SU1755142A1 - Device for determining protein content in grain, grain products and animal formula feed - Google Patents

Abstract

The invention relates to nuclear physical analysis methods and can be used for the rapid determination of protein content in food products. The purpose of the invention is to improve accuracy by reducing the background load or gamma capture rays generated in the source envelope. The device comprises a measuring chamber 1 in which the product under investigation is placed. The product is irradiated with the fast neutrons of source 3. which are slowed by the nitrogen nuclei, hydrogen and other elements, and the capture gamma quanta are recorded by the detector b. The protective screen 4 serves to reduce the flux of thermal and resonant neutrons incident on the source 3 sheath. ate uu1j

Description

The invention relates to nuclear physical analysis methods and can be used for the rapid determination of protein content in food products, food raw materials and feeds.

Known is the nuclear-physical method of analyzing a substance for its nitrogen content by activating nitrogen with neutrons using a neutron generator station. The measurement results are recalculated; The nitrogen content of the calibration curves., „„., - Activation methods using neutrons are inapplicable for express protein analysis, since -the time spent more than one measurement reaches 30 minutes, which is determined mainly by the exposure time required for phosphorus-30 and capillary-38 isotopes with the same nitrogen-13 decomposition scheme.

The closest in technical essence and the achieved result is a device for determining the nitrogen content, containing a radioisotope source of fast neutrons, a detector of capture gamma-quanta of nitrogen, a spectrometric tract, a biological protection system registering the instruments. The measurements are based on the detection of a 10.8 MeV gammas quattb, arising from the capture of nitrogen samples contained in the sample being analyzed, thermal neutrons that are generated when a fast-neutron moderated fast-neutron mode material passes through a special block. Be source, and comparing the data obtained with the calibration curve, built on samples of materials with a known nitrogen content.

A disadvantage of the known device is the effect on the stainless steel shell of thermal neutrons generated from the slow neutrons slow down in the slowed down product, which leads to the capture of thermal neutrons from the shell elements: iron, nickel, chromium, in which highly heterogeneous gamma quanta are emitted . The overlap of the yr-line leads to an increase in the detector count, much higher than the count rate from nitrogen quanta. For grains with T5 protein content - 20% of the excess reaches 3-4 times. This leads to a multiple increase in measurement errors and excludes the possibility of applying the proposed method for the determination of nitrogen under actual production conditions.

The purpose of the invention is to improve accuracy by reducing the background load from

capture gamma quanta generated in the source envelope.

The goal is achieved due to the fact that in a device containing a radioisotope source of fast neutrons, a detector of capture gamma quanta of nitrogen, a spectrometric tract, a recording device and a biological protection system, the source of fast neutrons is surrounded by an additional screen of a material freely transmitting fast neutrons and absorbing thermal neutrons. .

The drawing shows a diagram of the device.

The device consists of a measuring chamber 1, where a calorific-252 neutron source 3 in a boron carbide shield 4 and a bismuth filter 5, detector b are installed in a special holder 2.

capture gamma quanta (Nal (TI) with PMT) and protection of 7 from borated polyethylene. The detector b and boron counter 8 are connected to radiation detection devices 9-12 associated with the personal computer 13. For

feeding and disposal of the product are used labyrinth channels 14 and 15. Chamber 1 is surrounded by biological protection from a mixture of polyethylene and boron.

The device operates as follows 3GM.

Through the channel 14, the analyzed product is introduced into the measuring chamber 1. The fast neutrons of source 3 are slowed down by the nuclei of nitrogen, hydrogen and other elements.

Capture gamma quanta are recorded with a spectrometer based on detector 6. The product itself placed in measuring chamber 1 in the native state is used as a fast neutron moderator, and to make a correction for humidity and bulk weight of the product, the flow is recorded by simultaneously recording the number of capture gamma quanta of nitrogen. thermal neutrons in the analyzed

the product and the number of capture gamma-quanta from the nuclei contained in this hydrogen product and periodically record the flux of thermal neutrons in the product-free measuring chamber 1. Content

Protein race - formula:

d - A CN F) FQ. to

L-Ap. K,

where C is the protein content, wt.%;

IN is the number of registered gamma-quanta resulting from the capture of thermal neutrons by hydrogen nuclei in the product of thermal neutrons;

IH is the number of registered gamma quanta resulting from the capture of neutrons in the product by hydrogen nuclei;

F is the number of thermal neutrons recorded in the ana / shyruym product; ..; FQ is the number of thermal neutrons recorded in the product-free measuring chamber; :,:

f - gamma background in the energy zone of 10.8 MeV; ; Y ,:

 the proportionality coefficient determined by the calibration curve;

K is the standard transition coefficient from the total nitrogen content of a product to its protein content.

When measuring, the boron carbide shield 4 does not prevent the passage of the stoker 3 fast neutrons into the measured product and, at the same time, reduces the total backscattered thermal and resonant neutron flux falling on the source shell 3 in 20 - 30 times, which leads to a decrease in gamma background in the area of the nitrogen peak to negligible values. . ..

Formula of a device and a device for determining the protein content in grain, grain products and compound feeds, containing a radion-ssotope source of fast neutrons, a detector of capture gamma-ray nitrogen, a spectrometric tract, a recording instrument and a biological protection system, characterized in that, in order to improve accuracy by reducing the background load from the capture gamma quanta formed in the source envelope, the source of fast neutrons is surrounded by an additional screen made of a material freely transmitting fast Defense and absorbs thermal neutrons.

Claims (1)

Claim A device for determining the protein content in grain, grain products and compound feeds, containing a 10 radioactive isotope source of fast neutrons, a detector of capture gamma-quanta of nitrogen, a spectrometric path, a recording device and a biological protection system, characterized in that, in order to increase accuracy by 15 reducing background loading from capture gamma rays generated in the source shell, the fast neutron source is surrounded by an additional screen of material that freely transmits fast neutrons and absorbs pilaf neutrons.