Measurement of the activation cross section for the (p,xn) reactions in niobium with potential applications as monitor reactions

Excitation functions of the ⁹³Nb(p,n)^93mMo, ⁹³Nb(p,pn)^92mNb and ⁹³Nb(p,αn)⁸⁹Zr nuclear reactions were measured up to 17.4 MeV by the conventional activation method using the stacked-foil technique. Stacks were irradiated at different incident energies on the TR19/9 cyclotron at the Edmonton PET Centre. The potential of the measured excitation functions for use as monitor reactions was evaluated and tested by measuring activity ratios at a different facility. Single Nb foils were irradiated at incident energies in the range from 12 to 19 MeV on the TR19/9 cyclotron at Brookhaven National Laboratory. Results are compared with the published data and with theoretical values as determined by the nuclear reaction model code EMPIRE.     

Study of the excitation functions for K, Sc and Ti by proton irradiation on Sc up to 37 MeV

The excitation functions of proton induced reactions on Sc targets (100% ⁴⁵Sc), leading to the formation isotopes ⁴³K, ⁴³Sc, ^44mSc, ^44gSc and ⁴⁴Ti were studied by the stacked foil activation technique up to 37 MeV. High-resolution gamma-spectrometry measurements were performed on an HPGe detector in order to determine the activity of the irradiated Sc₂O₃ pellets and Ti monitor foils. The reaction cross-sections were measured from their respective thresholds up to E_p = 36.4 MeV and were compared with previous values reported in literature. Possible batch yields and optimal irradiation parameters for generator ⁴⁴Ti -^44gSc in high current accelerators are discussed.     

Measurement of isomeric yield ratios for 90Zr(γ, n)89m,gZr, natZr(γ, xn1p)86m,gY, and 89Y(γ, xn)87m,g,86m,gY reactions with 50-, 60-, and 70-MeV bremsstrahlung

We measured the isomeric yield ratios in the photonuclear reactions of ^natZr(γ, n)^89m,gZr, ^natZr(γ, xn1p)^86m,gY, and ⁸⁹Y(γ, xn)^87m,g,86m,gY by the activation method. The high-purity natural Zr and Y metallic foils in disc shape were irradiated with uncollimated bremsstrahlung beams of 50-, 60-, and 70-MeV generated from an electron linear accelerator at Pohang Accelerator Laboratory. The induced activities in the irradiated foils were measured by the high-resolution γ-ray spectrometric system consisting of a high-purity germanium detector and a multichannel analyzer. The obtained isomeric yield ratios in the formation of ^89m,gZr, ^87m,gY, and ^86m,gY are compared with the corresponding values found in the literature. The measured isomeric yield ratios at the bremsstrahlung energies of 50-, 60-, and 70-MeV are the first measurement except ⁸⁷Y at 50-MeV bremsstrahlung.     

Measurements of the Y(n,γ)Y cross-section in the neutron energy range of 13.5-14.6 MeV

The ⁸⁹Y(n,γ)^90mY cross-section has been measured at three neutron energy points between 13.5 and 14.6 MeV using the activation technique and a coaxial HPGe γ-ray detector. The data for the ⁸⁹Y(n,γ)^90mY cross-sections are reported to be 0.39 ± 0.02, 0.43 ± 0.02, and 0.38 ± 0.02 mb at 13.5 ± 0.2, 14.1 ± 0.1, and 14.6 ± 0.2 MeV incident neutron energies, respectively. The first data for the ⁸⁹Y(n,γ)^90mY reaction at neutron energy points of 13.5 and 14.1 MeV are presented. The natural high-purity Y₂O₃ powder was used as target material. The fast neutrons were produced by the T(d,n)⁴He reaction. Neutron energies were determined by the method of making cross-section ratios of ⁹⁰Zr(n,2n)^89m+gZr and ⁹³Nb(n,2n)^92mNb reactions, and the neutron fluencies were determined using the monitor reaction ⁹³Nb(n,2n)^92mNb. The results obtained are compared with existing data.     

Measurements of activation cross sections for Lu(n, α)Tm,Lu(n, α)Tm and Lu(n, p)Yb reactions induced by neutrons around 14 MeV

The cross sections for the ¹⁷⁵Lu(n, α)¹⁷²Tm, ¹⁷⁶Lu(n, α)¹⁷³Tm and ¹⁷⁵Lu(n, p)^175m+gYb reactions have been measured in the neutron energy range of 13.5–14.8 MeV using the activation technique. The first data for ¹⁷⁵Lu(n, α)¹⁷²Tm reaction cross sections are presented. In our experiment, the fast neutrons were produced via the ³H(d, n)⁴He reaction on K-400 Neutron Generator at Chinese Academy of Engineering Physics (CAEP). Induced gamma activities were measured by a high-resolution (1.69 keV at 1332 keV for ⁶⁰Co) 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 fluences were determined by the cross section of ⁹³Nb(n, 2n)^92mNb or ²⁷Al(n, α)²⁴Na reactions. The neutron energy in the measurement was by the cross section ratios of ⁹⁰Zr(n, 2n)^89m+gZr and ⁹³Nb(n, 2n)^92mNb reactions. The results were discussed and compared with experimental data found in the literature and with results of published empirical formulae.     

Measurement of isomeric yield ratios in In and Sn with 50, 60, and 70 MeV bremsstrahlung photons

The isomeric yield ratios of ^110m,gIn, ^111m,gIn, ^112m,gIn, and ^117m,gIn were measured in photonuclear reactions for the end point energies of bremsstrahlung about 50, 60, and 70 MeV. The isomeric yield ratios were determined from the induced activities in the irradiated samples using a high-purity germanium detector equipped with a multichannel analyzer. The results are the first measurements in this energy region. Experimental values of the isomeric yield ratios are compared with the corresponding values found in the literature.     

Isomeric yield ratios for the formation of Sc in the Sc(γ,n), Ti(γ,xnp), Fe(γ,xn5p) and Cu(γ,xn8p) reactions with 2.5 GeV bremsstrahlung

We measured the isomeric yield ratios for the ^44m,gSc isomeric pairs produced from four different photonuclear reactions ⁴⁵Sc(γ,n)^44m,gSc, ^natTi(γ,xn1p)^44m,gSc, ^natFe(γ,xn5p)^44m,gSc, and ^natCu(γ,xn8p)^44m,gSc by using the activation method. The high purity natural Sc, Ti, Fe, and Cu metallic foils in disc shape were irradiated with uncollimated 2.5 GeV 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 ⁴⁵Sc(γ,n)^44m,gSc, ^natTi(γ,xn1p)^44m,gSc, ^natFe(γ,xn5p)^44m,gSc and ^natCu(γ,xn8p)^44m,gSc reactions are 0.25 ± 0.03, 0.43 ± 0.05, 1.38 ± 0.14, and 1.89 ± 0.21, respectively. The present result for the ^natCu(γ,xn8p)^44m,gSc reaction is in good agreement with the existing data. Our results for the ⁴⁵Sc(γ,n)^44m,gSc, ^natTi(γ,xn1p)^44m,gSc, and ^natFe(γ,xn5p)^44m,gSc reactions are the first measurements at 2.5 GeV bremsstrahlung. The obtained results are compared with the corresponding values found in the literature. The relation between the isomeric yield ratios and the complexity of the photonuclear reactions is discussed.     

Cross-section for proton-tritium scattering from 1.4 to 3.4 MeV at the laboratory angle of 165°

The elastic scattering cross-section for proton scattering from tritium was measured at a laboratory angle of 165° and over an incident proton energy range from 1.4 to 3.4 MeV. A thin solid target containing 1.62 × 10¹⁷ T atoms/cm² was prepared by absorption of tritium into a film of titanium on aluminium foil backing. The cross-section increases almost linearly with decreasing energy in the higher energy region of 2-3.4 MeV. The currently measured cross-section data are compared with data available in the literature values and they show a similarly linear trend in a similar higher energy range. The maximum difference in the cross-section at almost the same scattering angle between current data and the previous results is no worse than 2.3%.     

Investigation of the Zn(p, 2p)Cu nuclear reaction: New measurements up to 40 MeV and compilation up to 100 MeV

The excitation function was measured for the ⁶⁸Zn(p, 2p)⁶⁷Cu nuclear reaction from its threshold energy up to 40 MeV. Nine pieces of highly enriched ⁶⁸Zn (>98%) metal foils were irradiated to obtain reliable cross-sections using the usual stacked-foil technique. All foils were subjected to high efficiency radiochemical separation before the activity measurements. A critical compilation of the available experimental cross-section results was also performed. Thick target yields of ⁶⁷Cu and the longer-lived copper radio-contaminants (⁶¹Cu and ⁶⁴Cu) were calculated using the reliable literature results up to 100 MeV. Additionally, EOB (End Of Bombardment) contamination levels as a function of bombarding energy and irradiation time were deduced.     

Activation cross-section for reactions induced by 14 MeV neutrons on natural silver

Cross-sections for (n, 2n), (n, p), and (n, α) reactions have been measured on silver isotopes at the neutron energies from 13.5 to 14.8 MeV using the activation technique in combination with high-resolution γ-ray spectroscopy. Corrections were made for the literature cross-sections of ¹⁰⁹Ag(n, 2n) ^108mAg reaction with incorrect half-life of product ^108mAg. Neutrons were produced via the ³H(d, n)⁴He reaction using solid TiT. 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: ¹⁰⁹Ag(n, 2n)^108mAg, ¹⁰⁷Ag(n, 2n)^106mAg, ¹⁰⁹Ag(n, p)^109m+gPd, and ¹⁰⁹Ag(n, α)^106mRh. The cross-sections were discussed and compared with experimental data found in the literature, and with the comprehensive evaluation data in ENDF/B-VII, JENDL-3.3, and JEFF-3.1/A libraries.     

Activation cross sections of deuteron-induced nuclear reactions on hafnium

Experimental excitation functions for deuteron-induced reactions up to 20 MeV on high purity natural hafnium were measured with the activation method using a stacked foil irradiation technique. Metallic hafnium foils with thickness of 10 μm were stacked together with 50 μm thick aluminium and 12 μm thick titanium foils. The aluminium foils served as energy absorber while the titanium foils were used to monitor the energy and intensity of the bombarding deuteron beam. From a detailed remeasurement of the complete excitation function of the ^natTi(d,x)⁴⁸V monitor reaction it was possible to adopt the proper incident energy and beam intensity by comparing the results with the recommended values. High resolution off-line gamma-ray spectrometry was applied to assess the activity of each foil. From the measured activity independent and/or cumulative elemental or isotopic cross section data for production of Ta, Hf and Lu radioisotopes by (d,x) reactions were determined. No experimental cross section data have been published earlier for these reactions in the investigated energy region. The work focuses on the production of ^177gLu that one of the promising radionuclides for small tumor therapy due to appropriate average energy of the emitted β-particles and the main gamma-rays that are suitable for detection by gamma-camera.The presented experimental data and results predicted by the TALYS theoretical code are compared. Thick target yields for production of the investigated radionuclides were calculated from a fit to our experimental excitation curves.     

Excitation functions of the proton induced nuclear reactions on natural zirconium

Excitation functions for the ^natZr(p,xn)^{90,92m,95g,96}Nb, ^natZr(p,pxn)^88,89Zr, and ^natZr(p,αxn)^{86,87m,87mg,88}Y reactions were measured by using a stacked-foil activation technique in combination with HPGe γ-ray spectroscopy using the MC50 cyclotron at the Korean Institute of Radiological and Medical Sciences, Korea. In this way the proton beam energy range 4-40 MeV was covered. We report new data for these processes. The data were compared with the results of precompound-hybrid model calculations, whereby only a partial agreement was obtained.     

Stopping power and energy straggling of protons in graphite and amorphous carbon obtained from a resonance in BS spectra

Backscattering (BS) spectra with a sharp 4.8-MeV resonance for carbon targets have been measured using proton beams in an energy range 4.85-6.1 MeV per 100-keV step. By systematic analyses of the resonance peak profiles, values of stopping power and energy straggling have been deduced for proton energies from 0.8 to 3.4 MeV which corresponds to a penetration depth of 88 μm. In particular, to investigate the difference in stopping power and straggling caused by target inhomogeneity, we used two target materials which were highly oriented pyrolytic graphite (HOPG, 2.26 g/cm³) as a homogeneous material and amorphous carbon (1.73 g/cm³) as an inhomogeneous material. We describe a method of measuring stopping power and straggling using a resonance in the BS spectra. The stopping powers obtained are compared with the values determined by SRIM-2006. Moreover, collision straggling and a density straggling due to the inhomogeneity of the target materials are evaluated from the width broadening of resonance peaks.     

Excitation functions of proton induced nuclear reactions on W up to 40 MeV

We measured the excitation functions for the production of the ^{181,182m,182g,183,184g,186}Re radioisotopes from proton bombardment of natural tungsten by using a stacked-foil activation technique in the energy range from threshold energy to 40 MeV at the MC50 cyclotron of the Korea Institute of Radiological and Medical Science. The results were compared with the earlier reported experimental data and the model calculations using codes TALYS and ALICE-IPPE. The present values are in good agreement with some of the previously reported literature. The integral yields for thick targets were also deduced from the measured excitation functions of the produced radioisotopes. The deduced yield values were compared with the available directly measured thick target yield, and found acceptable agreement. The investigated radioisotope ¹⁸⁶Re has remarkable applications in the field of nuclear medicine, whereas the data of ^183,184gRe have potential applications in thin layer activation analysis.     

Applications of a compact ionization chamber in AMS at energies below 1 MeV/amu

The increasing demand for measuring long-lived radionuclides with small AMS machines at energies below 1 MeV per nucleon raises the need for compact detectors which still have a decent energy resolution and allow for a clear identification of the incident particles. Based on a design by the AMS group at the ETH Zurich a compact gas ionization chamber was built and installed at the 3 MV tandem AMS facility VERA (Vienna Environmental Research Accelerator). The main challenge in AMS is the detection of rare isotope species in the presence of strong isotopic and isobaric interferences. The task of the ionization chamber is the suppression of the unwanted isobar by separating the ions via their different stopping powers. Measurements of ³⁶Cl at VERA showed an achieved suppression of the unwanted stable isobar ³⁶S of 3 × 10⁻⁴ and measurements of ¹⁰Be showed an achieved suppression of ¹⁰B of at least 3 × 10⁻⁶. Additional suppression of the isobaric ions can be achieved by a degrader foil technique applied to ¹⁰Be measurements by G.M. Raisbeck. In combination with the new ionization chamber the achieved suppression of ¹⁰B is at least 10⁻¹⁰. Measurements of blank samples at VERA show that the background for AMS with ¹⁰Be is below 2 × 10⁻¹⁵.     

Energy loss and straggling of Li ions in the polymer foils

Energy loss and straggling of 0.18-0.78 MeV/amu ⁷Li ions in polycarbonate, polyethylene terephthalate and polypropylene foils were measured by means of a transmission technique with a half-covered detector. The stopping force measurements are compared with the SRIM 2006 calculation and the database of the ICRU report 73. The measured energy loss straggling are in satisfactory agreement with the results yielded using the empirical formula at the higher energy region. The obtained data also demonstrated that the validity of Bragg’s rule applied to stopping force and energy loss straggling for ⁷Li ions in polymer foils.     

Production cross-sections of residual radionuclides from proton-induced reactions on Ag up to 40 MeV

We measured the cross-sections of the ^{104g,105,106m}Ag and ^104,107Cd radionuclides produced by proton-induced reactions on natural silver by using a stacked-foil activation technique in the energy range from a threshold energy to 40 MeV at a MC50 cyclotron. The results showed generally good agreement with available data as well as the theoretical data. The integral yields for thick targets were also deduced using the measured cross-sections and the stopping power of ^natAg over the energy range from a threshold energy to 40 MeV, taking into account that the total energy is absorbed in the targets. The production cross-sections for the ^104gAg and the ¹⁰⁴Cd radionuclides from natural silver were measured for the first time.     

Improved energy resolution of a cyclotron beam for RBS measurements

For RBS (Rutherford Back Scattering) analysis, the quality of the beam is of premium importance because the depth profile resolution of the method is strongly dependent on the energy resolution of the probing beam. A magnetic analyzer, consisting of two 90 left-right bending magnets forming an achromatic doublet has been adapted to the Liege 20 MeV (proton) AVF (Azimuthal Varying Field) cyclotron. The energy resolution of that system has been measured by recording the resonance width of a ³²S(p,p′γ)³²S (3.38 MeV. p⁺ lab. energy). We have obtained a value of ΔE = ± 2 keV, reducing by a factor of 20 the natural dispersion of our cyclotron.We describe our magnetic analyzer system and present the results of our RBS measurements at energies up to 14 MeV α.     

Alpha induced reactions on Cd and Cd: An experimental study of excitation functions

Excitation functions of alpha induced reactions on enriched ¹¹⁴Cd and ¹¹⁶Cd targets, leading to the formation of the ^117m,119mSn, ^{114m₁,115m,116m,117m,g}In, ^115gCd isotopes, were studied by the stacked foil activation technique. Reaction cross-sections were measured from their respective thresholds up to E_α = 38.9 MeV. Quantification of induced isotopes has been made by gamma and X-ray spectrometry. The experimental cross-sections are compared, where available, with values reported previously in literature. Thick target yield for the medically important radionuclide ^117mSn is calculated based on discrete values of measured cross-sections.     

Some cross sections of Bromine isotopes induced by 14 MeV neutrons

Activation cross sections of Bromine isotopes induced by 14 MeV neutrons were measured. The cross sections for three (n, 2n), two (n, p) and one (n, α) reactions are reported in this work. The cross sections for ⁸¹Br (n, 2n) ^80gBr, ⁸¹Br (n, 2n) ^80mBr and ⁸¹Br (n, p) ^81gSe reactions at neutron energy of 13.5 MeV; and ⁸¹Br (n, p) ^81gSe at 14.1 MeV are given for the first time. The measured results are discussed and compared with the previous works.