A detector member (12) having the property of forming damage tracks along the paths traversed by impinging alpha particles is provided with at least two opposing detection surfaces (12a,12) exposed on respective opposite sides of the detector member (12). The opposing detection surfaces (12a,12b) enable the detector member to form damage tracks by alpha particles impinging either of the detection surfaces which are simultaneously exposed to irradiation. Conventional cellulosic film such as cellulose nitrate can be employed with both sides of the film serving as detection surfaces (12a,12b). The dual-surfaced film can be framed (14) and packaged (16) in a compact configuration convenient to use in homes or offices. The damage tracks from both the irradiated surfaces (12a,12b) can be simultaneously counted using preferred spark counting techniques.

- Mesure de radiation.

- Le détecteur est caractérisé en ce que :

. l'embase (2) délimite un logement (5) de réception du couvercle en position de fermeture,

. le logement comporte des moyens de liaison articulée du couvercle et des moyens (20) d'immobilisation de ce couvercle en position d'ouverture,

. et le couvercle comporte, sur sa face interne (22) en position de fermeture, des moyens (26, 27) assurant le maintien du substrat et son exposition en position d'ouverture dudit couvercle.

Application à la mesure dans les locaux d'habitation.

An alpha recoil ion-implantation method uses an alpha-emitting source that is a radioactive parent of the daughter isotope of interest to implant into a suitable substrate the recoil daughter ions resulting from alpha decay of the parent. For example, a ²⁴¹Am source in thin layer form is placed next to a substrate such as a solid state track recorder in a vacuum which houses an assembly for rotating opposing disks receiving the alpha-emitting source and the substrate, respectively. Each alpha decay of ²⁴¹Am results in a ²³⁷Np ion with enough recoil energy to be implanted into the substrate.

A method is described for determining the amount and spatial distribution of impurity actinides in fission­able deposits used for measurement of solid state track recorder fission rate and neutron fluence. For example, a ²³⁹Pu fissionable deposit is autoradiographed with an alpha particle-sensitive track recorder which is then subjected to a four hour etch at room temperature. The etch induc­tion time for the ²³⁹Pu alpha particles is just barely exceeded, so that the²³⁹Pu tracks appear as very immature dots on the surface of the solid state track recorder. The ²³⁵U tracks, on the other hand, are correspondingly etched longer than their respective shorter etch induction time and appear as much more mature, longer tracks. The amounts of ²³⁵U and ²³⁹Pu present can be calculated from the numbers of different tracks that are counted.

A method for producing ultralow-mass fissionable deposits for nuclear reactor dosimetry is described, including the steps of holding a radioactive parent until the radioactive parent reaches secular equilibrium with a daughter isotope, chemically separating the daughter from the parent, electroplating the daughter on a suitable substrate, and holding the electroplated daughter until the daughter decays to the fissionable deposit.

A solid state track detector composed of a cross-linked copolymer, said copolymer consisting essentially of

• (A) units derived from an alkylene glycol bisallyl carbonate represented by the general formula wherein R, represents an alkylene group having 2 to 6 carbon atoms, and n is an integer of from 1 to 6, and
• (B) units derived from an alkyl acrylate or methacrylate represented by the general formula wherein R₂ represents a hydrogen atom or a methyl group and R₃ represents an unsubstituted or substituted alkyl group having 6 to 20 carbon atoms, the proportion of said units derived from the alkyl acrylate or methacrylate of formula (II) being 0.5 to 3 mole% based on the crosslinked copolymer.

A compact low cost track registration detector for radon gas and radon daughter products includes a housing (11) with a removable closure cap (40) for retaining a strip of track registration material (30) having the property of forming damage tracks along paths traversed by alpha particles. The strip (30) is retained within the housing by integrally formed upstanding ribs (21-28) located closely adjacent diametrically opposite inner side wall portions of the housing, a first set of ribs (21-24) forming a pedestal support and a second set of longer ribs (25-28) providing transverse support. A microporous filter (50) impervious to particles and radon daughter products admits only radon gas to the interior of the housing. The apertured closure cap (40) has a central solid portion (44) providing a radiation shield for the upper surface of the strip (30) to enable the loser exposure surface to be readily distinguished after the detector has been retrieved from an exposure site. The housing (11) is fabricated from a pure polyethylene material free from any residual alpha particle radiation. A flexible strip (60) wrapped about the exterior of the housing (11) affords both a hanging strap and an information sheet for user entry of exposure information.

A radiation detector utilising track registration material having the property of forming damage tracks therein along paths traversed by alpha particles characterised in that the detector is in the form of a low cost disposable unit comprising:

• a substrate layer (10) providing a support surface;
• a strip (14) of said track registration material; and a top layer (12) adhered to said substrate layer and
• cooperative therewith for removably securing said strip to said substrate layer, said top layer having an aperture (15) formed therein in a predetermined location and at least one tab portion (16, 17) adjacent said aperture bendable out of the plane of said top layer and overlapping a portion of one end of said strip of track registration material for retaining said strip in said aperture.

0 Die Erfindung betrifft ein passives Dosimeter zum Nachweis von Radon und/oder Thoron und deren Folgeprodukte mit einer Diffusionskammer, die zwei Stirnseiten aufweist, wovon die eine mittels einer Kernspurdetektorfolie oder einem integrierenden a-Detektor und die andere mittels einem für Radon und/oder Thoron durchlässigen Filter abgeschlossen ist, und mit der der Radon-und Thoronzerfall und die daraus resultierenden Folgeprodukte nachgewiesen werden.

Mit der Erfindung soll der Meßeinfluß von Radon/ Thoron getrennt und ausschließlich Radon/Thoron-Folgeprodukte nachgewiesen werden, welche jedoch wegen ihrer unterschiedlichen a-Energie einen unterschiedlichen Beitrag zur α-Energiekonzentration ergeben, was insbesondere auch der Nachteil der bekannten Diffusionskammer ist, wo keine Unterscheidung zwischen RaA, RaC' und ThC' möglich ist.

Hierzu ist eine zweite, der Diffusionskammer im Aufbau entsprechende Kammer vorgesehen, deren eine Stirnseite von der der Diffusionskammer gegenüberliegenden Seite des Filters und deren zweite Stirnseite von einer weiteren Kernspurdetektorfolie oder integrierenden a-Detektor abgeschlossen ist. Sie weist Öffnungen auf, durch die das auszumessende Gas mit Radon und Thoron und Folgeprodukten in die zweite Kammer hineintritt.

Im Gegensatz zu den bekannten Dosimetern wird also erfindungsgemäß ein passives Radon/Thoron-Dosimeter benutzt, welches ohne Pumpe arbeitet und in welchem ein Kernspurdetektor oder integrierender x-Detektor langzeitigen Einsatzes (1 Woche bis 3 Monate) a-Teilchen von ²²⁰Rn/²²²Rn und deren Folgeprodukte aus einem definierten Luftvolumen registriert.