scholarly journals Determination of Sulfur and Copper Profile with nuclear reactions

2019 ◽  
Vol 10 ◽  
pp. 1
Author(s):  
S. Kossionides ◽  
G. Kaliambakos ◽  
R. Vlastou ◽  
C. T. Papadopoulos
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Ground State ◽  
Nuclear Reactions ◽  
Nuclear Reaction Analysis ◽  
The Third ◽  
First Excited State ◽  
Γ Ray ◽  
Resonant Reaction

The concentration and depth profile of Cu and S in patinna samples have been determined by using Nuclear Reaction Analysis (NRA) and Rutherford Backscattering Spectroscopy (RBS). For the NRA the differential cross section was mesaured for the 1327 keV 7-ray deexciting the third excited state to the ground state of 6 3Cu through the reaction 63Cu(p,p'7), as well as, for the 2230 keV γ-ray deexciting the first excited state to the ground state through the resonant reaction 32S(p,p'7). The mesaurements of both excitation functions were performed in the energy range 3.0 - 3.7 MeV in 20 keV steps and at an angle of 125°.

scholarly journals Copper and sulphur depth profile in patina layers using NRA and RBS

2019 ◽  
Vol 11 ◽  
Author(s):  
G. Kalliabakos ◽  
S. Kossionides ◽  
P. Misailides ◽  
C. T. Papadopoulos ◽  
R. Vlastou
Keyword(s):  
Excited State ◽  
Cross Sections ◽  
Ground State ◽  
Depth Distribution ◽  
Nuclear Reaction Analysis ◽  
Beam Direction ◽  
The Third ◽  
First Excited State ◽  
Γ Ray

A combination of nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy (RBS) were utilized in order to obtain information on the depth distribution of sulphur and copper in artificially produced and natural patina layers. The copper profiling was performed by using the reaction 63Cu(p,p'y)6 3Cu and detecting the 1327 keV γ-ray deexciting the third excited state to the ground state of 6 3Cu produced. For the determination of sulfur the 2230 keV γ-ray was used, deexciting the first excited state to the ground state of 32S formed through the reaction 3 2S(p,p'y)3 2S, which exhibits three sharp resonances at projectile energies 3.094, 3.195 and 3.379 MeV. The relevant cross-sections were measured in the energy range between 3.0 and 3.7 MeV in steps of 20 keV at 125° to the incident proton beam direction. Supporting information on the depth distribution of oxygen and the other elements of the patina samples was obtained by p-RBS (Ep = 1.5 MeV; θ = 160°).

Photoneutron cross sections in 7Li

1977 ◽  
Vol 55 (5) ◽  
pp. 428-433 ◽  
Author(s):  
H. Ferdinande ◽  
N. K. Sherman ◽  
K. H. Lokan ◽  
C. K. Ross
Keyword(s):  
Fine Structure ◽  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Ground State ◽  
Reasonable Agreement ◽  
Branching Ratio ◽  
Energy Spectra ◽  
Average Value ◽  
First Excited State

Photoneutron energy spectra from 7Li have been measured by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 13 to 25 MeV. The ground-state and approximate first-excited-state differential cross sections at 90° have been obtained from 8.5 to 23 MeV. No pronounced fine structure has been observed. The measured branching ratio to the first excited state falls from an average value of 0.70 between 10.3 and 14.5 MeV to an average of 0.29 between 14.5 and 18 MeV, and rises again to an average of 0.38 between 18 and 23 MeV. This behaviour can be explained by a crude theoretical model in which 1p → 2s and 1p → 1d single particle transitions dominate below 18 MeV. The calculation predicts a branching ratio of 0.50 near threshold, falling to 0.23 at higher energies, in reasonable agreement with the experiment. The integrated value of the ground-state cross section up to 23 MeV is about (38.7 ± 3.9) MeV mb, while that for the first excited state is about (17.2 ± 3.4) MeV mb. Together they account for 39% of the exchange-augmented dipole sum of 7Li.

Photoneutron Reactions in 18O

1975 ◽  
Vol 53 (8) ◽  
pp. 786-794 ◽  
Author(s):  
J. D. Allan ◽  
J. W. Jury ◽  
R. G. Johnson ◽  
K. G. McNeill ◽  
J. G. Woodworth ◽  
...  
Keyword(s):  
Excited State ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Ground State ◽  
Energy Spectra ◽  
Continuum State ◽  
Average Value ◽  
First Excited State ◽  
Time Of Flight Spectroscopy

Photoneutron energy spectra from 18O have been measured by time-of-flight spectroscopy at bremsstrahlung endpoint energies from 11 to 18 MeV in 1 MeV steps to obtain the (γ, n0) and (γ, n1) differential cross sections. The ground state photoneutron cross section contains at least 8 major resonances in the region from 10 to 17 MeV and has an average value of 100 μb/sr. The cross section to the first excited state of 17O contains only two major resonances, at 11.4 and 14.4 MeV, and the average cross section in the region from 11 to 16 MeV is about 40 μb/sr. Of particular interest is a resonance at 14.4 MeV which appears to reflect a simple excitation of one of the valence neutrons to the 2p3/2 state. Analysis of the (γ, n0) and (γ, n1) cross sections for this continuum state leads to estimates of the configuration amplitudes of the 2s1/2 and 1d5/2 components of this state to be 0.62 ± 0.06 and 0.78 ± 0.08 respectively and the ratio of the (2s1/2)2 to (1d5/2)2 amplitudes in the ground state of 18O to be 0.39 ± 0.02.

Angular distributions from ( d, p ) and ( d, n ) nuclear reactions

1951 ◽  
Vol 208 (1095) ◽  
pp. 559-579 ◽  
Keyword(s):  
Excited States ◽  
Ground State ◽  
Nuclear Reactions ◽  
Energy Levels ◽  
Angular Distributions ◽  
Angular Momenta ◽  
First Excited State ◽  
Compound Nucleus Formation ◽  
Initial Nucleus

Experimental angular distributions from (d, p) and (d, n) nuclear reactions involve con­tributions from incident angular momenta much higher than is compatible with compound nucleus formation, and indicate that these reactions must proceed to a large extent by means of a stripping process. The angular distributions to be expected from a stripping process are calculated, and these are found to be very sensitive to the angular momenta which can be accepted by the initial nucleus, i.e. to the spins and parities of the energy levels involved. In any one case there is found excellent agreement between the experimental curve and just one of the possible theoretical curves, and if the spin and parity of the ground state of the initial nucleus is known, this allows of a determination of the spin and parity of the appropriate level of the final nucleus. In this way it is found, for example, that the ground state of 17 O has spin ⅝ or ⅜ and even parity, and that the first excited state of 17 O (0.88 MeV above ground) has spin ½ and even parity. Determinations are also made of the spins and parities of the ground states and several excited states of 13 C, 15 N and 28 Al. Families of theoretical curves for a variety of incident and outgoing energies are presented in order to facilitate further spin and parity determinations from future experimental results.

Determination of a High Potential Barrier Hindering Internal Rotation from the Microwave Ground State Spectrum The Methylbarrier of Antiperiplanar and Synclinal Normal Propyl Fluoride

1986 ◽  
Vol 41 (7) ◽  
pp. 944-954
Author(s):  
W. Kasten ◽  
H. Dreizler
Keyword(s):  
Excited State ◽  
Ground State ◽  
Barrier Heights ◽  
Distortion Analysis ◽  
First Excited State ◽  
High Potential Barrier ◽  
The Difference ◽  
Methyl Torsion ◽  
Approximate Treatment

The microwave ground state spectra of antiperiplanar and synclinal normal propyl fluoride have been measured by microwave Fourier transform spectroscopy and analysed for methyl torsion fine structure. Additionally, the spectrum of the synclinal form in the first excited state of the methyl group has been investigated due to methyl torsion. The difference of the values determined for the barrier heights in the ground and first excited state of the synclinal form is discussed by an approximate treatment of the coupling of CH3 and C - C torsional motions. As high J transitions were measured a centrifugal distortion analysis was necessary.

FURTHER MEASUREMENTS ON THE γ RAYS PRODUCED BY NEUTRON CAPTURE IN BERYLLIUM AND CARBON

1953 ◽  
Vol 31 (1) ◽  
pp. 49-54 ◽  
Author(s):  
G. A. Bartholomew ◽  
B. B. Kinsey
Keyword(s):  
Excited State ◽  
Ground State ◽  
Neutron Capture ◽  
First Excited State ◽  
Γ Rays ◽  
Γ Ray

New measurements have been made of the neutron capture radiation from beryllium and carbon using a more sensitive pair spectrometer. From beryllium, γ rays with energies of 6.81 and 3.41 ± 0.06 Mev. were detected. The former is the ground state γ ray previously reported. The 3.41 Mev. γ ray, which has an intensity of about 0.25 photon per capture, seems to be due to the excitation of the first excited state in Be10. From carbon, in addition to the 4.95 Mev. ground state γ ray previously reported, a γ ray was found with an energy of 3.68 ± 0.05 Mev. and with an intensity of about 0.3 photon per capture. No γ rays were observed which could be associated with the excitation of the level at 3.9 Mev. in C13.

A meta-analysis and review examining a possible role for oxidative stress and singlet oxygen in diverse diseases

2017 ◽  
Vol 474 (16) ◽  
pp. 2713-2731 ◽  
Author(s):  
Athinoula L. Petrou ◽  
Athina Terzidaki
Keyword(s):  
Oxidative Stress ◽  
Excited State ◽  
Singlet Oxygen ◽  
Ground State ◽  
Meta Analysis ◽  
Common Mechanism ◽  
High Electron ◽  
A Value ◽  
First Excited State

From kinetic data (k, T) we calculated the thermodynamic parameters for various processes (nucleation, elongation, fibrillization, etc.) of proteinaceous diseases that are related to the β-amyloid protein (Alzheimer's), to tau protein (Alzheimer's, Pick's), to α-synuclein (Parkinson's), prion, amylin (type II diabetes), and to α-crystallin (cataract). Our calculations led to ΔG≠ values that vary in the range 92.8–127 kJ mol−1 at 310 K. A value of ∼10–30 kJ mol−1 is the activation energy for the diffusion of reactants, depending on the reaction and the medium. The energy needed for the excitation of O2 from the ground to the first excited state (1Δg, singlet oxygen) is equal to 92 kJ mol−1. So, the ΔG≠ is equal to the energy needed for the excitation of ground state oxygen to the singlet oxygen (1Δg first excited) state. The similarity of the ΔG≠ values is an indication that a common mechanism in the above disorders may be taking place. We attribute this common mechanism to the (same) role of the oxidative stress and specifically of singlet oxygen, (1Δg), to the above-mentioned processes: excitation of ground state oxygen to the singlet oxygen, 1Δg, state (92 kJ mol−1), and reaction of the empty π* orbital with high electron density regions of biomolecules (∼10–30 kJ mol−1 for their diffusion). The ΔG≠ for cases of heat-induced cell killing (cancer) lie also in the above range at 310 K. The present paper is a review and meta-analysis of literature data referring to neurodegenerative and other disorders.

scholarly journals Study of the 232Th(n,f) Cross section at NCSR ‘Demokritos’ using Micromegas Detectors

2020 ◽  
Vol 27 ◽  
pp. 106
Author(s):  
Sotirios Chasapoglou ◽  
A. Tsantiri ◽  
A. Kalamara ◽  
M. Kokkoris ◽  
V. Michalopoulou ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Detection Efficiency ◽  
High Energy ◽  
Tandem Accelerator ◽  
Line Detector ◽  
Accelerator Driven Systems ◽  
The Masses

The accurate knowledge of neutron-induced fission cross sections in actinides, is of great importance when it comes to the design of fast nuclear reactors, as well as accelerator driven systems. Specifically for the 232Th(n,f) case, the existing experimental datasets are quite discrepant in both the low and high energy MeV regions, thus leading to poor evaluations, a fact that in turn implies the need for more accurate measurements.In the present work, the total cross section of the 232Th(n,f) reaction has been measured relative to the 235U(n,f) and 238U(n,f) ones, at incident energies of 7.2, 8.4, 9.9 MeV and 14.8, 16.5, 17.8 MeV utilizing the 2H(d,n) and 3H(d,n) reactions respectively, which generally yield quasi-monoenergetic neutron beams. The experiments were performed at the 5.5 MV Tandem accelerator laboratory of N.C.S.R. “Demokritos”, using a Micromegas detector assembly and an ultra thin ThO2 target, especially prepared for fission measurements at n_ToF, CERN during its first phase of operations, using the painting technique. The masses of all actinide samples were determined via α-spectroscopy. The produced fission yields along with the results obtained from activation foils were studied in parallel, using both the NeusDesc [1] and MCNP5 [2] codes, taking into consideration competing nuclear reactions (e.g. deuteron break up), along with neutron elastic and inelastic scattering with the beam line, detector housing and experimental hall materials. Since the 232Th(n,f) reaction has a relatively low energy threshold and can thus be affected by parasitic neutrons originating from a variety of sources, the thorough characterization of the neutron flux impinging on the targets is a prerequisite for accurate cross-section measurements, especially in the absence of time-of-flight capabilities. Additional Monte-Carlo simulations were also performed coupling both GEF [3] and FLUKA [4] codes for the determination of the detection efficiency.

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