An Apparatus for Absolute Neutron Flux Measurement
Abstract
A fully-absorbing neutron detector is being developed to measure the absolute flux (s-1) of a cold neutron beam at the level of 0.1,%. The device will be used to calibrate a neutron flux monitor used in an in-beam neutron lifetime measurement performed at NIST (τn= (886.3 ±3.4) s). The precision of the measurement was limited by the uncertainty in the efficiency of the neutron flux monitor (0.3,%). The flux monitor operates by counting charged particles produced when neutrons impinge on a ^6Li (or ^10B) foil. Its efficiency was calculated from the cross section, the solid angle subtended by the charged particle detectors, and the amount of neutron-absorbing material present on the foil. Successful calibration would reduce the neutron lifetime uncertainty to approximately 0.25,%. In addition, using the measured solid angle and amount of material on the deposit, a new experimental value for the ^6Li or (^10B) capture cross section will be obtained. Details of the apparatus and the measurement technique along with the status of the experiment will be discussed.
- Publication:
-
APS Division of Nuclear Physics Meeting Abstracts
- Pub Date:
- October 2007
- Bibcode:
- 2007APS..DNP.CD011Y