Measurement Of Activation Cross Sections Research Articles

Characterization of a HPGe detector response for activation cross section measurements: regression method versus Monte Carlo method

ABSTRACT The full energy peak efficiencies and covariances of a high purity germanium (HPGe) detector studied by the regression method and Monte Carlo method were compared. The impact of the obtained results on the neutron activation cross-sections measured relative to monitor cross-sections was studied. In the regression method, the efficiencies measured for a set of calibration point sources were analysed by the least-squares analysis. In the Monte Carlo method, the efficiencies for the calibration point sources were calculated by MCNP. The covariances of the efficiencies determined by the regression method were calculated analytically. Perturbation analysis was performed to estimate the covariances of the efficiencies calculated by the Monte Carlo method. Positive correlations higher than 0.8 were found in the uncertainties of the MCNP data for point-like sources. In the case of the regression method, the correlation coefficient contains both positive and negative terms. The efficiencies and their covariances for finite sample geometry were also estimated by both methods to take into account sample effects such as geometrical effect, and gamma-ray self-absorption, and found considerable differences in the cross-sections and their uncertainties for reaction products quantified with low energy gammas. The efficiencies and covariances were clearly affected by the properties of the sample.

Measurement of fast-neutron activation cross section of the 109Ag(n,2n)108mAg reaction and its theoretical calculation of excitation function

The cross section values of the 109Ag(n,2n)108mAg reaction at four neutron energies 13.5, 14.1, 14.4 and 14.8 Me were measured relative to those of the monitor reaction 93Nb(n,2n)92mNb by using the activation technique and using off-line γ-ray spectrometry. Fast neutrons were produced by the T(d,n)4He reaction. The excitation function of this reaction in the neutron energies from the reaction threshold to 20 MeV was obtained based on the nuclear theoretical model program system TALYS-1.95 with the adjusted relevant parameters. The measured results were discussed and compared with the experimental data of literature, and the evaluated data from the evaluated libraries of TENDL-2021 and JEFF-3.1.2, as well as with the theoretical values based on TALYS-1.95.

Activation cross section measurement of alpha-particle induced nuclear reactions on tantalum

Activation cross sections induced by 50 MeV alpha-particle beam on natural tantalum were measured at the AVF cyclotron of the Nishina Center of RIKEN. The well-established stacked target technique and activation method were applied followed by high-resolution gamma spectrometry to determine the reaction cross sections. The experiment aimed to determine activation cross sections for the longer-lived reaction product. Accordingly, activation cross sections were deduced for the formation of 181, 182m, 182g, 183, 184m, 184gRe and 178g, 182gTa.

Measurement of dosimetrical cross sections with 14.05 MeV neutrons from compact neutron generator

This paper deals with the measurement of the differential dosimetry cross sections using a small compact D-T neutron generator with 14.05 ± 0.08 MeV neutron emission (1 × 108 n/s into 4π). In spite of low neutron flux, it is possible to get measurable gamma-ray activities by irradiating a larger amount of target material placed in close geometry. The experimentally determined cross sections are in good agreement with the cross sections in the IRDFF-II dosimetry library. The comparison with other nuclear data libraries was performed as well. It is worth noting that the mean standard deviation in IRDFF-II library is about 4 %, while in the case of other data libraries they are from 5.5 % to 7.5 %. This result can be understood as a validation of IRDFF-II using 14.05 MeV neutrons and also a confirmation of the applicability of small compact generators in the measurement of activation cross sections.

Activation Cross Section Measurement of the (n,2n) Reaction on 203Tl at 16.4 MeV, 18.9 MeV and Theoretical Calculations via the EMPIRE code

The aim of the present work was to study the cross-section of the (n,2n) and (n,3n) reactions on 203Tl, by irradiating a natural TlCl pellet target with monoenergetic neutron beams at 16.4, and 18.9 MeV. The cross section measurements were carried out using the activation method, with respect to the 197Au(n,2n)196Au and 27Al(n,α)24Na reference reactions. The monoenergetic neutron beams were generated in the 5.5 MV Tandem accelerator of NCSR “Demokritos”, using the 3H(d,n)4He reaction. Monte Carlo simulations have been performed to take into account the gamma-ray self-absorption results as well as the estimation of the neutron flux through the reference foils. Theoretical calculations with the code EMPIRE have also been performed, using the same parameterization implemented in the theoretical study of Ir and Au nuclei in an attempt to find a suitable model for the description of all the experimental results in this mass region.

Deuteron and α-particle-induced nuclear reactions on 45Sc: activation cross section measurement and thick target yield evaluation

Systematic measurements of nuclear reaction cross sections were done in the low energy range for the two reactions 45Sc(d,p)46Sc and 45Sc(α,n)48V. Thin foils of high-purity (99.95%) natural Sc targets (100% 45Sc), purchased from Good-Fellow, were irradiated with 10 and 20 MeV incident deuteron and α-particle energies, respectively, at beam current of 100 nA using MGC-20 cyclotron. For precise measurements, high-purity Ti and Cu foils were used for monitoring the actual deuteron and α-particle beam intensities, respectively. The conventional stacked-foil technique was applied for measurement and calculation of the cross section values using a high-resolution γ-ray spectrometer for measuring the radioactivity. Nuclear model code EMPIRE-3.2 was used for calculation of the investigated excitation functions. The obtained results were compared with the experimental values and TENDEL-2021 data which are based on TALYS-1.96 code calculations. The integrated yields for the two reactions, based on the proposed average excitation functions, were estimated.

Activation cross-sections for short-lived reaction products on hafnium isotopes induced by 1 – 20 MeV neutrons

Results of new activation cross-section measurements for production of 178m1Hf (T1/2 = 4.0 s) and 179m1Hf (T1/2 = 18.67 s) are presented for the following reactions: 178Hf(n,n´)178m1Hf, 179Hf(n,2n)178m1Hf, 180Hf(n,3n)178m1Hf, 179Hf(n,n´)179m1Hf, and 180Hf(n,2n)179m1Hf. The irradiations were carried out at the 7-MV Van de Graaff accelerator at EC-JRC, Geel. Neutrons in the 1-3 MeV energy range were produced via the 3H(p,n)3He reaction. Deuteron beam and a deuterium gas target were used to produce 5 and 6 MeV neutrons. For the production of quasi-monoenergetic neutrons between 16 and 19.5 MeV the 3H(d,n)4He reactions was employed. Both samples with natural composition and isotopic enrichment were employed to differentiate reactions leading to the same product. An automated pneumatic system was used for the sample irradiation, transport and radioactivity measurements. The radioactivity of the samples was determined by standard gamma-spectrometry using HPGe detector. The results obtained in the present work are compared with the data from other authors and TENDL-2017 evaluation.

An overview of activation cross-section measurements of some neutron and charged-particle induced reactions in Bangladesh

Abstract Over the last several decades, our research group has been working on nuclear data measurements using a J-25 Neutron Generator, a TRIGA Mark II Research Reactor and a Tandem Accelerator at Savar, as well as an Am/Be neutron source at Rajshahi. The spectrum of fast neutrons having energies from 0.5 to 20 MeV in the core of the TRIGA reactor as well as from 1.5 to 11 MeV of the Am/Be source was well characterized for validation of evaluated data of neutron threshold reactions. Spectrum-averaged cross sections were determined by integral measurements. The integral values measured at both the reactor and the Am/Be source were compared with the integrated data deduced from measured and evaluated excitation functions of some nuclear reactions given in some data libraries. As example, the details on the integral and integrated cross sections of the 64Zn(n,p)64Cu and 60Ni(n,p)60Co reactions are discussed. In both cases, integral test shows that further improvement of the evaluated excitation function reported in data libraries is needed. The use of a newly developed facility at the 3 MV Tandem Accelerator in measurement of proton induced reaction cross sections in the energy region below 5 MeV is outlined, and new results on the 64Ni(p,n)64Cu and natNi(p,x)61Cu processes below 3 MeV are discussed.

Activation cross section measurements and estimation of photon and neutron induced nuclear reactions for ytterbium isotopes with covariance analysis

The cross sections of the 168Yb(n,2n)167Yb, 174Yb(n,p)174Tm, 173Yb(n,p)173Tm, 174Yb(n,α)171Er, 170Yb(n,2n)169Yb and 176Yb(n,2n)175Yb nuclear reactions at 14.77 MeV neutron energy and the flux weighted average cross sections of the 168Yb(γ,n)167Yb, 170Yb(γ,n)169Yb and 176Yb(γ,n)175Yb nuclear reactions at 10 and 15 MeV bremsstrahlung endpoint energies are measured using offline gamma spectroscopy. The bremsstrahlung photon-induced reactions are reported for the first time at these energies. The results are compared with the evaluated nuclear data from the ENDF/B.-VIII.0, JEFF-3.3 and TENDL-2019 libraries. The theoretical model calculations are performed with the TALYS-1.95 nuclear code with parameters tuned to reproduce the measured data. The measured cross sections are in good agreement with the literature and evaluated data. The results are significant for the experimental nuclear database and reactor technology development.

Activation cross-section measurement of fast neutron-induced reactions in Al, Au, Bi, Co, F, Na, and Y

This paper describes cross-section measurements by means of the neutron activation method using an accelerator-driven fast neutron source at the Nuclear Physics Institute of the Czech Academy of Sciences in Řež. It extends previous studies published in papers (Vrzalová et al. (2013); Chudoba et al. (2018)). A quasi-monoenergetic neutron source based on the p+Li(C) reaction was used to irradiate Al, Au, Bi, Co, NaF, and Y samples with neutrons at the energies of 17.5(10) MeV, 19.8(9) MeV and 27.5(7) MeV. Irradiated foils were analyzed by means of gamma-ray spectrometry and reaction yields were obtained. Cross sections of several fast neutron-induced reactions were determined on the basis of the measurement of neutron spectra and their corresponding reaction yields. The production cross sections of isomeric states were determined as well. This paper also describes the measurements of the positron emitters using annihilation gamma-ray spectrometry. The sources of uncertainties in the various parts of the experiment are discussed. The resulting cross sections might be useful for the further development of advanced nuclear reactors and fast neutron dosimetry.

The activation cross section measurements of proton-induced reactions on Li and Ta in the energy region 12.5–34 MeV

The experimental data on cross sections are necessary to clarify existing ideas on the mechanisms of nuclear reactions and for testing of nuclear models. Proton-induced reaction on 7Li serves as a source of quasi-monoenergetic neutrons which are widely used in the measurement of cross sections for neutron induced reactions. Tantalum plays an important role in technology and nuclear facilities mainly for its low induced activity (screens, degraders). In order to investigate the important nuclides, we have carried out the irradiation experiments with the variable-energy cyclotron U-120M of the NPI CAS Řež. The cross section of the reaction 7Li(p,n)7Be(ground state+0.43 MeV) and the cross sections of the nuclides 180,178mTa, 178W and 175Hf from reactions on natural tantalum were investigated, of which 181Ta(p,n)180gTa for the first time. The stacked-foil technique was utilized. The comparison of new results with prior data and predictions of evaluations is discussed.

Activation cross section measurement of alpha-particle induced reactions on natural neodymium

Excitation functions of alpha-particle induced reactions on natNd up to 50 MeV were measured at the RIKEN AVF cyclotron. To derive cross sections activation method, stacked target technique and gamma-ray spectrometry were adopted. Formations of 153,145Sm, 151,150,149,148m,148g,144,143Pm, and 149,147Nd were investigated. The results were compared with the previous experimental data and the TENDL-2019 data. Discrepancies among most of them were found.

Activation cross section measurement of the 100Mo(α,n)103Ru reaction for optical potential studies

The light neutron-rich nuclei can be synthesized via (α,n) reactions in the so-called weak r-process. The abundances of these species are derived using reaction network calculations. Such a simulation has astrophysical and nuclear physics inputs, one of the most uncertain parameter is the α-nucleus optical potential. (α,n) cross section measurements can be used to evaluate α-optical potentials. For this purpose, the activation cross section measurement of the 100Mo(α,n)103Ru reaction is in progress at Atomki.

A modified unscented transformation method for uncertainty propagation in neutron induced cross section measurement

This paper investigates the application of the modified unscented transformation (MUT) method for uncertainty propagation in neutron induced cross section measurement in Nuclear Science. The method is the improvement on unscented transformation (UT) technique by incorporating more parameters (not random) to increase the number of sigma points.We examined the application of MUT method for covariance analysis of cross section measurement in comparison to the first order sensitivity analysis method and Monte Carlo methods. The MUT method is simple to use and easier to implement in comparison to the sandwich formula. The Monte Carlo simulations had been carried out to illustrate the good performance of the MUT method in covariance analysis in neutron activation cross section measurement.

Activation cross section measurement of the deuteron-induced reaction on yttrium-89 for zirconium-89 production

Activation cross sections of the deuteron-induced reactions on 89Y were measured up to 24 MeV deuteron energy. The experiment was performed at the RIKEN AVF cyclotron. Excitation functions of the reactions 89Y(d,x)88,89Zr, 88,90mY, 87mSr were obtained by using the stacked-foil activation method and gamma-ray spectrometry. The results were compared with previous experimental data and the prediction of the TALYS nuclear reaction model code adopted from TENDL-2017 library. Physical thick target yield of 89Zr was derived from the measured cross sections.

Measurement of activation cross-sections of natDy(p,x) reactions up to 45 MeV

We activated natDy with a 45-MeV energetic proton beam and studied the production cross-sections of the reaction products 162m,161,159Ho, 159,157,155Dy, and 161,160,156,155Tb. The activation was carried out using an external beam from the MC-50 Cyclotron at the Korea Institute of Radiological and Medical Sciences, Korea. The stacked-foil activation method and off-line γ-ray spectrometry were used to measure the excitation functions of the natDy(p,x) reactions. The thick target yields of the reaction products were also estimated. The excitation functions of the natDy(p,x) reactions were theoretically calculated using TALYS 1.9 code. The measured results were compared with the literature data and the calculated values from the TENDL-2017 library and were found to be in close agreement for most of the reactions.

Measurement of activation cross sections of deuteron induced reactions on natIr in the 17–50 MeV energy range

In the frame of a thorough investigation of activation cross sections of deuteron induced nuclear reactions, excitation functions on iridium were investigated up to 50 MeV deuteron energy. Production cross sections were measured for the 193mPt, 191Pt, 189Pt, 188Pt, 187Pt, 194m2Ir, 194gIr(m1 + ), 192gIr(m1 + ), 190m2Ir, 190gIr(m1 + ), 189Ir, 188Ir, 187Ir and 191gOs(m1 + ) radionuclides. Activation method, stacked foil irradiation technique and off-line gamma-ray spectrometry were used for quantification of the radionuclides. The experimental results are compared with earlier data in the overlapping energy range. We discuss theoretical predictions obtained from the ALICE-IPPE-D and EMPIRE-II-D codes. The experimental data are also compared with calculated values reported in the TENDL-2017 on-line library calculated by using the TALYS code.

Measurement of nuclear activation cross sections of protons on natural carbon for proton beam energies between 100 and 220 MeV

In this work, we present measurements of nuclear activation cross sections from carbon. Carbon can be used for proton fluence calculation in proton therapy by measurements of the activity after irradiation. The cross sections are measured on a high-precision level with systematic uncertainties of approx. 2.8% for proton beam energies between 100 and 220 MeV. The targets are activated at the West German Proton Therapy Centre Essen. The determination of the activity is based on gamma-ray spectrometry measurements at the Dortmund Low Background Facility. For the natC(p,x)11C-reaction the results of this experimental study are comparable with several measurements reported in the literature. For the natC(p,x)7Be-reaction, the results calculated by several groups are reproduced by these measurements up to 180 MeV. Above 180 MeV, the observed energy dependence is weaker than the one measured by other groups. The reproducibility of the experimental setup is demonstrated with a measurement of the cross sections from aluminum.

Activation cross section measurement of the (n,2n) reactions on natural Ir isotopes

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Measurement of activation cross sections of aluminum for protons with energies between 0.4 GeV and 3.0 GeV at J-PARC

Measurement of activation cross sections of aluminum for protons with energies between 0.4 GeV and 3.0 GeV at J-PARC