The analysis of element and isotope composition by

neutron spectroscopy method

N.V. Bazhazhina, Yu. D. Mareev, L.B. Pikelner, P.V. Sedyshev, V.N. Shvetsov

 Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research

Excited states of compound nucleus

Neutron transmission measurement

Partial cross sections measurements

IREN parameters

Peak current, A 3

Repetition rate, Hz 25

Electron pulse duration, ns 100

Electron energy, MeV 30

Neutron intensity, n/s 1011

General view of the detector

Request of Central Geological Laboratory of Mongolia

Time-of-flight spectrum for sample from Mongolia

250 ns

Amount of the element is determined by an intensity of the resonance area

- number of neutrons which crossed all area of the sample during measurement

- detection efficiency

- radiation width of the resonance

- total width of the resonance

- resonance area on the transmission curve,

where is defined as function of the resonance parameters and the sample thickness (nuclei/cm2).

Used curves for the analysis of neutron resonances

Results of analysis

ElementWeight of the element in

sample, g

Mass concentration of the element in sample, (g/kg)

Pt 2.7±0.3 180±20

Pd 0.1±0.02 6.7±1.34

Ir 5.2±0.6 347±40

Ru 1.14±0.2 76±13

Os 4.3±0.5 287±33

Boron enriched unfired phosphate ceramics

Determination of B content in composite material

1 1 2 20

exp[ ( ( ))]N

T n n EN

- the number of target nuclei per 1 cm2 , which do not have resonances and they have only the constant elastic cross section. - the number of target nuclei per 1 cm2 , which have the energy

dependence of the cross section.

))(exp()( i

tii EnET

Determination of B content in composite material

Determination of B content in composite material

Weight of sample, g.

, сm-2

Weight of in the sample, g

Weight of B in the sample, g

Weight%

4.88 1.7±0.2 0.22±0.03 1.08±0.13 22.1±2.7

2110Bn

Thanks for your attention