Measured Cross Section Values Research Articles

Activation cross section for 85Rb(n,2n)84mRb and 85Rb(n,p)85mKr reactions with uncertainty propagation and covariance analysis

The cross section of 85Rb(n,2n)84mRb and 85Rb(n,p)85mKr reactions were measured at neutron energy range 12–20 MeV using activation analysis followed by off-line γ-ray spectroscopic technique. The quasi mono-energetic neutrons were produced through 7Li(p,n)7Be reaction. The measurements were done relative to 27Al(n,α)24Na reference monitor reaction cross section. The detailed uncertainty propagation from the attributes present in measurements was performed using covariance analysis. The γ-ray self-attenuation and background low neutron energy corrections were performed in the measurement studies. Theoretical calculations were performed by TALYS-1.96 nuclear code. The comparison of measured values with the available data in EXFOR database and evaluated data from JENDL-5 and EAF-2010 shows the measured cross section values of 85Rb(n,p)85mKr reaction were slightly higher than the published values, evaluated data and theoretical data while for 85Rb(n,2n)84mRb, the measured values were consistent with the published data.

Measurement of the neutron capture cross section of 185Re in the keV energy region

ABSTRACT Despite various applications of Rhenium in nuclear science and engineering, there have been limited measurements of the neutron capture cross section of 185Re in the keV energy region, with existing data showing discrepancies. To address this, the study employed the time-of-flight method to measure the neutron capture cross section of 185Re. The prompt γ-rays from the neutron capture reactions were detected using a NaI(Tl) detector. The pulse-height weighting technique was employed to determine the neutron capture yield. The measured cross-section values were determined relative to the neutron capture cross section of 197Au in the energy range from 15 to 90 keV. Additionally, the obtained results were corrected for neutron transport effects and impurities. The results of the measurement provided improved accuracy compared to previous studies, contributing to the nuclear data for the capture cross section of 185Re in the keV energy range.

A Study of Complete and Incomplete Reactions of 12C + 169Tm System at Energy Range ≈ 4.16 –7.5 MeV/Nucleon

An attempt was made in this study to measure the excitation functions of 169Tm(12C, 4n)177Re, 169Tm(12C, 5n)176Re, 169Tm(12C, αn)176Ta, 169Tm(12C, α2n)175Ta, 169Tm(12C, α3n) 174Ta, 169Tm(12C, α4n)173Ta and 169Tm(12C, 2α2n)171Lu reaction channels populated in the interaction of 12C projectile with 169Tm target were considered in order to investigate the mechanisms of complete and incomplete fusion reactions. The theoretically predicted excitation functions using the PACE4 code were compared with the previously measured excitation functions. For non α emitting channels cross-section values predicted by PACE4 in general were found to be in good agreement with the experimentally measured values. However, for α-emitting channels, the measured cross-section values were found to be higher than the values predicted by PACE4. The observed disagreement may be credited to projectile break-up in the vicinity of n-n interaction.

A new empirical systematic for (n, 2p) reaction cross sections around 14 MeV

In the present work, we proposed a new empirical systematic with which we can predict the (n, 2p) cross sections as an extension of the empirical rule on the basis of the statistical theory of nuclear reactions. It is obtained by fitting the experimental cross sections as a function of mass number, reaction Q–value, threshold energy and projectile energy. A new analysis of experimental data is performed for (n, 2p) reactions around 14 MeV energy. Besides, the present formula was expressed by a simple systematic with two fitting parameters. The predictions of this formula were discussed and compared with cross section measurements and empirical formulas found in the literature. Results show that the new empirical formula gives a good fit to predict the (n, 2p) cross sections around 14 MeV. This study can provide a reference to the (n, 2p) reaction channel considering the lack of measured cross section values.

Methods to subtract the effect of the decay of different nuclear reaction products on the cross-section measurements and their application to the reactions studied

Two methods used to subtract the effect of the decay of different nuclear reaction products on the cross-section measurement of the studied nuclear reaction were given. Taking the cross-section measurement of the $^{91}\mathrm{Zr}(n,p)^{91\mathrm{m}}\mathrm{Y}$ reaction as an example, the accurate and reliable cross section of the $^{91}\mathrm{Zr}(n,p)^{91\mathrm{m}}\mathrm{Y}$ reaction in the neutron energy range of 13.5--14.8 MeV was measured by using the activation technique and the above two methods. Moreover, the excitation function in the neutron energies from the threshold to 21 MeV was calculated by using the nuclear theoretical model program system talys--1.9 with the adjusted relevant parameters. The measured cross-section values were discussed and compared with previous experiments by other researchers and with the theoretical values based on talys--1.9. The experimental values obtained by the above two methods were highly consistent within experimental error, and at some neutron energies they were consistent, within experimental error, with those of the fitting line of previous experiments at the corresponding energies, and were also consistent with those of theoretical excitation curve at the corresponding energies. The obtained theoretical excitation curve can match most of the experimental data.

A new empirical formula for cross-sections of (n,nα) reactions

Studies on the cross-sections of (n,n[Formula: see text]) reactions which are energetically possible, about 14 MeV neutrons are quite scarce. In this paper, the cross-sections of (n,n[Formula: see text] nuclear reactions at [Formula: see text]14–15 MeV are analyzed by using a new empirical formula based on the statistical theory. We show that neutron cross-sections are closely related to the [Formula: see text]-value of nuclear reaction, in particular for (n,n[Formula: see text]) channels. Results obtained with this empirical formula show good agreement with the available measured cross-section values. We hope that the estimations on the cross-sections using the present formalism may be helpful in future studies in this field.

Searching for ( γ,α)/(γ,n ) branching points in the γ -process path near A=100

Four $(\ensuremath{\alpha},\ensuremath{\gamma})$ cross-section measurements on stable nuclei in the $A=100$ mass range were performed at the University of Notre Dame Nuclear Science Laboratory. The $^{102}\mathrm{Pd}(\ensuremath{\alpha},\ensuremath{\gamma})^{106}\mathrm{Cd}$ and $^{110}\mathrm{Cd}(\ensuremath{\alpha},\ensuremath{\gamma})^{114}\mathrm{Sn}$ reactions were measured for the first time. The $^{90}\mathrm{Zr}(\ensuremath{\alpha},\ensuremath{\gamma})^{94}\mathrm{Mo}$ and $^{108}\mathrm{Cd}(\ensuremath{\alpha},\ensuremath{\gamma})^{112}\mathrm{Sn}$ results extended the measured range down to energies lower than those of the previous experiments. These reactions were studied as possible branching points in $\ensuremath{\gamma}$-process reaction networks. The measured cross-section values were compared to the nonsmoker database as well as to calculations performed with talys 1.9. The combination of parameters available in talys that gave the best fit to the data was found and the corresponding reaction rates were obtained. The inverse $(\ensuremath{\gamma},\ensuremath{\alpha})$ rates were then obtained and compared to the corresponding $(\ensuremath{\gamma},n)$ rates to investigate the relative strength between the two reaction pathways. It was found that in all four cases the $(\ensuremath{\gamma},\ensuremath{\alpha})$ reaction pathway begins to dominate within the 1.5--3.5 GK temperature range.

Experimental determination of the 16O(3He,p0)18F differential cross section

The differential cross section for the 16O(3He,p0)18F nuclear reaction is measured for a reaction angle of 135° in the laboratory frame for 3He energies between 1800 keV and 6100 keV. SiO2 thin films thermally grown on crystalline Si were used as reference samples. Their oxygen content was quantified by 3He Rutherford backscattering. The p0 cross section shows several resonances with the largest reaching 6.2 mbarn/sr at 4400 keV. At 2390 keV the measured cross section value coincides nicely with the measurement of Lennard et al. (1989). As an example, the oxygen areal density of the native oxygen coverage of polycrystalline tungsten was determined to be (11 ± 1) × 1015 O/cm2.

Cross section measurements of radiative KL2,3 RRS in 24Cr and L3M4,5 RRS in 59Pr for Mn Kα1,2 X-rays

The KL2,3 and L3M4,5 radiative resonant Raman scattering (RRS) cross sections have been measured for the quasimonochromatic Mn Kα1,2 X-rays (5.895keV) in 24Cr (K-shell level width (ΓK) =1.08eV) and 59 Pr (L3-subshell level width (ΓL3) =3.60eV), respectively, using targets in metallic and various chemical forms. The incident Mn Kα1,2 X-ray energy is lower than the K-shell binding energy of 24Cr and L3-subshell binding energy of 59Pr by ~94 ΓK (Cr) and ~94 ΓL3 (Pr), respectively. The experimental measurements were performed with a low energy Ge detector (LEGe) and a radioactive 55Fe annular source in conjunction with 24Cr absorber. The measured cross section values for the 24Cr and 59 Pr elements in their various oxidation states are found to be same within experimental errors. The measurements were further extended to investigate alignment of the intermediate L3-subshell (J =3/2) virtual vacancy states in 59Pr through angular distribution measurements for RRS photon emission, which is found to be isotropic within experimental errors.

Measurement of the t t ¯ $$ \mathrm{t}\overline{\mathrm{t}} $$ production cross section in the eμ channel in proton-proton collisions at s = 7 $$ \sqrt{s}=7 $$ and 8 TeV

The inclusive cross section for top quark pair production is measured in proton-proton collisions at sqrt(s) = 7 and 8 TeV, corresponding to 5.0 and 19.7 invers-femtobarns, respectively, with the CMS experiment at the LHC. The cross sections are measured in the electron-muon channel using a binned likelihood fit to multi-differential final state distributions related to identified b quark jets and other jets in the event. The measured cross section values are 173.6 +/- 2.1 (stat) +4.5-4.0 (syst) +/- 3.8 (lumi) pb at sqrt(s) = 7 TeV, and 244.9 +/- 1.4 (stat) +6.3-5.5 (syst) +/- 6.4 (lumi) pb at sqrt(s) = 8 TeV, in good agreement with QCD calculations at next-to-next-to-leading-order accuracy. The ratio of the cross sections measured at 7 and 8 TeV is determined, as well as cross sections in the fiducial regions defined by the acceptance requirements on the two charged leptons in the final state. The cross section results are used to determine the top quark pole mass via the dependence of the theoretically predicted cross section on the mass, giving a best result of 173.8 +1.7-1.8 GeV. The data at sqrt(s) = 8 TeV are also used to set limits, for two neutralino mass values, on the pair production of supersymmetric top squarks with masses close to the top quark mass.

Measurements of proton induced γ-ray emission cross-sections on Mg from 1.0 to 3.0 MeV

Differential cross-section of proton induced γ-ray emission from the reactions 24Mg(p,p′γ)24Mg (Eγ=1369keV), 25Mg(p,p′γ)25Mg (Eγ=390, 585, 975keV) and 26Mg(p,γ)27Al (Eγ=1014keV) were measured for proton energies from 1 to 3MeV using a 60μg/cm2 Mg target evaporated on a 40μg/cm2 Ag thin film. The γ-rays were collected by a 50% relative efficiency HPGe detector placed at an angle of 90° with respect to the beam direction, while the backscattered protons were collected by an ion implanted Si detector placed at a scattering angle of 165°. Simultaneous collection of γ-ray and RBS spectra is a great advantage of this approach which makes differential cross-section measurements independent on the collected beam charge. Measured cross-section values were compared with the previously reported data in the literature. Absolute γ-ray differential cross-sections were obtained with an overall systematic uncertainty of about ±6% and statistical uncertainty of less than ±5% for proton energies higher than 2.24MeV.

Scattering cross-sections of common calibration gases measured by IBBCEAS technique

In this study, incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) was used to measure scattering cross-sections of a few common gases in the 650–670nm spectral range relative to that of dry air. Precise measurements of scattering cross-sections of these calibration gases in the visible spectral range are important. The IBBCEAS system developed in the laboratory was calibrated with a low-loss optical window. The measurements made at 660nm were compared with previously measured cross-section values and found to be in good agreement with the existing measurements.

Measurement of three-jet production cross-sections in [Formula: see text] collisions at 7[Formula: see text] centre-of-mass energy using the ATLAS detector.

*************Double-differential three-jet production cross-sections are measured in proton–proton collisions at a centre-of-mass energy of sqrt{s} = 7mathrm ,TeV{} using the ATLAS detector at the large hadron collider. The measurements are presented as a function of the three-jet mass (m_{jjj}), in bins of the sum of the absolute rapidity separations between the three leading jets (left| Y^{*}right| ). Invariant masses extending up to 5 TeV are reached for 8< left| Y^{*}right| < 10. These measurements use a sample of data recorded using the ATLAS detector in 2011, which corresponds to an integrated luminosity of 4.51~text{ fb }^{-1}. Jets are identified using the anti-k_{t} algorithm with two different jet radius parameters, R=0.4 and R=0.6. The dominant uncertainty in these measurements comes from the jet energy scale. Next-to-leading-order QCD calculations corrected to account for non-perturbative effects are compared to the measurements. Good agreement is found between the data and the theoretical predictions based on most of the available sets of parton distribution functions, over the full kinematic range, covering almost seven orders of magnitude in the measured cross-section values.

Standard Model measurements with the ATLAS detector

Various Standard Model measurements have been performed in proton-proton collisions at a centre-of-mass energy of √ s = 7 and 8 TeV using the ATLAS detector at the Large Hadron Collider. A review of a selection of the latest results of electroweak measurements, W/Z production in association with jets, jet physics and soft QCD is given. Measurements are in general found to be well described by the Standard Model predic- tions. been performed in proton-proton collisions at a centre-of-mass energy of √ s = 7 and 8 TeV using the ATLAS detector (1) at the LHC. These allow for precision tests of the electroweak dynamics of the Standard Model, but also challenge next-to-next-to-leading-order predictions. Differences between measurements and Standard Model predictions could prove evidence for new phenomena. Recent Quantum Chromo Dynamics (QCD) results highlight the importance of precision QCD measurements for improving state-of-the-art theoretical tools and searching for new physics. A selection of the latest results of electroweak measurements, W/Z production in association with jets, jet physics and soft QCD is reported. These consist of the measurement of the WW cross section, first evidence of the electroweak production of W ± W ± jj , and electroweak Zj jproduction. Measurements are in general found to be well described by the Standard Model predictions. Measurements of differential produc- tion cross sections of a Z boson in association with b-jets, the production cross section of the W boson in association with jets as well as the ratio of the production cross sections for W and Z bosons in association with jets are presented. The measurements are compared to next-to-leading-order pertur- bative QCD calculations and to predictions from different Monte Carlo (MC) generators implement- ing leading-order matrix elements supplemented by parton showers. Various inclusive, differential or double differential jet measurements are presented. The dominant experimental uncertainty on these measurements comes from the jet energy scale. Next-to-leading order QCD calculations corrected to account for non-perturbative effects are compared to the measurements. A good agreement between the data and the theoretical predictions based on most of the global parton distribution functions is found over the full kinematic range, covering almost seven orders of magnitude in the measured cross-section values. A measurement of charged-particle distributions sensitive to the properties of

Modeling of Neutron Spectra Based on Activation Analysis

Safe and economical use of nuclear energy and particularly the development of GEN-IV reactors impose a better understanding of prompt neutron emission in fission, as well as of the fission process as such. Therefore, accurate measurements of the prompt fission neutron spectra (PFNS) are very important. In this work, we are testing the possibility to determine the PFNS by an activation method called DONA (DOsimetry and Spectroscopy using Neuron Activation) recently developed at IRMM (Wieslander et al., 2010, Lövestam et al., 2009). This type of modeling of the neutron spectra, based on the activation analysis, can provide new information about an old problem which still exists today, i.e. the discrepancy between measured integral and differential data (Capote et al., 2012). The problem is that the calculated average cross section for a certain neutron reaction, by using the differential experimental PFNS, in many cases cannot reproduce satisfactorily the integral measured cross section values. The modeling of the neutron spectra by the DONA technique was tested with the standard neutron spectrum of the spontaneous fission of 252Cf. We analyzed the sensitivity of the unfolding procedure to the initial neutron energy spectrum, the influence of the neutron scattering, the possibility of using different activation reactions and we also made an estimation of the lowest measurable neutron fluence rate.

Measurement of theRe187(α,n)Ir190reaction cross section at sub-Coulomb energies using the Cologne Clover Counting Setup

Uncertainties in adopted models of particle+nucleus optical-model potentials directly influence the accuracy in the theoretical predictions of reaction rates as they are needed for reaction-network calculations in, for instance, {\gamma}-process nucleosynthesis. The improvement of the {\alpha}+nucleus optical-model potential is hampered by the lack of experimental data at astrophysically relevant energies especially for heavier nuclei. Measuring the Re187({\alpha},n)Ir190 reaction cross section at sub-Coulomb energies extends the scarce experimental data available in this mass region and helps understanding the energy dependence of the imaginary part of the {\alpha}+nucleus optical-model potential at low energies. Applying the activation method, after the irradiation of natural rhenium targets with {\alpha}-particle energies of 12.4 to 14.1 MeV, the reaction yield and thus the reaction cross section were determined via {\gamma}-ray spectroscopy by using the Cologne Clover Counting Setup and the method of {\gamma}{\gamma} coincidences. Cross-section values at five energies close to the astrophysically relevant energy region were measured. Statistical model calculations revealed discrepancies between the experimental values and predictions based on widely used {\alpha}+nucleus optical-model potentials. However, an excellent reproduction of the measured cross-section values could be achieved from calculations based on the so-called Sauerwein-Rauscher {\alpha}+nucleus optical-model potential. The results obtained indicate that the energy dependence of the imaginary part of the {\alpha}+nucleus optical-model potential can be described by an exponential decrease. Successful reproductions of measured cross sections at low energies for {\alpha}-induced reactions in the mass range 141{\leq}A{\leq}187 confirm the global character of the Sauerwein-Rauscher potential.

Cross-section measurement of theBa130(p,γ)La131reaction forγ-process nucleosynthesis

Background: Deviations between experimental data of charged-particle-induced reactions and calculations within the statistical model are frequently found. An extended data base is needed to address the uncertainties regarding the nuclear-physics input parameters in order to understand the nucleosynthesis of the neutron-deficient $p$ nuclei.Purpose: A measurement of total cross-section values of the $^{130}\mathrm{Ba}(p,\ensuremath{\gamma})^{131}\mathrm{La}$ reaction at low proton energies allows a stringent test of statistical model predictions with different proton+nucleus optical model potentials. Since no experimental data are available for proton-capture reactions in this mass region around $A \ensuremath{\approx}130$, this measurement can be an important input to test the global applicability of proton+nucleus optical model potentials.Method: The total reaction cross-section values were measured by means of the activation method. After the irradiation with protons, the reaction yield was determined by use of $\ensuremath{\gamma}$-ray spectroscopy using two clover-type high-purity germanium detectors. In total, cross-section values for eight different proton energies could be determined in the energy range between 3.6 MeV $\ensuremath{\le}{E}_{p}\ensuremath{\le}$ 5.0 MeV, thus, inside the astrophysically relevant energy region.Results: The measured cross-section values were compared to Hauser-Feshbach calculations using the statistical model codes TALYS and SMARAGD with different proton+nucleus optical model potentials. With the semimicroscopic JLM proton+nucleus optical model potential used in the SMARAGD code, the absolute cross-section values are reproduced well, but the energy dependence is too steep at the lowest energies. The best description is given by a TALYS calculation using the semimicroscopic Bauge proton+nucleus optical model potential using a constant renormalization factor.Conclusions: The statistical model calculation using the Bauge semimicroscopic proton+nucleus optical model potential deviates by a constant factor of 2.1 from the experimental data. Using this model, an experimentally supported stellar reaction rate for proton capture on the $p$ nucleus $^{130}\mathrm{Ba}$ was calculated. At astrophysical temperatures, an increase in the stellar reaction rate of 68% compared to rates obtained from the widely used NON-SMOKER code is found. This measurement extends the scarce experimental data base for charged-particle-induced reactions, which can be helpful to derive a more globally applicable proton+nucleus optical model potential.

Measurements of multiphoton action cross sections for multiphoton microscopy.

We report quantitative measurements of two-, three-, and four-photon excitation action cross sections of several commonly used fluorophores and fluorescent proteins at three different excitation wavelengths of 800 nm, 1300 nm, and 1680 nm. The measured cross section values are consistent with simple quantum mechanic estimations. These values indicate that the optimum repetition rate for deep tissue 3-photon microscopy is approximately 1 to 2 MHz. We further demonstrate that it is feasible to perform 4-photon fluorescence microscopy of GFP labeled microglia in mouse brain in vivo at 1700 nm. 4-photon excitation increases the accessibility of fluorophores at the long wavelength spectral window of 1700 nm.

Measurement of gamma-ray production cross sections for nuclear reactions 14N(d,pγ)15N and 28Si(d,pγ)29Si

In this work the differential cross sections for gamma-ray emission from the 14N(d,pγ)15N (Eγ=1885, 2297, 7299 and 8310keV) and from the 28Si(d,pγ)29Si (Eγ=1273, 2028, 2426 and 4934keV) were measured simultaneously with the 14N(d,p4,5,6,7)15N differential cross sections and 14N(d,d)14N elastic scattering cross section using a HPGe detector at 55° and an ion implanted Si detector at 135° with respect to the beam direction in the deuteron energy range 0.65–2.0MeV. The target was a thin silicon-nitride film. Gamma-ray angular distribution measurements were performed to determine the possible anisotropy of the gamma-ray emission, and the measured cross section values were converted into total gamma-ray producing cross sections for most of the gamma-ray emissions. The average uncertainties of nitrogen and silicon gamma-ray production cross sections are 5% and 12%, respectively and 8% concerning the particle production cross section of natN(d,d0)natN and 14N(d,p4,5,6,7)15N reactions.

Production cross section of At radionuclides from7Li+natPb and9Be+natTl reactions

Earlier we reported theoretical studies on the probable production of astatine radionuclides from $^{6,7}$Li and $^{9}$Be-induced reactions on natural lead and thalliun targets, respectively. For the first time, in this report, production of astatine radionuclides has been investigated experimentally with two heavy ion induced reactions: $^{9}$Be+$^{\textrm{nat}}$Tl and $^{7}$Li+$^{\textrm{nat}}$Pb. Formation cross sections of the evaporation residues, $^{207,208,209,210}$At, produced in (HI, xn) channel, have been measured by the stacked-foil technique followed by the off-line $\gamma$-spectrometry at the low incident energies ($<$50 MeV). Measured excitation functions have been explained in terms of compound nuclear reaction mechanism using Weisskopf-Ewing and Hauser-Feshbach model. Absolute cross section values are lower than the respective theoretical predictions.