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A linear fast neutron beam chopper has been deployed at the prompt gamma activation analysis instrument, enabling in-beam activation analysis of short-lived (T1/2 > 10 ms) neutron capture products without needing sample transfer. This paper describes the design and operation of the chopper system, and measurement results from test samples containing Se-77 (T1/2 = 17.36 s) and Yb-175m (T1/2 =0.0682 s). The chopper timing was optimized for a specific isotope in each measurement, demonstrating an advantage of the programmable system. The linear response of the total gated counts in the decay phase to the incremented Se and Yb masses demonstrated the suitability of the system for quantitative analysis. Theoretical calculations based on the experimental parameters shows good agreement. An example of separating overlapping energy peaks by using time-stamped list mode data acquisition is shown in a sample containing Yb-175m and Dy-165 (T1/2 = 75.4 s).
Turkoglu, D.
and Chen-Mayer, H.
(2021),
Chopped Cold Neutron Beam Activation Analysis, IEEE Transactions on Nuclear Science, [online], https://doi.org/10.1109/TNS.2021.3080682, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931844
(Accessed October 10, 2025)