scholarly journals Measurement of the 234U(n,f) cross section in the energy range between 14.8 and 17.8 MeV using Micromegas detectors

2020 ◽  
Vol 27 ◽  
pp. 25
Author(s):  
Antigoni Kalamara ◽  
S. Chasapogloou ◽  
V. Michalopoulou ◽  
A. Stamatopoulos ◽  
Z. Eleme ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Volume Fraction ◽  
Tandem Accelerator ◽  
Driven Systems ◽  
Accelerator Driven Systems ◽  
New Generation ◽  
Actinide Targets ◽  
Fission Yields

Neutron induced fission cross sections of actinides present special interest, since they lead to the design optimization of new generation reactors (Generation IV) as well as Accelerator Driven Systems (ADS). In the present work, the 234U(n,f) cross section was measured for which only a few available discrepant data exist in literature leading to poor evaluations. More specifically, four irradiations were performed at the 5.5 MV Tandem Accelerator Laboratory of NCSR “Demokritos” using quasi-monoenergetic neutrons produced by the 3H(d,n)4He reaction in the 14.8-19.2 MeV energy range. The 234U(n,f) cross section was measured relatively to the 235U(n,f) and 238U(n,f) reference ones and in order to perform the in-beam measurements for each of the actinide targets (234U, 238U, 235U), a Micromegas detector was used to record the fission fragments. The target-detector pairs were placed in an Al chamber filled with a Ar:CO2 (in 80:20 volume fraction) gas mixture at atmospheric pressure and temperature. The efficiency of the Micromegas detectors was estimated by Monte-Carlo simulations using the GEF and FLUKA codes. In addition, a detailed study of the neutron energy spectra was carried out by coupling both NeuSDesc and MCNP5 codes in order to take into account and correct for the contribution of low energy parasitic neutrons in the fission yields.

scholarly journals Study of the 234,236U(n,f) and 232Th(n,f) cross sections in the energy range between 14.8 and 19.2 MeV with Micromegas detectors

2019 ◽  
Vol 26 ◽  
pp. 231
Author(s):  
S. Chasapoglou ◽  
V. Michalopoulou ◽  
A. Stamatopoulos ◽  
A. Kalamara ◽  
M. Kokkoris ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Nuclear Reactors ◽  
Driven Systems ◽  
Monoenergetic Neutron ◽  
Accurate Knowledge ◽  
Induced Fission ◽  
Accelerator Driven Systems ◽  
Thorium Cycle

The design of fast nuclear reactors and accelerator driven systems is very strongly based on the accurate knowledge of neutron-induced fission cross sections on several actinides, such as 234,236U and 232Th. Specifically, these isotopes play an important role in the thorium cycle. Regarding (n,f) reactions on these isotopes (namely 234,236U(n,f)), few available discrepant cross-section datasets exist in literature in the energy range between 14-20 MeV, accompanied by relatively large errors, resulting to poor evaluations. In the present work, the study of the fission cross sections of the 234,236U and 232Th was possible with the use of quasi-monoenergetic neutron beams at 14.8, 15.2, 17.8 and 19.2 MeV at the 5.5 MV Tandem Van de Graaff accelerator of NCSR “Demokritos”, produced via the 3H(d,n)4He reaction. Moreover, a methodology is presented for the estimation of the parasitic neutrons present in the experimental area, for facilities with no complementary time-of-flight installation.

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.

scholarly journals First results of the differential cross sections of 9Be(d,d0) at energies and angles suitable for Elastic Backscattering Spectroscopy

2019 ◽  
Vol 26 ◽  
pp. 158
Author(s):  
E. Ntemou ◽  
M. Kokkoris ◽  
A. Lagoyannis ◽  
C. Lungu ◽  
K. Mergia ◽  
...  
Keyword(s):  
Elastic Scattering ◽  
Differential Cross Section ◽  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Differential Cross Sections ◽  
Tandem Accelerator ◽  
First Results ◽  
Elastic Backscattering

The differential cross sections of the 9Be(d,d0) elastic scattering were determined in the present work in the energy range of Ed,lab = 740 - 2200 keV in variable steps, mainly 20 keV at five backscattering angles (120o, 140o, 150o, 160o and 170o). The measurements were performed at the 5.5 MV TN11 HV Tandem Accelerator of the N.C.S.R. “Demokritos” implementing a high precision goniometer. The target used was a thin Si3N4 target with a Beryllium layer on top. The obtained differential cross section values are compared to the ones existing in literature and the observed similarities and discrepancies are discussed.

scholarly journals Elastic Electron Scattering from Methane Molecule in the Energy Range from 50–300 eV

2021 ◽  
Vol 22 (2) ◽  
pp. 647
Author(s):  
Jelena Vukalović ◽  
Jelena B. Maljković ◽  
Karoly Tökési ◽  
Branko Predojević ◽  
Bratislav P. Marinković
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Electron Gun ◽  
Methane Molecule ◽  
Edge Plasma ◽  
Electron Interaction ◽  
Outer Planet ◽  
Elastic Electron

Electron interaction with methane molecule and accurate determination of its elastic cross-section is a demanding task for both experimental and theoretical standpoints and relevant for our better understanding of the processes in Earth’s and Solar outer planet atmospheres, the greenhouse effect or in plasma physics applications like vapor deposition, complex plasma-wall interactions and edge plasma regions of Tokamak. Methane can serve as a test molecule for advancing novel electron-molecule collision theories. We present a combined experimental and theoretical study of the elastic electron differential cross-section from methane molecule, as well as integral and momentum transfer cross-sections in the intermediate energy range (50–300 eV). The experimental setup, based on a crossed beam technique, comprising of an electron gun, a single capillary gas needle and detection system with a channeltron is used in the measurements. The absolute values for cross-sections are obtained by relative-flow method, using argon as a reference. Theoretical results are acquired using two approximations: simple sum of individual atomic cross-sections and the other with molecular effect taken into the account.

Differential cross-section measurements in positron–argon collisions

1996 ◽  
Vol 74 (7-8) ◽  
pp. 505-508 ◽  
Author(s):  
R. M. Finch ◽  
Á. Kövér ◽  
M. Charlton ◽  
G. Laricchia
Keyword(s):  
Elastic Scattering ◽  
Differential Cross Section ◽  
Inelastic Scattering ◽  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Differential Cross ◽  
Coupling Effect ◽  
Channel Coupling ◽  
Scattering Cross

Differential cross sections for elastic scattering and ionization in positron–argon collisions as a function of energy (40–150 eV) are reported at 60°. Of particular interest is the energy range 55–60 eV, where earlier measurements by the Detroit group found a drop in the elastic-scattering cross section of a factor of 2. This structure has been tentatively attributed to a cross channel-coupling effect with an open inelastic-scattering channel, most likely ionization. Our results indicate that ionization remains an important channel over the same energy range and only begins to decrease at an energy above 60 eV.

scholarly journals Measurement of the 241Am(n,2n)240Am cross section at 17.5 MeV

2019 ◽  
Vol 21 ◽  
pp. 160
Author(s):  
A. Kalamara ◽  
R. Vlastou ◽  
M. Diakaki ◽  
M. Kokkoris ◽  
M. Anastasiou ◽  
...  
Keyword(s):  
Cross Section ◽  
Neutron Beam ◽  
Cross Sections ◽  
Reaction Cross ◽  
Activation Technique ◽  
Tandem Accelerator ◽  
Hpge Detectors ◽  
Reaction Cross Sections ◽  
Reference Reaction ◽  
High Radioactivity

The 241Am(n,2n)240Am reaction cross section has been measured at neutron beam energy 17.5 MeV, relative to the 27Al(n,α)24Na, 197Au(n,2n)196Au and 93Nb(n,2n)92mNb reference reaction cross sections, using the activation technique. The irradiation was carried out at the Van der Graaff 5.5 MV Tandem accelerator laboratory of NCSR “Demokritos” with monoenergetic neutron beam provided by means of the 3H(d,n)4He reaction, implementing a new Ti-tritiated target. The high purity Am target has been constructed at IRMM, Geel, Belgium and consisted of 40 mg 241Am in the form of AmO2 pressed into pellet with Al2O3 and encapsulated into Al container. Due to this high radioactivity (5 GBq), the Am target was enclosed in a Pb container for safety reasons. After the end of the irradiation, the activity induced by the neutron beam at the target and reference foils, was measured off-line by two 100%, a 50% and a 16% relative efficiency, HPGe detectors.

DOUBLE PION PHOTOPRODUCTION EXPERIMENT AT LNS–TOHOKU

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2313-2316 ◽  
Author(s):  
◽  
H. KANDA ◽  
N. CHIGA ◽  
Y. FUJII ◽  
K. FUTATSUKAWA ◽  
...  
Keyword(s):  
Total Cross Section ◽  
Energy Range ◽  
Cross Section ◽  
Cross Sections ◽  
Pion Photoproduction ◽  
Total Cross Sections ◽  
Free Proton ◽  
Double Pion ◽  
The Cross

The total cross sections for the π+π− photoproduction on the deuteron were measured in an energy range of 0.8 to 1.1 GeV. The obtained total cross section for the quasi-free π+π− photoproduction on the deuteron was about 60 % of those on the free proton. The cross section for Δ++Δ− photoproduction was derived from the non-quasi-free π+π− photoproduction events. It was smaller than the previous data.

scholarly journals A Complete Cross Section Data Set for Electron Scattering by Pyridine: Modelling Electron Transport in the Energy Range 0–100 eV

2020 ◽  
Vol 21 (18) ◽  
pp. 6947
Author(s):  
Filipe Costa ◽  
Ali Traoré-Dubuis ◽  
Lidia Álvarez ◽  
Ana I. Lozano ◽  
Xueguang Ren ◽  
...  
Keyword(s):  
Energy Range ◽  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Transport Model ◽  
Theoretical Data ◽  
Double Differential Cross Section ◽  
Transmission Experiment ◽  
Data Set ◽  
Section Data

Electron scattering cross sections for pyridine in the energy range 0–100 eV, which we previously measured or calculated, have been critically compiled and complemented here with new measurements of electron energy loss spectra and double differential ionization cross sections. Experimental techniques employed in this study include a linear transmission apparatus and a reaction microscope system. To fulfill the transport model requirements, theoretical data have been recalculated within our independent atom model with screening corrected additivity rule and interference effects (IAM-SCAR) method for energies above 10 eV. In addition, results from the R-matrix and Schwinger multichannel with pseudopotential methods, for energies below 15 eV and 20 eV, respectively, are presented here. The reliability of this complete data set has been evaluated by comparing the simulated energy distribution of electrons transmitted through pyridine, with that observed in an electron-gas transmission experiment under magnetic confinement conditions. In addition, our representation of the angular distribution of the inelastically scattered electrons is discussed on the basis of the present double differential cross section experimental results.

scholarly journals ENERGY LOSS IN CONDENSED MATTER OF H1 AND He4 IN THE ENERGY RANGE 4 < E < 30 kev

1962 ◽  
Vol 40 (12) ◽  
pp. 1749-1764 ◽  
Author(s):  
Arie Van Wijngaarden ◽  
Henry E. Duckworth
Keyword(s):  
Thin Films ◽  
Aluminum Oxide ◽  
Energy Loss ◽  
Energy Range ◽  
Energy Dependence ◽  
Cross Section ◽  
Cross Sections ◽  
Condensed Matter ◽  
Forward Direction ◽  
Electronic Component

Measurements are reported of the energy loss suffered by H1 and He4 particles, of 4- to 30-kev energy, in passing through thin films of carbon, aluminum oxide, and VYNS. Only those particles that emerged in the forward direction were studied. Evidence is presented for identifying the stopping cross sections per atom observed in this way with Se, the electronic component of the total stopping cross section per atom. It appears that the calculated energy dependence of [Formula: see text] is somewhat in error, and that the magnitudes of the Se's for He4 are systematically too small by 10–15%.

Spallation-reaction cross-sections relevant for accelerator-driven systems

1998 ◽  
Vol 111 (8-9) ◽  
pp. 1097-1103
Author(s):  
F. Farget ◽  
J. Benlliure ◽  
T. Enqvist ◽  
J. Taieb ◽  
K. -H. Schmidt ◽  
...  
Keyword(s):  
Cross Sections ◽  
Reaction Cross ◽  
Spallation Reaction ◽  
Driven Systems ◽  
Accelerator Driven Systems ◽  
Reaction Cross Sections
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