scholarly journals Activation cross section of the (n,2n) reaction on Hf isotopes

2019 ◽  
Vol 23 ◽  
pp. 47
Author(s):  
A. Kalamara ◽  
M. Serris ◽  
A. Spiliotis ◽  
D. Sigalos ◽  
N. Patronis ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross Section ◽  
Beam Energy ◽  
Reaction Cross ◽  
Activation Technique ◽  
Incident Neutron ◽  
Activation Cross Section ◽  
Reference Reaction

Cross sections of the 174Hf(n,2n)173Hf and 176Hf(n,2n)175Hf reactions have been experimentally determined relative to the 27Al(n,α)24Na reference reaction at incident neutron energies of 15.3 and 17.1 MeV by means of the activation technique. The irradiations were carried out at the 5 MV tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" with monoenergetic neutron beams provided via the 3H(d,n)4He reaction, using a new Ti-tritiated target of 373 GBq activity. In the determination of the 176Hf(n,2n)175Hf reaction cross section the contamination of the 174Hf(n,γ)175Hf and 177Hf(n,3n)175Hf reactions has been taken into account. Moreover, the neutron beam energy has been studied by means of Monte Carlo simulation codes and the neutron flux has been determined via the 27Al(n,α)24Na reference reaction.

scholarly journals Experimental study of the 197Au(n,2n) reaction cross section

2019 ◽  
Vol 17 ◽  
pp. 9
Author(s):  
A. Tsinganis ◽  
M. Kokkoris ◽  
A. Lagoyannis ◽  
E. Mara ◽  
C. T. Papadopoulos ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Isomeric State ◽  
Reaction Cross Section ◽  
Reaction Cross ◽  
Activation Technique ◽  
Incident Neutron ◽  
Mcnp Code ◽  
Foil Activation ◽  
24Na Reaction

In the present work, the 197Au(n,2n) reaction cross section is experimentally determined relative to the 27Al(n,α)24Na reaction at incident neutron energies of 9.0 to 10.5 MeV by means of the activation technique. The quasi-monoenergetic fast neutron beam was produced via the 2H(d,n)3He reaction at the 5.5 MV Tandem Van de Graaff accelerator at the NCSR “Demokritos” and was studied to determine the contribution of background “parasitic” neutrons using the multiple foil activation technique and the SULSA unfolding code. The cross sections for the population of the second isomeric state (12−) of 196Au and the sum of the ground (2−) and first isomeric state (5−) population cross sections were independently determined. Auxiliary Monte Carlo simulations were performed with the MCNP code.

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.

TOWARDS THE DETERMINATION OF THE π-p → f2(1270)n REACTION CROSS-SECTION

1993 ◽  
Vol 08 (25) ◽  
pp. 2343-2350 ◽  
Author(s):  
N. N. ACHASOV ◽  
G. N. SHESTAKOV
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross Section ◽  
Branching Ratios ◽  
Reaction Cross ◽  
Precise Estimation ◽  
The One ◽  
Reaction Cross Sections

In this letter, the necessity of a more precise estimation of the data on the reaction π-p → f2(1270)n → π0π0n is mentioned. The total cross-section σ(π-p → f2(1270)n) obtained from the data on the reaction π-p → π0π0n is shown to be approximately three times smaller than that following from the π-p → π+π-n data and also four times smaller than the prediction of the one-pion-exchange model. It is very important to resolve this disagreement because the results on the reaction π-p → f2(1270)n → π0π0n are used directly for the normalization of other reaction cross-sections and determination of branching ratios for some resonances.

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 239 ◽  
pp. 05005
Author(s):  
A. Kalamara ◽  
S. Chasapoglou ◽  
V. Michalopoulou ◽  
A. Stamatopoulos ◽  
Z. Eleme ◽  
...  
Keyword(s):  
Cross Section ◽  
Reaction Cross Section ◽  
Reaction Cross ◽  
Cross Section Data ◽  
Fission Yield ◽  
Active Mass ◽  
Section Data ◽  
Set Up ◽  
Reference Reaction

The 234U(n,f) reaction cross section was measured for three neutron energies 14.8, 16.5 and 17.8 MeV, relative to the238U(n,f) reference reaction. The in-beam measurements were carried out by using a set-up based on Micromegas detectors, while the quasi-monoenergetic neutron beams were produced by means of the 3H(d,n)4He reaction at the 5.5MV Tandem T11/25 Accelerator Laboratory of the National Center for Scientific Research "Demokritos" in Athens (Greece). Additionaly, α-spectroscopy measurements were performed in order to determine the active mass of the samples and the corresponding impurities. In order to estimate the fission-fragment detection efficiency, Monte Carlo simulations were carried out using the GEF and FLUKA codes. Furthermore, simulations were also performed by coupling the NeuSDesc and MCNP5 codes for the determination of the neutron energy distribution in all the irradiated samples and the results were used in order to correct for the contribution of low energy parasitic neutrons in the fission yield. The final cross section data are presented, along with the methodology adopted for the treatment of the parasitic neutrons.

scholarly journals Attempted study of the 237Np(n,2n)236Np reaction cross section at 9.5 MeV

2019 ◽  
Vol 18 ◽  
pp. 101
Author(s):  
M. Diakaki ◽  
R. Vlastou ◽  
M. Kokkoris ◽  
C. T. Papadopoulos ◽  
A. Tsinganis ◽  
...  
Keyword(s):  
Cross Section ◽  
Gamma Ray ◽  
Gamma Spectroscopy ◽  
Reaction Cross ◽  
Activation Technique ◽  
Incident Neutron ◽  
Incident Neutron Energy ◽  
Tandem Accelerator ◽  
Section Measurement ◽  
High Gamma

The cross section measurement of the 237Np(n,2n)236Np reaction has been attempted at an incident neutron energy of 9.5 MeV by means of the activation technique. The neutron beam was produced via the 2H(d,n)3Ηe reaction at the VdG Tandem accelerator of NCSR “Demokritos”. It is the second time that this measurement has been tried with a gamma spectroscopy method and the difficulties faced due to the high gamma ray background produced by the sample itself and the fission fragments produced by the irradiation, in combination with the very low intensity of the gamma ray of interest are being reported.

Production and isobaric separation of 63Ni ions for determination of the 62Ni(n,γ)63Ni reaction cross section at stellar temperatures

2004 ◽  
Vol 746 ◽  
pp. 613-616 ◽  
Author(s):  
H. Nassar ◽  
S. Ghelberg ◽  
M. Paul ◽  
S. Dababneh ◽  
M. Heil ◽  
...  
Keyword(s):  
Cross Section ◽  
Reaction Cross Section ◽  
Reaction Cross ◽  
Stellar Temperatures ◽  
Isobaric Separation

Reaction cross section calculations via second beta decay using the activation method for the p-process

2019 ◽  
Vol 97 (11) ◽  
pp. 1206-1209
Author(s):  
Ezgi Tantoğlu ◽  
Nalan Özkan ◽  
R. Taygun Güray
Keyword(s):  
Beta Decay ◽  
Cross Section ◽  
Cross Sections ◽  
Half Life ◽  
Reaction Cross Section ◽  
Experimental Studies ◽  
Reaction Cross ◽  
Activation Method ◽  
Alternative Method ◽  
The Cross

There are 35 proton-rich isotopes between 74Se and 196Hg that cannot be synthesized through neutron captures and β− decays (s- and r-processes). A third process is therefore required for the production of these nuclei, the so-called p-process. The abundance and the origin of the p-nuclei are still not fully understood even though significant experimental and theoretical efforts in astrophysical modeling have been expended in the last two decades. The experimental studies with the activation method to measure cross sections of the relevant reactions have some limitations: the reaction product must be radioactive, should have an appropriate half-life, and its decay should be followed by proper γ-radiations. If the cross section cannot be calculated with the radiation followed by the first beta decay of the product, it can be measured using the second beta decay as an alternative method. In this study, the method and candidate reactions for the cross-section measurements via the second beta decay of the reaction product using the activation method are discussed.

scholarly journals Improved accuracy in the determination of the thermal cross section of ${}^{14}{\rm N}({\rm n},{\rm p}){}^{14}{\rm C}$ for neutron lifetime measurement

2019 ◽  
Vol 2019 (9) ◽  
Author(s):  
R Kitahara ◽  
K Hirota ◽  
S Ieki ◽  
T Ino ◽  
Y Iwashita ◽  
...  
Keyword(s):  
Cross Section ◽  
Lifetime Measurement ◽  
Reaction Cross ◽  
Proton Accelerator ◽  
Incident Neutron ◽  
Neutron Lifetime ◽  
The Cross ◽  
Thermal Cross Section ◽  
Improved Accuracy

Abstract In a neutron lifetime measurement at the Japan Proton Accelerator Complex, the neutron lifetime is calculated from the neutron decay rate and the incident neutron flux. The flux is obtained by counting the protons emitted from the neutron absorption reaction of ${}^{3}{\rm He}$ gas, which is diluted in a mixture of working gas in a detector. Hence, it is crucial to determine the amount of ${}^{3}{\rm He}$ in the mixture. In order to improve the accuracy of the number density of the ${}^{3}{\rm He}$ nuclei, we have suggested using the ${}^{14}{\rm N}({\rm n},{\rm p}){}^{14}{\rm C}$ reaction as a reference because this reaction involves similar kinetic energy to the $^3$He(n,p)$^3$H reaction and a smaller reaction cross section to introduce reasonable large partial pressure. The uncertainty of the recommended value of the cross section, however, is not satisfied with our requirement. In this paper we report the most accurate experimental value of the cross section of the $^{14}$N(n,p)$^{14}$C reaction at a neutron velocity of 2200 m s$^{-1}$, measured relative to the $^3$He(n,p)$^3$H reaction. The result was 1.868 $\pm$ 0.003 (stat.) $\pm$ 0.006 (sys.) b. Additionally, the cross section of the $^{17}$O(n,$\alpha$)$^{14}$C reaction at the neutron velocity is also redetermined as 249 $\pm$ 6 mb.

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