Experimental study of the Ho(d, 2n) and Ho(d, p) nuclear reactions up to 20 MeV for production of the therapeutic radioisotopes Er and Ho

The radioisotope ¹⁶⁵Er (T_1/2 = 10.36 h) is a candidate for Auger-electron therapy. The β⁻-emitting ^166gHo (T_1/2 = 26.83 h) is now being explored for various therapeutic applications. In the frame of our systematic study of charged particle production routes of therapeutic radionuclides the excitation functions of the ¹⁶⁵Ho(d, 2n)¹⁶⁵Er and ¹⁶⁵Ho(d, p)^166gHo reactions were measured up to 20 MeV by using a stacked foil irradiation technique and X/γ-ray spectroscopy. The excitation function of the ¹⁶⁵Ho(d, 2n)¹⁶⁵Er reaction was measured for the first time while for the ¹⁶⁵Ho(d, p)^166gHo reaction only a single dataset of earlier measured cross-sections was found. The measured excitation functions were compared to the results of different nuclear reaction model codes. The calculated thick target yield of the ¹⁶⁵Ho(d, 2n) reaction is significantly higher over the optimal energy range than that for the ¹⁶⁵Ho(p, n) reaction investigated earlier by us. The integral yield of the ¹⁶⁵Ho(d, p)^166gHo reaction is rather low compared to the established ¹⁶⁵Ho(n, γ)¹⁶⁶Ho reaction in a nuclear reactor.     

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.     

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.     

Production cross-sections for the residual radionuclides from the Cd(p, x) nuclear processes

We measured the production cross-sections of the ^{107,111m,115g}Cd, ^{108m,108g,109g,110m,110,111g,113m,114m,115m,116m}In and ^{104g,105g,106m,110m,111g,113g}Ag radionuclides for proton-induced reactions on cadmium by using a stacked-foil activation technique in the energy rangy between 3 and 40 MeV at the MC-50 cyclotron of the Korea Institute of Radiological and Medical Science. The measured cross-sections were compared with the available literature data and the theoretical calculations by the model codes TALYS and ALICE-IPPE. The integral yields for thick targets were also obtained from the measured cross-sections of the produced radionuclides. The measured cross-sections, especially the indium (In) radionuclides have a significance for various practical applications; thin layer activation analysis, nuclear medicine, nuclear technology, radioactive waste handling, etc.     

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.     

Measurement of cross-sections for the (p, xn) reactions in natural molybdenum

Cross-sections for the residual radionuclide productions by proton-induced activation on natural molybdenum were measured up to 40 MeV by using a stacked-foil technique at the MC50 cyclotron of the Korea Institute of Radiological and Medical Sciences (KIRAMS). This work has given a new data set for the formation of the investigated radionuclides. The present results for most of the radionuclides showed in general good agreement with the earlier reported data as well as the theoretical data taken from the calculations based on the ALICE-IPPE code. The integral yields for thick targets were also deduced from the measured cross-sections of the produced radionuclides. The optimum production of the ^99mTc radionuclide with minimum impurities can be obtained at the energy ranges from 10 to 23 MeV, where the production yields were obtained as 597.15 MBqμA⁻¹h⁻¹ at saturation. The measured cross-sections are used for production of medically important radionuclides such as ^99mTc, ^94mTc and ^93m,gTc by using the medium-energy cyclotrons.     

Activation cross sections and isomeric cross section ratios for the (n,2n) reactions on Lu, Pt and Se from 13.5 to 14.6 MeV

The cross sections for the ¹⁷⁵Lu(n,2n)^174m,gLu, ¹⁹⁸Pt(n,2n)^197m,gPt and ⁸²Se(n,2n)^81m,gSe reactions and their isomeric cross section ratios σ_m/σ_g have been measured in the neutron energy range of 13.5-14.6 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 the (n,2n) reaction on ¹⁷⁵Lu, ¹⁹⁸Pt and ⁸²Se are compared with experimental data found in the literature, with results of published empirical formulae, and with values of model calculations including the pre-equilibrium contribution.     

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 the production of helium, neon and argon isotopes by proton-induced reactions on iron and nickel

We measured integral thin target cross sections for the proton-induced production of ³He, ⁴He, ²¹Ne, ²²Ne, ³⁶Ar and ³⁸Ar from Fe and Ni from the respective reaction thresholds up to 1.6 GeV. The production of noble gas isotopes, especially ⁴He, from Fe and Ni is of special importance for design studies of accelerator driven systems and/or energy amplifier, because Fe is the main structural material in almost every design study. Furthermore, the cross sections are needed to establish the first physical model calculations for the production of cosmogenic nuclides in iron meteorites. As a result of our new measurements there now exist for both target elements a complete and consistent database for the production of noble gas isotopes. The experimental data are compared to results from the theoretical nuclear model codes INCL4/ABLA and TALYS. This comparison clearly demonstrates again that experimental data are still needed because the predictive power of nuclear model codes, though permanently improving, does still not allow reliably predicting the cross sections needed for most applications and irradiation experiments remain indispensable.     

New measurement and evaluation of the excitation function of Ni(p,n) reaction for the production of Cu

One of the radioisotopes for which a growing interest exists in nuclear medicine is ⁶⁴Cu. Its branched decay makes it suitable for both diagnostic and therapeutic purposes. Activation cross sections of the proton induced reaction on enriched ⁶⁴Ni have been studied using the stacked foil technique up to 24 MeV. The experimental cross sections are compared with values available from literature. Thick target yields, based on the discrete measured values of the cross sections are calculated and allow a better estimation of the optimum production parameters.     

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.     

Excitation functions of the proton-induced nuclear reactions on Sn up to 40 MeV

We have measured the production cross-sections of the residual radionuclides for proton-induced reactions on natural tin by using a stacked-foil activation technique in the energy range from threshold energy to 40 MeV at the MC-50 cyclotron of the Korea Institute of Radiological and Medical Sciences. The results were compared with the earlier reported experimental data and theoretical calculations based on the TALYS and the ALICE-IPPE codes. The present results are in general good agreement with the available literature data and calculated results by using the computer codes TALYS and ALICE-IPPE. The thick target integral yields were also deduced from the measured excitation functions of the produced radionuclides.     

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.     

Differential cross section measurements of the S(d,p)S reaction for nuclear reaction analysis purposes

Differential cross sections of the ³²S(d,p_{0,1,2,3,4-6,7}) reactions were determined for deuteron energies E_lab = 1975-2600 keV (in steps of 25 keV) and for detector angles between 140-170° in steps of 10°. A comparison of the experimental data with the existing ones and possible applications to nuclear reaction analysis (NRA) studies are discussed.     

Excitation functions for some W, Ta and Hf radionuclides obtained by deuteron irradiation of Ta up to 40 MeV

Experimental excitation functions for deuteron induced reactions up to 40 MeV on mono-isotopic Ta (¹⁸¹Ta) were measured with the activation method using a stacked foil irradiation technique. From high resolution gamma spectrometry and X-ray analysis cross-section data for the production of ¹⁸¹W, ^{177,178g,180g,182m+g}Ta, and ^179m2,180mHf were determined. Comparison with the scarce earlier published data are presented and results for values predicted by different theoretical codes, adapted for more reliable calculations for d-induced reactions, are included. Thick target yields for ^{182m+g,180g,178g}Ta and ¹⁸¹W were calculated from a fit to our experimental excitation curves. Using dose conversion factors and irradiation scenarios, possible occupational doses to maintenance or scientific personnel around high power accelerators where Ta based structural elements (collimators, beam stoppers, shielding) are present could be derived.     

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.     

Investigation of excitation functions of alpha induced reactions on Xe: Production of the therapeutic radioisotope Cs

Excitation functions were measured for alpha-particle induced nuclear reactions on natural xenon leading to the formation of the radionuclides ^{129m(rel),129g,131m,131mg,133m,135m,137m,139cum}Ba and ^{129cum,130mg,132,134m,135m,136mg,138mg}Cs from the respective thresholds up to 40 MeV. 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. The feasibility of the production of the therapeutic radioisotope ¹³¹Cs by using gas target technology was investigated. Comparison of reactor and cyclotron production routes of ¹³¹Cs was given.     

Calculation and evaluation of cross-sections for p+Fe reactions up to 250 MeV

All cross-sections of proton-induced reactions, angular distributions and the energy spectra of neutron, proton, deuteron, triton, helium and alpha-particle emission are consistent calculated and analyzed for p+^{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, preequilibrium and equilibrium reaction theories. Especially, the cross-sections of the light composite particle (d, t, ³He and α) emissions are improved based on the exciton model including the pick-up mechanism. Theoretical calculated results are compared with existing experimental data.     

Detailed spatial measurements and Monte Carlo analysis of the transportation phenomena of thermal and epithermal neutrons from the 12-GeV proton transport line to an access maze

In order to investigate the neutron transportation from a beam-line tunnel to an access maze at a 12-GeV proton accelerator, we measured the spatial distribution of thermal and epithermal neutrons by using the Au activation method in detail. Gold foils were placed at about 70 positions in the maze in the case of the insertion (or extraction) of a copper target of 1 mm thickness into (or from) the beam axis in front of the maze. After the end of accelerator operation, relative activities of the Au foils were simultaneously measured by using an imaging plate technique and the radioactivity of one reference foil was also measured with a HPGe detector to convert to the absolute activities of all foils.It was found that the neutrons reach to the depth of the maze in the case of the insertion of the copper target. This result reflects higher proportion of high-energy particles from the copper target to that from other beam loss points and high-energy particles become the successive source of low-energy neutrons. Furthermore, it was found that several circumstances such as door walls and electric wire cables obviously affect the absorption effect of thermal neutrons. The reaction rates obtained in this study were also used for the benchmark of the Monte Carlo simulation code, MARS15 (version of February 2008). The results of the MARS15 calculations precisely reproduced experimental results and significant effects of the electric wire cables and door walls.