Fission cross-section measurements for the 238U(n,f)97m+gNb, 238U(n,f)133gTe and 238U(n,f)130gSb reactions induced by D-T neutrons.

In this study, we conducted measurements of the independent fission cross-sections of 238U(n, f)97m+gNb, 238U(n, f)133gTe reactions and the cumulative cross section of 238U(n, f)130gSb reactions induced by neutron at energies around 14 MeV, i.e., 14.1 ± 0.3, 14.5 ± 0.3 and 14.7 ± 0.3 MeV. The measurement results were obtained by the neutron activation method in combination with off-line γ-ray spectrometry techniques. The neutron flux was monitored on line by the accompanying α-particle from T(d, n)4He reaction, and the neutron energies were determined by the cross-section ratio of 90Zr(n, 2n)8+gZr to 93Nb(n, 2n)92mNb reactions. The independent fission cross-sections of the fission reactions were obtained by subtracting the influence of precursor nuclei or excited states. The obtained results are as follows: for 238U(n, f)97m+gNb, the independent cross sections are 1.0 ± 0.89, 0.98 ± 0.85 and 0.78 ± 0.70 mb at the specified neutron energy points. For 238U(n, f)133gTe, the independent fission cross-sections are 26.8 ± 2.8, 27.7 ± 2.9 and 20.5 ± 2.3 mb, respectively, at the same neutron energy points. As for 238U(n, f)130gSb, the obtained cumulative fission cross-sections are 5.35 ± 0.58, 5.05 ± 0.53 and 4.03 ± 0.44 mb, respectively, at the specified neutron energy points.

Optimization design of the portable cylindrical water injection multilayer neutron spectrometer.

The currently widely used multi-sphere neutron spectrometers still have many drawbacks, including complex design and processing, the need for multiple moderating spheres, high costs, large volumes, and complicated measurement procedures. This work proposes the portable cylindrical water injection multilayer neutron spectrometer (CWNS) as a promising alternative based on water pumping injection. The structure of CWNS consists of a central thermal neutron detector and a surrounding 6-layer of coaxial cylindrical water bags with varying diameters. During non-measurement periods, this CWNS is convenient to carry due to the absence of the need to inject moderating water. To optimize the CWNS design, we employed FLUKA simulation software to study and refine various parameters, including the thickness of the water bag, the material composition of the water bag, and the parameters of the supporting column. We finally achieved an optimized design. Specifically, the water bag of the CWNS is constructed using a 0.3 mm thick polyethylene film. The supporting column for the water bag is made of aluminum, providing stability and support to the overall structure. These optimized design parameters determine the specific size and configuration of the CWNS. The CWNS offers the benefits of convenient carrying, simplified processing, cost-effectiveness, and straightforward measurement. It has a promising potential use for the directional neutron dose monitoring.

Measurement of fission cross sections for 232Th(n,f)XZ84 reaction around the neutron energy of 14 MeV.

Neutron induced fission cross sections of 232Th(n,f)84Se, 232Th(n,f)84mBr, 232Th(n,f)84gBr reactions were measured based on neutrons from the D-T source. The α-particles emitted from the T(d,n)4He reaction were measured to monitor the neutron flux, while the ratio of 90Zr(n,2n)89Zr to 93Nb(n,2n)92mNb reactions was used to determine the neutron energy. The gamma-ray activity of samples was measured with a well calibrated HPGe-γ detector. In the 232Th(n,f) reaction at the neutron energies of 14.1 ± 0.3, 14.5 ± 0.3 and 14.7 ± 0.1 MeV, the cross sections are 2.74 ± 0.23, 2.75 ± 0.25, and 2.30 ± 0.21 mb for 84mBr, 3.41 ± 0.37, 3.35 ± 0.37, and 3.81 ± 0.42 mb for 84gBr, and roughly 8.79 ± 0.58, 9.36 ± 0.62, and 9.26 ± 0.62 mb for 84Se, respectively.

Cross sections of (n,x) reactions on cerium isotopes induced by D-T neutrons.

Neutron induced reaction cross sections of Cerium isotopes (136Ce, 138Ce, 140Ce, 142Ce) were investigated for the (n, 2n), (n, α), (n, p) and (n, γ) reactions in the neutron energy around 14 MeV. Experimental cross sections have been obtained for 136Ce(n, 2n)135m+gCe, 138Ce(n, 2n)137mCe, 140Ce(n, 2n)139m+gCe, 142Ce(n, 2n)141gCe, 140Ce(n, p)140gLa, 142Ce(n, p)142gLa, 140Ce(n, α)137mBa, 142Ce(n, α)139Ba and 142Ce(n, γ)143Ce reactions. The measured values were compared with the literature data as well as the evaluated nuclear data from ENDF/B-VII.1, CENDL-3.1, JENDL-4.0 and the calculated results by Talys-1.8 code.

Measurement of cross-sections for 14MeV neutron interaction with 175Lu.

The cross-sections for 14MeV neutron interaction with 175Lu were precisely measured by the neutron activation and off-line gamma ray technique. The neutron fluence was monitored by the accompanying α-particle of the T(d,n)α reaction, and the neutron energies were determined by using the cross-section ratio method of 90Zr(n,2n)89Zr to 93Nb(n,2n)92mNb reactions. As a result, the cross-sections of 175Lu(n,2n)174mLu, 175Lu(n,2n)174gLu, 175Lu(n,p)175m+gYb and 175Lu(n,α)172Tm reactions have been deduced at En = 14.1 ± 0.3MeV, 14.5 ± 0.3MeV and 14.7 ± 0.3MeV, respectively. Meanwhile, the comparisons between this work and the date reported by other groups previously were also given. For the comparison, it was found that there were nonnegligible discrepancies among these experimental data, as well as for several databases. As a conclusion, present data seem to be more consistent with the database of ENDF/B-VII.1, but trend to be lower than those of JEFF-3.2 and FENDL-3.1b, except the 175Lu(n,2n)174m+gLu reaction which are all in agreement.

Half life of 175Hf.

This work measured the half life of radioisotope (175)Hf, which was produced by neutron activation method at the ZF-300-II Intense Neutron Generator in Lanzhou University. The half life of (175)Hf, measured by γ-ray spectrometry using a well calibrated GEM-60P coaxial High Purity Germanium (HPGe) detector, has been found to be 70.65±0.19 days. The present result agrees with the literature data well, while the accuracy was improved.

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

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,alpha)61Fe, 165Ho(n,alpha)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,alpha)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.