Flux-weighted Average Cross-sections Research Articles

A method of determining the bremsstrahlung flux-weighted average photonuclear cross section

Based on a developed analytical model, a method is proposed for measuring the photonuclear cross section averaged over bremsstrahlung flux without application of additional target-monitor of photon flux. The method involves the use of a thin isotopic target, that completely overlaps the photon beam (a photonuclear converter), as well as an algorithm for processing the data on the yield of a reaction under study in such a target. The novel technique was validated on the reactions 100Mo(γ,n)99Mo and 58Ni(γ,n)57Ni in the range of photon end-point energy of 40.7–93.9 MeV. The photon flux-weighted average cross sections of the reactions measured experimentally are in good agreement with Monte Carlo simulations and TALYS predictions on their excitation functions.

Research on natAg(γ,xn)103-106Ag reaction cross sections with the bremsstrahlung end-point energy of 70 and 75 MeV

The flux-weighted average cross sections of natAg(γ,xn)103-106Ag reactions were measured with the bremsstrahlung end-point energy of 70 and 75 MeV using an activation and off-line γ-ray spectrometric technique. The GEANT4 code was used for the simulation of the bremsstrahlung spectra. The cross sections of natAg(γ,xn) 103-106Ag reactions as a function of mono-energetic photons were theoretically calculated by using the TALYS-1.96 code. The data of the present work and literature at different bremsstrahlung end-point energy are found to be in agreement with the theoretical values within the uncertainty limit. It can be seen that the flux-weighted average cross sections of the natAg(γ,xn)105.106Ag reactions increase with bremsstrahlung energy up to the Giant Dipole Resonance region. Thereafter, a small decrease trend with the bremsstrahlung energy was seen due to the opening of another reaction channel.

New measurements of 92Mo(γ, n) and (γ, 3n) reactions using laser-driven bremsstrahlung γ-ray

The flux-weighted average cross sections and isomeric ratios of 92Mo(γ, n)91m,gMo and 92Mo(γ, 3n)89Mo reactions were measured through activation methods. Laser-driven bremsstrahlung γ-ray were generated by the laser wakefield accelerated quasi-monoenergetic electrons using the 200 TW laser in the Compact Laser Plasma Accelerator laboratory, Peking University. The results showed good agreements with previous works using traditional γ-ray sources, and were compared with TALYS 1.9 calculations. We extended the experimental results of 92Mo photonuclear reactions to higher energies, the experimental discrepancies of 92Mo(γ, n)91m,gMo isomeric ratios at high energy region were clarified, and the cross sections of 92Mo(γ, 3n)89Mo reaction were first obtained.

Investigation of photonuclear reactions on isotopes 51V, natCu, natMo, 115In and 207Pb at photon energy Eγmax= 20–70 MeV

The targets with masses in range of 51–207 a.u. have been exposed to the bremsstrahlung photon beam of the electron linear accelerator of AANL (Yerevan Physics Institute). Yields of (γ, α), (γ, αxn) and (γ, xpyn) reactions have been measured at the maximum bremsstrahlung photon energy of 20, 30, 40 and 70 MeV. The yields and the flux-weighted average cross sections of a number of the reactions were compared with the results of calculation in the frames of the TALYS-1.9 model. Agreement between the calculated and experimental data was obtained within a factor of two.

Measurements of natCd(γ, x) reaction cross sections and isomer ratio of 115m,gCd with the bremsstrahlung end-point energies of 50 and 60 MeV * *Supported by the National Research Foundation of Korea (NRF) through a grant provided by the Ministry of Science and ICT (NRF-2017R1D1A1B03030484, NRF-2013M7A1A1075764, NRF-2018R1A6A1A06024970)

The flux-weighted average cross sections of natCd(γ, xn)115g,m,111m,109,107,105,104Cd and natCd(γ, x)113g,112,111g,110mAg reactions were measured at the bremsstrahlung end-point energies of 50 and 60 MeV. The activation and off-line γ-ray spectrometric technique was carried out using the 100 MeV electron linear accelerator at the Pohang Accelerator Laboratory, Korea. The natCd(γ, xn) reaction cross sections as a function of photon energy were theoretically calculated using the TALYS-1.95 and the EMPIRE-3.2 Malta codes. Then, the flux-weighted average cross sections were obtained from the theoretical values of mono-energetic photons. These values were compared with the flux-weighted values from the present study and were found to be in general agreement. The measured experimental reaction cross-sections and integral yields were described for cadmium and silver isotopes in the natCd(γ, xn)115g,m,111m,109,107,105,104Cd and natCd(γ, x)113g,112,111g,110mAg reactions. The isomeric yield ratio (IR) of 115g,mCd in the natCd(γ, xn) reaction was determined for the two bremsstrahlung end-point energies. The measured isomeric yield ratios of 115g,mCd in the natCd(γ, xn) reaction were also compared with the theoretical values of the nuclear model codes and previously published literature data of the 116Cd(γ, n) and 116Cd(n, 2n) reactions. It was found that the IR value increases with increasing projectile energy, which demonstrates the characteristic of excitation energy. However, the higher IR value of 115g,mCd in the 116Cd(n, 2n) reaction compared to that in the 116Cd(γ, n) reaction indicates the role of compound nuclear spin alongside excitation energy.

Investigation of Flux-Weighted Average Cross Sections for Reactions on $${}^{{93}}$$Nb with Bremsstrahlung of LUE-75

Investigation of Flux-Weighted Average Cross Sections for Reactions on $${}^{{93}}$$Nb with Bremsstrahlung of LUE-75

Photo-neutron cross-section of $${}^{{\mathrm {nat}}}{\mathrm {Dy}}$$ in the bremsstrahlung end-point energies of 12, 14, 16, 65, and 75 MeV

The flux-weighted average cross-sections of $${}^{\mathrm {nat}}{\mathrm {Dy}}(\upgamma , {\mathrm {xn}}){}^{{159,157,155}}{\mathrm {Dy}}$$ reactions were measured at the bremsstrahlung end-point energies of 12, 14, 16, 65 and 75 MeV with the activation and off-line $$\upgamma $$ -ray spectrometric technique using the 20 MeV Electron Linac for beams with high Brilliance and low Emittance (ELBE) at Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany and the 100 MeV electron linac at the Pohang Accelerator Laboratory, Korea. The $${}^{\mathrm {nat}}{\mathrm {Dy}}(\upgamma , {\mathrm {xn}}){}^{{157,155}}{\mathrm {Dy}}$$ reaction cross-sections as a function of photon energy were also calculated theoretically using TALYS 1.9 code. Then the flux-weighted average values at different end-point energies were obtained based on the theoretical values of mono-energetic photons. These values were compared with the flux-weighted values of present work and are found to be in general agreement. It was also found that the experimental and theoretical formation cross sections of $${}^{159}{\mathrm {Dy}}$$ , $${}^{157}{\mathrm {Dy}}$$ and $${}^{155}{\mathrm {Dy}}$$ from the $${}^{\mathrm {nat}}{\mathrm {Dy}}(\upgamma , {\mathrm {xn}})$$ reactions increased from their respective threshold values to a certain energy where other reaction channels opened. After reaching a maximum value, the individual reaction cross-sections slowly decreased with the increase of the bremsstrahlung energy due to the initiation of other competing reactions at higher energy, which indicates the impact of the excitation energy. However, the production cross sections of $${}^{157}{\mathrm {Dy}}$$ and $${}^{155}{\mathrm {Dy}}$$ from the $${}^{\mathrm {nat}}{\mathrm {Dy}}(\upgamma , {\mathrm {xn}})$$ reactions slightly increase in between and then decreased slowly with bremsstrahlung energy, which is due to the contributing reactions of higher mass isotopes.

Production cross-sections of Mo-isotopes induced by fast neutrons based on the 9Be(p, n) reaction

We measured the flux-weighted average cross-sections of the 100Mo(n, 2n)99Mo and 92Mo(n, 3n)90Mo reactions with the average neutron energies between 14.0- and 31.8-MeV by using an activation and off-line γ-ray spectrometric technique. The fast neutrons were generated based on the 9Be(p, n) reaction with the proton energies of 25-, 35- and 45-MeV from the MC-50 Cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). The neutron flux was measured by using the 27Al(n, α)24Na monitor reaction, whereas the neutron spectra were simulated by using the MCNPX 2.6.0 code. The theoretical cross-sections of the 100Mo(n, 2n)99Mo and 92Mo(n, xn)91.90,89Mo reactions as a function of mono-energetic neutron were calculated by using the TALYS-1.9 code. The present results for the 100Mo(n, 2n)99Mo and 92Mo(n, 3n)90Mo reactions are compared with the calculated neutron flux-weighted average values based on the literature data and theoretical cross-sections as a function of mono-energetic neutron energy, and show a good agreement.

Excitation of 177,178Lu in reactions with bremsstrahlung with escaping of charged particles

Isomeric yields ratio and flux-weighted average cross-sections of 177Lum,g in (γ,α)- and 178Lum,g in (γ,pn)-reactions were determined for the first time for the bremsstrahlung end-point energies of 37 and 55 MeV, properly by activation and off-line γ-ray spectrometric technique. The results of modeling in the framework of the EMPIRE-3.2 code demonstrate the dominance of non-statistical processes.

Photo-neutron reaction cross-sections of 59Co in the bremsstrahlung end-point energies of 65 and 75 MeV

The flux-weighted average cross-sections for the 59Co($ \gamma$, xn)58-55Co reactions have been measured with the bremsstrahlung end-point energies of 65 and 75 MeV by using the activation method in combination with the off-line $ \gamma$-ray spectrometry. The measured cross-sections for the $ (\gamma,\mathrm{n})$, $ (\gamma,2\mathrm{n})$, $ (\gamma,3\mathrm{n})$ and $ (\gamma,4\mathrm{n})$ reactions of 59Co at 65 MeV are $ 15.828\pm 0.491$, $ 5.003\pm 0.206$ , $ 0.408\pm 0.047$ and $ 0.039\pm 0.008$ mb, whereas at 75 MeV are $ 15.653\pm 0.361$, 4.965±0.289, $ 0.389\pm 0.062$ and $ 0.036\pm 0.007$ mb, respectively. The 59Co($ \gamma$, xn) reaction cross-sections as a function of photon energy were also theoretically simulated by using TALYS 1.9 code. Then the flux-weighted average cross-sections at different bremsstrahlung energies were obtained from the theoretical values and the literature data at lower energy based on mono-energetic photons. The present data are measured for the first time and are found to be in good agreement with the theoretical flux-weighted average values. It was found that the 59Co($ \gamma$, xn)58-55Co reaction cross-sections increase from their threshold values to a certain bremsstrahlung energy. After a certain energy, the individual 59Co($ \gamma$, xn) reaction cross-sections decrease with the increase of bremsstrahlung energy due to opening of other reaction channels. These two observations indicate the role of excitation energy and its partition in different reaction channels. All the four cobalt isotopes produced from the 59Co($ \gamma$, xn) reactions have medical and other applications.

Flux-weighted average cross sections of medical isotopes in the 127I(γ,xn) reactions with the bremsstrahlung end-point energies of 50 and 70MeV

The flux-weighted average cross sections of 127I(γ,xn)126,124,123I reactions were experimentally determined with the bremsstrahlung end-point energies of 50 and 70 MeV by activation and off-line γ-ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory, Korea. The 127I(γ,xn)126−121I reaction cross sections as a function of photon energy were theoretically calculated using the TALYS 1.8 code. The flux-weighted average cross sections of 127I(γ, xn)126,124,123I reactions as a function of bremsstrahlung end-point energies were also obtained from the literature and TALYS data based on mono-energetic photons and are found to be in close agreement with the present data. The experimental and theoretical 127I(γ, xn)126−121I reaction cross-sections increase with bremsstrahlung energy, which indicates the role of excitation energy. After a certain energy, the individual 127I(γ, xn)126−121I reaction cross sections decrease with increase of bremsstrahlung energy due to opening of other reactions, which indicates sharing of energy in different reaction channels. The radioactive iodine isotopes production cross-sections are important for the useful medical purpose.

Excitation of 179Hfm2 with (γ,n)-reaction

Isomeric yields ratio, the integral and flux-weighted average cross-sections of 179m2Hf population were determined for the first time in (γ,n)-reaction for the bremsstrahlung end-point energies of 14.5 and 14.8 MeV by activation and off-line γ-ray spectrometric technique. The results of modeling in the framework of the TALYS-1.6 and EMPIRE-3.2 codes demonstrate the dominance of non-statistical processes.

Population cross-section of 179m2Hf from the reactions on hafnium and tantalum targets

The integral and flux-weighted average cross-sections of the 180Hf(γ,n)179m2Hf and 181Ta(γ,pn(d))179m2Hf reactions for the bremsstrahlung end-point energy of 37 MeV were determned by activation and off-line γ-ray spectrometric technique. Also by this techinque, the cross-section of the 178Hf(nr,γ)179m2Hf reaction was determined for reactor neutrons.

Flux weighted average cross-sections of natNi(γ, x) reactions with the bremsstrahlung end-point energies of 55, 59, 61 and 65 MeV

We measured the flux weighted average cross-sections of the natNi(γ,xn)56,57Ni and natNi(γ, pxn)55,56,57,58Co reactions with the bremsstrahlung end-point energies of 55, 59, 61 and 65 MeV by using an activation cum off-line γ-ray spectrometric technique at the Pohang Accelerator Laboratory (PAL), Korea. The natNi(γ, xn) and natNi(γ, pxn) reaction cross-sections as a function of monoenergetic photon were calculated theoretically by using the computer code TALYS-1.8. The flux-weighted average cross-sections of the natNi(γ, xn) and natNi(γ, pxn) reactions from the present work were compared with the similar data from the literature as well as the theoretical values from the TALYS-1.8 code and the TENDL-2015 data library. Both the experimental and theoretical values increase sharply from the reaction threshold to a maximum value where the next reaction channel opens. After the maximum value, individual reaction cross section decreases slowly with increase of bremsstrahlung end-point energy, which may be due to the opening of other possible reaction channels.

Neutron-induced reaction cross-sections of 93Nb with fast neutron based on 9Be(p,n) reaction

The cross-sections of the 93Nb(n,2n)92mNb, 93Nb(n,3n)91mNb and 93Nb(n,4n)90Nb reactions with the average neutron energies of 14.4 to 34.0 MeV have been determined by using an activation and off-line γ-ray spectrometric technique. The fast neutrons were produced using the 9Be(p,n) reaction with the proton energies of 25-, 35- and 45-MeV from the MC-50 Cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS). The neutron flux-weighted average cross-sections of the 93Nb(n,xn;x=2–4) reactions were also obtained from the mono-energetic neutron-induced reaction cross-sections of 93Nb calculated using the TALYS 1.8 code, and the neutron flux spectrum based on the MCNPX 2.6.0 code. The present results for the 93Nb(n,xn;x=2–4) reactions are compared with the calculated neutron flux-weighted average values and found to be in good agreement.

Measurement of photo-neutron cross sections and isomeric yield ratios in the 89Y(γ,xn)89−x Y reactions at the bremsstrahlung end-point energies of 65, 70 and 75 MeV

Abstract The flux-weighted average cross sections of the 89Y(γ,xn; x=1–4)89−x Y reactions and the isomeric yield ratios of the 87m,gY, 86m,gY, and 85m,gY radionuclides produced in these reactions with the bremsstrahlung end-point energies of 65, 70 and 75 MeV have been determined by an activation and off-line γ-ray spectrometric technique using the 100 MeV electron linac in Pohang Accelerator Laboratory, Korea. The theoretical 89Y(γ,xn; x=1–4)89−x Y reactioncross sections for mono-energetic photonshave been calculated using the computer code TALYS 1.6. Then the flux-weighted theoretical values were obtaind to compare with the present data. The flux-weighted experimental and theoretical 89Y(γ,xn; x=1–4)89−x Y reaction cross sections increase very fast from the threshold values to a certain bremsstrahlung energy, wherethe other reaction channels open up. Thereafter it remains constant a while and then slowly decreases with the increase of cross sections for other reactions. Similarly, the isomeric yield ratios of 87m,gY,86m,gY and 85m,gY in the 89Y(γ,xn; x=2–4)89−x Y reactions from the present work and literature data show an increasing trend from their respective threshold values to a certain bremsstrahlung energy. After a certain point ofenergy, the isomeric yield ratios increase slowly with the bremsstrahlung energy. These observations indicate the role of excitation energy and its partitioning in different reaction channels.

Measurement of flux-weight average cross-sections of natZn(γ,xn) reactions in the bremsstrahlung end-point energies of 50, 55, 60, and 65 MeV

The flux-weighted average cross-sections of (γ,xn) reactions on natZn induced by the bremsstrahlung end-point energies of 50, 55, 60, and 65 MeV have been determined by activation and off-line γ-ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The theoretical photon-induced reaction cross-sections of natZn as a function of photon energy were taken from TENDL-2014 nuclear data library based on TALYS 1.6 program. The flux-weighted average cross-sections were obtained from the literature data and the theoretical values of TENDL-2014 based on mono-energetic photon. The flux-weighted reaction cross-sections from the present work and literature data at different bremsstrahlung end-point energies are in good agreement with the theoretical values. It was found that the individual natZn(γ,xn) reaction cross-sections increase sharply from reaction threshold to certain values where the next reaction channel opens. There after it remains constant for a while, where the next reaction channel increases. Then it decreases slowly with increase of bremsstrahlung end-point energy due to opening of different reaction channels.

Determination of flux-weighted average cross-sections of natPb( $\gamma$ γ ,xn), 208Pb( $\gamma$ γ ,xn), and 209Bi( $\gamma$ γ ,xn) reactions using bremsstrahlung end-point energies of 50-70 MeV

The flux-weighted average cross-sections of the natPb(\(\gamma\),xn)198-204Pb reaction for the bremsstrahlung end-point energies of 50-70MeV were determined by activation and off-line \( \gamma\) -ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory (PAL), Korea. The relative cross-sections of the 208Pb(\(\gamma\),xn)202-204Pb and 209Bi(\(\gamma\),xn)203-206Bi reactions from our earlier work were updated to absolute values and compared with the present data. The photo-neutron cross-sections of natPb, 208Pb, and 209Bi were also calculated, as a function of the photon energy using the TALYS 1.6 code. The flux-weighted average cross-sections were obtained from the theoretical values of the TALYS 1.6 code, based on mono-energetic photons, and compared with the present experimental data. The values were found to be in good agreement with the present data for the 209Bi(\(\gamma\),xn)203-206Bi, 208Pb(\(\gamma\),xn)202-204Pb, and natPb(\(\gamma\),xn)198-202Pb reactions. However, the present data for the natPb(\(\gamma\),xn)203, 204Pb reactions were higher than the flux-weighted values obtained using the TALYS 1.6 code.

Measurement of flux-weighted average cross-sections and isomeric yield ratios for 103Rh( $\gamma$ ,xn) reactions in the bremsstrahlung end-point energies of 55 and 60 MeV

We measured the flux-weighted average cross-sections and the isomeric yield ratios of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( $ \gamma$ , xn) reactions with the bremsstrahlung end-point energies of 55 and 60MeV by the activation and the off-line $ \gamma$ -ray spectrometric technique, using the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Korea. The flux-weighted average cross-sections were calculated by using the computer code TALYS 1.6 based on mono-energetic photons, and compared with the present experimental data. The flux-weighted average cross-sections of 103Rh( $ \gamma$ , xn) reactions in intermediate bremsstrahlung energies are the first time measurement and are found to increase from their threshold value to a particular value, where the other reaction channels open up. Thereafter, it decreases with bremsstrahlung energy due to its partition in different reaction channels. The isomeric yield ratios (IR) of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( $ \gamma$ , xn) reactions from the present work were compared with the literature data in the 103Rh(d, x), 102-99Ru(p, x) , 103Rh( $ \alpha$ , $ \alpha$ n) , 103Rh( $ \alpha$ , 2p3n) , 102Ru(3He, x), and 103Rh( $ \gamma$ , xn) reactions. It was found that the IR values of 102, 101, 100, 99Rh in all these reactions increase with the projectile energy, which indicates the role of excitation energy. At the same excitation energy, the IR values of 102, 101, 100, 99Rh are higher in the charged particle-induced reactions than in the photon-induced reaction, which indicates the role of input angular momentum.

Photo-neutron reaction cross-sections for natMo in the bremsstrahlung end-point energies of 12-16 and 45-70 MeV

The natZr(\(\gamma\), xn) 89-86Zr reaction cross-sections were experimentally determined at the bremsstrahlung end-point energies of 12, 14, 16, 45, 50, 55, 60 and 70MeV by activation and off-line \(\gamma\)-ray spectrometric technique using the 20 MeV electron linac (ELBE) at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, and the 100 MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The natZr(\(\gamma\), xn) 89-86Zr reaction cross-sections as a function of photon energy were also calculated using the TALYS 1.4 computer code. The flux-weighted average cross-sections at the end-point energies of 12-16 and 45-70 MeV were obtained using the literature and the TALYS calculation data based on mono-energetic photons and are found to be in good agreement with the present data. It was also found that the present data and the flux-weighted literature and theoretical values for the natZr(\(\gamma\), xn) 89-86Zr reaction cross-sections increase from the threshold values to a certain energy, where other reaction channels open. This indicates the role of excitation energy. However, the increasing trend of the natZr(\(\gamma\), xn) 89,88Zr reaction cross-sections are sharper from the threshold value up to end-point bremsstrahlung energies of 17-22 MeV compared to the same for the natZr(\(\gamma\), xn) 87, 86Zr reactions. This is due to the Giant Dipole Resonance (GDR) effect besides the role of excitation energy. After a certain value, the individual natZr(\(\gamma\), xn) reaction cross-sections decrease with the increase of bremsstrahlung energy due to opening of other reactions, which indicates partitioning of energy in different channels.