scholarly journals High-energy neutron facility at the Athens Tandem Accelerator NCSR “Demokritos”

2019 ◽  
Vol 21 ◽  
pp. 123 ◽  
Author(s):  
R. Vlastou ◽  
M. Anastasiou ◽  
A. Kalamara ◽  
M. Diakaki ◽  
M. Kokkoris ◽  
...  
Keyword(s):  
Cross Section ◽  
Reaction Cross Section ◽  
Neutron Fluence ◽  
High Energy ◽  
Reaction Cross ◽  
Activation Technique ◽  
Tandem Accelerator ◽  
Foil Activation ◽  
Energy Neutron ◽  
Neutron Facility

In the 5.5 MV tandem T11/25 Accelerator Laboratory of NCSR “Demokritos” monoenergetic neutron beams have been produced in the energy range ∼16–19 MeV using a new Ti-tritiated target of 373 GBq activity, by means of the 3H(d,n)4He reaction. The corresponding beam energies obtained from the accel- erator, were 0.8–3.7 deuterons. The maximum flux has been determined to be of the order of 106 n/s·cm2, implementing reference reactions. An investigation of the energy dependence of the neutron fluence has been carried out with the multiple foil activation technique. The beam has been used for the measurement of (n,2n) reaction cross section on several isotopes at 16.7 and 17 MeV.

scholarly journals Investigation of (n,2n) reactions using the high energy neutron facility at NCSR “Demokritos”

2019 ◽  
Vol 24 ◽  
pp. 117
Author(s):  
R. Vlastou ◽  
A. Kalamara ◽  
M. Kokkoris ◽  
M. Serris ◽  
N. Patronis ◽  
...  
Keyword(s):  
Neutron Beam ◽  
Reaction Cross Section ◽  
High Energy ◽  
Reaction Cross ◽  
Activation Technique ◽  
Flux Variation ◽  
High Energy Neutron ◽  
Foil Activation ◽  
Energy Neutron ◽  
Neutron Facility

In the high energy neutron facility at the 5.5MV tandem T11/25 Accelerator of NCSR "Demokritos", the neutron beam is produced by means of the 3H(d,n)4He reaction in the energy range ~15-21 MeV and at a flux of the order of 105 -106 n/cm2s. The beam has been characterized by means of the NeuSDesc and MCNP5 Monte Carlo simulations along with the multiple foil activation technique at various neutron energies. The neutron flux has been deduced using reference reactions, such as the 27Al(n,α) reaction, while the flux variation of the neutron beam was monitored by using a BF3 detector. After the characterization, the neutron beam has been used for (n,2n) reaction cross section measurements on Hf, Au and Ir isotopes via the activation technique. The irradiations were carried out at 15.3 and 17.1 MeV.

scholarly journals Neutron induced reactions at the Athens Tandem accelerator NCSR "Demokritos"

2019 ◽  
Vol 14 ◽  
pp. 1
Author(s):  
R. Vlastou ◽  
C. T. Papadopoulos ◽  
M. Kokkoris ◽  
G. Perdikakis ◽  
S. Galanopoulos ◽  
...  
Keyword(s):  
Energy Range ◽  
Energy Dependence ◽  
Neutron Beam ◽  
Neutron Fluence ◽  
Liquid Scintillator ◽  
Activation Technique ◽  
Flux Variation ◽  
Tandem Accelerator ◽  
Foil Activation ◽  
Neutron Facility

The neutron facility at the 5.5 MV Tandem Tll/25 accelerator of NCSR "Demokritos" has been used to produce monoenergetic neutron beams in the energy range 120-650 keV and 4-11.5 MeV via the 7Li(p,n) and 2H(d,n) reactions, respectively. The flux variation of the neutron beam was monitored by using a BF3 detector, while an investigation of the energy dependence of the neutron fluence has been carried out with a liquid scintillator BC501A detector as well as with the multiple foil activation technique. The 232Th(n,2n)231Th and 241Am(n,2n)240Am as well as (n,2n), (n,p) and (η,α) reactions on natural Ge and Hf isotopes, have been investigated from threshold up to 11.5 MeV, by using the activation method.

scholarly journals Influence of parasitic neutrons to the 176Hf(n,2n)175Hf reaction cross section

2019 ◽  
Vol 18 ◽  
pp. 83
Author(s):  
R. Vlastou ◽  
M. Kokkoris ◽  
M. Serris ◽  
M. Lambrou ◽  
L. Sofokleous ◽  
...  
Keyword(s):  
Cross Sections ◽  
Reaction Cross Section ◽  
Liquid Scintillator ◽  
Reaction Cross ◽  
Energy Spectra ◽  
Recoil Energy ◽  
Activation Technique ◽  
Tandem Accelerator ◽  
Analysis Technique ◽  
Foil Activation

Cross sections for 176Hf(n,2n)175Hf reaction have been measured at the VdG Tandem accelerator of NCSR \Demokritos", in the neutron energy region from 8.80 to 11.02 MeV, using the activation technique. In order to account for the contamination of the 176Hf(n,2n)175Hf by the 174Hf(n,γ)175Hf reaction activated by the presence of parasitic neutrons, an experimental method has been developed based on the influence of the parasitic neutrons in the case of the (n,2n) and (n,γ) reactions on 197Au. The results were found to be consistent with the energy spectrum of the neutron beam which has been studied by means of the multiple foil activation analysis technique as well as by a liquid scintillator BC501A detector and subsequent deconvolution of its recoil energy spectra.

scholarly journals Study of the (n,2n) reaction cross section on 174,176Hf isotopes

2020 ◽  
Vol 15 ◽  
pp. 188
Author(s):  
M. Serris ◽  
Et Al.
Keyword(s):  
Statistical Model ◽  
Cross Section ◽  
Neutron Energy ◽  
Energy Region ◽  
Reaction Cross Section ◽  
Reaction Cross ◽  
Activation Technique ◽  
Tandem Accelerator ◽  
Model Calculations ◽  
Input Parameters

Cross section measurements of the 174Hf(n,2n)173Hf and 176Hf(n,2n)175Hf reactions have been performed at the VdG Tandem accelerator of NCSR “Demokritos” in Athens, in the neutron energy region from 8.8 to 11.5 MeV, using the activation technique. Statistical model calculations based on the Hauser - Feshbach theory have also been implemented by using the code EMPIRE-II with different sets of input parameters. The predictions were compared to the data of the present work as well as data from literature.

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.

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.

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.

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