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 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.

Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I

1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Range ◽  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Solar Neutron ◽  
Low Altitude

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.

scholarly journals Optical Afterglows as Probes for the Central Engine and Fireball of Gamma-Ray Bursts

2012 ◽  
Vol 8 (S290) ◽  
pp. 263-264
Author(s):  
Liang Li ◽  
En-Wei Liang ◽  
He Gao ◽  
Bing Zhang
Keyword(s):  
Statistical Analysis ◽  
Gamma Rays ◽  
Density Profile ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Gamma Ray Bursts ◽  
Prompt Gamma ◽  
Medium Density ◽  
Central Engine ◽  
Prompt Emission

AbstractWell-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are compiled from literature. We identify possible emission components based on our empirical fits and present statistical analysis for these components. We find that the flares are related to prompt emission, suggesting that they could have the same origin in different episodes. The shallow decay segment is not correlated with prompt gamma-rays. It likely signals a long-lasting injected wind from GRB central engines. Early after onset peak is closely related with prompt emission. The ambient medium density profile is likely n ∝ r−1. No correlation between the late re-brightening bump and prompt gamma-rays or the onset bump is found. They may be from another jet component.

scholarly journals Compact lightweight imager of both gamma rays and neutrons based on a pixelated stilbene scintillator coupled to a silicon photomultiplier array

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jihwan Boo ◽  
Mark D. Hammig ◽  
Manhee Jeong
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Sampling Rate ◽  
High Sensitivity ◽  
Pulse Shape Discrimination ◽  
Nuclear Materials ◽  
Silicon Photomultiplier ◽  
Analog To Digital ◽  
Particle Imaging ◽  
Imaging Plane

AbstractDual particle imaging, in which both neutrons and gamma-rays in the environment can be individually characterized, is particularly attractive for monitoring mixed radiation emitters such as special nuclear materials (SNM). Effective SNM localization and detection benefits from high instrument sensitivity so that real-time imaging or imaging with a limited number of acquired events is enabled. For portable applications, one also desires a dual particle imager (DPI) that is readily deployable. We have developed a hand-held type DPI equipped with a pixelated stilbene-silicon photomultiplier (SiPM) array module and low sampling-rate analog-to-digital converters (ADCs) processed via a multiplexed readout. The stilbene-SiPM array (12 × 12 pixels) is capable of effectively performing pulse shape discrimination (PSD) between gamma-ray and neutron events and neutron/gamma-ray source localization on the imaging plane, as demonstrated with 252Cf neutron/gamma and 137Cs gamma-ray sources. The low sampling rate ADCs connected to the stilbene-SiPM array module result in a compact instrument with high sensitivity that provides a gamma-ray image of a 137Cs source, producing 6.4 μR/h at 1 m, in less than 69 s. A neutron image for a 3.5 × 105 n/s 252Cf source can also be obtained in less than 6 min at 1 m from the center of the system. The instrument images successfully with field of view of 50° and provides angular resolution of 6.8°.

scholarly journals Improving the performance of 241Am-Be for PGNAA applications using a proper shielding for neutron source and the NaI detector

2010 ◽  
Vol 25 (3) ◽  
pp. 205-211 ◽  
Author(s):  
Hamed Panjeh ◽  
Hashem Hakimabad ◽  
Lalle Motavalli
Keyword(s):  
Gamma Rays ◽  
Energy Region ◽  
Gamma Ray ◽  
Region Of Interest ◽  
High Rate ◽  
Prompt Gamma ◽  
Peak Resolution ◽  
Set Up ◽  
Gamma Ray Detector

The gamma ray spectrum resolution from a 241Am-Be source-based prompt gamma ray activation analysis set-up has been observed to increase in the energy region of interest with enclosing the NaI detector in a proper neutron and gamma ray shield. We have investigated the tact that the peak resolution of prompt gamma rays in the region of interest from the set-up depends on the source activity to the great extent, size and kind of the detector and the geometry of the detector shield. In order to see the role of a detector shield, five kinds of the detector shield were used and finally the proper kind was introduced. Since the detector shield has an important contribution in the reduction of the undesirable and high rate gamma rays coming to the gamma ray detector, a good design of a proper shield enables the elimination of the unwanted events, such as a pulse pile-up. By improving the shielding design, discrete and distinguishable photoelectric peaks in the energy region of interest have been observed in the spectrum of prompt gamma rays.

scholarly journals INTERNAL ENERGY DISSIPATION OF GAMMA-RAY BURSTS OBSERVED WITHSWIFT: PRECURSORS, PROMPT GAMMA-RAYS, EXTENDED EMISSION, AND LATE X-RAY FLARES

2014 ◽  
Vol 789 (2) ◽  
pp. 145 ◽  
Author(s):  
You-Dong Hu ◽  
En-Wei Liang ◽  
Shao-Qiang Xi ◽  
Fang-Kun Peng ◽  
Rui-Jing Lu ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Internal Energy ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Prompt Gamma ◽  
X Ray ◽  
Extended Emission

scholarly journals Potential of prompt $$\gamma $$-ray emission studies in fast-neutron induced fission: a first step

2020 ◽  
Vol 56 (3) ◽  
Author(s):  
L. Qi ◽  
C. Schmitt ◽  
M. Lebois ◽  
A. Oberstedt ◽  
S. Oberstedt ◽  
...  
Keyword(s):  
Fast Neutron ◽  
Gamma Ray ◽  
Prompt Gamma ◽  
Induced Fission ◽  
Gamma Ray Emission ◽  
Emission Studies

scholarly journals Prompt Fission Neutron Spectra for Neutron-Induced Fission of 239Pu and 235U

2020 ◽  
Vol 239 ◽  
pp. 01003
Author(s):  
Matthew Devlin ◽  
Jaime A. Gomez ◽  
Keegan J. Kelly ◽  
John M. O'Donnell ◽  
Robert C. Haight ◽  
...  
Keyword(s):  
Fission Neutron ◽  
Science Center ◽  
Detector Arrays ◽  
Neutron Spectra ◽  
Lithium Glass ◽  
Wide Range ◽  
Induced Fission ◽  
Large Effort ◽  
Prompt Fission ◽  
Prompt Fission Neutron

We report the current results of a large effort to accurately measure the Prompt Fission Neutron Spectra (PFNS) for neutron-induced fission of 235U and 239Pu for incident neutrons with energies from 1 to 20 MeV. The Chi-Nu experiment at the Los Alamos Neutron Science Center used an unmoderated, white spectrum of neutrons to induce fission in actinide samples that were placed inside a parallel plate avalanche counter to provide a fast fission signal. A double time-of-flight technique was used to determine the incoming and outgoing neutron energies. Two neutron detector arrays, one with 54 liquid scintillators and another with 22 lithium glass detectors, were used to detect the outgoing neutrons and measure the PFNS distributions over a wide range in outgoing neutron energy, from below 100 keV to 10 MeV. Extensive Monte Carlo modeling was used to understand the experiment response and extract the PFNS. Systematic errors and uncertainties in the method have been examined and quantified. A summary of these results for incoming energies from 1 to 5 MeV is presented here.

scholarly journals Measurement of the ROT effect in the neutron induced fission of 235U in the 0.3 eV resonance at a hot source of polarized neutrons

2018 ◽  
Vol 169 ◽  
pp. 00010 ◽  
Author(s):  
Yuri Kopatch ◽  
Vadim Novitsky ◽  
Gadir Ahmadov ◽  
Alexei Gagarsky ◽  
Daniyar Berikov ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Particle Emission ◽  
Prompt Gamma ◽  
Ternary Fission ◽  
Spin States ◽  
Heavy Nuclei ◽  
Polarized Neutrons ◽  
Order Of Magnitude ◽  
Series Of Experiments ◽  
Induced Fission

The TRI and ROT asymmetries in fission of heavy nuclei have been extensively studied during more than a decade. The effects were first discovered in the ternary fission in a series of experiments performed at the ILL reactor (Grenoble) by a collaboration of Russian and European institutes, and were carefully measured for a number of fissioning nuclei. Later on, the ROT effect has been observed in the emission of prompt gamma rays and neutrons in fission of 235U and 233U, although its value was an order of magnitude smaller than in the α-particle emission from ternary fission. All experiments performed so far are done with cold polarized neutrons, what assumes a mixture of several spin states, the weights of these states being not well known. The present paper describes the first attempt to get “clean” data by performing the measurement of gamma and neutron asymmetries in an isolated resonance of 235U at the POLI instrument of the FRM2 reactor in Garching.

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