scholarly journals Prompt fission gamma-ray emission spectral data for 239Pu(n,f) using fast directional neutrons from the LICORNE neutron source

2018 ◽  
Vol 169 ◽  
pp. 00018 ◽  
Author(s):  
L. Qi ◽  
J.N. Wilson ◽  
M. Lebois ◽  
A. Al-Adili ◽  
A. Chatillon ◽  
...  
Keyword(s):  
Neutron Source ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Average Energy ◽  
Fast Neutrons ◽  
Complementary Information ◽  
Total Energy Release ◽  
The Mean ◽  
Induced Fission ◽  
Prompt Fission

Prompt fission gamma-ray spectra (PFGS) have been measured for the 239Pu(n,f) reaction using fast neutrons at Ēn=1.81 MeV produced by the LICORNE directional neutron source. The setup makes use of LaBr3 scintillation detectors and PARIS phoswich detectors to measure the emitted prompt fission gamma rays (PFG). The mean multiplicity, average total energy release per fission and average energy of photons are extracted from the unfolded PFGS. These new measurements provide complementary information to other recent work on thermal neutron induced fission of 239Pu and spontaneous fission of 252Cf.

scholarly journals Prompt Fission Gamma-Ray Measurements at UML Research Reactor

2020 ◽  
Vol 242 ◽  
pp. 01009
Author(s):  
Razvan Stanescu ◽  
Hadrick Green ◽  
Toby Morris ◽  
Gencho Rusev ◽  
Marian Jandel
Keyword(s):  
Gamma Rays ◽  
Research Reactor ◽  
Gamma Ray ◽  
Fission Neutron ◽  
Pulse Shape Discrimination ◽  
Prompt Gamma ◽  
Fission Reaction ◽  
Induced Fission ◽  
Enriched Uranium ◽  
Prompt Fission

Neutron-induced fission of 235U was studied at the thermal column of the UMass Lowell 1 MW Research Reactor. A collimated, 2.25-inch diameter beam of thermal neutrons with the flux of ~5x105 n/cm2/sec induced fission reaction on a plate of low-enriched uranium with the areal density ~25 mg/cm2 of 235U. We have used the prompt fission-neutron tagging method to identify the fission reaction in the off-line analysis. The method employs the pulse-shape discrimination of neutrons and gamma-ray events in stilbene scintillator and enables identification of coincidence events of prompt fission gamma-rays and prompt fission neutrons in coincidence time intervals less than 20-30 ns. The prompt gamma-ray radiation was detected using two co-linear NaI(Tl) detectors. The measured spectra of prompt-fission gamma rays between 150 keV and 6 MeV are presented. The results from these initial measurements demonstrate the feasibility of the experimental method. Future measurements with extended arrays of detectors are planned.

scholarly journals Gamma-rays from Solar Flares

2000 ◽  
Vol 195 ◽  
pp. 123-132 ◽  
Author(s):  
R. Ramaty ◽  
N. Mandzhavidze
Keyword(s):  
Energy Release ◽  
Gamma Rays ◽  
Solar Flares ◽  
Gamma Ray ◽  
Particle Interaction ◽  
Mass Motion ◽  
Relativistic Electrons ◽  
Total Energy Release ◽  
Flare Energy ◽  
Accelerated Particles

Gamma-ray emission is the most direct diagnostic of energetic ions and relativistic electrons in solar flares. Analysis of solar flare gamma-ray data has shown: (i) ion acceleration is a major consequence of flare energy release, as the total flare energy in accelerated particles appears to be equipartitioned between ≳ 1 MeV/nucleon ions and ≳ 20 keV electrons, and amounts to an important fraction of the total energy release; (ii) there are flares for which over 50% of the energy is in a particles and heavier ions; (iii) in both impulsive and gradual flares, the particles that interact at the Sun and produce gamma rays are essentially always accelerated by the same mechanism that operates in impulsive flares, probably stochastic acceleration through gyroresonant wave particle interaction; and (iv) gamma-ray spectroscopy can provide new information on solar abundances, for example the site of the FIP-bias onset and the photospheric 3He abundance. We propose a new technique for the investigation of mass motion and mixing in the solar atmosphere: the observations of gamma-ray lines from long-term radioactivity produced by flare accelerated particles.

Detection of Combined n/γ Fission Signatures Induced by an Epithermal Neutron Source

2017 ◽  
Vol 3 (3) ◽  
Author(s):  
A. Ocherashvili ◽  
T. Bogucarska ◽  
A. Beck ◽  
G. Heger ◽  
M. Mosconi ◽  
...  
Keyword(s):  
Neutron Source ◽  
Proper Time ◽  
Pulse Shape Discrimination ◽  
Fast Neutrons ◽  
Nuclear Materials ◽  
Test Assembly ◽  
Fission Neutrons ◽  
Pulsed Neutron ◽  
Prompt Fission ◽  
Multiple Detectors

In this paper, a method is presented for the detection of special nuclear materials (SNMs) in shielded containers, which is both sensitive and applicable under field conditions. The method uses an external pulsed neutron source to induce fission in SNM and subsequent detection of the fast prompt fission neutrons. The detectors surrounding the container under investigation are liquid scintillation detectors able to distinguish gamma rays from fast neutrons by means of pulse shape discrimination method (PSD). One advantage of these detectors, besides the ability for PSD analysis, is that the analog signal from a detection event is of very short duration (typically few tens of nanoseconds). This allows the use of very short coincidence gates for the detection of the prompt fission neutrons in multiple detectors, while benefiting from a low background coincidence rate, yielding a low detection limit. Another principle advantage of this method derives from the fact that the external neutron source is pulsed. By proper time gating, the interrogation can be conducted by epithermal source neutrons only. These neutrons do not appear in the fast neutron signal following the PSD analysis, thus providing a fundamental method for separating the interrogating source neutrons from the sample response in the form of fast fission neutrons. This paper describes laboratory tests with a configuration of eight detectors in the Pulsed Neutron Interrogation Test Assembly (PUNITA). Both the photon and neutron signature for induced fission is observed, and the methods used to isolate these signatures are described and demonstrated.

scholarly journals Systematic study of the de-excitation of neutron-rich nuclei produced in different fission reactions

2021 ◽  
Vol 256 ◽  
pp. 00012
Author(s):  
Andreas Oberstedt ◽  
Angélique Gatera ◽  
Alf Göök ◽  
Matthieu Lebois ◽  
Stephan Oberstedt ◽  
...  
Keyword(s):  
Energy Release ◽  
Systematic Study ◽  
Time Window ◽  
Spectral Characteristics ◽  
Average Energy ◽  
Average Multiplicity ◽  
Fast Neutrons ◽  
Fission Reactions ◽  
Timing Resolution ◽  
Prompt Fission

In this paper we present results from two recent studies, both related to the emission of prompt fission γ rays. Firstly, we have analyzed data from the reaction 235U(n, f) induced by fast neutrons of average energy E̅n = 1.7 MeV. The deduced spectral characteristics are an average multiplicity M̅γ = 7.11 ± 0.44 γ rays per fission and an average total γ-ray energy release in fission E̅γ,tot = 5.51 ± 0.46 MeV, corresponding to an average γ-ray energy ɛ̅γ = 0.77 ± 0.08 MeV. Secondly, we have addressed – and answered – the question how those characteristics in general depend on the width of the chosen prompt time window and the timing resolution, determined by the employed detectors and electronics. The conclusion is that once this is known, it is possible to compare results from different experiments in a more meaningful way.

An investigation of the 35Cl(n,γ)36Cl reaction

1981 ◽  
Vol 59 (1) ◽  
pp. 93-108 ◽  
Author(s):  
T. J. Kennett ◽  
M. A. Islam ◽  
W. V. Prestwich
Keyword(s):  
Gamma Rays ◽  
Decay Scheme ◽  
Gamma Ray ◽  
Average Energy ◽  
High Energy ◽  
Neutron Separation Energy ◽  
Transition Energies ◽  
New Findings ◽  
Deconvolution Techniques ◽  
Average Uncertainty

A detailed study of the neutron-capture gamma-ray spectrum for chlorine, above an energy of 1.6 MeV, has revealed a total of 234 transitions with intensity greater than 0.04%. Consistency tests indicate that the average energy uncertainty for the entire set of gamma rays is 0.1 keV. Data reduction was accomplished by invoking spectral deconvolution techniques with the result that many previously reported transitions were found to be multiplets. A decay scheme was derived by making use of both these new findings and the high energy precision attained for the transition energies. The proposed decay scheme accounts for more than 98% of the observed intensity and the energy of the levels included were found to have an average uncertainty of 0.08 keV. Based upon an error-free 15N neutron separation energy of 10 833.30 keV, the Q values for 35Cl(n,γ)36Cl and 37Cl(n,γ)38Cl were found to be 8579.82 (2) and 6107.85 (10) keV, respectively.

scholarly journals High resolution gamma-ray spectroscopy of fast-neutron induced fission

2021 ◽  
Vol 256 ◽  
pp. 00019
Author(s):  
Jonathan Wilson ◽  
Damien Thisse ◽  
Matthieu Lebois ◽  
Nikola Jovancevic ◽  
Rhiann Canavan ◽  
...  
Keyword(s):  
Fast Neutron ◽  
Gamma Ray ◽  
Precision Spectroscopy ◽  
Fast Timing ◽  
Experimental Campaign ◽  
Γ Rays ◽  
Fission Neutrons ◽  
Induced Fission ◽  
Multiplicity Distributions ◽  
Prompt Fission

Experiments to perform precision spectroscopy of fast neutron induced fission were carried out during the ν-Ball experimental campaign at the ALTO facility of IJC Laboratory Orsay. Low energy fission of 232Th(n,f), 238U(n,f) and spontaneous fission of 252Cf were studied using this hybrid highresolution spectrometer and calorimeter. New observables such as γ-ray multiplicity distributions correlated with specific fission fragments are presented and discussed. A new method using fast-timing techniques to detect prompt fission neutrons in coincidence with prompt fission γ-rays is described.

scholarly journals Shielding Properties of Some Marble Types: A Comprehensive Study of Experimental and XCOM Results

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4194
Author(s):  
Mohamed Elsafi ◽  
Mohamed A. El-Nahal ◽  
M. F. Alrashedi ◽  
O. I. Olarinoye ◽  
M. I. Sayyed ◽  
...  
Keyword(s):  
Attenuation Coefficient ◽  
Gamma Ray ◽  
Mean Free Path ◽  
Mass Attenuation Coefficient ◽  
Fast Neutrons ◽  
Linear Attenuation Coefficient ◽  
Protective Shield ◽  
Removal Cross Section ◽  
The Mean ◽  
Good Agreement

In this work, some marble types were collected from Egypt, and their shielding characteristics were estimated. Their rigidity, in addition to their elegant shape, led us to consider their use as a protective shield, in addition to making the workplace more beautiful. The mass attenuation coefficient (μ/ρ) was calculated for three types of marble (Breshia, Galala, and Trista) experimentally, using a narrow gamma ray source and sodium iodide scintillation detector (NaI). The results obtained were compared with the XCOM program and indicated a very good agreement between the two methods. The linear attenuation coefficient (μ) was evaluated to calculate the half and tenth value layers. The maximum value of 1.055, 1.041, and 1.024 cm−1 was obtained for Breshia, Galala, and Trista, respectively, at 0.06 MeV. The mean free path for studying the materials was compared with other shielding materials and showed good results at different energy scales. The energy absorption (EABF) and exposure buildup factors (EBF) were determined at different mean free paths. The fast neutron removal cross section ∑R was calculated and expresses the ability of the marbles to slow down fast neutrons through multiple scattering. This is the ability of the marbles to shield fast neutrons.

scholarly journals Study of gamma-ray background noise for radioactive waste drum characterization with plastic scintillators

2020 ◽  
Vol 225 ◽  
pp. 05004
Author(s):  
V. Bottau ◽  
L. Tondut ◽  
P.G. Allinei ◽  
B. Perot ◽  
C. Eleon ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Detection Efficiency ◽  
Fission Neutron ◽  
High Energy ◽  
Fast Neutrons ◽  
Coincidence Counting ◽  
Useful Signal ◽  
Plastic Scintillators

In the framework of the radioactive waste drum characterization using neutron coincidence counting, the Nuclear Measurement Laboratory of CEA Cadarache is studying plastic scintillators as an alternative to ideal but costly 3He gas proportional counters. Plastic scintillators are at least 5 times cheaper for the same detection efficiency, and in addition, they detect fast neutrons about three orders of magnitude faster than 3He detectors. However, they are sensitive to gamma rays, which implies the necessity to identify precisely gamma background sources that may affect the useful signal. This paper presents a detailed analysis of the gamma-ray spectrum of a radioactive waste drum containing glove box filters contaminated by plutonium dioxide. Gamma emissions accompanying inelastic scattering (n,n’) and (α,n) reactions that can lead to neutron-gamma coincidences parasitizing useful coincidences from plutonium spontaneous fissions are identified. Some of these parasitic gamma rays having energies up to several MeV, we plan to reject high-energy scintillator pulses with an electronics rejection threshold above 1 MeV, which should preserve the major part of useful fission neutron pulses.

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