Activation Cross Sections Research Articles

Measurement of (n,α) and (n,2n) reaction cross sections at a neutron energy of 14.92 ± 0.02 MeV for potassium and copper with uncertainty propagation * *For the flawless operation of the PURNIMA neutron generator during the experiment, we gladly acknowledged the assistance of scientific officers (SO's) of Purnima laboratory and Analytical Chemistry Division, BARC, Mumbai, India. For the financial assistance

Experimentally measured neutron activation cross sections are presented for the (n,α) , (n,α) , and (n,2n) reactions with detailed uncertainty propagation. The neutron cross sections were measured at an incident energy of 14.92 ± 0.02 MeV, and the neutrons were based on the t(d,n)α fusion reaction. The (n,α) reaction was used as a reference reaction for the normalization of the neutron flux. The pre-calibrated lead-shielded HPGe detector was used to detect the residues' γ-ray spectra. The data from the measured cross sections are compared to the previously measured cross sections from the EXFOR database, theoretically calculated cross sections using the TALYS and EMPIRE codes, and evaluated nuclear data.

Activation cross sections of some neutron-induced reactions in the energy range of 13.82–14.71 MeV

Abstract The cross sections of the reactions 70Zn(n,2n)69mZn,74Ge(n,α)71mZn and 90Zr(n,2n)89m,gZr in the energy range of 13.82–14.71 MeV were measured by the activation technique in combination with HPGe detector γ-ray spectroscopy. The measured results were compared with other experimental data and with the data given in the library TENDL-2019. A nuclear model calculation based on the code TALYS-1.8 was also performed after adjustment of an input parameter for the spin distribution of level density. The results of this work strengthen the database and could be useful in further evaluation of the data.

Activation cross sections of proton-induced reactions on praseodymium up to 30 MeV

Activation cross sections of proton-induced reactions on 141Pr were measured. Stacked foil activation technique and γ-ray spectrometry were adopted to derive the cross sections. The production cross sections of 141,140,139mNd, and 139Ce were determined up to 30 MeV. The physical yield of 140Nd was deduced using the measured cross sections of the 141Pr(p,2n)140Nd reaction. The physical yields of the proton- and deuteron-induced reactions on 141Pr and 3He-induced reaction on natCe for 140Nd production were compared.

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.

Assessment of Long Lived Isotopes in Alkali-Silica Resistant Concrete Designed for Nuclear Installations.

The design of concrete for radiation shielding structures is principally based on the selection of materials of adequate elemental composition and mix proportioning to achieve the long-term durability in nuclear environment. Concrete elements may become radioactive through exposure to neutron radiation from the nuclear reactor. A selection of constituent materials of greatly reduced content of long-lived residual radioisotopes would reduce the volume of low-level waste during plant decommissioning. The objective of this investigation is an assessment of trace elements with a large activation cross section in concrete constituents and simultaneous evaluation of susceptibility of concrete to detrimental alkali-silica reaction. Two isotopes 60Co and 152Eu were chosen as the dominant long-lived residual radioisotopes and evaluated using neutron activation analysis. The influence of selected mineral aggregates on the expansion due to alkali-silica reaction was tested. The content of 60Co and 152Eu activated by neutron radiation in fine and coarse aggregates, as well as in four types of Portland cement, is presented and discussed in respect to the chemical composition and rock origin. Conflicting results were obtained for quartzite coarse aggregate and siliceous river sand that, despite a low content, 60Co and 152Eu exhibited a high susceptibility to alkali-silica reaction in Portland cement concrete. The obtained results facilitate a multicriteria selection of constituents for radiation-shielding concrete.

Experimental consolidation and absolute measurement of the ^text {nat}C(p,x)^{11}C nuclear activation cross section at 100\xa0MeV for particle therapy physics

The ^text {nat}C(p,x)^{11}C reaction has been discussed in detail in the past [EXFOR database, Otuka et al. (Nuclear Data Sheets 120:272–276, 2014)]. However, measured activation cross sections by independent experiments are up to 15% apart. The aim of this study is to investigate underlying reasons for these observed discrepancies between different experiments and to determine a new consensus reference cross section at 100 MeV. Therefore, the experimental methods described in the two recent publications [Horst et al. (Phys Med Biol https://doi.org/10.1088/1361-6560/ab4511, 2019) and Bäcker et al. (Nuclear Instrum Methods Phys Res B 454:50–55, 2019)] are compared in detail and all experimental parameters are investigated for their impact on the results. For this purpose, a series of new experiments is performed. With the results of the experiments a new reference cross section of (68±3) mb is derived at (97±3) MeV proton energy. This value combined with the reliably measured excitation function could provide accurate cross section values for the energy region of proton therapy. Because of the well-known gamma-ray spectrometer used and the well-defined beam characteristics of the treatment machine at the proton therapy center, the experimental uncertainties on the absolute cross section could be reduced to 3%. Additionally, this setup is compared to the in-beam measurement setup from the second study presented in the literature (Horst et al. 2019). Another independent validation of the measurements is performed with a PET scanner.

Activation cross sections of gamma-emitters produced in deuteron induced reactions on {}^{{209}}Bi up to 50 MeV

Deuteron induced reactions on natural bismuth targets were investigated with the stacked foil activation technique up to 50 MeV. Excitation functions for the reactions ^{mathrm {209}}Bi(d,xn)^{mathrm {207,206,205}}Po, Bi(d,x)^{mathrm {207,205}}Bi and ^{mathrm {209}}Bi(d,x)^{mathrm {203}}Pb obtained from gamma-spectra of decay products were compared with the results of our ALICE-D and EMPIRE-D model calculations, with the result of TALYS code taken from TENDL-2019 on-line library and the results of the only measurement performed earlier. Thick target yields were deduced from the fitted experimental cross sections.

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.

Production cross sections of dysprosium, terbium and gadolinium radioisotopes from the alpha-particle-induced reactions on natural gadolinium up to 50 MeV

The activation cross sections of the alpha-particle-induced reactions on natural gadolinium up to 50 MeV were measured. The stacked foil technique, the activation method and the γ-ray spectrometry were used for the measurement. We determined the experimental production cross sections of 155,157,159Dy, 153,155,156g,160,161Tb and 153Gd. No previous experimental data of 155,159Dy, and 153Gd were found in the literature. The measured values were compared with the previous experimental data and the TENDL-2019 data.

Copper neutron transport libraries validation by means of a 252Cf standard neutron source

Copper is an important structural material in various nuclear energy applications, therefore the correct knowledge of copper cross sections is crucial. The presented paper deals with a validation of different copper transport libraries by means of activation of selected samples. An intense 252Cf(sf) source with a reference neutron spectrum was used as a neutron source. After irradiation, the samples were measured using a high purity germanium detector and the dosimeter reaction rates were inferred. These experimental data were compared with MCNP6 calculations using CENDL-3.1, JENDL-4.0, ENDF/B-VII.1, ENDF/B-VIII.0, JEFF-3.2 and JEFF-3.3 evaluated Cu transport libraries. The experiment specifically focuses on 58Ni(n,p)58Co, 93Nb(n,2n)92mNb, 197Au(n,g)198Au and 55Mn(n,g)56Mn dosimetry reactions. Evaluated activation cross sections of these dosimetric reactions were taken from the IRDFF-II library. The best library performance depends on the energy region of interest.

Activation cross sections of deuteron-induced reactions on praseodymium up to 24 MeV

We measured activation cross sections of deuteron-induced reactions on 141Pr. The production cross sections of 141,140Nd, 142Pr, and 139Ce were determined up to 24 MeV using the stacked-foil activation technique and high-resolution γ-ray spectrometry. The derived cross sections were compared with experimental data studied earlier and theoretical model calculations. Our results are consistent with part of the previous data.

Investigation of cross sections of deuteron induced nuclear reactions on selenium up to 50 MeV

In the frame of a systematic study of deuteron induced nuclear reactions on all elements, activation cross sections on ^{mathrm {nat}}Se were investigated. Excitation functions were measured up to 50 MeV particle energy for production of ^{mathrm {82}}Br(m+),^{mathrm {80m}}Br, ^{mathrm {77}}Br(m+),^{mathrm {76}}Br(m+), ^{mathrm {75}}Br, ^{mathrm {75}}Se(cum), ^{mathrm {73}}Se(cum), ^{mathrm {76}}As,^{mathrm {74}}As, ^{mathrm {73}}As(cum), ^{mathrm {72}}As and ^{mathrm {71}}As(cum) by using the activation method through stacked foil irradiation followed by off-line gamma-ray spectrometry. The experimental results were compared to the earlier experimental data and to excitation functions calculated with the ALICE-D and EMPIRE-D theoretical model codes and data given in the TENDL-2019 on-line library based on TALYS calculations.

Towards using secondary gamma-rays from proton-induced radioactivation of titanium implants for off-line field verification

This experimental study investigates the radioactivation of titanium during proton therapy. Titanium is a commonly used material for implants. Because of its fixed position, the activation of those implants might be useful for post-irradiation field. Various titanium samples are irradiated at the West German Proton Therapy Centre Essen. The activities of the produced radionuclides are obtained with a low-level gamma-ray spectrometry system at the Dortmund Low Background Facility. Furthermore, an irradiated titanium sample is placed in a pre-clinic PET/CT scanner to investigate the potential of the implants for range verification. With the gamma-ray spectrometry technique a number of radionuclides are identified as candidates for range verification with delayed secondary gamma-rays. Furthermore, activation cross sections are calculated with the activities for the identified radionuclides. The depth distribution of the activity as obtained with the PET/CT scans has a characteristic rise towards the distal end similar to the depth dose curve.

Activation cross section data of deuteron induced nuclear reactions on rubidium up to 50 MeV

Activation cross sections of the ^{mathrm {nat}}hbox {Rb (d,xn)}^{87mathrm {m,85m,85g,83,82}}hbox {Sr}, ^{mathrm {nat}}hbox {Rb(d,x)}^{mathrm {86,84,83,82m}}hbox {Rb} and ^{mathrm {nat}}hbox {Rb(d,x)}^{85mathrm {m}}hbox {Kr} nuclear reactions have been measured for the first time through an activation method combining the stacked foil irradiation technique and gamma-ray spectrometry. The provided cross sections from the present investigation are all new, in such a way contribute to the completeness of the experimental database. The experimental cross sections were compared with the theoretical prediction in the TENDL-2019 TALYS based library and with our calculation using ALICE-D and EMPIRE-D model codes in order the improve their predictivity. Thick target production yields were calculated form the new cross sections for all investigated radioisotopes. Practical applications of the results are shortly discussed.

Cosmogenic activation of silicon

The production of $^{3}$H, $^{7}$Be, and $^{22}$Na by interactions of cosmic-ray particles with silicon can produce radioactive backgrounds in detectors used to search for rare events. Through controlled irradiation of silicon CCDs and wafers with a neutron beam that mimics the cosmic-ray neutron spectrum, followed by direct counting, we determined that the production rate from cosmic-ray neutrons at sea level is ($112 \pm 24$) atoms/(kg day) for $^{3}$H, ($8.1 \pm 1.9 $) atoms/(kg day) for $^{7}$Be, and ($43.0 \pm 7.1 $) atoms/(kg day) for $^{22}$Na. Complementing these results with the current best estimates of activation cross sections for cosmic-ray particles other than neutrons, we obtain a total sea-level cosmic-ray production rate of ($124 \pm 24$) atoms/(kg day) for $^{3}$H, ($9.4 \pm 2.0 $) atoms/(kg day) for $^{7}$Be, and ($49.6 \pm 7.3 $) atoms/(kg day) for $^{22}$Na. These measurements will help constrain background estimates and determine the maximum time that silicon-based detectors can remain unshielded during detector fabrication before cosmogenic backgrounds impact the sensitivity of next-generation rare-event searches.

Investigation of activation cross-sections of deuteron induced reactions on ruthenium up to 50 MeV

The activation cross sections of deuteron induced reactions on natural ruthenium have been measured up to 50 MeV for production of radioisotopes of rhodium (105Rh, 102mRh,102gRh,101mRh,101gRh, 100gRh, 99mRh, 99gRh), ruthenium (105Ru,103Ru (cum), 102Ru (cum), 97Ru (cum), 95Ru (cum)) and of technetium (99mTc, 96gTc (m+), 95mTc (cum), 95gTc (cum), 94gTc,93gTc (m+)). The results are compared with the predictions of the most common theoretical nuclear reaction model codes (ALICE-D, EMPIRE-D and TALYS (TENDL)). From the measured cross section physical yields have been calculated for all measured radioisotopes. The medically important radioisotopes are discussed from the point of view of production routes by charged particle methods and other alternatives.

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.

Production cross sections of 45Ti in the deuteron-induced reaction on 45Sc up to 24 MeV

Activation cross sections of the medically interesting radionuclide 45Ti were investigated in the deuteron-induced reaction on 45Sc. 45Ti can be produced in a radioactive-contamination-free form in the 45Sc(d,2n)45Ti reaction below 15 MeV deuteron energy. The stacked foil activation technique and γ-ray spectrometry were used to determine the cross sections. The physical yield of 45Ti was deduced from the measured cross sections.

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.

High precision half-life measurement of ^{95}hbox {Ru}, ^{95}hbox {Tc} and ^{95m}hbox {Tc} with gamma -spectroscopy

The precise knowledge of the half-life of the reaction product is of crucial importance for a nuclear reaction cross section measurement carried out with the activation technique. The cross section of the ^{92}hbox {Mo}(alpha ,n)^{95}hbox {Ru} reaction was measured recently using this experimental approach. The preliminary results indicated that the literature half-life of ^{95}hbox {Ru}, derived about half a century ago, is overestimated. Therefore, the half-lives of ^{95}hbox {Ru} and its daughter isotope ^{95}hbox {Tc} and ^{95m}hbox {Tc} have been measured with high precision using gamma -spectroscopy. The results are hbox {t}_{1/2} =1.6033 pm 0.0044 h for ^{95}hbox {Ru}, hbox {t}_{1/2} =19.258 pm 0.026 h for ^{95}hbox {Tc} and hbox {t}_{1/2} =61.96 pm 0.24 d for ^{95m}hbox {Tc}. The precision of the half-life values has been increased, consequently the recently measured ^{92}hbox {Mo}(alpha ,n)^{95}hbox {Ru} activation cross section will become more precise.