24Na Reaction Research Articles

Measurement of nuclide production cross sections for GeV-region proton-induced reactions on [formula omitted]Mg, [formula omitted]Si, [formula omitted]Fe, [formula omitted]Cu, and [formula omitted]Zn

Nuclide production cross sections for proton-induced reactions on natMg, natSi, natFe, natCu, and natZn at several GeV were measured using an activation technique at Japan Proton Accelerator Research Complex. The aggregate results of 250 cross sections were successfully acquired. The cross sections of the natFe(p,X)44mSc, natZn(p,X)22Na, natZn(p,X)28Mg, natZn(p,X)48Sc, and natZn(p,X)69mZn reactions were acquired for the first time. The cross sections of the natFe(p,X)46Sc, natFe(p,X)52Fe, natCu(p,X)43Sc, natCu(p,X)48Sc, natCu(p,X)58Co, and most of the natZn(p,X) reactions above about 1 GeV were firstly measured. The data obtained in this study were compared with the results from nuclear reaction models in PHITS and the data retrieved from Japanese Evaluated Nuclear Data Library High Energy file 2007 (JENDL/HE-2007). As the nuclear reaction models, Liège IntraNuclear Cascade, two versions of JAERI Quantum Molecular Dynamics, and Jet AA Microscopic Transport Model coupled with an evaporation process were applied. Among all of the models, INCL/GEM, JENDL/HE-2007, and JAM/GEM generally showed the good agreement.

Cross section measurements of 27Al(γ, x)24Na reactions as monitors for laser-driven bremsstrahlung γ-ray

The accurate monitors of the electron beams and γ-ray fluxes are very important for laser-driven photonuclear studies. The flux-weighted average cross sections and average cross sections per equivalent quantum of 27Al(γ,x;x=2pn,pd,H3e)24Na reactions were measured above the giant dipole resonance region through activation methods. Laser-driven ultra-intense bremsstrahlung γ-rays, generated by laser wakefield accelerated quasi-monoenergetic electrons, were used in the experiment at the 200 TW laser facility of the Compact Laser Plasma Accelerator Laboratory, Peking University. The results demonstrated good agreement with previous works and were compared with theoretical values given by TALYS 1.9 calculations. The experimental cross sections were confirmed to be 2.4 times higher than TALYS 1.9 with default options. This work proved the feasibility of using the 27Al(γ,x)24Na reactions as monitors for laser wakefield accelerated electrons and their bremsstrahlung γ-ray fluxes.

Study of the 20Ne(p,γ)21Na reaction at LUNA

The NeNa-MgAl cycles are involved in the synthesis of Ne, Na, Mg, and Al isotopes. The 20Ne(p,γ)21Na (Q = 2431.68 keV) reaction is the first and slowest reaction of the NeNa cycle and it controls the speed at which the entire cycle proceeds. At the state of the art, the uncertainty on the 20Ne(p,γ)21Na reaction rate affects the production of the elements in the NeNa cycle. In particular, in the temperature range from 0.1 GK to 1 GK, the rate is dominated by the 366 keV resonance corresponding to the excited state of EX = 2797.5 keV and by the direct capture component. The present study focus on the study of the 366 keV resonance and the direct capture below 400 keV. At LUNA (Laboratory for Underground Nuclear Astrophysics) the 20Ne(p,γ)21Na reaction has been measured using the intense proton beam delivered by the LUNA 400 kV accelerator and a windowless differential-pumping gas target. The products of the reaction are detected with two high-purity germanium detectors. The experimental details and preliminary results on the 366 keV resonance and on the direct capture component at very low energies will be shown, together with their possible impact on the 20Ne(p,γ)21Na reaction rate.

On the accuracy of cross-section measurements of neutron-induced reactions using the activation technique with natural targets: The case of Ge at E[formula omitted] MeV

Several cross-section measurements of neutron-induced reactions on Ge found in literature, are performed utilizing natGe targets. The production of the same residual nucleus as the measured one might occur as a result of the unavoidable presence of neighboring isotopes in the same target, acting as a contamination. Corrections must be made based on theoretical calculations and models in order to resolve this problem. The accuracy and limits of a methodology for these “theoretical corrections” are investigated in this work using isotopically enriched targets, which can produce very accurate results without the need for such corrections. Experimental cross-section measurements have been made for the 76Ge(n,2n)75Ge, 72Ge(n,α)69mZn and 72Ge(n,p)72Ga reactions, via the activation technique, with the 27Al(n,α)24Na reaction used as reference, employing both a natGe and isotopically enriched Ge targets. The 3H(d,n)4He (D–T) reaction was used for producing the quasi-monoenergetic neutron beam in the 5.5 MV Tandem Accelerator Laboratory of the National Centre for Scientific Research “Demokritos” in Athens, Greece, at an incident deuteron beam energy of 2.9 MeV. Using HPGe detectors, γ-ray spectroscopy was applied to determine the induced γ-ray activity of the residual nuclei.

20Ne(α,p)23Na studied to constrain type Ia nucleosynthesis

The 20Ne(α,p)23Na reaction rate is important in determining the final abundances of various nuclei produced in type Ia supernovae. Previously, the ground state cross section was calculated from time reversal reaction experiments using detailed balance. The reaction rates extracted from these studies do not consider contributions from the population of excited states, and therefore, are only estimates. A resonance scan, populating both the ground and first excited states, was performed for the 20Ne(α,p)23Na reaction, measuring between 2.9 and 5 MeV center of mass energies at the Nuclear Science Lab at the University of Notre Dame. Data analysis is underway and preliminary results show substantial contribution from the excited state reaction.

A study of the reaction 55Mn(p,4n)52Fe: excitation function and medical applications

The present study concerns the medical applications and production of 52Fe via the reaction 55Mn(p,4n)52Fe together with the reference reaction 27Al(p,x)22Na employed in cross section measurements. Experimental excitation functions from threshold up to 200 MeV are compared with the predictions of the TALYS 1.95 code and the semi-empirical formulas SPACS and Silberberg & Tsao. We obtained two TALYS parameter sets for the 55Mn(p,4n)52Fe and 27Al(p,x)22Na reactions which give a good description of the excitation functions for energies up to 85 MeV. Discrepancies observed at higher energies require further investigation. The semi-empirical formulas provide a good description of the excitation functions above 120 MeV.

Investigation of charged-particle induced reactions on 27Al up to 100 MeV leading to the formation of 22Na and 24Na

Abstract Studies using theoretical models are of great importance for understanding of reaction process and its nature. In this study, nuclear level density model calculations of the cross sections of 27Al are investigated by using TALYS 1.96 computer code. The cross section calculations of 27Al(α,x)22Na, 27Al(α,x)24Na, 27Al(3He,x)22Na, 27Al(3He,x)24Na, 27Al(p,x)22Na and 27Al(p,x)24Na reactions were carried out for incident particle energy up to 100 MeV. In these calculations, four nuclear level density models, namely constant temperature model (CTM), back-shifted Fermi gas model (BSFGM), generalized superfluid model (GSM) and recently proposed semi-classical Fermi gas model (CSCFGM) are used. This model is developed using the simplest model BSFGM. The most obvious difference between CSCFGM and other models is the inclusion of the collective effects in the base of the formulation. The predicted results are discussed and compared with each other and the available experimental data taken from EXFOR library. In order to better evaluate the model results, chi-squared values are calculated and compared with each other for all analyzed reactions. According to the chi-squared results, CSCFGM gives closer predictions to the experimental data compared with the other models in 4 of the 6 analyzed reactions. Therefore, in this study, it is presented that this model can be reliably used in the reaction cross section calculations.

Impact of newly measured 26Al(n, p)26Mg and 26Al(n, α)23Na reaction rates on the nucleosynthesis of 26Al in stars

ABSTRACT The cosmic production of the short-lived radioactive nuclide 26Al is crucial for our understanding of the evolution of stars and galaxies. However, simulations of the stellar sites producing 26Al are still weakened by significant nuclear uncertainties. We re-evaluate the 26Al(n, p)26Mg, and 26Al(n, α)23Na ground state reactivities from 0.01 GK to 10 GK, based on the recent n_TOF measurement combined with theoretical predictions and a previous measurement at higher energies, and test their impact on stellar nucleosynthesis. We computed the nucleosynthesis of low- and high-mass stars using the Monash nucleosynthesis code, the NuGrid mppnp code, and the FUNS stellar evolutionary code. Our low-mass stellar models cover the 2–3 M⊙ mass range with metallicities between Z = 0.01 and 0.02, their predicted 26Al/27Al ratios are compared to 62 meteoritic SiC grains. For high-mass stars, we test our reactivities on two 15 M⊙ models with Z = 0.006 and 0.02. The new reactivities allow low-mass AGB stars to reproduce the full range of 26Al/27Al ratios measured in SiC grains. The final 26Al abundance in high-mass stars, at the point of highest production, varies by a factor of 2.4 when adopting the upper, or lower limit of our rates. However, stellar uncertainties still play an important role in both mass regimes. The new reactivities visibly impact both low- and high-mass stars nucleosynthesis and allow a general improvement in the comparison between stardust SiC grains and low-mass star models. Concerning explosive nucleosynthesis, an improvement of the current uncertainties between T9∼0.3 and 2.5 is needed for future studies.

Study of the20Ne(p,γ)21Na reaction at LUNA

The20Ne(p,γ)21Na is the first reaction of the NeNa cycle and having the slowest reaction rate, it controls the speed at which the entire cycle proceeds. This reaction is important in different stellar scenarios such as red giants stars (during H shell-burning), asymptotic giant branch stars, novae, and massive stars. Existing uncertainties on the20Ne(p,γ)21Na are now the ones that severely affect the estimated elements production in the NeNa cycle. In particular, such uncertainties affect the amount of produced22Na, a stellarγ-ray signature, and22Ne, an important neutron source in the s-process, via the22Ne(α,n)25Mg. Here, we propose to study the resonance atER= 366 keV and to measure the20Ne(p,γ)21Na reaction cross section at proton energies below 400 keV, in particular the contribution from the sub-threshold state, in order to better constrain the overall astrophysical rate of this important reaction. In this contribution, the experimental setup will be described and the expected results discussed.

Excitation function of proton induced reactions on iron in the energy range 85–100 MeV

Excitation functions of the natFe (p, x) 52,54Mn, 55Co, 51Cr, 52Fe, and 46Sc reactions were measured at the proton energy of 87, 94 and 100 MeV, using the stacked foil activation technique followed by the off-line γ-ray spectrometry. The experiment was carried out on the separated sector cyclotron at the Institute of Modern Physics, Chinese Academy of Sciences. The natNi (p, x)57Ni and natAl (p, x)22Na reactions with known cross sections was used to monitor the proton beam intensity. The results from this work were compared with the existing literature data available in EXFOR data library and were found to be in good agreement. TALYS-1.95 is able to reproduce, in most cases, the experimental trend. Our experimental results were also compared with evaluated nuclear data from the ENDF/B-VIII.0, JENDL-4.0/HE, and PADF-2007 libraries as a function of proton energy, which reproduced the trend of the excitation functions of the experimental natFe (p, x) reaction cross-sections. These data expand our knowledge on the related excitation functions to confirm the existing trends and to give additional experimental values on a wider energy range.

A Theoretical Study on the Production Cross–Section Calculations for 24Na Medical Isotope

24Na is a beta and gamma emitting radioisotope that is widely used in medical and engineering fields. It is often used in medical radiotracing. This radioisotope with a half-life of 15 hours is mostly produced in cyclotrons. The cross-section of a radioisotope is used to obtain various data about the production of that radioisotope. In cases where it is not possible to obtain experimental data, missing data can be completed with cross-section calculations and the obtained data can be compared with experimental, saving time, cost and effort. This study was carried out for detailed analysis of cross-section calculations for 24Na isotope, which has a wide range of usage in medicine and industry. In this direction, the cross-sections obtained from different simulation programs were compared with literature data of the reactions. Production cross-sections of the 24Na isotope were investigated in the 23Na(d,p)24Na, 24Mg(n,p)24Na, 25Mg(n,n+p)24Na, 25Mg(p,2p)24Na, 26Mg(d,α)24Na and 27Al(n,α)24Na reactions with the equilibrium and pre-equilibrium models of nuclear reaction codes of TALYS 1.95 and EMPIRE 3.2. Results were compared with experimental data from the EXFOR data library. The relevance of the models to the reactions was discussed and calculations were made using the relative variance analysis method to determine the best model.

Neutron Field Shaping Using Graphite for Reaction Rate Measurements

Abstract Neutron field shaping is the suitable method for validation of cross section in various energy regions. By increasing the share of neutrons of a certain energy interval and decreasing the share of other, a reaction becomes more sensitive to selected neutrons. As a result, reaction cross section can be validated in selected energy regions more precisely. The shaping can be carried out by both neutron filters which are materials with high absorption in some energy region, or by diffusion material changing the shape of neutron spectra by means of slowing down process. In the presented experiments, the neutron field of the light reactor 0 (LR-0) research reactor was shaped by both using graphite blocks inserted into the core and Cd cladding for increasing the epithermal reaction rate share in total reaction rates. The calculations were carried out with the Monte Carlo N-Particle Transport Code 6 (MCNP6) code and the most recent nuclear data libraries. The results in the pure graphite neutron field are in good agreement; in case of Cd cladding, significant discrepancies were reported. In case of the 23Na(n,γ)24Na reaction, overestimation by about 14% was reached in International Reactor Dosimetry and Fusion File (IRDFF-II), results in other libraries are comparable. In case of 58Fe(n,γ)59Fe, the overestimation as high as 18% is reported in IRDFF-II. For 64Zn(n,γ)65Zn reasonable agreement was reached in evaluated nuclear data file (ENDF/B-VIII), where discrepancies in pure graphite neutron field or in case of Cd cladding are about 10–15%.

Pairing of thorium with selected primary target materials in tandem configurations: Co-production of 225Ac/213Bi and 230U/226Th generators with a 70 MeV H[formula omitted] cyclotron

Several radionuclide production facilities based on a new generation of high-current, 70 MeV H− cyclotrons have been established in recent years and a number of new facilities are either under construction or being planned. In this study, the feasibility to produce 225Ac/213Bi and 230U/226Th generators via Th + p reactions at such a facility has been investigated. From the perspective of production yields, it has been found useful to compare the relevant reactions on thorium with those on other targets regularly employed in this energy region, in particular the natMg(p,x)22Na, natGa(p,x)68Ge, and natRb(p,x)82Sr reactions that have been exploited with 66 MeV proton beams at iThemba LABS for many years. Therefore, various tandem configurations of thorium with magnesium, gallium and rubidium are discussed based on the relevant nuclear data. In a few cases, the available data were judged to be insufficient in this energy region. New experimental cross sections are presented for 225Ac, 225Ra, and 230Pa in Th + p reactions as well as 22,24Na in natMg + p reactions. Integral yields have been derived for those radionuclides of main interest. Production yields expected from extended 70 MeV proton bombardments, on selected tandem-target configurations, are presented for 22Na, 68Ge, 82Sr, 225Ac, and 230Pa. It is concluded that 225Ac/213Bi generators can, in principle, be added to a production programme based at a 70 MeV H− cyclotron facility as the production rate is of similar magnitude to those of other well-established radionuclides in this energy region. Also, radio-contaminant levels for 225Ac are similar to those found in higher proton-energy windows. The scope for 230U/226Th generators, via bulk production of the precursor 230Pa, seems to be more limited due to a lower yield but can nevertheless be produced in clinically relevant quantities.

First inverse kinematics study of the Ne22(p,γ)Na23 reaction and its role in AGB star and classical nova nucleosynthesis

The abundances of sodium and oxygen are observed to be anti-correlated in all well-studied globular clusters. Asymptotic giant branch (AGB) stars undergoing hot bottom burning (HBB) are thought to be prime candidates for producing sodium-rich oxygen-poor material and expelling it into the cluster ISM. The 22Ne(p,gamma)23Na reaction has been shown to strongly influence the amount of 23Na produced during HBB. This reaction is also important for classical novae nucleosynthesis, with sensitivity studies showing that the abundances of several isotopes in the Ne-Al region are significantly altered when varying the reaction rate between available compilations. Here we present the first inverse kinematics measurements of key resonances strengths as well as the direct capture S-factor. Together, this study represents the largest centre of mass energy range (149-1222 keV) over which this reaction has been measured in a single experiment. Our results for low-energy resonances at Ecm=149, 181 and 248 keV are in good agreement with recent forward kinematics results; we also find a direct capture S-factor consistent with the literature value of 62 keV.b. However, in the case of the important reference resonance at Ecm = 458 keV we find a strength value of wg=0.44 +/- 0.02 eV, which is significantly lower than recent results. Using our new recommended rate we explore the impact of these results on both AGB star and classical novae nucleosynthesis. In the case of AGB stars we see very little abundance changes with respect to the rate included in the STARLIB-2013. However, we observe changes of up to a factor of 2 in isotopes produced in both the carbon-oxygen (CO) and oxygen-neon (ONe) classical novae models considered here. The 22Ne(p,gamma)23Na reaction rate is now sufficiently well constrained to not significantly contribute toward abundance uncertainties from classical novae nucleosynthesis models.

Cross-sections for , and reactions on molybdenum isotopes in the neutron energy range of 13 to 15 MeV * * Supported by the National Natural Science Foundation of China (11875016, 11565012, 11165007)

Given the insufficient cross-sectional data regarding the 14-MeV-neutron experiment of molybdenum, the vital fusion reactor structural material, and the significant heterogeneities among the reported values, this study examined the (n,2n), (n,α), (n,p), (n,d), and (n,t) reaction cross sections in molybdenum isotopes based on the neutrons produced via a T(d,n)4He reaction carried out in the Pd-300 Neutron Generator at the China Academy of Engineering Physics (CAEP). A high-resolution gamma-ray spectrometer, which was equipped with a coaxial high-purity germanium detector, was used to measure the product nuclear gamma activities. In addition, 27Al(n,α)24Na and 93Nb(n,2n)92mNb reactions were utilized as the neutron fluence standards. The experimental 92Mo(n,2n)91Mo, 94Mo(n,2n)93mMo, 100Mo(n,2n)99Mo, 98Mo(n,α)95Zr, 100Mo(n,α)97Zr, 92Mo(n,p)92mNb, 96Mo(n,p)96Nb, 97Mo(n,p)97Nb, 98Mo(n,p)98mNb, 92Mo(n,d)91mNb, and 92Mo(n,t)90Nb reaction cross sections were acquired within the 13–15 MeV neutron energy range. Thereafter, we compared and analyzed these obtained cross sections based on the existing IAEA-EXFOR database-derived experimental data, together with evaluation results corresponding to ENDF/B-VIII.0, JEFF-3.3, BROND-3.1, and CENDL-3.1 and the theoretical outcomes acquired through TALYS-1.95 and EMPIRE-3.2.3 (nuclear-reaction modeling tools).

23Ne production at SARAF-I

In this article, we present a measurement of flow rate, yield and effusion time of a 23Ne production and transport system. We used an accelerator-driven Li(d,n) neutron source to produce neutrons up to 20 MeV. The radioactive atoms were produced by a 23Na(n,p) reaction at a NaCl target. Later, the atoms were diffused out from the NaCl crystals and effused from the production chamber via a 10 m hose to a measurement cell and their decay products were detected using High Purity Germanium (HPGe) and plastic scintillator detectors. The resulting flow rate was 6.9±0.7⋅104atomssec and the total yield was 3.2±0.6⋅10−9atomsdeuteron. We summarize our methods and estimates of efficiencies, rates of production and effusion.

First inverse kinematics measurement of key resonances in the 22Ne(p,γ)23Na reaction at stellar temperatures

In this Letter we report on the first inverse kinematics measurement of key resonances in the Ne22(p,γ)23Na reaction which forms part of the NeNa cycle, and is relevant for 23Na synthesis in asymptotic giant branch (AGB) stars. An anti-correlation in O and Na abundances is seen across all well-studied globular clusters (GC), however, reaction-rate uncertainties limit the precision as to which stellar evolution models can reproduce the observed isotopic abundance patterns. Given the importance of GC observations in testing stellar evolution models and their dependence on NeNa reaction rates, it is critical that the nuclear physics uncertainties on the origin of 23Na be addressed. We present results of direct strengths measurements of four key resonances in Ne22(p,γ)23Na at Ec.m. = 149 keV, 181 keV, 248 keV and 458 keV. The strength of the important Ec.m. = 458 keV reference resonance has been determined independently of other resonance strengths for the first time with an associated strength of ωγ = 0.439(22) eV and with higher precision than previously reported. Our result deviates from the two most recently published results obtained from normal kinematics measurements performed by the LENA and LUNA collaborations but is in agreement with earlier measurements. The impact of our rate on the Na-pocket formation in AGB stars and its relation to the O-Na anti-correlation was assessed via network calculations. Further, the effect on isotopic abundances in CO and ONe novae ejecta with respect to pre-solar grains was investigated.

Determination of the cross-section for (n,p) and (n,α) reactions on 153Eu at neutron energies from 13 to 15 MeV

The cross-sections of 153Eu(n,p)153Sm and 153Eu(n,α)150Pm reactions have been measured experimentally. Monoenergetic neutron beams were produced via the 3H(d,n)4He reaction using the K-400 neutron generator at China Academy of Engineering Physics (CAEP). The activity of the reaction products were measured using high-resolution gamma-ray spectroscopy. Using the 27Al(n,α)24Na reaction as the neutron fluence standard, the experimental cross-sections of the reactions 153Eu(n,p)153Sm and 153Eu(n,α)150Pm were obtained and the results are 3.6 ± 0.5, 3.8 ± 0.6, 4.5 ± 0.7 mb and 1.25 ± 0.07, 1.46 ± 0.08, 1.71 ± 0.11 mb at neutron energies 13.5 ± 0.2, 14.1 ± 0.2, 14.8 ± 0.2 MeV, respectively. These experimentally measured cross-sections were discussed and compared with some previously reported experimental results from the literature and with the evaluation data obtained from ENDF/B-VIII.0, JEFF-3.3, JENDL-4.0, RUSFOND and CENDL-3, in addition to the theoretical results obtained by using the nuclear-reaction modeling tool TALYS-1.95.

Neutron-induced activation cross-sections for fusion technology applications

Activation method was employed to measure the cross section for the 58Ni(n,pα)54Mn and 63Cu(n,pα)59Fe reactions in the energy range from the threshold up to 21 MeV. The quasi-monoenergetic neutrons in the energy range from 14 to 21 MeV were produced via the 3H(d,n)4He reaction at 1, 2, 3 and 4 MeV incident deuteron energies. High purity Ni and Cu samples with natural isotopic composition and dimensions of ϕ12x5 mm and ϕ20x5 mm respectively were utilized. The gamma-ray spectrometry using HPGe detector was utilized to measure the activity induced in the sample. The cross sections were determined relative to the standard cross section the 27Al(n,α)24Na reaction. The results for the 63Cu(n,pα)59Fe reaction cross section were obtained for the first time.

Isomeric Cross Section Study of Neutron Induced Reactions on Ge Isotopes

In the present work, natural Ge targets have been irradiated by neutron beams of 17.7 and 19.3 MeV, at the 5MV tandem accelerator of NCSR "Demokritos". The cross section of the 72,74Ge(n,α)69,71Zn and 76Ge(n,2n)75Ge reactions, leading to the population of isomeric states, has been deduced with respect to the 27Al(n,α)24Na and 93Nb(n,2n)92mNb reference reactions. After the neutron irradiations, the induced γ-ray activity of the Ge target and reference foils, was measured with high-resolution HPGe detectors.