Off-line Γ-ray Spectrometric Technique Research Articles

Measurement of the cross-sections of the 106m,gAg, 105gAg, and 104m,gAg from the natAg(n, x) reactions induced by neutrons with the energies of 14–37 MeV

The natAg(n, xn)106m,g,104m,g,105gAg reaction cross-sections within the neutron energies of 14–37 MeV were determined by using an activation and off-line γ-ray spectrometric technique. The quasi-mono energetic neutron beams were produced from the 9Be(p, xn)9B reaction by using the proton beams of 25, 35, and 45 MeV at the Korean Institute of Radiological and Medical Sciences, Korea. Monte Carlo simulation code MCNPX was used to simulate the neutron energy spectra, whereas the theoretical cross-sections were calculated using the TALYS 1.8 code. The experimental and theoretical reaction cross-sections show similar trends from lower to higher neutron energy. The isomeric cross-section ratios of 104m,gAg and 106m,gAg for the natAg(n, xn) reactions were also obtained from the experimental values of present work and compared with the literature data.

Charge distribution of light mass fission products in the fast neutron induced fission of 232Th, 238U, 240Pu and 244Cm

Fractional cumulative yields (FCY) of various light mass fission products in the fast neutron induced fission of 232Th, 238U, 240Pu and 244Cm have been determined by using the off-line γ-ray spectrometric technique. From present and literature data, width of isobaric charge distribution (σZ), the most probable charge (ZP) and the experimental charge polarization (∆ΖEXPT) as a function of fragment mass were deduced. The ∆ΖEXPT values from the present work for light mass chains and earlier work for heavy mass chains show oscillating nature due to nuclear structure effect. The ∆ΖMPE values based on minimum potential energy surface were theoretically calculated, which shows a systematic decrease trend with the approach of symmetric split due to the liquid drop behaviour of the fissioning nucleus.

Measurement of [formula omitted] reaction cross-section within the proton energy range of 3.38 to 19.63 MeV

The Fe58(p,n)Co58 reaction cross-section within Giant Dipole Resonance (GDR) region i.e. from 3.38 to 19.63 MeV was measured by stacked-foil activation and off-line γ-ray spectrometric technique using the BARC-TIFR Pelletron facility at Mumbai. The present data were compared with the existing literature data and found to be in good agreement. The Fe58(p,n)Co58 reaction cross-section as a function of proton energy was also theoretically calculated by using the computer code TALYS-1.8 and found to be in good agreement, which shows the validity of the TALYS-1.8 program.

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.

Measurement of excitation functions of the natAg(α,x) reactions up to 45 MeV

We measured excitation functions for the production of the 108m,108g,109g,110m,110g,111gIn, the 109g,111mCd, and the 105g,106m,110m,111gAg in alpha-induced reactions on natAg in the energy range from their respective threshold to 45 MeV by using a stacked-foil activation and off-line γ-ray spectrometric technique. The present data were compared with the literature data and the theoretical values obtained from the TENDL-2015 library based on the TALYS-1.8 code. The integral yields for a thick target of the investigated radionuclides were also obtained from their measured cross sections and the stopping power. The measured excitation functions play important roles in various applications such as medical and industrial radioisotope production as well as for the improvement of nuclear model calculations.

Determination of 55Mn(n,γ)56Mn reaction cross-section at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

Abstract The 55Mn(n,γ)56Mn reaction cross-sections at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV were determined by using activation and off-line γ-ray spectrometric technique. The neutron energies of 1.12 and 2.12 MeV were generated from the 7Li(p,n) reaction by using the proton energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at BARC. For the neutron energies of 3.12 and 4.12 MeV, the proton energies used were 5 and 6 MeV from the Pelletron facility at TIFR, Mumbai. The 115In(n,γ)116mIn reaction cross-section was used as the neutron flux monitor. The 55Mn(n,γ)56Mn reaction cross-section at the neutron energies of 4.12 MeV are reported for the first time, whereas at 1.12, 2.12 and 3.12 MeV, they are in between the literature data. The 55Mn(n,γ)56Mn reaction cross-section was also calculated theoretically by using the computer code TALYS 1.6 and EMPIRE 3.2.2. The experimental data of present work are found to be in between the theoretical values of TALYS and EMPIRE.

Measurement of fission products yields in the quasi-mono-energetic neutron-induced fission of 232Th

The cumulative yields of various fission products in the 232Th(n, f) reaction at average neutron energies of 5.42, 7.75, 9.35 and 12.53 MeV have been determined by using an off-line γ-ray spectrometric technique. The neutron beam was produced from the 7Li(p, n) reaction by using the proton energies of 7.8, 12, 16 and 20 MeV. The mass chain yields were obtained from the cumulative fission yields by using the charge distribution correction of medium energy fission. The fine structure in the mass yield distribution was interpreted from the point of nuclear structure effect. On the other hand, the higher yield around mass number 133–134 and 143–144 as well as their complementary products were explained based on the standard I and standard II asymmetric mode of fission. From the mass yield data, the average value of light mass (〈AL〉), heavy mass (〈AH〉), the average number of neutrons (〈ν〉) and the peak-to-valley (P/V) ratios at different neutron energies of present work and literature data were obtained in the 232Th(n, f) reaction. The different parameters of the mass yield distribution in the 232Th(n, f) reaction were compared with the similar data in the 232Th(γ, f) reaction at comparable excitation energy and a surprising difference was observed.

Measurement of flux-weighted average cross sections for 197Au(γ, xn) reactions and isomeric yield ratios of 196m,gAu with bremsstrahlung

Photo-neutron cross sections of 197Au were experimentally determined for the bremsstrahlung end-point energies of 50, 60, and 70 MeV, by utilizing activation and off-line γ-ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The 197Au(γ, xn; x=1–6) reaction cross sections were calculated as a function of the bombarding photon energy by using the TALYS 1.6 computer code with default parameters. The flux-weighted average cross sections were obtained from the literature data and the theoretical values of TALYS 1.6 and TENDL-2014, for mono-energetic photons, and are found to be in good agreement with the present data. Isomeric yield ratios of 196m2,gAu from the 197Au(γ, n) reaction were also determined for the bremsstrahlung end-point energies of 50, 60, and 70 MeV, from the reaction cross sections of m2- and g-states, based on the present experimental data, and are found to be in good agreement with the theoretical values based on TALYS 1.6 and TENDL-2014.

Preparation of 99Mo from the 100Mo(γ, n) reaction and chemical separation of 99mTc

The radionuclide 99Mo has been prepared by 100Mo(γ, n) reaction using two types of natural molybdenum compound (molybdenum trioxide and zirconium molybdate gel) with the bremsstrahlung end-point energies of 10 and 15 MeV. After the equilibrium, 99mTc was separated as NaTcO4 from the irradiated samples using two different chemical procedures to examine the chemical yield. The separated Na[99mTc]TcO4 from the ZrMo gel has the 99Mo breakthrough of 99 % as well as chemical impurities of Al, Mo and Zr < 10 ppm. The estimation of 99Mo and 99mTc was done by using off-line γ-ray spectrometric technique. The chemical yield of the separated 99mTc from the dissolved molybdenum trioxide is 70.7–75.2 %, whereas in the undissolved zirconium molybdate gel, it is 19.1–43 %. The second method is preferable because it is user friendly in hospital radiopharmacy throughout the shelf-life.

Measurement of 197Au(n,γ)198gAu reaction cross-section at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

Abstract The 197Au(n, γ)198Au reaction cross-sections at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV were determined by using activation and off-line γ-ray spectrometric technique. The mono-energetic neutron energies of 1.12–4.12 MeV were generated from the 7Li(p, n) reaction by using the proton energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at BARC as well as 5 and 6 MeV from the Pelletron facility at TIFR, Mumbai. The 115In(n,γ)116mIn reaction cross-section was used as the neutron flux monitor. The 197Au(n, γ)198Au reaction cross-section at the neutron energies of 3.12 and 4.12 MeV are reported for the first time. The 197Au(n, γ)198Au reaction cross-sections at 1.12 and 2.12 MeV are close to the literature data of in between neutron energies. The 197Au(n, γ)198Au cross-section was also calculated theoretically by using the computer code TALYS 1.6 and found to be higher than the experimental data of present work and literature data within the neutron energies of 0.8 to 4 MeV.

Measurement of the 115In(n,γ)116m In reaction cross-section at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

The 115In(n,γ)116m In reaction cross section at neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV was determined by using an activation and off-line γ-ray spectrometric technique. The monoenergetic neutron energies of 1.12 − 4.12 MeV were generated from the 7Li(p,n) reaction by using proton beam with energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at Bhabha Atomic Research Centre (BARC) and with energies of 5 and 6 MeV from the Pelletron facility at Tata Institute of Fundamental Research (TIFR), Mumbai. The 197Au(n,γ)198Au reaction cross-section was used as the neutron flux monitor.The 115In(n,γ)116m In reaction cross section at neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV was determined by using an activation and off-line γ-ray spectrometric technique. The monoenergetic neutron energies of 1.12 − 4.12 MeV were generated from the 7Li(p,n) reaction by using proton beam with energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at Bhabha Atomic Research Centre (BARC) and with energies of 5 and 6 MeV from the Pelletron facility at Tata Institute of Fundamental Research (TIFR), Mumbai. The 197Au(n,γ)198 Au reaction cross-section was used as the neutron flux monitor. The 115In(n,γ)116m In reaction cross-sections at neutron energies of 1.12 – 4.12 MeV were compared with the literature data and were found to be in good agreement with one set of data, but not with others. The 115In(n,γ)116m In cross-section was also calculated theoretically by using the computer code TALYS 1.6 and was found to be slightly lower than the experimental data from the present work and the literature.)198Au reaction cross-section was used as the neutron flux monitor. The 115In(n,γ)116m In reaction cross-sections at neutron energies of 1.12 − 4.12 MeV were compared with the literature data and were found to be in good agreement with one set of data, but not with others. The 115In(n,γ)116m In cross-section was also calculated theoretically by using the computer code TALYS 1.6 and was found to be slightly lower than the experimental data from the present work and the literature.

Measurement of activation cross-sections for high-energy neutron-induced reactions of Bi and Pb

The cross-sections for 209Bi(n, 4n)206Bi, 209Bi(n, 5n)205Bi, natPb(n,xn)204mPb, natPb(n,xn)203Pb, natPb(n,xn)202mPb,natPb(n,xn)201Pb, natPb(n,xn)200Pb, natPb(n,αxn)203Hg and natPb(n, pxn)202Tl reactions were determined at the Korean Institute of Radiological and Medical Sciences (KIRAMS), Korea in the neutron energy range of 15.2 to 37.2 MeV. The above cross-sections were obtained by using the activation and off-line γ-ray spectrometric technique. The quasi-monoenergetic neutron used for the above reactions are based on the 9Be(p, n) reaction. Simulations of the spectral flux from the Be target were done using the MCNPX program. The cross-sections were estimated with the TALYS 1.6 code using the default parameter. The data from the present work and literature were compared with the data from the EAF-2010 and the TENDL-2013 libraries, and calculated values of TALYS 1.6 code. It shows that appropriate level density model, the γ-ray strength function, and the spin cut-off parameter are needed to obtain a good agreement between experimental data and theoretical values from TALYS 1.6 code.

151Eu(n,γ)152m1Eu reaction cross-section measurement at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

The 151Eu(n,γ)152m1Eu reaction cross-section at the neutron energies (En) of 1.12, 2.12, 3.12 and 4.12 MeV was determined by using activation and off-line γ-ray spectrometric technique. The mono-energetic neutrons of 1.12–4.12 MeV were generated from the 7Li(p,n) reaction by using the proton beam energies of 3–6 MeV. The 197Au(n,γ)198Au reaction cross-section was used as the neutron flux monitor. The 151Eu(n,γ)152m1Eu reaction cross-section was also calculated by using computer code TALYS 1.6 and compared with the experimental data to check its validity. The Eu(n,γ) reaction cross-section is important for the safety of the fast reactor and conventional fission reactor.

Determination of 110Cd(n,γ)111mCd and 111Cd(n,n′)111mCd reaction cross-sections at the neutron energies of 1.12–4.12 MeV

The 110Cd(n,γ)111mCd and 111Cd(n,n′)111mCd reaction cross-sections at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV were determined for the first time by using activation and off-line γ-ray spectrometric technique. The values from preset work and literature data at other neutron energies are compared with the theoretical values based on TALYS 1.6 and found to be in agreement. The formation cross-section of 111mCd from the (n,γ) and (n,n′) reaction of natCd is important for neutron economy and estimation of dose of the Cd control rod use in the reactor.

Measurement of fission product yields in the quasi-mono-energetic neutron-induced fission of 238U

The cumulative yields of various fission products in the 6.35, 8.53, 9.35 and 12.52 MeV quasi-mono-energetic neutron induced fission of 238U have been determined by using the off-line γ-ray spectrometric technique. The mass chain yields were obtained from the fission product yields by using charge distribution correction. From the mass yield data, the peak-to-valley (P/V) ratio, the average value of light mass (〈AL〉), heavy mass (〈AH〉) and thus the average number of neutrons (〈υ〉expt) were obtained in the 238U(n,f) reaction for the above mentioned four neutron energies. The present and literature data in the 238U(n,f) and 238U (γ,f) reactions at various energies were compared to arrive at the following conclusions. (i) The yields of fission products for A=133–134, A=138–140, and A=143–144 and their complementary products in the 238U(n,f) and 238U(γ,f) reactions are higher than other fission products, which has been explained from the point of even–odd effect and standard I and standard II asymmetric mode of fission. (ii) The yields of symmetric products increase and thus the peak-to-valley (P/V) ratios decrease with excitation energy, whereas the 〈ν〉expt values increase with excitation energy. (iii) The variation of 〈AL〉,〈AH〉 and 〈υ〉expt values with excitation energy behave differently in between 238U(n,f) and 238U(γ,f) reactions, which may be due to the different types of reaction mechanism for the neutron and photon with 238U.

Measurement of isomeric yield ratios in the photo-production of 133m,g;137m,gCe from natCe using 55-, 60-, and 65-MeV bremsstrahlung

The isomeric yield ratios of 133m,gCe and 137m,gCe produced from the natCe(γ,xn) reactions were determined by using the activation and the off-line γ-ray spectrometric technique with the end-point bremsstrahlung energies of 55-, 60-, and 65-MeV at 100-MeV electron linac of the Pohang accelerator laboratory. The induced activities in the irradiated foils were measured by using an energy- and efficiency-calibrated HPGe detector coupled to a PC based multi-channel analyzer. The necessary corrections were made to improve the accuracy of the experimental results. The experimental results at bremsstrahlung energies of 55-, 60-, and 65-MeV were 0.324±0.089, 0.331±0.086, and 0.403±0.089 for the 133m,gCe, and 0.210±0.062, 0.221±0.061, and 0.262±0.061 for the 137m,gCe, respectively. The present results for natCe(γ,xn)133m,g;137m,gCe in this energy region were obtained for the first time which has no comparable literature data. The obtained isomeric yield ratios are compared with the calculated values based on the statistical model code TALYS 1.6.

Excitation function and isomeric ratio of Tc-isotopes from the 93Nb(α, xn) reaction

Abstract The excitation functions of 94–96Tc isotopes and independent isomeric ratios of 93m, gTc, 94m, gTc, and 95m, gTc from the 93Nb(α, xn) reaction within the energy range below 40 MeV have been determined by using a stacked-foil activation and an off-line γ-ray spectrometric technique at the Variable Energy Cyclotron Center, Kolkota, India. The excitation function of 94–96Tc in the 93Nb(α, xn) reaction was also calculated by using the computer code TALYS 1.6. The present data are found to be in general agreement with the literature data but have similar trend with some deviation from calculated data of the TALYS 1.6 code. The isomeric ratios of 93m, gTc, 94m, gTc, and 95m, gTc in the 93Nb(α, xn) reactions from the present work and literature data were compared with similar data in the 93Nb(3He, xn) and 96Mo(p, xn) reactions. In all the three reactions, the isomeric ratios increase with the increasing excitation energy. However, at all excitation energies, the isomeric ratios of 93m, gTc, 94m, gTc, and 95m, gTc in the 93Nb(α, xn) and 93Nb(3He, xn) reactions are higher than those in the 96Mo(p, xn) reactions, which indicate the role of input angular momentum besides excitation energy. Above the excitation energy of 35–55 MeV, the isomeric ratios of 95m, gTc, 94m, gTc, and 93m, gTc decrease in all the 93Nb(α, xn), 93Nb(3He, xn) and 96Mo(p, xn) reactions. This decreasing trend at higher excitation energy indicates the starting of pre-equilibrium reaction, which depends on the target, projectile, and type of reaction products.

Flux-weighted average cross-sections of natAg(γ, xn)103–106Ag reactions with end-point bremsstrahlung energies of 45–60 MeV

The flux-weighted average cross-sections of the natAg(γ, xn)103–106Ag reaction with the end-point bremsstrahlung energies of 45, 50, 55, and 60 MeV were determined by activation and the off-line γ-ray spectrometric technique using the 100 MeV electron linac at the Pohang accelerator laboratory (PAL). The natAg(γ, xn)103–106Ag reaction cross-sections as a function of the photon energy were estimated from the TENDL-2013 library based on the TALYS 1.6 computer code. The flux-weighted average cross-sections at the end-point bremsstrahlung energies of 45-60MeV were obtained from the literature data and the theoretical data based on the mono-energetic photons. We found that the present data and the flux-weighted theoretical values for the natAg(γ, xn)103–106Ag reaction increase sharply from their threshold values to certain energies where other reaction channels are opened. Then, the first reaction remains constant until the second one reaches its maximum. Thereafter, the first reaction decreases slowly with an increase in the end-point bremsstrahlung energy due to the opening of different reaction channels.

Measurement of reaction cross-sections for89Y at average neutron energies of 7.24-24.83 MeV

We measured neutron-induced reaction cross-sections for 89Y(n,γ)90mY and 89Y(n,α)86Rb reactions with the average neutron energy region from 7.45 to 24.83 MeV by an activation and off-line γ-ray spectrometric technique using the MC-50 Cyclotron at Korea Institute of Radiological and Medical Sciences. The neutron-induced reaction cross-sections of 89Y as a function of neutron energy were taken from the TENDL-2013 library. The flux-weighted average cross-sections for 89Y(n,γ)90mY and 89Y(n,α)86Rb reactions were calculated from the TENDL-2013 values based on mono-energetic neutron and by using the neutron energy spectrum from MCNPX 2.6.0 code. The present results are compared with the flux-weighted values of TENDL-2013 and are found to be in good agreement