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A neutron depth profiling (NDP) device was developed on China advanced research reactor (CARR) of China Institute of Atomic Energy (CIAE). The CARR-NDP device uses cold neutron beams transmitted by a neutron guide from the cold neutron source of CARR, and it is composed of a neutron beam collimator, and a vacuum target chamber containing a beam stopper and a detection system. The neutron flux at 1 m from the end of neutron guide is about 4.8 × 10 8 n cm -2 s -1 under operating power of 15 MW. A standard reference material SRM-2137 sample and a multilayer film sample were utilized to verify the performances of the CARR-NDP device., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Sampling behavior of multielements in a stream sediment matrix was studied with sample sizes in a range of 9 orders of magnitude by a combination of INAA, PIXE and SR-XRF. For accurately weighable sample sizes (>1mg), sampling uncertainties for 16 elements are better than 1% by INAA. For sample sizes that cannot be accurately weighed (<1mg), PIXE and SR-XRF were used and the effective sample sizes were estimated. Sampling uncertainties for seven elements are better than 1% at sample sizes of tenth mg level, and that for three elements are better than 10% on ng levels.