Top PDF Evaluation of the 93Nb(n,γ) Reaction Cross-Section

Evaluation of the 93Nb(n,γ) Reaction Cross-Section

Evaluation of the 93Nb(n,γ) Reaction Cross-Section

At present there are 3 cross-section evaluations [2–4] and the recommended data by Mughabghab [5]. At the thermal point, the evaluated cross-sections agree with each other and the recommended data (1.15 ± 0.5 b) within declared uncertainties. In the resolved resonance region the evaluated data is somewhat contradictory. The total numbers of the resonances identified in the ENDF/B-VII.1, JENDL-4.0, ROSFOND evaluations and Mughabghab’s systematics are similar (194, 201, 199 and 202 resonances, correspondingly, see Table 1). At the same time, there exists a considerable disagreement between the numbers of the s- and p-resonances. In particular, authors of the ENDF/B-VII.1, JENDL- 4.0, ROSFOND evaluations and Mughabghab presented the parameters of 148, 139, 99, 66 s-resonances and 46, 62, 100, 136 p-resonances, respectively (the difference is more than 2 times). As follows from the ENDF/B-VII.1 and JENDL-4.0 evaluations, the density of the p-resonances decreases with increasing the neutron energy E. This fact looks suspicious because the average neutron width of the p-resonances is proportional toE 3/2 . In crude approximation, the density of levels is proportional to
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Strong γ-ray emission from neutron unbound states populated in β-decay: Impact on (n,γ) cross-section estimates

Strong γ-ray emission from neutron unbound states populated in β-decay: Impact on (n,γ) cross-section estimates

angular momentum l and channel spin s are selected by spin and parity conservation. For the calculations we used parameters retrieved from the RIPL-3 reference input parameter library [16]. The NLD corresponds to that calculated using a Hartree-Fock-Bogoliubov (HFB) plus combinatorial approach adjusted to experimental information [17]. The PSF is obtained from Generalized Lorentzian (E1 transitions) or Lorentzian (M1 and E2 transitions) type functions using parameters from systematics. The NTC is obtained from the Optical Model (OM) using the TALYS-1.6 software package [18] with parameters taken from the so-called local parametrization of Ref. [19]. It is assumed that the actual widths for individual transitions are subject to statistical fluctuations of the Porter-Thomas (PT) type around the average values. The PT distribution, a chi-square distribution with one degree of freedom, is a very asymmetric distribution. This can introduce significant corrections [20] when calculating width ratios. In the case of reaction cross sections, for example the neutron radiative capture which depends on γ n / tot , the width fluctuation correction (WFC) is
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A unified understanding of (γ, n) and (n, γ) reactions and direct neutron-multiplicity sorting

A unified understanding of (γ, n) and (n, γ) reactions and direct neutron-multiplicity sorting

whose energy varies with the square of the electron energy, is energy-tunable from 4 to 38 MeV (8 to 76 MeV) with the use of the λ = 1064 nm (532 nm) photons at the NewSUBARU synchrotron radiation facility where the electron beam energy can be changed from 0.5 to 1.5 GeV. The LCS γ -ray beam is quasi-monochromatic with energy spreads essentially determined by the electron beam emittance and size of the collimator. A typical energy spread is 1–2% in FWHM in photoneutron cross section measurements around neutron threshold [6,7]. The LCS γ -ray beam is background-free in the quasi-monochromatic region, which is in sharp contrast to the fact that γ -ray beams produced by the positron annihilation in flight are accompanied by considerable background γ -rays generated by the positron bremsstrahlung [9].
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Measurement of 73Ge(n,γ) cross sections and implications for stellar nucleosynthesis

Measurement of 73Ge(n,γ) cross sections and implications for stellar nucleosynthesis

The neutron flux was measured in a dedicated campaign us- ing reactions with well known cross sections and three different detection systems to minimise systematic uncertainties. The flux measurement was performed with a set of silicon detectors using 6 Li(n , t) reactions (SiMon detector), a Micromegas detector mea- suring 6 Li( n , t ) and 235 U( n , f ), and an ionisation chamber provided by Physikalisch Technische Bundesanstalt Braunschweig, measuring 235 U(n , f ). The data were then combined to produce a reliable flux over the entire neutron energy range. The final evaluated neutron flux has a systematic uncertainty below 1% for neutron energies < 3 keV, and of 3.5% between 3 keV and 1 MeV [17]. More details on the neutron flux evaluation at n_TOF can be found in Ref. [18]. The neutron fluence was monitored throughout the measurement by recording the number of protons impinging on the spallation target (provided by PS detectors). This was cross checked using the SiMon detector which was operational throughout the run. In addition, the stability of the C 6 D 6 detectors was monitored by inte- grating the total number of counts in a strong 73 Ge
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New measurement of the 242Pu(n,γ) cross section at n_TOF

New measurement of the 242Pu(n,γ) cross section at n_TOF

reactors allows substituting a large fraction of the enriched Uranium by Plutonium repro- cessed from spent fuel. With the use of such new fuel composition rich in Pu, a better knowledge of the capture and fission cross sections of the Pu isotopes becomes very im- portant. In particular, a new series of cross section evaluations have been recently carried out jointly by the European (JEFF) and United States (ENDF) nuclear data agencies. For the case of 242 Pu, the two only neutron capture time-of-flight measurements available,

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(n,xn γ) reaction cross section measurements for (n,xn) reaction studies

(n,xn γ) reaction cross section measurements for (n,xn) reaction studies

For this measurement, data were accumulated during 1200 hours with a sample of 10 g. Unlike the case of 235 U we are able to identify about 30 γ -transitions and we have determined 20 preliminary cross sections. It has to be noticed that we are able to extract also cross sections for the transition from the first inelastic level at 45 keV to the ground state [12] but with limited statistical and systematical accuracy due to the high conversion coe ffi cient and sample sel attenuation for this γ transition. Our experimental data are compared to TALYS-1.2 calculations made by P. Romain (CEA). In EXFOR data base, four (n,nγ ) measurements are available [14, 13, 15, 16].
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Capture reaction cross-section measurements relevant to p process: the case of (α , γ) reactions on 63Cu, 72Ge,118Sn and the 107Ag(ρ, γ)108Cd reaction

Capture reaction cross-section measurements relevant to p process: the case of (α , γ) reactions on 63Cu, 72Ge,118Sn and the 107Ag(ρ, γ)108Cd reaction

According to Fig. 2, the use of the latter α OMP in HF calculations delivers -on the average- cross sections smaller than those derived with the phenomenological αOMP of [26]. In addition, at energies below the (α, n) threshold that is indicated in Fig. 2 with a grey arrow, the TALYS-2, TALYS-3 and TALYS-4 semi-microscopic calculations are in better agreement with the experimental ones compared to those of TALYS-default. Notably, these three semi- microscopic combinations use the semi-microscopic αOMP of [22]. It is worth noting that at energies above the opening the (α, n) channel, the HF calculations depend not only on the αOMP but also to the other nuclear parameters (NLDs, γSFs) entering the calculations. Therefore any comparison regarding the predictive power of the different αOMPs should be limited to energies below the (α, n) threshold. Under these conditions, the data measured for 74 Ge(α, γ) 78 Se and 118 Sn(α, γ) 122 Te are not suitable to draw any conclusion on the pre- dictive power of different α OMP models. These considerations apply also in the case of the
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How well do we understand the reaction rate of C burning?

How well do we understand the reaction rate of C burning?

Abstract. Carbon burning plays a crucial role in stellar evolution, where this reaction is an important route for the production of heavier elements. A particle-γ coincidence technique that minimizes the backgrounds to which this reaction is subject and provides reliable cross sections has been used at the Argonne National Labo- ratory to measure fusion cross-sections at deep sub-barrier energies in the 12 C

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Effective photoexcitation cross section of 115In(γ,γ′)115mIn from photoactivation data

Effective photoexcitation cross section of 115In(γ,γ′)115mIn from photoactivation data

calculated using the TALYS code [24], with input parameters which will be discussed in Section 4. The calculated ratio between 114gs In and 114m In yields is of the order of 27% over the 10 to 18 MeV energy range. This ratio is applied to the measured yields of 114m In to obtain the ones of 114gs In. Fig- ure 4 presents the obtained photoneutron production yields, corresponding to the above-mentioned reactions. A total of 7 × 10 5 neutrons per μC of electron beam is produced in the samples in the worst

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(n,α) reactions cross section research at IPPE

(n,α) reactions cross section research at IPPE

neutron energy range 1.7 – 7 MeV was made. The result is shown in figure 4. As is shown our data are in good agreement with the ENDF/B-VII evaluation and Gabbard et al. [3] data in the energy ranges 1.7-3 and 6-7 MeV but in the energy range 4-6 MeV a large discrepancy by a factor of up to 3 and more exists. A possible explanation of this discrepancy was found by analysis of energy spectra. For the 4-6 MeV energy range there is a minimum for the cross section to the left of which there is a broad region with a very high cross section level. For this condition a small number of background neutrons (with low energy) can produce a lot of α particles. If the detector energy resolution is low this background will be added to the real events resulting in a measured cross section which has a larger value than the real one.
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Total and partial photoneutron reactions cross sections – new analysis and evaluation

Total and partial photoneutron reactions cross sections – new analysis and evaluation

Because data of both laboratories agree as to total number of neutrons detected, the differences in their reaction cross sections  (,n) and  (,2n) were proposed [7] to arise from the separation of counts into 1n and 2n events (neutron multiplicity sorting). In [7] the results obtained using neutron multiplicity sorting were compared with those obtained using alternative method of induced activity in which concrete partial reactions are identified using detection of not outgoing neutrons but of formatting final nucleus. That was shown that results of
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Be 7 (n,p) Li 7 Reaction and the Cosmological Lithium Problem : Measurement of the Cross Section in a Wide Energy Range at n-TOF at CERN

Be 7 (n,p) Li 7 Reaction and the Cosmological Lithium Problem : Measurement of the Cross Section in a Wide Energy Range at n-TOF at CERN

Li reaction, as a function of neutron energy, compared with the two pre- vious direct measurements and with the current ENDF evaluation. In the figure only the statistical errors are shown. The systematic uncertainty, mainly related to the sample inhomogeneity, is 10% from thermal to 50 keV, and could reach 15% above it, due to the estimated effect of the angular distribution assumption. The present data are 35% and 40% higher than those of Koehler et al. [8] and the ENDF/B-VII.1 evaluation [16], respectively, while they are consistent with the results of Hanna [17], Gledenov et al. [7], and Č ervená et al. [18] at thermal neutron energy. Our experimental value is set at 52 . 3 5 . 2 kb.
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Inelastic scattering of fast neutrons from 56Fe

Inelastic scattering of fast neutrons from 56Fe

time-of-flight facility nELBE. The scattering cross section was determined via the measurement of the γ -ray production and by means of a kinematically complete double time-of-flight method. In a further measurement the γ -ray angular distribution was determined to correct the measured cross sections for anisotropy. The resulting inelastic scattering cross section determined from the photo production cross sections is in very good agreement with evaluations and previous measurements. In contrast, the result of the double time-of- flight measurement is about 10% lower than these data, giving a hint to neutron-γ -ray angular correlations in the process of inelastic neutron scattering.
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Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Modeling of Sic Power Semiconductor Devices For Switching Converter Applications

Studying the nuclear reaction n(p, d)γ and calculating its cross-section is not only a matter of interest from theoretical particle physics point of view but also from the viewpoint of cosmology. We now know that the universe is made up of only ≈ 5 % baryonic matter. So, computing the density of baryons is of particular importance to physicists in general and cosmologists in particular. Deuterium production during Big Bang Nucleo-synthesis (BBN) is very sensitive to the density of baryons, thus baryon density can be inferred from the abundance of deuterium. In order to calcu- late deuterium abundance one needs to use the cross-section of np → dγ reaction as one of the inputs. Hence, the importance of this cross-section calculation.
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Statistical Model Analysis of (n, α) Cross Sections for 4.0-6.5 MeV Neutrons

Statistical Model Analysis of (n, α) Cross Sections for 4.0-6.5 MeV Neutrons

The α -clusterization factor, which takes into account α -particle formation probability on the sur- face of the compound nucleus, was not considered in formulae (6), (7) and (8). So, these for- mulas should be correct for neutron induced nucleon emission reactions. As to ( n, α ) reaction, the α-clusterization effect should be considered in the cross section formula.

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High-resolution evaluation of the U5(n,f) cross section from 3 keV to 30 keV

High-resolution evaluation of the U5(n,f) cross section from 3 keV to 30 keV

Accurate data on the fission of heavy nuclei at energies beyond the resolved resonance region (RRR) are of a renewed interest for both fundamental and applied nuclear physics. Most neutron cross section measurements are made relative to the neutron cross section standards, being so the basis for measurements and evaluations. Very few cross sections can be measured absolutely and in most cases cross sections are measured relative to the standards or to the data files retrieved from the evaluated libraries. An important point is that the accuracy of a cross section is limited by the uncertainty in the reference cross section relative to which it is measured. There is so a need for additional data related to standard isotopes used as reference and the extension in energy range of certain cross sections, as remarked in Ref [1].
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CROSS SECTION MEASUREMENT OF (n,2n) REACTIONS ON 14,1 MeV NEUTRONS  EUR 245e

CROSS SECTION MEASUREMENT OF (n,2n) REACTIONS ON 14,1 MeV NEUTRONS EUR 245e

We have measured the absolute cross-section of the reaction n, 2n in twelve nuclei having ß+ residual activity, using neutrons of 14.1 MeV.. The results are compared with data existing i[r]

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The cross-section data from neutron activation experiments on niobium in the NPI p-7Li quasi-monoenergetic neutron field

The cross-section data from neutron activation experiments on niobium in the NPI p-7Li quasi-monoenergetic neutron field

We will discuss the e ff ect of low-energy cross-section bump (neutron energies < ∼ 20 MeV) on our data in more details (reactions (n,2n) and (n,α)). For this purposes we introduce the coefficient M which multiply EAF data in this region (M = 1 means EAF-2007 library). Examples of such analyses are shown in Figs. 10, 11 for the reactions (n,2n) and (n,α), respectively.

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Reaction Cross Section of Heavy Projectiles Using Coulomb Modified Glauber Model

Reaction Cross Section of Heavy Projectiles Using Coulomb Modified Glauber Model

projectiles taken from ref. [14]. From the figures, one may see that the calculated reaction cross sections with in-medium effects show good agreement with the experimental values within the experimental error for different projectiles. The reaction cross section values strongly depend on the projectile mass number (A P ). From eqs. (7) - (9), we have calculated

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Synthesis and Evaluation of the Antimicrobial Activity of Dodecyl Trimethyl Ammonium and N-(N, N-Dimethylamino) Propyl Glucosylamine

Synthesis and Evaluation of the Antimicrobial Activity of Dodecyl Trimethyl Ammonium and N-(N, N-Dimethylamino) Propyl Glucosylamine

1-Dodecylamine (0.0539 mole) was dissolved in 20 mL of chloroform. The mixture was refluxed at 50°C and under stirring a small quantity of sodium sulphate was added. After 30 min of reaction, 0.2158 mole of dimethyl sulphate was carefully added to the mixture and reflux was maintained for 6 hours. Solvent was then removed under reduced pressure and residue was co- evaporated four times in methanol to recuperate a white solid which was finally recristallized in ethanol to obtain 9 grams of DTA (Figure 1).

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