Development of a gaseous proton-recoil telescope for neutron flux measurements between 0.2 and 2 MeV neutron energy

Absolute measurements of neutron fluence are an essential prerequisite of neutron-induced cross section measurements, neutron beam lines characterization and dosimetric investigations. The H(n,p) elastic scattering cross section is a very well known standard used to perform precise neutron flux measurements in high precision measurements. The use of this technique, with proton recoil detectors, is not straightforward below incident neutron energy of 1 MeV, due to a high background in the detected proton spectrum. Experiments have been carried out at the AIFIRA facility to investigate such background and to determine its origin and components. Based on these investigations, a gaseous proton-recoil telescope has been designed with a reduced low energy background. A first test of this detector has been carried out at the AIFIRA facility, and first results will be presented

Measurements of (n,γ\gamma) neutron capture cross-sections with liquid scintillator detectors

A method for measuring (n,$\gamma$) neutron capture cross-sections using liquid scintillator detectors has been investigated. If the response function of the detector is known, and the efficiency as a function of energy is low and approximately constant, then gamma cascades can be counted via a method that is independent of the cascade path provided the detector response is manipulated to allow detection efficiency to be proportional to emitted gamma-ray energy. In this paper, we demonstrate the measurement of efficiency and response functions for a C6D6 liquid scintillator using gamma-ray sources and (p,$\gamma$) reactions on light nuclei. Methods to reproduce the detector response and efficiency data successfully using simulations are presented and discussed. An entire response matrix for the detector has been constructed using a new interpolation technique, allowing weighting functions that force the detector efficiency to be proportional to gamma-ray energy to be calculated. An analysis of the sources of error involved in making (n,$\gamma$) cross-section measurements with this method has been undertaken using Monte-Carlo simulation techniques

Efficiency and response function of a C−6-{6}D6_{6} detector used for (n,γ\gamma) capture reaction cross-section measurements

In this contribution we describe the measurement of the efficiency and response functions of a liquid scintillator dectector (C$-{6}$D$_{6}$) using scaled gamma ray sources and (p, $\gamma$) reactions with light nuclei. The measured functions have also been compared to functions calculated using Monte Carlo simulation techniques. If these two functions are known over a wide range of gamma energy, then gamma cascades generated in a (n,$\gamma$) capture reaction can be counted via a method that is independent of their pathways provide the detector response is weighted by functions that force the detection efficiency to be proportional to the emitted gamma ray energy

Measurement of 242^{242}Pu(n,f) in the 1-2 MeV energy range

International audienceThe design of new generation fast nuclear reactors requires highly accurate cross-section measurements in the MeV energy region. The 242Pu fission cross section is of particular interest for Pu incineration and nuclear waste production. There are discrepancies around 1 MeV incident neutron energy between libraries and among experimental data. Some data suggest the presence of a strong structure between 1 and 1.2 MeV whereas it is barely visible on some other data and its shape is very different among evaluations. The large majority of the 242Pu(n,f) measurements have been carried out with respect to the 235U(n,f) secondary-standard cross section. This introduces a strong correlation between measurements from different research teams. Moreover, this reference cross section exhibits structures, in particular a steep increase of +10% at 1 MeV. Therefore, we aim to re-measure the 242Pu(n,f) cross section relative to the primary-standard 1H(n,n)p cross section, by using a proton recoil detector. This standard has a very high accuracy (0.4%), is not used for other 242Pu measurements, and is structureless. An experiment has been carried out in October 2022 at the MONNET facility in JRC Geel, with incident neutron energies from 0.9 MeV to 2.0 MeV. The experimental setup will be presented, and the analysis procedure will be detailed

Development of a Gaseous Proton-Recoil Detector for neutron flux measurements between 0.2 and 2 MeV neutron energy

Absolute measurements of neutron fluence are an essential prerequisite of neutron-induced cross section measurements, dosimetric investigations and neutron beam lines characterisation. Independent and precise neutron flux measurements can be performed with respect to the H(n,p) elastic cross section. However, the use of silicon proton recoil detectors is not straightforward below incident neutron energy of 1 MeV, due to a high background in the detected proton spectrum. A new gaseous proton-recoil detector has been designed to answer the challenge. The detector is described in details and results of the commissioning tests are presented

Measurement of 242^{242}Pu(n,f) in the [1;2MeV] energy range

International audienceThe design of new generation fast nuclear reactors requires highly accurate cross-section measurements in the MeV energy region. The 242 Pu fission cross section is of particular interest for Pu incineration and nuclear waste production. There are discrepancies around 1 MeV incident neutron energy between libraries and among experimental data. Some data suggest the presence of a strong structure between 1 and 1.2 MeV whereas it is barely visible on some other data and its shape is very different among evaluations. The large majority of the 242 Pu(n,f) measurements have been carried out with respect to the 235 U(n,f) secondary-standard cross section. This introduces a strong correlation between independent measurements and this cross section exhibits structures, in particular a steep increase of +10% at 1 MeV. Therefore, we aim to re-measure the 242 Pu(n,f) cross section relative to the primary-standard 1 H(n,n)p cross section, by using a proton recoil detector. This standard has a very high accuracy (0.4%), is not used for of other 242 Pu measurements, and is structureless. An experiment has been carried out in October 2022 at the MONNET facility in JRC Geel, with incident neutron energies from 0.9 MeV to 2.0 MeV. The experimental setup will be presented, and the analysis procedure will be detailed

Measurement of 242^{242}Pu(n,f) in the [1;2MeV] energy range

International audienceThe design of new generation fast nuclear reactors requires highly accurate cross-section measurements in the MeV energy region. The 242 Pu fission cross section is of particular interest for Pu incineration and nuclear waste production. There are discrepancies around 1 MeV incident neutron energy between libraries and among experimental data. Some data suggest the presence of a strong structure between 1 and 1.2 MeV whereas it is barely visible on some other data and its shape is very different among evaluations. The large majority of the 242 Pu(n,f) measurements have been carried out with respect to the 235 U(n,f) secondary-standard cross section. This introduces a strong correlation between independent measurements and this cross section exhibits structures, in particular a steep increase of +10% at 1 MeV. Therefore, we aim to re-measure the 242 Pu(n,f) cross section relative to the primary-standard 1 H(n,n)p cross section, by using a proton recoil detector. This standard has a very high accuracy (0.4%), is not used for of other 242 Pu measurements, and is structureless. An experiment has been carried out in October 2022 at the MONNET facility in JRC Geel, with incident neutron energies from 0.9 MeV to 2.0 MeV. The experimental setup will be presented, and the analysis procedure will be detailed