DD300616A7 - Dosimeter with evaluation device for measuring quantum radiation - Google Patents

Abstract

The invention relates to a dosimeter with Auswertegeraet for measuring quantum radiation for use in personal, disaster and tactical dosimetry. The aim and object of the invention is to design a simple, small portable on the body single dosimeter, which is connected to a simple Auswertegeraet or evaluated by a centrally located Auswertegeraet. The dosimeter works on the principle of the radiation element. The electrical charges formed in the interior of the radiation element as a result of photoeffects and Compton effects are derived for determining the radiation dose to aussen on a capacitor attached to the radiating element and auschnzen mechanically ausetigenden contact. The voltage of the capacitor is measured electrometrically and brought about an evaluation and display electronics to a dose equivalent display. Both the dosimeter and the evaluation unit can form a mechanical unit as well as be handled separately. figure

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a portable on the body or installable anywhere arbitrary dosimeter for quantum radiation, which operates on the principle of the radiation element and either as often evaluated with an immediately assigned or externally stationed evaluation and while solved simultaneously.

The application extends to all possibilities of personal, accidental and tactical dosimetry, as well as the special dosimetry of radiation flashes in nuclear explosions.

Characteristic of the known state of the art

A known measuring method for determining the local dose in quantum radiation with directly integrated character, as it is mainly used for portable on the body dosimeter application is that by means of radiation element according to Hosemann and Warrikhoff.

This type of Dosimetern are usually constructed in the form of an evacuated cylinder capacitor. X-ray or gamma radiation produces a dose-dependent voltage as a result of the photoelectrons formed in the electrodes, which have a very different atomic number. The voltage is measured by means of an idiostatic circuit built into the vacuum with a quartz filament electrometer. The dose value can be read on a calibrated scale with a microscope.

As disadvantages of the previously known Dosimeterausführungen with radiating element are:

An external and electrically direct evaluation and thus accurate, objective computer-aided, if necessary encrypted data acquisition is very difficult and cumbersome. Due to the extremely high insulation requirements of> 10 ¹⁸ ohms and with a capacity of the inner electrode of only a few pF, a permanent electrical connection to the outside is not possible in order to prevent disturbing fading. Thus, the otherwise excellent dosimetric properties of the beam element can only be used imperfectly.

Other disadvantages are the shock and Schwingungsempfindlichkeikt the quartz filament, the square display in idiostatic circuit (without application of an external auxiliary voltage), and the small and non-switchable range. A radiation detector that best meets most requirements is the radiating element. However, the previously known and proven integrating dosimeter with radiation element only in completely closed evacuated containers and using the best insulation of> 10 ¹⁸ ohms possible. These dosimeters can then store the electrical charge for months to years. For this reason, the dosemeters with radiation element are produced only with a built-in and visually readable quartz filament electrometer of highest insulation. Each permanent, outgoing electrical connection degrades the insulation value by orders of magnitude and thus jeopardizes the function of the integrating radiation element. Radiation elements for dose rate measurements - ie current supplying elements - are not subject to these high insulation requirements and can therefore be plated through to the outside.

Another way of measuring the radiation element for dose measurement -. B. by an electronic Ladungsbzw. Spannungsmessung- with its extensive possibilities of measuring data acquisition and processing does not yet exist. The measuring range of the previously known dosimeter with radiation element is 0.1 to 5 Gy and is practically determined by the voltage sensitivity of the element of 100V / Gy and the measuring range of the quartz filament with microscope reading of 10V to 500 V given a square display. By contrast, an electronic charge measurement would allow a measurement range of 0.1 mGy to a few 100 Gy.

Explanation of the essence of the invention

The aim of the invention is to bring a dosimeter for quantum radiation, which works on the principle of the radiating element to apply, in which a relatively simple and small, portable on the body single dosimeter is connected either directly to a simple electronic, battery-powered evaluation or the central is evaluated by a larger equipped with multiple functions computerized evaluation. In the first case, the sum or single dose can be determined immediately for a specific period of time or after an event. In the second case, a long-term dose detection z. B., taking into account a residual value encrypted or unencrypted possible. In both cases, due to the low energy consumption of the evaluation devices a long battery operation is possible or many 100 to 1000 evaluations can be performed with a battery pack. This allows the dosimeter to be widely used in both civilian and military radiation protection.

The invention has for its object to provide a dosimeter using the known radiation element, with which a large part of the most known Dosimeterprinzipien different building-related disadvantages are avoided. In particular, it is the fading, the temperature behavior, the shaking and impact resistance, the number of evaluations, the dose rate dependence of the measured value, the linearity, the geometric dimensions, the mass, the evaluation effort and especially the energy required for the evaluation. The technical problem is thus to provide the radiation element a way to measure the stored charge on the inner electrode for the purpose of evaluation at any desired time. The old charge should be deleted and a new measurement cycle at 0 should be started. If necessary, the radiation dose determined per cycle and dosimeter is stored in the evaluation unit. This measure must not degrade the charge retention in the radiation element until interrogation.

The object is achieved with a dosimeter with evaluation device for measuring quantum radiation, which operates on the principle of the radiation element, consisting of an evacuated cylinder capacitor with outer and inner electrodes whose materials have different atomic numbers, wherein the radiating element is manufactured in shell construction and an electronic electrometer with Followed electronics used, achieved in that according to the invention a hollow cylindrical inner electrode is provided at their ends with plate-shaped quartz insulators, on which a hollow cylindrical outer electrode is seated. The negative charge of the inner electrode formed by the quantum radiation via photoelectrons is dissipated by means of a mechanically actuated contact to the outside to a capacitor. The on the capacitor

resulting voltage U = -, which is thus a measure of the absorbed absorbed dose in the radiating element, is from

Evaluation unit measured. Selecting the capacitor capacity can set the sensitivity of the dosimeter.

The charge for transferring the charge accumulated on the inner electrode of the radiating element to the condenser consists of a resilient, externally bendable, vacuum-tight and insulated metal contact tube with an electrical contact fused into the end wall of the radiating element.

In the event that the received radiation dose can be queried at any time by the wearer of the dosimeter, radiation element and evaluation are firmly connected and form a single unit. The measuring process can then be initiated by hand by pressing a button or with the help of a key.

If, on the other hand, a larger number of dosemeters are to be measured with only one evaluation device, then radiation elements and evaluation device are to be measured, so radiation elements and evaluation device are separated. The measuring process is then initiated when inserting the dosimeter in the evaluation.

In both cases, when evaluating the dosimeter, a short mechanical pressure is applied to the flexible metal tube so that the contact contacts the inner electrode of the radiating element. This process can be repeated as often as desired.

In order to avoid that the dosimeter due to coarse mechanical effects z. B. is unintentionally discharged by impact, shock and vibration by touching the inner electrode through the metal tube, occurs outside the time of evaluation, a mechanical lock in place. This can be done in the case of the fixed connection of radiation element and evaluation by a locking mechanism in the separate version by a protective cap, which also protects the radiation element or dosimeter from contamination.

While the inner electrode of the radiation element must be kept extremely high, about 10 ¹⁸ ohms to keep fading over months to years low, sufficient for the isolation of the contact tube, the capacitor and the electrometer about 10 ¹³ ohms, since the rush hour only a few seconds.

Execution example

The invention will be explained in more detail below using an exemplary embodiment. The accompanying drawing shows the sectional view of a dosimeter according to the invention. The dosimeter or radiation element consists of the cylindrical steel sleeve 1. This carries outside the outer surface electrode 2 of high atomic number, e.g. Lead and inside coaxial and highly insulating means quartz insulators 3, the tubular inner electrode 4 of a substance of low atomic number, z. As aluminum. In order to guarantee the effectiveness of the radiating element, it must have a permanent vacuum of at least 0.01 Torr.

In the inner electrode 4, the flexible contact tube 5 is arranged so that in the resting state of the electrical contact 6, the inner wall of the inner electrode 4 is not affected. Position A. The contact tube 5 is held by the sintered glass plate 7, in which it is sealed and which closes off the steel sleeve 1 in a vacuum-tight manner.

When quantum radiation strikes the radiating element, the light-atomic internal electrode 4 charges electrically negatively compared with the heavy-atomic external electrode 2 as a result of the greatly differing photoelectron generation of the outside and inside electrodes.

If the same is bent by a lateral pressure on the outwardly extended contact tube 5 by the pushbutton 8, the contact 6 lays against the inner wall of the inner electrode 4, whereby the negative charge Q ₄ can be discharged to the outside, position B.

The evaluation device consists of the isolated button 8, the short-circuit contacts 9 and 10, the capacitor 11, the electrometer 12 and the evaluation and display part 13. For the purpose of evaluation, the negative charge of the inner electrode 4 flows with the capacitance C ₄ by pressing the Button 8 in the position B, directly on the capacitor 11. The

Q ₄

thereby adjusting voltage across the capacitor 11 Un = is measured with the electrometer 12 for a short time. With

C4 + _C11

the capacitance C _{11 of} the capacitor 11, the voltage U ₁₁ and thus the radiation sensitivity of the measuring system can be set within wide limits. The measured voltage value U ₁₁ is then brought via the evaluation and display part 13 in the desired voltage-dose relationship and signaled.

The short-circuit contact 9 of the button 8 is used to keep the capacitor 11 in the rest position, not pressed 8, discharged, position A. With the short-circuit contact 10, the capacitor 11 and the inner electrode 4 can be discharged together. The latter occurs when the button 8 is fully depressed after reading the measurement result while the short-circuit contact 10 is closed, position C. Thus, the entire integrated charge is deleted and a new start of measurement takes place after releasing the button. 8

The total dose measurement is structured as follows:

Operation button 8 contact position

I.Messen: Position A Kontakt6offen

Short-circuit contact 9 closed short-circuit contact 10 open

2. Evaluate: Position B contact 6 closed

Short-circuit contact 9 and 10 open

3. Delete: position C contact 6 closed

Short-circuit contact 9 open short-circuit contact 10 closed

Claims (5)

1. Dosimeter with evaluation device for measuring quantum radiation, which operates on the principle of the radiation element, consisting of an evacuated cylindrical capacitor with outer and inner electrodes, whose materials have different atomic numbers, the radiation element is manufactured in shell construction and uses an electronic electrometer with subsequent electronics, characterized in that a hollow cylindrical inner electrode is provided at its end faces with plate-shaped quartz insulators (3), on which a hollow cylindrical outer electrode (2) is seated and that in one end face of the radiation element, a resilient externally bendable contact tube (5) made of metal, vacuum sealed and isolated in that the contact tube (5) has a contact (6) for three different positions (A; B; C) on the inner wall of the inner electrode (4) and that it can be selected outside the radiating element with a capacitor (11) of selectable capacitance v is linked. 2. Dosimeter according to item 1, characterized in that the capacitor (11) with an electrometer (12) is connected in parallel, which is followed by an evaluation and display part (13). 3. Dosimeter according to item 1, characterized in that a button (8) with three positions (A; B; C) is provided, which is connected to the outside of the radiating element located in the contact tube (5). 4. dosimeter according to item 1, characterized in that a protective cap over the contact tube (5) is arranged. 5. dosimeter according to item 1 and 4, characterized in that a locking mechanism is arranged on the contact tube (5).