THE PRELIMINARY CHOICE OF DESIGN PARAMETERS FOR NEUTRON CHOPPERS
Some of the factors affecting the counting rate achieved by a neutron chopper spectrometer are investigated. It is shown that in a chopper of optimum design the counting rate per channel at any given energy is proportional both to the slit width and to the square of the resolution in mu sec/m, as well as to the cutoff velocity vc of the rotor; this last is because a larger number of bursts per second become possible as vc is increased. For an idealized cutoff function, it is shown that the total running time for measuring a spectrum is minimum when the ratio of cutoff velocity to peripheral velocity of the rotor is such that approximately 1.67 runs per energy decade are required; this means that the chopper speed and the time-channel width are changed by a factor of two from one run to the next. (auth)
- Research Organization:
- Argonne National Lab., Ill.
- DOE Contract Number:
- W-31109-ENG-38
- NSA Number:
- NSA-16-003180
- OSTI ID:
- 4832050
- Report Number(s):
- ANL-6449
- Country of Publication:
- United States
- Language:
- English
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