The determination of the average energy of a fast neutron flux with portable neutron survey instruments
The determination of the average energy of a fast neutron flux with portable neutron survey instruments
For routine measurements of local dose rates, battery operated instruments are often used. Such instruments measure the neutron flux by counting the $\alpha$-particles produced in the reaction B$^{10}$(n,$\alpha$) Li$^{7}$. In general, BF$_{3}$ type counter tubes are employed. To compensate for the...
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Personal Name(s): | Nachtigall, D. (Corresponding author) |
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Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
Imprint: |
Jülich
Kernforschungsanlage Jülich, Verlag
1962
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Physical Description: |
8 p., Fig., Anh. |
Document Type: |
Report Book |
Research Program: |
Addenda |
Series Title: |
Berichte der Kernforschungsanlage Jülich
90 |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
For routine measurements of local dose rates, battery operated instruments are often used. Such instruments measure the neutron flux by counting the $\alpha$-particles produced in the reaction B$^{10}$(n,$\alpha$) Li$^{7}$. In general, BF$_{3}$ type counter tubes are employed. To compensate for the low effiency in boron response at fast neutron energies, ordinarily a 1" thick moderator of polyethylene or paraf fin wax is placed around the tube to reduce a fraction of the fast neutron flux to energy levels which will reactefficiently with the B$^{10}$ For absorbing thermal neutrons an outer cadmium cover is used. An instrument of this type is quite sensitive, but its response is not proportional to the dosage. For determining dose rates, in addition to the reading and the energy sensitivity of the instrument, the knowledge of the average energy of the neutrons being measured is necessary but seldom known.We can obtain the average energy of a neutron flux outside the shielding of a reactor by taking the ratio of the count rate as measured with outer cadmium cover , moderator,and BF$_{3}$ tube combination, and the count rate as measured with outer cadmium cover, moderator, tube, and internal cadmium shield between them. Experimental values are given. |