Excitation Functions Of Nuclear Reactions Research Articles

Newly developed semi-empirical formulas of nuclear excitation functions for (n,α) reactions at the energy range 12 ≤ En ≤ 20 MeV and mass number range 30 ≤ A ≤ 128

A new semi-empirical systematics of (n,α) reaction excitation functions for nuclei with mass number 30≤A≤128 at neutron induced energy range 12≤En≤20 MeV is obtained. It is based on the evaporation model and the pre-equilibrium exciton model. The Droplet model of Myers and Swiatecki was used to express the reaction energy Q. The Dostrovsky formula was introduced to formulate the expression of the inverse cross section channel.The systematics behavior of the different terms of the Droplet model involved in the reaction energy Q(n,α) was verified individually before choosing the relevant terms and setting up the formulae. By fitting these formulae to the existing cross-section data, the adjustable parameters have been determined and the systematics of the (n,α) reaction have been studied. The new semi-empirical formula has been verified for predictions of the excitation functions of nuclear reactions not used in the fitting. The calculated excitation functions were compared to the experimental data and EMPIRE-3.2 code calculations. A good agreement between excitation functions systematics and EXFOR data was observed for great number of (n,α) reactions.

Quantitative analysis of Li by PIGE technique

In this work, the cross section of the reactions 7Li(p,pγ)7Li (γ – 478keV) at the proton energy range 2.0–4.2MeV was measured. The measurements were carried out at the 3MV Tandem Accelerator at the CTN/IST Laboratory in Lisbon. To validate the obtained results, calculated gamma-ray yields were compared, at several proton energy values, with experimental yields for thick samples made of inorganic compounds containing lithium. In order to quantify the light elements present in the samples, we used a standard free method for PIGE in thick samples, based on a code – Emitted Radiation Yield Analysis (ERYA), which integrates the nuclear reaction excitation function along the depth of the sample. We also demonstrated the capacity of the technique for analysis of Li ores, as Spodumene, Lithium Muscovite and Holmquistite, and Li-alloys for plasma facing materials showing that this is a reliable and accurate method for PIGE analysis of Li in thick samples.

Excitation functions for the formation of longer lived isotopes by deuteron irradiation of Europium

Excitation functions for nuclear reactions induced on natural europium targets by energetic deuterons were studied up to 50MeV. A standard stacked foil technique was used for irradiation and high resolution gamma spectrometry was applied for activity assessment. Direct or cumulative cross sections for reaction products with half-life longer than 2h were determined. Reactions leading to the formation of the radionuclides 147,149,151,153Gd, 147,148,149,150m,150g,152m,152g,154gEu, 153Sm and 150Pm were studied. In most cases no earlier data were available in the literature. The new experimental results were compared with values tabulated in the on-line TENDL2011 library.

New measurements and evaluation of database for deuteron induced reaction on Ni up to 50 MeV

Excitation functions for nuclear reactions induced by deuterons up to 50MeV on natural nickel targets were studied in five experiments using a standard stacked foil technique and non destructive high resolution gamma spectrometry. Reaction products with half life of more than 2h were assessed. The elemental activation cross sections were determined for reactions resulting in the radionuclides 61Cu, 56,57Ni, 55,56,57,58,60Co, 52,54,56Mn and 51Cr. The new experimental results were compared with earlier evaluated data and with values tabulated in the online TENDL2011 library.

PIGE analysis of magnesium and beryllium

Abstract In this work, we present an alternative method for PIGE analysis of magnesium and beryllium in thick samples. This method is based on the ERYA – Emitted Radiation Yield Analysis – code, which integrates the nuclear reaction excitation function along the depth of the sample. For this purpose, the excitations functions of the 25Mg(p,p′γ)25Mg (Eγ = 585 keV) and 9Be(p,γ)10B (Eγ = 718 keV) reactions were employed. Calculated gamma-ray yields were compared, at several proton energy values, with experimental yields for thick samples made of inorganic compounds containing magnesium or beryllium. The agreement is better than 5%. Taking into consideration the experimental uncertainty of the measured yields and the errors related to the stopping power values, this agreement shows that effects as the beam energy straggling, ignored in the calculation, seem to play a minor role.

PIGE analysis and profiling of aluminium

In this work we present an alternative method for PIGE analysis of aluminium in thick samples. This method is based on the ERYA – emitted radiation yield analysis – code, which integrates the nuclear reaction excitation function along the depth of the sample. For this purpose, the excitations functions of the 27Al(p,p′γ1,2)27Al reaction (with gamma-ray energies of 844 and 1014keV) were employed. Calculated gamma-ray yields were compared, at several proton energy values, with experimental yields for thick samples made of inorganic compounds containing aluminium. The agreement is better than 5%.The 1684keV resonance of the same reaction, with a natural width of 100eV, was used to profile samples of Ti implanted with several doses of Al. We show that this resonance, stronger than the 992keV resonance of the 27Al(p,γ)28Si usually employed for aluminium profiling, leads to similar depth resolution in shorter collection time.

Proton Activation Data File” to Study Activation and Transmutation of Materials Irradiated with Protons at Energies up to 150 MeV

To satisfy growing needs in nuclear data at intermediate energies, the Proton Activation Data File (PADF) has been prepared. It contains 418,575 excitation functions of nuclear reactions for 2,355 target nuclei from Mg to Ra at proton energies up to 150 MeV. The data are available in the PADF for stable and unstable target nuclei including isomeric targets with the half-life more than one second. Cross-sections included in the PADF were obtained by using the TALYS code, the modified ALICE code, and the available experimental data.

Quantitative analysis of light elements in aerosol samples by PIGE

Quantitative PIGE analysis of aerosol samples collected on nuclepore polycarbonate filters was performed by a method that avoids the use of comparative standards. Nuclear cross sections and calibration parameters established before in an extensive work on thick and intermediate samples were employed. For these samples, the excitation functions of nuclear reactions, induced by the incident protons on target’s light elements, were used as input for a code that evaluates the gamma-ray yield integrating along the depth of the sample. In the present work we apply the same code to validate the use of an effective energy for thin sample analysis. Results pertaining to boron, fluorine and sodium concentrations are presented. In order to establish a correlation with sodium values, PIXE results related to chlorine are also presented, giving support to the reliability of this PIGE method for thin film analysis.

Carbon-10: Example of cyclotron production of positron emitters as an open research field

This paper supports the thesis that significant improvement of PET output response to clinical questions can be achieved by innovation in radionuclide production. Moreover, that development can be performed with the resources available at a clinical centre. Carbon-10 production parameters studies are used as example. A technical methodology for measurement of excitation function of nuclear reactions yielding short-lived radionuclides, performed to measure cross section values of the 10B(p,n) 10C reaction in a PET-devoted cyclotron, is presented.

Excitation functions of nuclear reactions induced by 3He-particles on cobalt

Activation cross-sections for production of 54Mn, 56,57,58,60Co and 60,61Cu radioisotopes in 3He-induced reactions on Co were measured from the respective thresholds up to 26 MeV. The stacked foil irradiation method was used to produce the activation products and the emitted gamma photons were detected by high-resolution gamma-spectroscopy. The obtained new cross-sections are compared with literature data. The possible applications of the available excitation function data are discussed.

Measurement of the inelastic scattering of protons by 23Na in the energy range 1.25–2.40 MeV

The inelastic scattering of protons by the 23Na isotope induces, with high probability, gamma-ray emission that can be easily detected by a HpGe detector. This is the basis of the PIGE analysis. PIGE analysis of thick and intermediate samples is usually performed with the help of standards. This method only gives good results when the standard is similar to the sample to be analysed. A more precise method can be implemented based on a code that integrates the nuclear reaction excitation function along the depth of the sample. For that purpose, it is necessary to measure it in the exact analytical conditions. The energy steps needed to define accurately the excitation function are used as energy intervals for the integration procedure. From the fundamental point of view, elastic and inelastic reactions have an important role for the correct description of the entrance channel of all nuclear reactions induced in 23Na by protons, namely the reaction 23Na(p,γ) 24Mg relevant for stellar nucleosynthesis. Interaction potentials and the definition of intervening states may be extracted from fitting to elastic and inelastic cross-sections. This work presents cross-sections of the nuclear reaction 23Na(p,p ′γ) 23Na, measured in the energy range from 1.25 to 2.40 MeV, with an accurate method not dependent on the absolute values of the collected beam charge and of the target thickness.

Quantitative analysis of light elements in thick samples by PIGE

PIGE analysis of thick and intermediate samples is usually performed with the help of standards, but this method gives only good results when the standard is very similar to the sample to be analysed. In this work, we present an alternative method for PIGE analysis of light elements in thick samples. This method is based on a code that integrates the nuclear reaction excitation function along the depth of the sample. For the integration procedure the sample is divided in sublayers, defined by the energy steps that were used to measure accurately the excitation function. This function is used as input. Within each sublayer the stopping power cross-sections may be assumed as constant. With these two conditions the calculus of the contribution of each sublayer for the total yield becomes an easy task. This work presents results for the analysis of lithium, boron, fluorine and sodium in thick samples. For this purpose, excitation functions of the reactions 7Li(p,p ′γ) 7Li, 19F(p,p ′γ) 19F, 10B(p,α γ) 7Be and 23Na(p,p ′γ) 23 Na were employed. Calculated γ-ray yields were compared, at several proton energy values, with experimental yields for thick samples made of inorganic compounds of the referred elements. The agreement is better than 7.5%. Taking into consideration the experimental uncertainty of the measured yields and the errors related to the stopping power values used, this agreement shows that effects as the beam energy straggling, ignored in the calculation, seem to play a minor role.

Cyclotron production and quality control of “high specific activity' radionuclides in “no-carrier-added' form for radioanalytical applications in the life sciences

Radionuclides of very high specific activity AS(t) have great relevance for applications in the life sciences. Updated definitions of AS are given. The real AS(t) must be measured by analytical and radioanalytical techniques. No-carrier-added (NCA) radionuclides have AS(NCA) sometimes close to the carrier-free (CF) value AS(CF). The accurate knowledge of excitation functions of nuclear reactions vs. ion beam energy is mandatory to maximize AS(NCA); the minimization of isotopic dilution factor IDF(t) has been achieved too. A range of accelerator production and radioanalytical QC methods for AS(NCA) optimization and determination is presented.

Proton-induced γ-ray analysis of lithium in thick samples

A method for proton-induced γ-ray analysis (PIGE) of Li (either elemental or isotopic composition) in thick samples is presented in this work, which is based on a code that integrates the nuclear reaction excitation function, measured at the same experimental conditions, along the depth of the sample. The energy steps needed to define accurately the excitation function are used as energy intervals for the integration procedure. The excitation function and cross-sections of the reaction 7 Li (p,p ′γ) 7Li, for protons in the energy range 0.60–2.5 MeV, were obtained and used as input to calculate lithium concentrations in thick and intermediate samples. The calculated thick target yields of samples with several amounts of lithium were compared with the respective measured yields, showing that this is a reliable and accurate method for PIGE analysis of Li in thick samples.

Excitation functions of nuclear reactions induced by alpha particles up to 42 MeV on natTi for monitoring purposes and TLA

Excitation functions for the reactions induced by alpha particles on natTi foils and leading to the formation of 44m,44g,46,47,48Sc; 48,51Cr and 48V were determined using the stacked foil technique for energies from the respective reaction thresholds up to 42 MeV. The new experimental values are compared to earlier literature values and generally good accordance is found. It appears that the natTi(α,x)51Cr reaction is particularly useful for monitoring α-beams in the 10–20 MeV region while for energies above 20 MeV the natTi(α,x)47Sc reaction or the natTi(α,x)48V reaction are more suited. The excitation functions established can be used to determine calibration curves for thin layer activation (TLA) as well.

Excitation functions for nuclear reactions with interaction of up to 47-MeV deuterons with tin

The investigations, initiated in, of the deuteron excitation functions for nuclear reactions with interaction energies of up to several tens of MeV were continued. The aim of the investigations is to obtain experimental data that can be used to determine the concentration of nuclides forming as a result of the transmutation of nuclei of the deuteron-irradiated material as well as to study the possibilities of predicting the data theoretically. In the present work we measured the excitation function for reactions in which long-lived nuclides are formed under irradiation of tin by deuterons. Calculations of the excitation functions were performed on the basis of the model of pre-equilibrium emission of nucleons and evaporation of nucleons and {gamma}-rays from the compound nucleus using the program ALICE LIVERMORE. Conclusions are drawn on the basis of a comparison of the measurements and calculations about the role of the compound-nucleus mechanism in reactions with deuterons on tin and the possibility of using the ALICE LIVERMORE program for predicting reaction excitation functions. Thus far the only such investigation for tin is the experiment performed with deuteron energies up to 13.6 MeV.

Formation of long-lived radionuclides in the deuteron irradiation of zirconium

The total cross sections of nuclear reactions in the energy range between several MeV and several tens of MeV have not been sufficiently studied at the present time. In many cases there are no experimental data. There is often a question of accuracy with which the cross sections can be calculated using theoretical models. At the same time, these types of nuclear constants are essential for the development of every nuclear technology. In the present work, an excitation function of nuclear reactions has been experimentally studied by the formation of long-lived radionuclides from the interaction of 47 MeV deuterons with zirconium of natural isotopic abundance. The experimental results are compared with theoretical calculations performed within the framework of a preequilibrium emission model and the evaporation of particles from a compound nucleus. Earlier an analogous study of the excitation function of proton-induced reactions was conducted.

A code to determine the energy distribution, the incident energy and the flux of a beam of light ions into a stack of foils

The stacked-foil technique is one of the most used methods to obtain excitation functions of nuclear reactions using light ions as projectiles. The purpose of this program is the calculation of the energy of the beam in the stack, as well as to obtain the incident energy and the flux of the beam by using monitor excitation functions.

Triton reactions with some light and medium elements. Application to activation analysis

The excitation functions for nuclear reactions induced by tritons are determined up to about 3.5 MeV for some light and medium elements: fluorine, sodium, magnesium, aluminium, silicon, titanium and vanadium. Because of large cross-sections the activation technique was used with thin targets. Then the possibilities of using these reactions to analytical purposes are discussed.

Landolt-Börnstein—Numerical Data and Functional Relationships in Science and Technology. New series. Editor-in-chief:K.-H. Hellwege. Group I:Nuclear and Particle Physics.-Vol. 5:Q-Values and Excitation Functions of Nuclear Reactions. Part b:Excitation Functions for Charged-Particle Induced Nuclear Reactions: Edited byH. Schopper

Landolt-Börnstein—Numerical Data and Functional Relationships in Science and Technology. New series. Editor-in-chief:K.-H. Hellwege. Group I:Nuclear and Particle Physics.-Vol. 5:Q-Values and Excitation Functions of Nuclear Reactions. Part b:Excitation Functions for Charged-Particle Induced Nuclear Reactions: Edited byH. Schopper