ABSOLUTE STANDARDIZATION OF RADIOACTIVE NEUTRON SOURCES: I. ACTIVATION OF MANGANESE BATH

1959 ◽  
Vol 37 (3) ◽  
pp. 256-262 ◽  
Author(s):  
K. W. Geiger ◽  
G. N. Whyte
Keyword(s):  
Research Council ◽  
Emission Rate ◽  
Neutron Emission ◽  
International Comparisons ◽  
National Research Council ◽  
National Bureau ◽  
Neutron Sources ◽  
Manganese Bath ◽  
Absolute Standardization

The neutron emission rate of a Ra-α-Be source of the National Research Council has been measured by moderating the neutrons in manganese sulphate solution surrounding the source. Some of the thermal neutrons captured in the bath produce manganese-56, and the neutron emission rate is found from an absolute determination of the resulting activity. A number of corrections are discussed in detail. The value of (3.22 ± 0.05) × 106 neutrons per second found for the neutron emission rate shows satisfactory agreement with the results of our intercomparison with the primary neutron standard of the National Bureau of Standards, and allows a tie-in with a series of international comparisons of primary neutron sources.

ABSOLUTE STANDARDIZATION OF RADIOACTIVE NEUTRON SOURCES: II. THE USE OF THE F19(α, n)Na22 REACTION

1959 ◽  
Vol 37 (5) ◽  
pp. 550-556 ◽  
Author(s):  
K. W. Geiger
Keyword(s):  
Nuclear Reactions ◽  
Emission Rate ◽  
Neutron Emission ◽  
National Research Council ◽  
Neutron Output ◽  
Neutron Sources ◽  
Neutron Thermalization ◽  
Γ Rays ◽  
Absolute Standardization ◽  
Good Agreement

Fluorine has only one stable isotope, F19. If neutrons are produced by the F19(α, n)Na22 reaction the neutron output can be calculated from the yield of the resulting radioactive Na22. The growth of Na22 (half-life, 2.58 years) has been measured in a neutron source consisting originally of 1.6 curies Po210 mixed with CaF2 powder. Since Na22 is a positron emitter, discrimination against γ-rays from Po210 and from nuclear reactions could be achieved by detecting the two positron annihilation quanta in coincidence. The Na22 growth has been followed over 20 months and is in agreement with the theoretical growth curve. Comparison with a calibrated Na22 source yielded a neutron emission rate of (10.70 ± 0.25) × 104 sec−1. This resulted in a neutron emission rate of (3.16 ± 0.10) × 106 sec−1 for the Ra-α-Be source of the National Research Council, in good agreement with (3.22 ± 0.05) × 106 sec−1 obtained by a neutron thermalization method.

Impurity correction factor of MnSO4 compound for the determination of neutron emission rate on the manganese bath method

1999 ◽  
Vol 239 (3) ◽  
pp. 605-608 ◽  
Author(s):  
Kil-Oung Choi ◽  
Young-Seok Lee ◽  
Sun-Tae Hwang ◽  
Kwang-Pil Lee ◽  
Keung-Shik Park
Keyword(s):  
Correction Factor ◽  
Emission Rate ◽  
Neutron Emission ◽  
Manganese Bath

A determination of the differences in gravity between the National Physical Laboratory, Teddington, the Dominion Observatory, Ottawa, and the National Bureau of Standards, Washington

1955 ◽  
Vol 229 (1179) ◽  
pp. 445-458 ◽  
Keyword(s):  
Research Council ◽  
National Research Council ◽  
The United States ◽  
National Physical Laboratory ◽  
Reference Station ◽  
National Bureau ◽  
National Reference ◽  
Physical Laboratory ◽  
Good Agreement

Comparisons have been made with the Cambridge pendulum apparatus between the values of gravity at the National Physical Laboratory, Teddington, the Dominion Observatory, Ottawa, and the National Bureau of Standards, Washington. The three measured differences form a satisfactorily consistent set, and the connexion between Teddington and Washington is in good agreement with that determined in 1939 by Browne & Bullard (1940) with the same pendulums. Gravimeter observations have been used to relate the points occupied to the national reference station in Washington and to the site of the absolute determination in progress at the National Research Council, Ottawa. If the value on the Potsdam system for the British fundamental station at Teddington is taken as 981·1963 cm/s 2 , the following values are obtained for the national reference stations of the United States and Canada: Washington (Commerce) g = 980·1192 ± 0·00055 cm/s 2 Ottawa (pier) g = 980·6191 ± 0·00045 cm/s 2 .

DETERMINATION OF AN ABSOLUTE SCALE OF CAPACITANCE

1964 ◽  
Vol 42 (1) ◽  
pp. 53-69 ◽  
Author(s):  
A. F. Dunn
Keyword(s):  
Research Council ◽  
National Research Council ◽  
The Past ◽  
Absolute Scale ◽  
Measuring Techniques ◽  
The Absolute ◽  
Better Than

In the past decade or two, the measurement of capacitance has become of much greater importance in many fields of scientific and technological investigation as well as forming the basis of many production applications. The capabilities of the capacitance measuring techniques available are of great importance, and the measurement and maintenance of an absolute scale of capacitance has become of prime importance. In the National Research Council of Canada, the absolute unit of capacitance is now known with an accuracy better than ±0.0005%, with the capability of scaling the unit of capacitance over six decades of capacitance both above and below 1 pf (1 × 10−12 f) without introducing an additional indeterminacy any greater than ±0.0005% or ±0.3 af (af = attofarad = 10−18 f).

scholarly journals The Determination of Absolute Phase of a Long Baseline Interferometer and its Application to the Precise Measurement of the Constant of Nutation

1980 ◽  
Vol 78 ◽  
pp. 129-138
Author(s):  
W. H. Cannon ◽  
J. L. Yen
Keyword(s):  
Research Council ◽  
Precise Measurement ◽  
National Research Council ◽  
New Technique ◽  
Canadian Universities ◽  
Long Baseline ◽  
Absolute Phase

Long Baseline Interferometry (L.B.I.) refers to a dramatic technical breakthrough in astronomy accomplished almost exactly ten years ago in the spring of 1967 by a group of workers at the National Research Council of Canada and some major Canadian Universities. The Canadian effort was duplicated within a month by an independent American effort and it was realized soon afterward that the new technique of L.B.I. held enormous potential for geodynamical as well as astronomical studies.

DETERMINATION OF THE UNIT OF CAPACITANCE

1959 ◽  
Vol 37 (1) ◽  
pp. 35-46 ◽  
Author(s):  
A. F. Dunn
Keyword(s):  
Research Council ◽  
National Research Council ◽  
Absolute Sense ◽  
Measuring Bridge ◽  
Self Consistent ◽  
Consistent Group ◽  
Primary Standards ◽  
Conductance Measuring

As part of the program to establish a wholly self-consistent group of basic electrical units for the country, the unit of capacitance maintained in the National Research Council has been determined in an absolute sense in terms of the frequency and resistance units maintained in the laboratories, with an accuracy comparable to that of the primary standards. The determination was made by connecting additional components to an existing capacitance and conductance measuring bridge to form a modified Wien bridge network. The results obtained indicate an accuracy of ± 0.0025%.

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