Excitation functions of alpha-particle induced nuclear reactions on natural ytterbium

Excitation functions of the reactions ^natYb(α,xn)^{170,171,173,175,177m2}Hf, ^natYb(α,x)^{171g,172g,177g,178m}Lu and ^natYb(α,x)^169g,177gYb have been measured up to 39 MeV, among them seven (^{170,171,173,177m2}Hf, ^177g,178mLu, ^177gYb) are reported for the first time. The experimental excitation functions are compared to the theoretical calculations based on the model code ALICE-IPPE and to the only data-set found in the literature. Yields of different production routes of the therapeutically relevant ¹⁷⁷Lu are compared.     

Activation cross sections of proton induced nuclear reactions on ytterbium up to 70 MeV

Cross sections of proton induced nuclear reactions on ytterbium were measured up to 70 MeV by using the standard stacked foil irradiation technique and high-resolution gamma-ray spectroscopy. Experimental cross sections and derived integral yields are reported for the first time for the ^natYb(p,xn)^{173,172mg,171mg,170,167}Lu, ^natYb(p,x)^{175cum,166cum}Yb and ^natYb(p,x)^{173ind,172ind,168,167cum,165cum}Tm reactions. No earlier experimental cross section data were found in the literature. The experimental data were compared to and analyzed with the results of the theoretical model code ALICE-IPPE. Production routes of medical radioisotope ¹⁶⁷Tm are discussed.     

Excitation functions of alpha-induced nuclear reactions on natural erbium

Excitation functions of the reactions ^natEr(α, xn)^167,169Yb and ^natEr(α, x)^{165,167,172,173}Tm were measured up to 38 MeV. The experimental excitation functions are compared to the theoretical calculations based on the model code ALICE-IPPE and to the data found in the literature. Yields of different production routes (proton-, deuteron- and alpha-irradiation) of ¹⁶⁹Yb are compared.     

Cross sections for production of longer lived Tm in 16 MeV proton irradiation of Er

Reliable assessment of proton induced production of the long lived radionuclide ¹⁷⁰Tm (T_1/2 = 128.6 d) on ^natEr requires optimized irradiation and measurement conditions as only a weak 84.2 keV signal is emitted in its decay. Additional detector shielding helps reducing the contaminating Pb-X rays at that energy. Measuring the excitation function up to 16 MeV, normalized to standard monitor cross sections, and comparison with earlier measured data for ^167,168Tm results in new cross section data with reduced uncertainty. Comparison with values predicted by ALICE-IPPE, EMPIRE II and different versions of TALYS (EAF2007 and TENDL2010) shows rather good agreement for these simple (p,xn) reactions.     

Excitation functions for proton-induced reactions on natural hafnium: Production of 177Lu for medical use

There is an increasing interest in using radioisotopes of rare earth elements for internal radiotherapy and for imaging in nuclear medicine. ¹⁷⁷Lu is one of the promising radionuclides. This article reports on the first measurements of the excitation function for the production of ¹⁷⁷Lu with proton-beam energies up to 17 MeV on natural hafnium targets. The experimental cross sections for the reaction ^natHf(p,x)¹⁷⁷Lu were obtained by the activation of a stacked-foil target and subsequent gamma spectrometry. Theoretical cross sections were calculated up to 35 MeV with the EMPIRE nuclear reaction model code. The measured and calculated cross sections were used for deriving the thick-target yields and for estimating the production of other nuclides than ¹⁷⁷Lu. Measured production cross sections of ^{175,176,177,178}Ta on the same target are also presented.     

Study of activation cross sections of proton induced reactions on erbium for practical applications

Excitation functions of the ^natEr(p,x)^{163,166,167,168,170}Tm and ^natEr(p,x)^cum161Er reactions were measured experimentally from the respective threshold up to 36 MeV incident proton energy and in the range of 60-70 MeV. The cross sections were measured with activation method using the stacked foil irradiation technique. A theoretical interpretation of contributing reactions based on results of the ALICE-IPPE code was done. From our experimental cross section data integral production yields were calculated which were compared to the experimental integral yield data reported in the literature.     

Data evaluation of 169Yb-producing reactions by charged particles

Excitation functions for 169Yb production on low-medium energy accelerators, i.e. proton on 169Tm and natYb, deuteron on 169Tm, and 4He ion on natEr, were calculated by the ALICE/ASH and TALYS-1.0 codes. The target thickness was predicted by SRIM code. Theoretical integral yield for each reaction was compared with experimental data. The radionuclide purity of 169Yb from the 169Tm(p, n)169Yb reaction was determined, and maximum cross section predicted by the ALICE/ASH and TALYS-1.0 codes was about 182 and 154 mb at 11 and at 9 MeV, respectively.     

Activation Cross Sections for (n,p) and (n, α) Reactions on Nd,Sm, Yb and Lu at 14.6 MeV

Activation cross sections for the (n, p) and (n, α) reactions of Nd, Sm, Yb and Lu have been measured at 14.6 MeV by using a Ge(Li) γ-ray detector. The following cross sections (in millibarns) have been obtained: ¹⁵⁰Sm(n, p) ¹⁵⁰Pm, 7.19±1.01; ¹⁷³Yb(n, p) ¹⁷³Tm, 13.5±2.8; ¹⁷⁵Lu(n, p) ¹⁷⁵Yb, 18.5±2.2;¹⁴⁶Nd(n,α) ¹⁴³Ce, 4.42±0.47; ¹⁵²Sm(n, α) ¹⁴⁹Nd, 2.81±0.42; 174Yb(n, α)¹⁷¹Er, 1.22±0.23 and ¹⁷⁶Lu(n, α)¹⁷³Tm, 2.30±0.57. The results are compared with predictions based on the evaporation, the pre-equilibrium and other models. The present experimental (n, p) cross sections agree fairly well with the pre-equilibrium model predictions. A comparison made between the experimental (n, α) cross sections and the predictions of the pre-equilibrium model suggests the existence of a mechanism of pre-equilibrium emission in the (n, α) reaction in this mass region.     

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.     

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.     

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.     

Measured activation cross sections below 10 MeV for the V(n, p)Ti and V(n, α)Sc reactions

The activation method is used to measure cross sections for the ⁵¹V(n, p)⁵¹Ti reaction from E_n = 2.856 to 9.267 MeV and for the ⁵¹V(n, α)⁴⁸Sc reaction from 5.515 to 9.567 MeV. Both measurements utilize ENDF/B-V evaluated neutron-induced fission cross sections of ²³⁸U as a standard. The experimental results from this work are compared with corresponding ENDF/B-V evaluated cross sections for V and substantial differences are evident. The most significant difference is a tendency for the measured values to exceed evaluated ones by as much as 50% in the vicinity of 8 MeV.     

N(α,p)O nuclear reaction cross-section at 4.9–6.1 MeV

The ¹⁴N(α,p)¹⁷O nuclear reaction cross-section was measured in the energy range 4.9–6.1 MeV at the laboratory angle θ = 172° in order to apply ion beam analysis to the detection of N in metal oxynitride layers. Comparison between the new calculation and data in literature was performed, highlighting important discrepancies between the new results and old cross-section data. Application of the new calculations to a standard TiN film suggests improved accuracy for the data in the present work.     

Nuclear data sheets for A = 168

The 1964 version of the Nuclear Data Sheets has been revised according to experimental data received prior to May 1973, including approximately 120 papers.Data are presented for 6 nuclei (Ho, Er, Tm, Yb, Lu, and Hf), and Ta has been identified as a 2.5-m activity. The level structure of Er has been extensively studied via Ho decay, Tm decay, Er (n,γ), and various reactions. Comparison of these data has led to the addition of several new levels and suggested transitions in the three decay schemes. About 99 levels are now known in Er, with J^π assignments for about half of these. The Tm level scheme has been greatly expanded via stripping and pickup reactions and now includes ≈ 136 levels below 1.9 MeV, with about 50 J^π assignments. The Yb level scheme now includes ≈ 62 levels, primarily due to Lu decay and pickup reactions. The Lu activity has been identified as two separate isomers (5.3 m and 6.7 m), and tentative decay schemes are presented. For Hf, only the ground-state rotational band has been identified and no decay scheme has been proposed. Rotational band structure is presented for Er, Tm, Yb, and Hf and has been fit by the empirical formula for comparison to theoretical calculations and to aid in the identification of missing band members.There is presently no information on the level structure of Ho, Lu, or Ta. Lu could be most easily studied via Hf decay (25.95 m) or the ¹⁶⁸Yb(³He,t) reaction.     

Evaluated activation cross sections of longer-lived radionuclides produced by deuteron induced reactions on natural titanium

Selected charged particle induced reactions are used to monitor the actual parameters of bombarding particle beams. One of these reactions is ^natTi(d, x)⁴⁸V for which recommended cross section data are available in one of the databases of the International Atomic Energy Agency (http://www-nds.iaea.or.at/medical/). This database contains all together 22 monitor reactions for practical applications covering energy up to 100 MeV depending on the reactions. In the case of the ^natTi(d, x)⁴⁸V reaction recommended data are given in the 9-50 MeV energy interval because at the time of creation not precise enough experimental data were available to recommend values from threshold up to 9 MeV. In this work we measured the excitation function in this relevant low energy range, collected new experimental data and suggest high confidence recommended values for the missing low energy part of the monitor excitation function.     

On the 24Mg(t,p) Reaction in the Incident Energy Range of 1.65–3.4 MeV

Previously, cross sections and angular distributions of the ²⁴Mg(t, p) reaction were measured in the incident triton energy range of 1.65–3.4 MeV. Presently, the analysis of the reaction is made with a combined model of the resonance and direct reactions. Almost good agreement was obtained between the experiment and the analysis. Some excited states of the compound nucleus ²⁷Al in Ex = 19:68–21:23 MeV were determined by the resonance analysis.     

Measurement of thick target yields of the S(α,x)Cl nuclear reaction and estimation of its excitation function up to 70 MeV

Thick target yields of the ^natS(α,x)^34mCl nuclear reaction were measured in the energy region from 14.2 to 69.5 MeV. Our results were also compared to the only available literature dataset. Cross-sections of the above reaction were also estimated from the obtained thick target yields. Pure natural sulfur used as a target material resulted in a thick target saturation yield of 1557 ± 18 MBq (42.1 ± 0.5 mCi)/μA at 69.5 MeV. The estimated excitation function curve of the ^natS(α,x)^34mCl process showed a maximum cross-section of 122 mbarn at about 27.5 MeV.     

Light charged particle emission for p+Fe reactions

The energy spectra and double differential cross sections of nucleon and the light composite particle (d, t, ³He and α) emissions are studied based on the exciton model included the improved Iwamoto-Harada model. All cross sections of proton induced reactions, angular distributions and energy spectra are consistent calculated and analyzed for ^{54,56,57,58,nat}Fe at incident proton energies below 250 MeV by using nuclear theoretical models which integrate the optical model, the intra-nuclear cascade model, direct, pre-equilibrium and equilibrium reaction theories. Theoretical calculated results are compared with existing experimental data.