A comparison of some absolute methods of measuring fast neutron flux

1950 ◽  
Vol 46 (2) ◽  
pp. 339-352 ◽  
Author(s):  
K. W. Allen ◽  
D. L. Livesey ◽  
D. H. Wilkinson
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Cross Sections ◽  
Absolute Measurement ◽  
Fast Neutrons ◽  
Fast Neutron Flux ◽  
Cavendish Laboratory ◽  
The Individual ◽  
Nuclear Processes

The absolute measurement of fast neutron flux presents several difficult problems. Few methods have yet been described in the literature, although the experimental techniques developed by several authors for the detection of fast neutrons (Baldinger, Huber and Staub(7), Barshall and Kanner(9), Amaldi, Bocciarelli, Ferretti and Trabacchi (3), Gray (19), Barshall and Battat(8)) may easily be adapted to this type of measurement. It is, however, most important to have available methods of measuring fast neutron flux to permit the determination of cross-sections for nuclear processes induced by fast neutrons, and several such methods have been developed in the Cavendish Laboratory in recent years. They are the subjects of separate papers (Bretscher and French (13), Kinsey, Cohen and Dainty (21), Allen (l), Allen and Wilkinson (2)). The main purpose of the present paper is to describe the results of experiments carried out to compare these methods in order to test the validity of the assumptions implicit in the individual methods.

The ‘thick-film chamber’ method for the measurement of fast neutron flux

1948 ◽  
Vol 44 (4) ◽  
pp. 581-587 ◽  
Author(s):  
K. W. Allen ◽  
D. H. Wilkinson
Keyword(s):  
Angular Distribution ◽  
Neutron Flux ◽  
Fast Neutron ◽  
Cross Section ◽  
Absolute Measurement ◽  
Experimental Results ◽  
Incident Neutron ◽  
Fast Neutron Flux ◽  
Cavendish Laboratory ◽  
Wide Range

Several methods have been developed in recent years in the Cavendish Laboratory for the absolute measurement of fast neutron flux. All depend on observing the effects of elastic collisions between neutrons and light nuclei. The methods fall into two categories according as individual recoil nuclei are counted (1, 2), or the total ionization current due to the recoils is measured (3). In order completely to interpret the experimental results, it is necessary to know the cross-section for scattering and the angular distribution of the recoil nuclei. The total number of recoil nuclei and their energy distribution are then determined for a known incident neutron spectrum. For precise neutron flux measurements, recoil protons are invariably studied, as the neutron-proton scattering cross-section has been measured over a wide range of energies (4, 5), and the angular distribution of the recoils is isotropic in the centre of gravity space for neutrons of energy less than about 10 MeV. (6, 7). This makes the reduction of the experimental results particularly simple and certain.

The stopping power of polythene and fast neutron flux measurements

1948 ◽  
Vol 44 (1) ◽  
pp. 114-123 ◽  
Author(s):  
D. H. Wilkinson
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Forthcoming Paper ◽  
Average Density ◽  
Stopping Power ◽  
Atomic Composition ◽  
Energy Relation ◽  
Fast Neutron Flux ◽  
Cavendish Laboratory ◽  
Chamber Method

During the past few years, several methods for the measurement of fast neutron flux have been developed in the Cavendish Laboratory. A critical inter-comparison is given in a forthcoming paper by Allen, Livesey and Wilkinson. Some of the methods depend on the counting of protons which are projected by the neutrons from a film of hydrogen-rich material. Polythene is usually employed because its hydrogen content is high and accurately known. If the thickness of the film is comparable with the range of the fastest proton produced by the incident neutrons, it becomes necessary to know the range-energy relation for protons in polythene. This is particularly so in the ‘thick film chamber’ method to be described by Allen and Wilkinson. Another method, the ‘homogeneous ionization chamber’ method to be described by Bretscher and French makes use of the well-known principle that the average density of ionization obtaining in a chamber whose walls have an atomic composition identical with that of the gas which fills the chamber is the same as that in an infinite extent of that gas. This principle itself depends on the identity of mass stopping power of solid and gas of the same atomic composition. The chamber usually used has polythene walls and is filled with ethylene.

Determination of fast neutron flux distribution in irradiation sites of the Malaysian Nuclear Agency research reactor

2011 ◽  
Vol 69 (5) ◽  
pp. 762-767 ◽  
Author(s):  
A.R. Yavar ◽  
S.B. Sarmani ◽  
A.K. Wood ◽  
S.M. Fadzil ◽  
M.H. Radir ◽  
...  
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Flux Distribution ◽  
Research Reactor ◽  
Fast Neutron Flux ◽  
Neutron Flux Distribution

Determination of the fast-neutron flux density in a reactor of the Kola Atomic Power Plant

1982 ◽  
Vol 52 (6) ◽  
pp. 436-437
Author(s):  
Kh. Ya. Bondars ◽  
E. I. Ignatenko ◽  
A. A. Lapenas ◽  
V. I. Lobov ◽  
S. S. Lomakin ◽  
...  
Keyword(s):  
Power Plant ◽  
Neutron Flux ◽  
Fast Neutron ◽  
Flux Density ◽  
Atomic Power Plant ◽  
Fast Neutron Flux ◽  
Neutron Flux Density

scholarly journals Feasibility Study of Copper-64 Radioisotope Production by Secondary Fast Neutron Bombardment

2021 ◽  
Vol 927 (1) ◽  
pp. 012034
Author(s):  
I Kambali ◽  
I R Febrianto
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Nuclear Reaction ◽  
Target Thickness ◽  
Total Radioactivity ◽  
Radioactive Isotopes ◽  
Fast Neutrons ◽  
Fast Neutron Flux ◽  
Section Data ◽  
Theranostic Agent

Abstract As a beta and positron emitter, copper-64 (Cu-64) has been coined a theranostic agent in nuclear medicine. Copper-64 is generally produced by bombarding a nickel-64 target with a proton beam via 64Ni(p,n)64Cu nuclear reaction. In this work, secondary fast neutrons are proposed to produce Cu-64 radioisotope via 64Zn(n,p)64Cu nuclear reaction. The secondary fast neutrons were produced by a 10 MeV proton-irradiated primary titanium (Ti) target simulated using the PHITS 3.16 code. In the simulation, the Ti target thickness was varied from 0.01 to 0.1 cm to obtain the optimum secondary fast neutron flux, which was calculated in the rear, radial, and front directions. The Cu-64 radioactivity yield was then computed using the TENDL 2019 nuclear cross-section data. Also, the expected radioactive impurities during Cu-64 production were predicted. The simulation results indicated that the total fast neutron flux resulted from the 10-MeV proton bombarded Be target was 1.70x1012 n/cm2s. The maximum integrated Cu-64 radioactivity yield was 2.33 MBq/µAh when 0.03 cm thick Ti target was shot with 10-MeV protons. The most significant impurities predicted during the bombardment were radioactive isotopes e.g., Co-61, and Zn-65, with the total radioactivity yield estimated to be 0.28 Bq/µAh.

THE S32 (n,p) P32 REACTION AS A FAST-NEUTRON FLUX MONITOR

1963 ◽  
Vol 41 (1) ◽  
pp. 123-133 ◽  
Author(s):  
D. C. Santry ◽  
J. P. Butler
Keyword(s):  
Neutron Flux ◽  
Fast Neutron ◽  
Cross Sections ◽  
Extensive Study ◽  
Neutron Production ◽  
Flux Monitor ◽  
Fast Neutron Flux ◽  
Neutron Flux Monitor

An extensive study is made of the use of sulphur as a monitor for neutrons with energies from 2 to 20 Mev. Irradiated disks of pressed sulphur are burnt before counting to increase the efficiency and reproducibility of determining the P32 activity. It was established that on burning irradiated sulphur 95.5 ± 0.5% of the P32 activity is retained with a reproducibility of ± 1.0%. Measurements of relative cross sections for the S32 (n,p) P32 reaction have been extended to 20.3 Mev using the T (d,n) He4 and D (d,n) He3 reactions to produce monoenergetic neutrons. Neutron production using Zr−T targets is examined as is the effect of extraneous neutrons from the D (d,np) D process on the S32 (n,p) reaction.

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