a 0.55 eV. Using the measured cadmium ratios of ⁵⁵Mn and ¹⁷⁴Yb, the result for resonance integral of the ¹⁷⁴Yb(n,γ)¹⁷⁵Yb reaction has also been obtained relative to the reference value of the ⁵⁵Mn monitor. The present results for the ¹⁷⁴Yb(n,γ)¹⁷⁵Yb reaction agree well only with the recent experimental ones obtained by Kafala et al. [1] and De Corte and Simonits [2] within uncertainty limits. However, the previously reported experimental data for the thermal neutron cross-section for this reaction are distributed between 24 and 141 b, and similarly the experimental values for the resonance integral value also show a large scatter in the range of 30-69 b.     

Measurement of thermal neutron and resonance integral cross sections of the reaction V(n,γ)V using a 20 Ci Am–Be isotopic neutron source

The thermal neutron capture cross section (σ_o) and the resonance integral (I_o) of the ⁵¹V(n,γ)⁵²V reaction were measured with an activation method to provide fundamental data for reactor calculation, activation analysis, and other theoretical and experimental uses concerning the interaction of neutron with matter. The vanadium and manganese samples were irradiated within and without a Cd shield case using a 20 Ci Am–Be neutron source. The activities of the samples were measured using gamma-ray spectroscopy. The thermal neutron capture cross section and the resonance integral were determined relative to the reference reaction ⁵⁵Mn(n,γ)⁵⁶Mn and the values obtained are 5.16 ± 0.19 barns and 2.53 ± 0.1 barns respectively. The previous measurements of the σ_o and I_o of the reaction ⁵¹V(n,γ)⁵²V were reviewed and the difference between the present values and the previous results were discussed.     

Measurement of Activation Cross Sections for ~(159)Tb(n,γ)~(160)Tb and ~(169)Tm(n,γ)~(170)Tm Reactions

Introduction Both ~(159)Tb and ~(169)Tm are rare-earth elements. Their activation cross sections are a good indicator for nuclear science and technology applications. Precise values of the neutron capture cross section of terbium and thulium also are of practical importance in relation to reactor design since they are the fission product poisons.     

Measurement of thermal neutron capture cross section and resonance integral of the 138Ba(n, γ)139Ba reaction using 55Mn(n, γ)56Mn as a monitor

The thermal neutron capture cross section (σ_o) and the resonance integral cross section (I_o) of the ¹³⁸Ba(n, γ)¹³⁹Ba reaction have been measured by the activation method using the Ghana Research Reactor-1 (GHARR-1). The barium and manganese targets were irradiated within and without a cadmium capsule. The result of the thermal neutron capture cross section for the ¹³⁸Ba(n, γ)¹³⁹Ba reaction is 0.53 ± 0.01barns. The result was obtained relative to the reference value 13.2 barns of the ⁵⁵Mn(n, γ)⁵⁶Mn reaction. The resonance integral cross section for the ¹³⁸Ba(n, γ)¹³⁹Ba reaction was also measured relative to the reference value of 13.9 barns for the ⁵⁵Mn(n, γ)⁵⁶Mn reaction. The present resonance integral cross section for the ¹³⁸Ba(n, γ)¹³⁹Ba reaction is 0.380 ± 0.005 barns. The previous measurements of the σ_o and I_o of the reaction ¹³⁸Ba(n, γ)¹³⁹Ba were reviewed and the difference between the present values and the previous results were discussed. The present work was undertaken with the aim to contribute to the experimental basis of σ_o and I_o evaluations.     

Cross-section measurements for the (n,p) and (n,α) reactions on 23Na and for the (n,p) reaction on 26Mg at the neutron energies from 13.6 to 14.9 MeV

Cross sections were measured at neutron energies from 13.6 to 14.9 MeV for the reactions ²³Na(n,p)²³Ne and ²³Na(n,α)²⁰F, and ²⁶Mg(n,p)²⁶Na leading to short-lived products. The production of short-lived nuclei and the spectra accumulation have been carried out by cyclic activation method. Corrections were made for the effects of gamma ray attenuation, coincidence summing, pulse pile-up, dead time, neutron flux fluctuations and scattered low energy neutrons.