Isomeric yield ratios for the natNd(γ, xn) 139m,g; 141m,gNd reactions in the bremsstrahlung energy region from 45 to 60 MeV

The independent isomeric yield ratios (IR) for the ^139m,gNd and the ^141m,gNd isomeric pairs produced from the ^natNd(γ, xn) reactions were determined by the activation and the off-line γ-ray spectrometric technique at the end-point bremsstrahlung energies of 45, 50, 55, and 60 MeV in the 100 MeV electron Linac of the Pohang accelerator laboratory, Korea. The present IR for the ^141m,gNd isomeric pair were compared with those from the literature measured by the bremsstrahlung and the neutron to examine the role of excitation energy. The obtained IR for the ^139m,gNd and the ^141m,gNd isomeric pairs from ^natNd(γ, xn) reactions were compared with those from the ¹⁴¹Pr(p, x), the ^natCe(³He, x), and the ¹³⁶Ce(α, n) reactions to examine the role of parameters in entrance channel i.e. excitation energy and the effect of the input angular momentum. The present IR of ^139m,gNd and ^141m,gNd were compared with those calculated by using the TALYS 1.4 code as well as those from the literature data of above mentioned reactions.     

A novel technique for simultaneous diagnosis and radioprotection by radioactive cerium oxide nanoparticles: study of cyclotron production of <Superscript>137m</Superscript>Ce

Application of nanoparticles in nuclear medicine has aimed to develop diagnosis and therapeutic techniques. Cerium oxide nanoparticles (CNPs) are expected to be useful for protection of healthy tissue from radiation-induced harm and could serve therapeutic function. Among a variety of cerium radioisotopes, ^137mCe (T _1/2 = 34.4 h, IT (99.22%), β⁺ (0.779%)) could be a novel candidate radionuclide in the field of diagnosis owing to its appropriate half-life, 99.91% natural abundance of target and its intense gamma line at 254.29 keV. In this study, ^137mCe excitation function via the ^natLa(p,3n) reaction was calculated by TALYS-1.2 and EMPIRE-3 codes. The excitation function calculations demonstrated that the ^natLa(p,3n)^137mCe reaction leads to the formation of the ^136/138Ce isotopic contamination in the 22–35 MeV energy range. Interestingly, the isotopic impurities of ^137mCe could serve radio protector function. Overall results indicate that the cyclotron produced ^137mCeO₂ nanoparticles by irradiation of a target encompassing lanthanum oxide nanoparticles could be a potent alternative for conventional diagnostic radionuclides with simultaneous radioprotection capacity.     

Measurement of neutron-induced activation cross sections of lanthanum at 14.8 MeV

Cross-sections for (n,p), (n,α), (n,n′α), (n,t) and (n,2p) reactions have been measured on ¹³⁹La isotope at the neutron energy 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Neutrons were produced via the ³H(d,n)⁴He reaction using a solid tritium–titanium target. The neutron fluences were determined using the monitor reaction ²⁷Al(n,α)²⁴Na. The neutron energy in this measurement was determined by cross section ratios for the ⁹⁰Zr(n,2n)^89m+gZr and ⁹³Nb(n,2n)^92mNb reactions. Data are reported for the following reactions: ¹³⁹La(n,p)¹³⁹Ba, ¹³⁹La(n,α)¹³⁶Cs, ¹³⁹La(n,n′α)^135mCs, ¹³⁹La (n,t)^137mBa, and ¹³⁹La(n,2p)¹³⁸Cs. The cross sections were discussed and compared with experimental data found in the literature, and with the comprehensive evaluation data in ENDF/B-VII.0, JENDL-3.3, JEFF-3.1/A, and TENDL-2008 libraries.     

Computerized on-line measurement the yield of short-lived bromine and iodine isotopes from thermal neutron fission of235U

The short-lived bromine and iodine isotopes from thermal neutron fission of²³⁵U have been separated from fission products by one step solvent extraction combined with an ion exchange fast chemistry system. The measured gamma spectra have been acquisited by an automatic computer on-line system. The results include experimental independent fission yields of⁸⁶Br,^134mI,^134gI,^136mI, and^136gI, the cumulative yields of⁸⁷Br,⁸⁸Br,¹³⁷I,¹³⁸I. The isomeric yield ratio of¹³⁴I and¹³⁶I has been determined and the iodine isotopic distribution curve has been constructed and analyzed.     

Excitation functions of neutrons induced reactions on terbium from threshold to 20 MeV

Cross-sections for (n,2n), (n,p), and (n,α) reactions have been measured on terbium isotopes at the neutron energies from 13.5 to 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Data are reported for the following reactions: ¹⁵⁹Tb(n,2n)^158m+gTb, ¹⁵⁹Tb(n,p)¹⁵⁹Gd, and ¹⁵⁹Tb(n,α)¹⁵⁶Eu. The cross sections were also estimated with the TALYS-1.4 nuclear model code, at neutron energies varying from the reaction threshold to 20 MeV. The results were discussed and compared with experimental data found in the literature, and with the comprehensive evaluation data in ENDF/B-VII.1 and JENDL-4.0 libraries.     

Independent isomeric-yield ratio of 89m,gNb from 93Nb(γ, 4n), natZr(p,xn), and 89Y(α, 4n) reactions

The independent isomeric-yield ratios of ^89m,gNb for the ⁹³Nb(γ, 4n) ^89m,gNb reaction with bremsstrahlung energies of 45-, 50-, 55-, 60-, and 70-MeV were measured by the activation and the off-line γ-ray spectrometric technique at 100 MeV electron linac of the Pohang accelerator laboratory. The isomeric-yield ratios of ^89m,gNb for the ^natZr(p, xn) ^89m,gNb and the ⁸⁹Y(α, 4n) ^89m,gNb reactions were measured by using a stacked-foil activation technique with the proton energies of 19–45 MeV and alpha energies of 38.9-, 40.5-, and 42.5-MeV at the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences. The measured isomeric-yield ratio of ^89m,gNb from the ⁹³Nb(γ, 4n), ^natZr(p, xn), and ⁸⁹Y(α, 4n) reactions were compared with the similar literature data in the ⁸⁹Y(³He, 3n) reaction. It was found that the isomeric yield ratio of ^89m,gNb increases with projectile energy, which indicate the effect of excitation energy. However, for the similar compound nucleus with the same excitation energy, the isomeric-yield ratios of ^89m,gNb in the ⁸⁹Y(α, 4n) and ⁸⁹Y(³He, 3n) reactions are higher than those in the ⁹³Nb(γ, 4n) and ^natZr(p, xn) reactions, which indicates the role of input angular momentum. The isomeric-yield ratios of ^89m,gNb in the ⁹³Nb(γ, 4n), ^natZr(p, xn), ⁸⁹Y(α, 4n), and ⁸⁹Y(³He, 3n) reactions were also calculated theoretically using computer code TALYS 1.4. The theoretical isomeric-yield ratios of ^89m,gNb from four reactions increase with excitation energy. However, the theoretical value are significantly higher than the experimental data in the ⁹³Nb(γ, 4n) and ^natZr(p, xn) reactions but slightly lower or comparable in the ⁸⁹Y(α, 4n) rand ⁸⁹Y(³He, 3n) reactions.     

Independent isomeric yield ratios of 95m,gNb in the natMo(γ, pxn) and natZr(p,xn) reactions

The independent isomeric yield ratios of ^95m,gNb from the ^natMo(γ, pxn) reactions with bremsstrahlung end-point energies of 45, 50, 55, 60, and 70 MeV were determined by an activation and an off-line γ-ray spectrometric technique at the Pohang accelerator laboratory (PAL), Korea. The isomeric yield ratios of ^95m,gNb from the ^natZr(p, xn) reactions were also determined in eight different proton energies within 19.4–44.7 MeV by a stacked-foil activation and an off-line γ-ray spectrometric technique using the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences (KIRAMS), Korea. The measured isomeric yield ratios of ^95m,gNb from the present work and the literature data in the ^natMo(γ, pxn) and ^natZr(p, xn) reactions were compared with the similar literature data in the ^natMo(p, αxn) reactions. It was found that the isomeric yield ratio of ^95m,gNb increases with projectile energy, which indicate the effect of excitation energy. However, at the same excitation energy, the isomeric yield ratios of ^95m,gNb in the ^natZr(p, xn) and ^natMo(p, αxn) reactions are higher than those in the ^natMo(γ, pxn) reaction, which indicates the role of input angular momentum. The isomeric yield ratios of ^95m,gNb in the ^natMo(γ, pxn), ^natZr(p, xn), and ^natMo(p, αxn) reactions were also calculated using computer code TALYS 1.4. The calculated isomeric yield ratios of ^95m,gNb from three reactions increase with excitation energy. However, in all the three reactions, the calculated values are significantly higher than the experimental data.     

Activation cross sections and isomeric cross section ratios for 184Os(n,2n)183m,gOs, 190Os(n,p)190m,gRe and 86Sr(n,2n)85m,gSr reactions from 13.5 to 14.8 MeV

The cross sections for the ¹⁸⁴Os(n,2n)^183m,gOs, ¹⁹⁰Os(n,p)^190m,gRe and ⁸⁶Sr(n,2n)^85m,gSr reactions and their isomeric cross section ratios σ _m /σ _g have been measured in the neutron energy range of 13.5–14.8 MeV using the activation technique. Nuclear model calculations using the code HFTT, which employs the Hauser-Feshbach (statistical model) and exciton model (precompound effects) formalisms, were undertaken to describe the formation of the products. The total cross sections for ¹⁸⁴Os(n,2n)¹⁸³Os, ¹⁹⁰Os(n,p)¹⁹⁰Re and ⁸⁶Sr(n,2n)⁸⁵Sr reactions are compared with the experimental data found in the literature, with results of published empirical formulae, with values of model calculations including the pre-equilibrium contribution, and with the evaluation data of JEFF-3.1/A or ENDF/B-VII.     

Cross-section measurements for 141Pr isotope at neutron energies from 13.5 to 14.8 MeV

Cross-sections for (n,2n), (n,p), and (n,t) reactions have been measured on praseodymium isotopes at the neutron energies from 13.5 to 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Data are reported for the following reactions: ¹⁴¹Pr(n,2n)¹⁴⁰Pr, ¹⁴¹Pr(n,p)¹⁴¹Ce, and ¹⁴¹Pr(n,t)¹³⁹Ce. Nuclear model calculations using the code HFTT, which employs the Hauser–Feshbach (statistical model) and exciton model (precompound effects) formalisms, were undertaken to describe the formation of the products. The results were compared with previous data.     

Cross-sections for formation of <Superscript>178m2</Superscript>Hf and <Superscript>179m2</Superscript>Hf through reactions on natural hafnium at neutron energy 14.8 ± 0.2 MeV

The cross sections for formation of metastable state of ¹⁷⁸Hf (^178m2Hf, 574.215 keV, 31 y) and ¹⁷⁹Hf (^179m2Hf, 362.55 keV, 25.05 d) through reactions induced by 14.8 ± 0.2 MeV neutrons on natural hafnium were measured for the first time. The monoenergetic neutron beam was produced via the ³H(d, n)⁴He reaction on ZF-300-II Intense Neutron Generator at Lanzhou University. Induced gamma activities were measured by a gamma-ray spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The neutron fluence were determined by the cross section of ⁹³Nb(n, 2n)^92mNb reaction. The neutron energy in the measurement were by the cross section ratios of ⁹⁰Zr(n, 2n)^89m+gZr and ⁹³Nb(n, 2n)^92mNb reactions.     

Measurement of isomeric yield ratios for the natHo(γ,xn)164m,g;162m,gHo reactions in the bremsstrahlung energy region from 45 to 65 MeV

We have measured the isomeric yield ratios for the ^164m,gHo and the ^162m,gHo isomeric pairs formed via photonuclear reactions ¹⁶⁵Ho(γ,n)^164m,gHo and ¹⁶⁵Ho(γ,3n)^162m,gHo in the bremsstrahlung energy region from 45 to 65 MeV in steps of ?E = 5 MeV by the activation method. The induced γ-activities of the irradiated holmium foils were measured by a coaxial high-purity germanium detector coupled to a PC-based multichannel analyzer. In order to improve the accuracy of the experimental results the necessary corrections were made. The experimental results at bremsstrahlung energies of 45, 50, 55, 60, and 65 MeV are 0.408 ± 0.027, 0.413 ± 0.027, 0.427 ± 0.029, 0.452 ± 0.032, and 0.448 ± 0.031 for the ^164m,gHo isomeric pair, and 0.587 ± 0.041, 0.624 ± 0.044, 0.652 ± 0.045, 0.637 ± 0.045, and 0.668 ± 0.046 for the ^162m,gHo isomeric pair, respectively. The present results are the first measurements at bremsstrahlung energies just above the giant dipole resonance region. The obtained results confirm the dependence of isomeric ratios on the incident photon energy as observed in some earlier experiments.     

Induction and detection of radioactivity in foodstuffs irradiated with 10 MeV electrons and X-rays

Induction of radioactivity by direct (γn) and indirect (nγ) means was measured in solutions and foods irradiated with 10 MeV electrons and X-rays, to a dose of 20 kGy. Both types of reaction occur to a very limited extent following electron irradiation and this is attributed to the low efficiency of bremsstrahlung production in the target. For X-rays below the 1981 JECFI recommended 5 MeV upper limit of energy, only four (γn) reactions are possible and all have stable products. However, the neutrons generated can undergo moderation and capture by a variety of nuclides. Of particular interest is the reaction ²H(γn)¹H since this has an abnormally low (γn) threshold of 2.2 MeV and deuterium occurs with a natural abundance of 0.015%; hence some neutron production in food is inevitable. A neutron flux of 1.79 × 10⁵ [n cm⁻² s⁻¹] [μg(D) cm⁻³]⁻¹[kGy s⁻¹]⁻¹ was estimated from the activity induced in a variety of neutron monitors, especially manganese−55, as measured by gamma spectrometry and Cerenkov techniques. Induced activities at the end of irradiation calculated for beef using this flux value total 90 Bq kg⁻¹ which is of the same order as natural levels in food (approx. 100 Bq kg⁻¹), and are in broad agreement with NRPB data.     

Determination of the 54Fe(n, 2n)53gFe and 54Fe(n, 2n)53mFe cross sections averaged over a 235U fission neutron spectrum

The reaction cross sections averaged over a ²³⁵U fission neutron spectrum have been measured for the ⁵⁴Fe(n, 2n)^53gFe and ⁵⁴Fe(n, 2n)^53mFe threshold reactions. The values found are, respectively: (1.14±0.13) mb, and (0.52±0.16) mb. The measured cross sections are referred to the (111±3) mb standard cross section of the ⁵⁸Ni(n, p)^58m+gCo reaction. The (81.7±2.2) mb standard cross section value for the ⁵⁴Fe(n, p)⁵⁴Mn reaction, was also used as a monitor to check the results obtained with the Ni standard, leading to an excellent agreement.     

Activation cross sections for the element rhenium

The¹⁸⁵Re(n,)¹⁸²Ta,¹⁸⁷Re(n,)¹⁸⁴Ta,¹⁸⁷Re(n,p)¹⁸⁷W and¹⁸⁷Re(n,2n)^186gRe reaction cross sections included by 13.5–14.7 MeV neutrons were measured by the activition method. The neutron fluences were determined by the cross section of the²⁷Al(n,)²⁴Na reaction. The neutron energies in these measurements were determined by the cross section ratios for⁹⁰Zr(n,2n)^89m+gZr and⁹³Nb(n,2n)^92mNb reactions.     

Study of the isomeric ratios in photonuclear reactions of natural Selenium induced by bremsstrahlungs with end-point energies in the giant dipole resonance region

We have determined the isomeric ratios in ⁷⁴Se(γ, n)^73m,gSe and ⁸²Se(γ, n)^81m,gSe photonuclear reactions of natural Selenium induced by bremsstrahlungs with end-point energies in the giant dipole resonance region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured with spectroscopic system consisting of 8,192 channel analyzer and high-energy resolution (180 keV at gamma ray 1,332 keV of ⁶⁰Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results were discussed and compared with those of other authors.     

Isomeric yield ratios in the photoproduction of 52m,gMn from natural iron using 50-, 60-, 70-MeV, and 2.5-GeV bremsstrahlung

The isomeric yield ratios for the ^natFe(γ,xn1p)^52m,gMn reactions have been measured by the activation and the γ-ray spectroscopic methods at 50-, 60-, 70-MeV, and 2.5-GeV bremsstrahlung energies. The high purity natural iron foils in disc shape were irradiated with uncollimated bremsstrahlung beams of the Pohang Accelerator Laboratory. The induced activities in the irradiated foils were measured by the high-resolution γ-ray spectrometry with a calibrated high-purity Germanium (HPGe) detector. In order to improve the accuracy of the experimental results the necessary corrections were made in the gamma activity measurements and data analysis. The obtained isomeric yield ratios for the ^natFe(γ,xn1p)^52m,gMn reactions at 50-, 60-, 70-MeV, and 2.5-GeV bremsstrahlung energies are 0.27 ± 0.03, 0.33 ± 0.04, 0.34 ± 0.04, and 1.25 ± 0.15, respectively. The present results at 50-, 60-MeV, and 2.5-GeV bremsstrahlung energies are the first measurements. We found that the isomeric yield ratio of the ^natFe(γ,xn1p)^52m,gMn reaction depends on the incident bremsstrahlung energy and the mass difference between the product and the target nucleus when we compared the present results with other experimental data at different energies.     

Measurement of isomeric yield ratios of the 104m,g,106m,gAg in the 45- and 55-MeV bremsstrahlung induced reactions of natural silver

The isomeric yield ratios for the ^natAg(γ,xn)^{104m,g,106m,g}Ag reactions with the end-point bremsstrahlung energies of 45- and 55-MeV have been determined by the off-line γ-ray spectrometric technique using 100 MeV electron linac at Pohang accelerator laboratory, Korea. The present data were compared with literature data in comparable compound nucleus from the ^natAg(γ,xn), ^natPd(p,xn), and ¹⁰³Rh(α,xn) reactions to examine the effects of an excitation energy and an input angular momentum. It is observed that the isomeric yield ratios of ^104,106Ag in ^natAg(γ,xn), ^natPd(p,xn) and ¹⁰³Rh(α,xn) reactions increase with the end-point bremsstrahlung energy, proton and alpha energy, which indicate the role of excitation energy. It is also found that for the similar compound nucleus at same excitation energy, the isomeric yield ratio of ^104m,gAg is higher in the ^natPd(p,xn) and ¹⁰³Rh(α,xn) reactions than those in ^natAg(γ,xn) reaction, which indicate the effect of an input angular momentum.     

Determination of the fission-neutron averaged cross sections of some high-energy threshold reactions of interest for reactor dosimetry

For three high threshold reactions, we have measured the cross sections averaged over a ²³⁵U fission neutron spectrum. The measured reactions, and corresponding averaged cross sections found, are: ¹²⁷I(n,2n)¹²⁶I, (1.36±0.12) mb; ⁹⁰Zr(n,2n)^89mZr, (13.86±0.83) mb; and ⁵⁸Ni(n,d+np+pn)⁵⁷Co, (274±15) b; all referred to the well known standard of (111±3) mb for the ⁵⁸Ni(n,p)^58m+gCo averaged cross section. The measured cross sections are of interest in nuclear engineering for the characterization of the fast neutron component in the energy distribution of reactor neutrons.     

Multi-reaction proton activation analysis for traces of molybdenum

The application of proton activation analysis to the determination of molybdenum is described. Thick molybdenum targets were bombarded with 12-MeV and 15-MeV protons. The reactions studied were ⁹²Mo(p,n)⁹² Tc, ⁹⁴Mo(p,n)^94gTc + ⁹⁵Mo(p,2n)^94gTc, ⁹⁵Mo(p,n)^95m Tc + ⁹⁶Mo(p,2n)^95mTc, ⁹⁵Mo(p,n)^95g Tc + ⁹⁶Mo(p,2n)^95gTc, ⁹⁶Mo(p,n)^96gTc+⁹⁷Mo(p,2n)^96gTc and ¹⁰⁰Mo(p,n)^99m Tc. Except for the Mo + p→^905mTc reaction, all these reactions give high analytical sensitivities. For 12-MeV protons and an irradiation time of one half-life or a maximum of 2 h, the sensitivities range from 5 · 10² to 6· 10³ d.p.m./p.p.m. μA, and for 15-MeV protons and the same irradiation conditions from 10³ to 10⁴ d.p.m./p.p.m. μA. In addition to the high sensitivity, the great advantage of proton activation is that different principal reactions yield indicator radionuclides with half-lives between 4.4 min and 61 d. Simultaneous determinations by these reactions are of value for checking the accuracy. For each reaction, detailed data are given on nuclear and instrumental interferences. Analytical application of this multi-reaction proton activation analysis is illustrated by the instrumental determination of molybdenum in cobalt.     

Accurate determination of half-life and radionuclidic purity of reactor produced <Superscript>177g</Superscript>Lu (<Superscript>177m</Superscript>Lu) for metabolic radiotherapy

Thanks to its favorable decay characteristics, ^177gLu is finding several applications in nuclear medicine, especially for palliative metabolic radiotherapy of cancer and radioimunotherapy. ^177gLu is produced in thermal nuclear reactor either by direct neutron capture ¹⁷⁶Lu(n,γ)^177(m+g)Lu on either natural or enriched ¹⁷⁶Lu target, or by reaction on enriched ¹⁷⁶Yb target followed by negatron decay. The latter method does produce a high radionuclidic purity and high specific activity radionuclide in no-carrier-added form, since ¹⁷⁷Yb decays solely to the ground state ^177gLu. Conversely, the first method does produce a low specific activity ^177gLu in carrier-added form,¹ contaminated by the long-lived radioisotopic impurity ^177mLu. The accurate determination of radionuclidic purity and half-life of ^177gLu carried out by HPGe and LSCS is presented in some details.