GB2192277A

GB2192277A - Apparatus for use in isotopic x-ray fluorescence analysis

Info

Publication number: GB2192277A
Application number: GB8714194A
Authority: GB
Inventors: Yasen S Stamenov; Peyu H Peev; Sasho A Sevov; Petko I Petkov
Original assignee: INST CVETNA METALURGIA
Current assignee: INST CVETNA METALURGIA
Priority date: 1986-06-17
Filing date: 1987-06-17
Publication date: 1988-01-06
Anticipated expiration: 2007-06-17
Also published as: DD283532A7; AU595615B2; GB2192277B; GB8714194D0; JPS6352046A; FR2600165A1; FI871633A; FR2600165B1; AU7415787A; DE3718764A1; FI871633A0; BG44997A1

Description

GB2192277A 1 SPECIFICATION may be located in seats in different sections

of the conical passage. The aperture(s) in the Apparatus for use in isotopic X-ray fluores- conical shutter is/are so dimensioned with re cence analysis spect to the wall surface of the conical pas 70 sage as to be able to enter into alignment This invention relates to an apparatus for use with the surface of the or each source of in isotopic X-ray fluorescence analysis of com- excitation.

positions and which is particularly suited to It is possible according to the invention for the multi-element analysis of chemical ele- the number of apertures in the conical shutter ments present together in solid, pulverous or 75 to be larger than one so that, for each differ liquid samples. ent source of excitation, there will be a corre An apparatus for use in isotopic X-ray fluo- spondingly positioned aperture. It is also pos rescence analysis is described by R.Voldset in sible, however, that some of the sources of "Applied Spectrometry of X-ray Radiation", excitation may be of the same type, in which Moscow, Atomizdat, 1977, p.71, Fig. 2.22. 80 case the number of apertures in the conical This apparatus comprises a measuring head shutter will be equal to the number of types having a protective screen thereover which is of source.

disposed between the front of a detector and An advantage of apparatus embodying this a protective cylinder which, over part of its invention is that it allows greater range of us- length, lies around the detector. The protec- 85 age in isotopic X-ray fluorescence analysis. It tive cylinder is formed with a conically shaped is now possible to determine by X-ray-fluores passage therethrough with a seat for a source cence analysis any chemical elements present of excitation being disposed in the conical in- in solid, pulverous or liquid specimens under ternal wall surface of the protective cylinder. optimal conditions for efficient excitation, Positioned in front of the larger end of the 90 thereby additionally ensuring a high precision conical passage is a seat for the specimen to of analysis.

be studied, the seat being formed in a sample For a better understanding of the invention holder which comprises a body portion of hol- and to show how the same can be carried low cylindrical form whose inner surface eminto effect, reference will now be made by braces the protective cylinder. 95 way of example to the accompanying drawing A disadvantage of this apparatus, insofar as which is in longitudinal section through appa it is used in isotopic X-ray fluorescence analy- ratus according to the present invention for sis is concerned, is its limited utility in that it isotopic X-ray fluorescence analysis.

only allows a restricted number of chemical Referring to the drawing, what is shown is elements to be analysed therein. This is a re- 100 the measuring head of apparatus for use in X sult of the fact that as irradiation of the speci- ray fluorescence isotopic analysis. The mea men is carried out utilising a radioactive suring head comprises a detector shown source of the same type as the specimen, the generally at 1 and which may be for example characteristic X-ray lines of only a few chemi- a semiconductor body which is disposed cal elements which are in the narrow energy 105 along the axis of the measuring head which range specific to the corresponding source comprises a protective screen 2 at the for type are excited. ward end thereof and a protective cylinder 3 According to the present invention, there is disposed around the peripheral surface of the provided an apparatus for use in isotopic X- detector 1. The protective cylinder 3 has a ray fluorescence analysis comprising a measurcentral conical passage 4 in the wall surface ing head which includes, in coaxial arrange- of which are formed seats 5 in which, in use, ment, a sample holder for a sample to be are located sources 6 of excitation. In front of investigated, a detector and a protective cylin- the larger end of the conical passage 4 is der surrounding the detector, extending fordisposed a sample holder 7 for housing a wardly thereof towards the sample holder and 115 sample which is to undergo investigation. The being formed with a central conical passage in sample holder 7 is disposed in a seat in a whose larger end is disposed the sample hol- holder housing 8 which is disposed around a der and whose smaller end is disposed adja- body 9 in such manner that relative rotational cent a protective screen disposed between motion can take place between holder housing the front of the detector and the protective- 120 8 and the body 9 the inner surface of which cylinder, at least one seat for a source of is disposed around the protective cylinder 3.

excitation. being disposed in the wall surface A rotating conical shutter 10 with several of the conical passage and a rotating conical apertures 11 is disposed in the conical open shutter with at least one aperture alignable ing 4. The screen 2 is so formed in a cehtral with said seat(s) being placed within the coni- 125 region thereof adjacent the smaller end of the cal passage, the protective screen being conical passage as to engage the internal sur formed in the region of the smaller end of the face of the shutter 10 at the lower end region conical passage so as to engage the inside thereof. Sources 6 of excitation which may be wall surface of the shutter. disposed in seats 5 disposed in different re- In use, excitation sources of different type 130 gions of the conical passage 4 will generally 2 GB 2 192 277A 2 be of different type, for example iron 55, cad- rescence analysis. By suitable disposition of mium 109, americium 241. the source(s) 6, sample 10 and detector 1 Various provisions of aperture 11 may be under specific and optimal geometric condi made in the surface of the conical shutter 10. tions and by provision of the specially formed It is necessary that any aperture should be 70 conical shutter 10, efficient excitation and high dimensioned and positioned as to lie over the precision of analysis may be obtained.

active surface of at least one of the source 6

Claims

as the shutter is rotated into position. More CLAIMS particularly, it is

possible that there be a plu- 1. An apparatus for use in isotopic X-ray rality of apertures 11 whose number is equal 75 fluorescence analysis comprising a measuring to the number of sources 6 when for each head which includes, in coaxial arrangement, a source 6 of one specific type there will be a sample holder for a sample to be investigated, corresponding aperture 11 appropriately a detector and a protective cylinder surround aligned therewith or rotation of the shutter. ing the detector and extending forwardly However, if some of the sources of excitation 80 thereof towards the sample holder and being are of the same type then the number of formed with a central conical passage in apertures 11 may be equal merely to the whose larger end is disposed the sample hol number of sources of any one type, with as der and whose smaller end is disposed adja previously, there being appropriate alignment cent a protective screen disposed between 20- of aperture and source.

85 the front of the detector and the protective Although not shown, it is possible that procylinder, at least one seat for a source of vision be made for supplying to the chamber excitation being disposed in the wall surface defined by the surface of the conical passage of the conical passage and a rotating conical 4, the detector 1 and the sample holder 7 an shutter with at least one aperture alignable 25- inert gas, for example helium. 90 with said seat(s) being placed within the coni The apparatus of the present invention is cal passage, the protective screen being operated in the following manner: the speci- formed in the region of the smaller end of the men is placed in sample holder 7which is conical passage so as to engage the inside formed with a central opening, and sample wall surface of the shutter.

holder 7 is disposed in the appropriately 95
2. Apparatus for isotopic Xray fluorescence shaped seat in holder housing 8. Holder hous- analysis as claimed in claim 1, which com ing 8 and the conical shutter 10 are rotated, prises a plurality of sources of excitation set for example by means of a step motor and an in seats therefor, which sources are of differ electronic device (not shown in the figure). Ro- ent type and are disposed in different parts of tation takes place with respect to the body 9 100 the conical passage.

and the protective cylinder 2 until one of the
3. Apparatus for isotopic X-ray fluorescence apertures 11 is in alignment with one of the analysis according to claim 1 or 2, wherein operating sources 6. At that stage, a signal there is provided a single said aperture in the from the electronic device gives rise to dis- conical shutter, which aperture is dimensioned continuation of rotation and commencement of 105 with respect to the surface of the cone con measurement for that group of chemical eletaining the seats for sources of excitation so ments which is excited by the source 6 which as to expose to the interior of the cone in is now exposed. Characteristic X-ray irradia- turn all excitation source material which may tions from the elements are recorded by the be present in the seats.

detector 1 and are processed electronically, 110
4. Apparatus for isotopic X-ray fluorescence for example by means of a multi-channel ana- analysis according to claim 1 or 2, wherein lyser (not shown) until information about the the shutter is formed with a number of aper identity and concentration of particular ele- tures equal to the number of seats for ments has been obtained. In analogous man- sources of excitation whereby for each source ner, after further rotation of holder housing 8 115 of excitation in a seat there is provided an and shutter 10, apertures 11 are aligned, with aperture alignable therewith.

other radioactive sources and again the iden-
5. Apparatus for isotopic Xray fluorescence tity and concentration of respective groups.of analysis according to claim 1 for use with a elements can be determined. It is possible to plurality of sources of excitation some of _ have a position when two or more of the 120 which are of the same type, wherein the num apertures 11 are open to source material for ber of apertures in the conical shutter is equal parallel operation of several sources of the to the number of sources of the same type.

same type. In its final position, an idle posi
6. Apparatus for use in isotopic X-ray fluo tion, all sources 6 are closed off. rescence analysis, substantially as hereinbefore The apparatus of this invention enables dif125 described with reference to and as shown in ferent radioactive sources to be utilised simul- the accompanying drawing.

taneously or successively in the same appara- Printed for Her Majesty's Stationery Office tus thereby increasing the functional possibili- by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1988.

ties for multi-elemental analysis of all chemical Published at The Patent Office, 25 Southampton Buildings, elements determinable by isotopic X-ray fluo- London, WC2A 1AY, from which copies may be obtained.