Neutron spectra from isotopic (?, n) sources

1973 ◽  
Vol 34 (5) ◽  
pp. 436-440
Author(s):  
N. D. Tyufyakov ◽  
L. A. Trykov ◽  
A. S. Shtan'
Keyword(s):  
Neutron Spectra ◽  
N Sources

Calculated neutron spectra from 9Be(α, n) sources

1968 ◽  
Vol 46 (13) ◽  
pp. 1527-1536 ◽  
Author(s):  
L. Van der Zwan
Keyword(s):  
Simple Model ◽  
Neutron Spectrum ◽  
Neutron Yield ◽  
Cluster Size ◽  
Energy Losses ◽  
Neutron Spectra ◽  
N Sources ◽  
Similar Peak ◽  
Α Particles

The neutron spectra from 9Be(α, n) sources are calculated for the α emitters 241Am, 210Po,and 239Pu. For a Pu–Be source, peaks are found at neutron energies of 0.75, 1.20, 2.10, 3.15, 4.95, 6.50, 7.75, and 9.65 MeV. Similar peak positions are found for sources made with 241Am and 210Po. The effect of the α-energy losses in the α-emitting material is studied by means of a simple model consisting of clusters of the α-emitting material embedded in a matrix of beryllium. For sources composed of clusters of AmBe13 or PuBe13 in beryllium, the changes in shape of the neutron spectrum are minor as the cluster size is increased from 0.5 to 20 μ. However, for sources consisting of clusters of Pu and Am or Po embedded in beryllium, the spectrum is considerably distorted as the cluster size is varied from 0.5 to 10 μ. The neutron yield per 106 α particles is calculated for sources having Am, Po, or Pu clusters ranging in size from 0 to 20 μ and AmBe13 or PuBe13 clusters ranging from 0 to 40 μ. The percentage of neutrons below 1.5 MeV including the contribution from the multiparticle reaction 9Be(α, αn)8 Be is estimated to be 16% for an AmBe13 type of source and 12% for a PuBe13 type of source, each with a cluster size of 0.5 μ.

Neutron Spectra from Am/F and Am/Li (α,n) Sources

1983 ◽  
pp. 492-494 ◽  
Author(s):  
J. G. Owen ◽  
D. R. Weaver ◽  
J. Walker
Keyword(s):  
Neutron Spectra ◽  
N Sources

Yield and chlorophyll index in cabbage in function of enhanced-efficiency nitrogen fertilizers and urea

2020 ◽  
Vol 13 (2) ◽  
pp. 6
Author(s):  
J. J. Frazão ◽  
A. R. Silva ◽  
F. H. M. Salgado ◽  
R. A. Flores ◽  
E. P. F. Brasil
Keyword(s):  
Nitrogen Fertilizers ◽  
N Losses ◽  
N Sources ◽  
Promising Strategy ◽  
Applied Dose ◽  
Coated Urea ◽  
Chlorophyll Index ◽  
Polymer Coated Urea ◽  
N Rates ◽  
And Control

The increase of the efficiency of the nitrogen fertilization promotes reduction of the applied dose and decreases the losses of nitrogen (N) to the environment. The objective of this work was to evaluate the yield and the relative chlorophyll index (IRC) in cabbage crop under cover fertilization, using enhanced-efficiency nitrogen fertilizers, compared to urea, in variable doses. The experimental design was randomized blocks in a 3x4+1 factorial scheme (three sources, four rates and control), with four replications. The N sources used were: common urea (U), urea treated with urease inhibitor NBPT® (UN) and Kimcoat® polymer coated urea (UK). The N rates used were 0, 40, 80, 160 and 320 kg ha-1, divided in two fertilizations at 20 and 40 days after transplantation. Up to 160 kg ha-1 of N, there was no difference between N sources and N rates for both yield and RCI. The enhanced-efficiency N sources (UN and UK) promoted higher averages compared to common urea, possibly due to the higher N losses from common urea. Thus, the use of urease inhibitors or polymers associated with urea is a promising strategy to improve cabbage yield, as well as reducing N losses to the environment.

Tree species rather than type of mycorrhizal association drives inorganic and organic nitrogen acquisition in tree-tree interactions

2021 ◽  
Author(s):  
Robert Reuter ◽  
Olga Ferlian ◽  
Mika Tarkka ◽  
Nico Eisenhauer ◽  
Karin Pritsch ◽  
...  
Keyword(s):  
Tree Species ◽  
Mycorrhizal Fungi ◽  
Prunus Avium ◽  
N Uptake ◽  
Organic N ◽  
Acer Pseudoplatanus ◽  
N Sources ◽  
Mycorrhizal Association ◽  
N Acquisition ◽  
Inorganic And Organic

Abstract Mycorrhizal fungi play an important role for the nitrogen (N) supply of trees. The influence of different mycorrhizal types on N acquisition in tree-tree interactions is, however, not well understood, particularly with regard to the competition for growth-limiting N. We studied the effect of competition between temperate forest tree species on their inorganic and organic N acquisition in relation to their mycorrhizal type (i.e., arbuscular mycorrhiza or ectomycorrhiza). In a field experiment, we quantified net N uptake capacity from inorganic and organic N sources using 15N/13C stable isotopes for arbuscular mycorrhizal tree species (i.e., Acer pseudoplatanus L., Fraxinus excelsior L., and Prunus avium L.) as well as ectomycorrhizal tree species (i.e., Carpinus betulus L., Fagus sylvatica L., and Tilia platyphyllos Scop.). All species were grown in intra- and interspecific competition (i.e., monoculture or mixture). Our results showed that N sources were not used complementarily depending on a species´ mycorrhizal association, but their uptake rather depended on the competitor indicating species-specific effects. Generally, ammonium was preferred over glutamine and glutamine over nitrate. In conclusion, our findings suggest that inorganic and organic N acquisition of the studied temperate tree species is less regulated by mycorrhizal association, but rather by the availability of specific N sources in the soil as well as the competitive environment of different tree species.

14 MeV Neutron Spectra Measurements using Type IIa Diamond Detectors

1996 ◽  
Vol 66 (1) ◽  
pp. 371-374 ◽  
Author(s):  
M. Pillon ◽  
M. Angelone ◽  
A.V. Krasilniko
Keyword(s):  
Neutron Spectra

Simultaneous Evaluation of Neutron Spectra and 1-MeV-Equivalent (Si) Fluences at SPR-III and ACRR

2007 ◽  
Vol 54 (6) ◽  
pp. 2296-2302 ◽  
Author(s):  
John G. Williams ◽  
Patrick J. Griffin ◽  
Donald B. King ◽  
David W. Vehar ◽  
Tim Schnauber ◽  
...  
Keyword(s):  
Neutron Spectra ◽  
Simultaneous Evaluation

Measurement of neutron spectra generated from bombardment of 4 to 24 MeV protons on a thick9Be target and estimation of neutron yields

2014 ◽  
Vol 85 (6) ◽  
pp. 063501 ◽  
Author(s):  
Sabyasachi Paul ◽  
G. S. Sahoo ◽  
S. P. Tripathy ◽  
S. C. Sharma ◽  
Ramjilal ◽  
...  
Keyword(s):  
Neutron Spectra ◽  
Mev Protons

Characterization of the Caliban and Prospero Critical Assemblies Neutron Spectra for Integral Measurements Experiments

2014 ◽  
Vol 118 ◽  
pp. 554-557 ◽  
Author(s):  
P. Casoli ◽  
N. Authier ◽  
X. Jacquet ◽  
J. Cartier
Keyword(s):  
Neutron Spectra
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