Measurement of neutron binding energy of <sup>36</sup>Cl for a determination of N<inf>A</inf>h

Abstract

Precise wave length measurements of gamma rays emitted after thermal neutron capture reaction allow the determination of the neutron's binding energy within a nucleus. Comparing this energy to atomic mass measurements gives direct access to the molar Planck constant NAh. This result will be of utmost importance in the context of a re-definition of the kilogram via the Planck and the Avogadro constants. Having this in mind, any future measurement must yield a relative uncertainty of better then 5 times10-8. An essential step towards this goal is to demonstrate that there are no statistical limitations for such an experiment. In the present contribution we report on the results of the recently performed binding energy measurement on 36Cl using a modified version of the double flat crystal spectrometer GAMS4.