scholarly journals Neutron Detection in Mixed Neutron-Gamma Fields with Common NaI(Tl) Detectors

2021 ◽  
Author(s):  
Guntram Pausch ◽  
Achim Kreuels ◽  
Falko Scherwinski ◽  
Yong Kong ◽  
Mathias Küster ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Delay Time ◽  
Thermal Neutron Flux ◽  
Gamma Ray ◽  
Neutron Detection ◽  
High Energy ◽  
Detection Capabilities ◽  
Co Doped

<p>Searching digitized detector signals for piled-up delayed components with distinct energy and delay time signatures is a smart method to provide common NaI(Tl) detectors with additional neutron detection capabilities at no extra cost. This technique nicely complements the idea of neutron detection by analyzing events with high energy depositions above the range of common gamma-ray energies. In combination, both approaches can provide half of the neutron sensitivity offered by a commercial <sup>6</sup>Li co-doped NaI(Tl) (NaIL™) scintillator of the same size, at the price of higher and load-dependent background contributions. Delayed-coincidence techniques are most suitable for neutron monitoring or long-term measurements, where the statistics of the acquired delay-time distributions allows separate fitting of the effect and background contributions. In this case, the thermal neutron flux can be quantified in parallel to gamma-ray spectroscopy at overall detector loads exceeding 10 kcps.</p>

scholarly journals Neutron Detection in Mixed Neutron-Gamma Fields with Common NaI(Tl) Detectors

2021 ◽  
Author(s):  
Guntram Pausch ◽  
Achim Kreuels ◽  
Falko Scherwinski ◽  
Yong Kong ◽  
Mathias Küster ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Delay Time ◽  
Thermal Neutron Flux ◽  
Gamma Ray ◽  
Neutron Detection ◽  
High Energy ◽  
Detection Capabilities ◽  
Co Doped

<p>Searching digitized detector signals for piled-up delayed components with distinct energy and delay time signatures is a smart method to provide common NaI(Tl) detectors with additional neutron detection capabilities at no extra cost. This technique nicely complements the idea of neutron detection by analyzing events with high energy depositions above the range of common gamma-ray energies. In combination, both approaches can provide half of the neutron sensitivity offered by a commercial <sup>6</sup>Li co-doped NaI(Tl) (NaIL™) scintillator of the same size, at the price of higher and load-dependent background contributions. Delayed-coincidence techniques are most suitable for neutron monitoring or long-term measurements, where the statistics of the acquired delay-time distributions allows separate fitting of the effect and background contributions. In this case, the thermal neutron flux can be quantified in parallel to gamma-ray spectroscopy at overall detector loads exceeding 10 kcps.</p>

scholarly journals Determination of the Thermal Neutron Flux by Measuring Gamma Radiations with High and Low Resolution Detectors

2019 ◽  
Vol 6 (2) ◽  
pp. 187-193
Author(s):  
M. M. Hosamani ◽  
A. S. Bennal ◽  
N. M. Badiger
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Thermal Neutron Flux ◽  
High Energy ◽  
High Energy Resolution ◽  
Indium Foil ◽  
Hpge Detectors ◽  
Foil Activation ◽  
Gamma Radiations

Thermal neutron flux (Фth) of Americium-Beryllium (Am-Be) neutron source has been measured by adopting the foil activation method. The neutrons emitted from Am-Be source are used to activate the indium-115 (115In) foil. The gamma radiations emitted from the activated isomer 116m1In are measured with NaI(Tl) and HPGe detectors. The thermal neutron flux is measured by adopting the cadmium (Cd) foil difference technique in which the Cd foil placed in front of the source to prevent the thermal neutrons from entering into the indium foil. The neutron flux is determined by measuring the gamma radiation emitted from indium foil using a low and high energy resolution NaI(Tl) and HPGe detectors respectively. The measured thermal neutron flux obtained from both detectors has been compared and found that the Фth does not depend on the resolution and type of the detectors used in the present investigations.

Long-term variations in the natural thermal neutron flux at 4300 m above sea level

2017 ◽  
Vol 81 (2) ◽  
pp. 160-161 ◽  
Author(s):  
Yu. V. Stenkin ◽  
V. V. Alekseenko ◽  
A. S. Bagrova ◽  
V. I. Stepanov ◽  
O. B. Shchegolev ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Sea Level ◽  
Thermal Neutron Flux ◽  
Long Term Variations

scholarly journals Natural thermal neutron flux long-term variations at 4300 m a.s.l.

2017 ◽  
Author(s):  
Yuri Stenkin ◽  
V.V. Alekseenko ◽  
O.B. Shchegolev ◽  
S. W. Cui ◽  
Ya.Yu. He ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Thermal Neutron Flux ◽  
Long Term Variations

scholarly journals Investigation of thermal neutron detection capability of a CdZnTe detector in a mixed gamma-neutron radiation field

Nukleonika ◽  
2018 ◽  
Vol 63 (3) ◽  
pp. 59-64
Author(s):  
Haluk Yücel ◽  
R. Bora Narttürk ◽  
Senem Zümrüt ◽  
Gizem Gedik ◽  
Mustafa Karadag
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Radiation Field ◽  
Epithermal Neutron ◽  
Gamma Ray ◽  
Neutron Detection ◽  
Neutron Radiation ◽  
Detection Sensitivity ◽  
Shielding Effect ◽  
Cdznte Detector

Abstract The aim of this study was to investigate the thermal neutron measurement capability of a CdZnTe detector irradiated in a mixed gamma-neutron radiation field. A CdZnTe detector was irradiated in one of the irradiation tubes of a 241Am-Be source unit to determine the sensitivity factors of the detector in terms of peak count rate (counts per second [cps]) per neutron flux (in square centimeters per second) [cps/neutron·cm−2·s−1]. The CdZnTe detector was covered in a 1-mm-thick cadmium (Cd) cylindrical box to completely absorb incoming thermal neutrons via 113Cd(n,γ) capture reactions. To achieve, this Cd-covered CdZnTe detector was placed in a well-thermalized neutron field (f-ratio = 50.9 ± 1.3) in the irradiation tube of the 241Am-Be neutron source. The gamma-ray spectra were acquired, and the most intense gamma-ray peak at 558 keV (0.74 γ/n) was evaluated to estimate the thermal neutron flux. The epithermal component was also estimated from the bare CdZnTe detector irradiation because the epithermal neutron cutoff energy is about 0.55 eV at the 1-mm-thick Cd filter. A high-density polyethylene moderating cylinder box can also be fitted into the Cd filter box to enhance thermal sensitivity because of moderation of the epithermal neutron component. Neutron detection sensitivity was determined from the measured count rates from the 558 keV photopeak, using the measured neutron fluxes at different irradiation positions. The results indicate that the CdZnTe detector can serve as a neutron detector in mixed gamma-neutron radiation fields, such as reactors, neutron generators, linear accelerators, and isotopic neutron sources. New thermal neutron filters, such as Gd and Tb foils, can be tested instead of the Cd filter due to its serious gamma-shielding effect.

Study of changes of thermal neutrons intensity of lithospheric origin for the diagnostics and forecast of earthquakes

2020 ◽  
Author(s):  
Valentina Antonova ◽  
Sergey Kryukov ◽  
Vadim Lutsenko ◽  
Andrey Malimbaev
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Thermal Neutron Flux ◽  
Spectral Composition ◽  
Background Level ◽  
High Energy ◽  
Tien Shan ◽  
Necessary Condition ◽  
High Mountain ◽  
Thermal Neutrons

&lt;p&gt;Studies of variations in the intensity of thermal (epithermal) neutrons at the high-mountain station of cosmic rays near the fracture of the earth's crust (3340 m above sea level, Northern Tien- Shan) showed the promising of using them for the diagnosis and forecast of earthquakes in seismically active regions. A method is proposed for distinguishing features of changes in the intensity of thermal neutrons of lithospheric origin against the background of variations caused by solar and atmospheric disturbance sources. However, a necessary condition for this is the synchronous registration of high-energy neutrons of galactic origin.&lt;/p&gt;&lt;p&gt;It is known that neutrons in the Earth&amp;#8217;s atmosphere arise mainly as a result of the interaction of primary cosmic radiation with the nuclei of air atoms. Statistical analysis of neutron measurements during effective solar events (coronal mass ejections), changes of atmospheric pressure confirmed the genetic relationship of thermal neutrons near the Earth's surface with high-energy neutrons of galactic origin and the similarity of the spectral composition of their variations. The difference is observed only in the range (2&amp;#183;10&lt;sup&gt;-7&lt;/sup&gt;&amp;#247;2&amp;#183;10&lt;sup&gt;-6&lt;/sup&gt;)Hz. Variations with the period of 29.5 days (synodic lunar month), due to the gravitational influence of the moon, are present throughout the 12-year period of research of thermal neutrons. The amplitude and its changes were determined by the method of complex demodulation. The periodicity of 29.5 days is absent in the spectrum of high-energy neutrons variations.&lt;/p&gt;&lt;p&gt;&amp;#160;Analysis of experimental data during of seismic activity showed the frequent breakdown of the correlation between the intensity of thermal and high-energy neutrons. The cause of this phenomenon is the additional thermal neutron flux of the lithospheric origin, which appears under these conditions. Simple statistical processing of measured parameters makes it possible to exclude variations of interplanetary and atmospheric origin in the intensity of thermal neutrons and to isolate changes caused by seismic processes.&lt;/p&gt;&lt;p&gt;&amp;#160;We used this method for analysis of thermal neutrons intensity during earthquakes with intensity &amp;#8805; 3b in the vicinity of Almaty which took place in 2007-2018. The catalog includes 30 events. The increase of thermal neutrons flux was observed for ~ 60% of events. However, before the earthquake the increase of thermal neutron flux is only observed for ~ 25-30% of events. The amplitude of the additional thermal neutron flux of the lithospheric origin is equal to 5-7% of the background level. Sometimes it reaches values of 10-12%.&lt;/p&gt;&lt;p&gt;The analysis of our catalog of earthquakes in the vicinity of Almaty also showed that 70% of these events occurred during the full moon or new moon (+/- 2 days).&lt;/p&gt;

Activation Analysis of Normal and Atherosclerotic Aortas

1969 ◽  
Vol 23 (2) ◽  
pp. 121-124 ◽  
Author(s):  
W. H. Strain ◽  
C. G. Rob ◽  
W. J. Pories ◽  
R. C. Childers ◽  
M. F. Thompson ◽  
...  
Keyword(s):  
Activation Analysis ◽  
Neutron Activation ◽  
Neutron Flux ◽  
Thermal Neutron ◽  
Thermal Neutron Flux ◽  
Gamma Ray ◽  
Gamma Ray Spectrometry ◽  
Aortic Tissue ◽  
Pathological Changes ◽  
Upper Limits

Normal and atherosclerotic aortas from rats and man have been analyzed by neutron activation to determine changes in the content of Ca, Cd, Co, Cu, Mg, Mn, Se, V, and Zn with the development of degenerative changes. Samples of aortic tissue were weighed, dried at 110°C overnight, and irradiated for 30 min in a thermal neutron flux of 1.8X1012 n/cm2-sec in a TRIGA Mark I reactor. Immediately after irradiation, the samples were wet-ashed in the presence of carriers, the various elements were then radiochemically separated, and the separated fractions were counted by multichannel gamma-ray spectrometry. Definite values, or firm upper limits, for the elements were calculated by computer. With increasing degree of atherosclerosis, the Ca content rose from <350 to 36 000±2000 ppm; Co from undetectable to 0.34 ppm; Mg from <110 to 880 ppm; Mn from 0.34 to 1.26 ppm; and Zn from 37 to 152 ppm. Significant changes could not be detected in Cd, Se, and V; changes in Cu were not consistent. These results are discussed in relation to the pathological changes and to zinc therapy in the treatment of atherosclerosis.

Thermal-Neutron Flux Generation by High-Energy Protons

1968 ◽  
Vol 34 (2) ◽  
pp. 104-113 ◽  
Author(s):  
W. A. Coleman ◽  
R. G. Alsmiller
Keyword(s):  
Neutron Flux ◽  
Thermal Neutron ◽  
Thermal Neutron Flux ◽  
High Energy
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