JPS60146125A - Temperature measuring apparatus - Google Patents

Abstract

PURPOSE:To measure temperature regardless of the emmissivity and shape of a material to be measured and to make it possible to perform temperature measurement having high position resolution, by injecting positrons into a body, whose temperature is to be measured, and measuring the temperature based on the annihilation gamma-ray intensity of the positrons. CONSTITUTION:Positrons are emitted from a positron source 11 or converged by a convergent lens 12 and inputted to a body 1, whose temperature is to be measured. The positrons hit electrons in the body, whose temperature is to be measured, and they are annihilated as pairs. At this time, two gamma rays are issued in the reverse directions to each other. The pulse signal of the gamma rays, which are inputted to a gamma-ray detector 2, is converted into a digital signal through a preamplifier 4, a linear amplifier 5 and an A/D converter 6. Thereafter the signal is captured as a gamma-ray spectrum by a multichannel waveheight analyzer 7. The gamma-ray spectrum obtained by the analyzer 7 is further analyzed by a measuring and controlling computer 8 and the intesity of the gamma rays is obtained. The intensity is converted into a temperature based on a calibrating curve, which is obtained beforehand, and the result is outputted as temperature information. Therefore the temperature can be measured regardless of the emmissivity and shape of the material to be measured.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to a non-contact surface temperature 611] determination device.

In particular, the present invention relates to a non-contact surface temperature measuring device that measures temperature without being affected by the emissivity of the temperature-measuring object or the surrounding environment of the temperature-measuring object.

[Background of the invention]

Infrared thermometers are known as thermometers that can measure temperature without contact, and they can be used to measure the surface of steel plates and other objects that are heated in industrial furnaces (e.g., annealing furnaces) while stationary or running. Infrared thermometers are used for temperature measurement and process temperature control in many fields, not just industrial furnaces.

An infrared thermometer is based on the principle of obtaining the surface temperature of an object to be measured by measuring the radiant energy emitted from the object that is incident on the detection element of the infrared thermometer. Well, if the radiant energy is E, the surface temperature of the object to be measured is T, and the emissivity is 6, an approximate relationship expressed by a linear equation holds true.

E−ε−K −T” ・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・ (1) Here, K
The id constant, n, is a value expressed as a function of the radiation constant and the measurement wavelength. It is essential that the emissivity ε of the hot object is known or that the emissivity ε at the time of temperature measurement is known. The detection element of an infrared thermometer not only receives radiation from the temperature-measuring object, but also radiation from the environment surrounding the temperature-measuring object fc. therefore.

If a heater is provided around the object to be measured, it is highly likely that an error will be included in the temperature evaluation of the object to be measured.

Infrared thermometers and surface roughness measuring instruments (
A method has been proposed in which emissivity and surface temperature are measured simultaneously using an infrared thermometer (infrared thermometer), but none of the methods too.

There is a problem in that it is necessary to measure the emissivity of the temperature-measuring object, and furthermore, these methods have the problem that the surface condition of the temperature-measuring object changes from time to time due to oxidation, impurities, etc. However, if the emissivity changes accordingly, there is a drawback that the surface temperature cannot be measured continuously. In addition, as mentioned above, infrared thermometers are based on the principle of measuring the radioactivity from the object to be measured, so they require a measurement area larger than a certain amount (approximately 1 mm or more), There is a problem in that it is difficult to apply when the size of the hot object is extremely small or when measuring the temperature at an arbitrary position of the object to be measured.

[Purpose of the invention]

An object of the present invention is to provide a temperature measuring device that can measure the temperature of an object in a method for measuring the surface temperature of an object, regardless of the emissivity, shape, and environment of the object to be measured, and that has high positional resolution. Our goal is to provide the following.

[Summary of the invention]

By injecting positrons into the object whose temperature is to be measured, the intensity of the gamma rays generated when the positrons annihilate with the negative electrons in the object is dependent on the temperature of the object. It is based on the idea of measuring temperature.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

In this embodiment, the positron source 11. r-ray detector 2. γ-ray detector cooling device (cryostat) 3. Preamplifier 4. Main amplifier5. Analog-to-digital converter6. Multi-channel wave height analyzer 7, measurement/control computer 8. Sample drive device 10. Drive control system9. It consists of a focusing lens 12 and a high voltage power supply 13.

The positron source 11 emits positrons in order to inject the positrons into the object 1 to be temperature measured. As the positron source 11, it is convenient to use a nuclide that emits positrons by positron decay. Nuclides that undergo positron decay include 22
NB, Sec O, 118c □, ll? N
i, etc., but in the present invention, the half-life is about 2.6
Na is used as the positron source 11, which has a relatively long time of 20 years, and has a high positron decay rate of about 91%.

In this embodiment, a focusing lens 12 is used for the purpose of increasing the number of electrons incident on the object 1 to be temperature measured. In the focusing lens 12 portion, a high electric field is formed by the high voltage power supply 13, and it is also possible to cause the positrons emitted from the positron source 11 to enter a minute portion of the object to be temperature measured 1. Note that depending on the strength of the positron source 11 or the distance between the positron source 11 and the object to be measured 1, it is possible to use only the positron source 11 without using the focusing lens 12. Needless to say.

In FIG. 1, numerals 2 to 7 are commonly used gamma ray detection systems. Positrons emitted from the positron source 11, focused by the focusing lens 12, and incident on the temperature-measuring object 1 collide with electrons in the temperature-measuring object and are annihilated.
．． Two res with an energy of 511 MeV fly out in opposite directions. The γ-ray pulse signal incident on the γ-ray detector 2 is amplified by a preamplifier 4 and a linear amplifier 5, converted to a digital signal by an analog-to-digital converter 6, and then sent to a multi-channel pulse height analyzer 7. It can be captured as a υγ-ray spectrum.

The gamma ray spectrum obtained by the multi-channel pulse height analyzer 7 is analyzed by the measurement and control computer 8, the gamma ray intensity is determined, and a calibration curve determined in advance according to the principles of the present invention to be described later is calculated. It is converted to temperature based on the temperature and output as temperature information.

Note that the temperature-measuring object 1 is placed on a sample driving device 10 that can be moved slightly in the X direction and the Y direction.

The sample drive device 10 performs measurement and measurement via the drive device control system 9.
It is connected to the control computer 8 and has the function of making it possible to measure the temperature at any position on the surface of the temperature-measuring object 1 in response to instructions from the computer 8.

Next, the principle of the temperature measurement method according to the present invention will be described below.

Positrons have the same rest mass as electrons (negative electrons).

A particle that has a charge that is equal in absolute value and opposite in sign to the charge of an electron (negative is Xun). When a positron enters a substance,
In a short time of about IQ - 12 seconds, it is decelerated to the level of a thermonuclear force, is repelled by Coulomb interaction with the positively charged atomic nucleus, and as it moves relatively far from the atomic nucleus. It annihilates with an electron, and at this time, the energy equivalent to the rest mass of the electron (0.51tMev)
Two γ-rays having K are emitted in opposite directions (180° direction).

FIG. 2 is a diagram showing the principle of the positron annihilation experiment, in which positrons emitted from the positron source 11 enter the sample 14,
Two gamma rays are emitted in almost opposite directions by annihilation with electrons in the sample.

The light passes through the gap between the first slit 15 and the second slit 16, respectively, and enters the gamma ray detector 2 provided at the rear of each slit. now.

The first slit 15 is fixed, and the second slit 16 is inserted into the sample 1.
4 and measure the number of simultaneous measurements N(θ) as a function of the rotation angle θ, a curve (γ-
γ-angle correlation intensity curve) is obtained.

By the way, in this γ-γ angle correlation strength curve, for example, as shown in FIG. 4, the number of simultaneous measurements N(
0) depends on the sample temperature (f3.”f
, AoMckee etal, phys, iev, Le
tt.

28.358 (1972)) was found.

On the other hand, the energy distribution of γ rays accompanying positron annihilation deviates from 0.511 MeV because the kinetic energy of the annihilating electron is not 0 (several e), and is about 2 KeV as shown in Figure 5. The spectrum has a spread of 9.

In the γ-ray spectrum shown in Figure 5, 0.511M
Ratio of gamma ray intensity to total area in eV.

In other words, it has been reported that there is a correlation between the peak value/area value and the number of simultaneous measurements N(0) at θ-θ° of the γ-γ angle correlation intensity curve (Masao Doyama, Applied Physics 41). ,684
(1972)), and considering that the number of simultaneous measurements N(0) depends on temperature as mentioned above, it is clear that it is fully possible to measure temperature using annihilation gamma ray spectrum measurement. .

The present invention focuses on (peak value/area value) of this γ-ray spectrum.
This method measures the temperature of the object to be measured by utilizing the fact that it has a correlation with the number of simultaneous measurements N(0) that depends on the temperature, and it is physically different from the infrared 61 mixed method. It is something that is based on.

The rff# detector 2 for obtaining the γ-ray spectrum is a Na(1) detector or Ge(1,i), Ge
Although there is a (1111) detector, in consideration of engineering resolution, a germanium semiconductor detector is used in the present invention. In other words, the mechanical resolution (half width) of the germanium semiconductor detector is FwnM = 2.355 V'4E, IIE,...
...... It is expressed by (2). Here F
is a value called the Fano coefficient, which is approximately 0.05 to 0.1, and E is the value required to generate one electron-hole pair (2.96 e for germanium).
V), and E represent the gamma ray engineering key, and 0 to l.
．． 1. E,=,2.96 eV, E,=0.511M
eV (If the annihilation gamma ray is considered to be unkeen, the energy distribution ability is approximately 1 ke) (Masayasu Noguchi, "Gamma Ray Spectrometry", Nikkan Kogyo Shimbun, p. 67), and it is possible to measure the energy spectrum of the annihilation gamma ray. It can be seen that the energy resolution is sufficient.

The temperature measurement method of the present invention involves injecting positrons from the outside of the temperature-measuring object, and measuring the surface state of the temperature-measuring object and measuring the annihilation gamma rays with electrons in the temperature-measuring object. Reeds have the advantage of being completely unaffected by the environment. The energy of annihilation gamma rays is E. Lukey (o, 511 Mev), which is equivalent to the rest mass VC of an electron, and since this value does not change, the energy of the annihilation gamma ray is E. Luky (o, 511 Mev), which is equivalent to the rest mass of an electron. 0.511 MeV
) only annihilation gamma rays? : It has the advantage of having a good S/N ratio for temperature measurement because it can be measured selectively.

In terms of resolution, an infrared thermometer requires a temperature measurement area of a certain size or more (1 mnφ or more) due to its principle, whereas the temperature measurement method according to the present invention requires a temperature measurement area of a certain size or more (1 mnφ or more).

It is possible to make the positrons emitted from the positron source 11 enter a minute part of the temperature-measuring object 1 using the focusing lens 12, and it is possible to obtain a positional resolution that is at least about 10 times higher than that of an infrared thermometer. .

Furthermore, the present invention is a method for measuring the annihilation gamma-ray linear distribution, and compared to measuring the sample temperature using the gamma-gamma angle correlation intensity curve, there is no need for simultaneous measurements and the measurement system is simpler. It has the advantage of shortening the measurement time.

In order to evaluate the temperature of the temperature-measuring object from the annihilation gamma-ray spectrum using the present invention, in advance.

It is necessary to measure the gamma ray spectrum of a sample that has the same composition as the temperature-measuring object, and to determine the relationship between the (peak value/multilayer) ratio and temperature (measured with a thermocouple, etc.). It is oJ's ability to automatically output the temperature from the gamma ray spectrum using the related computer VCW1' calculator.

As described above, this embodiment has the effect of overcoming all the disadvantages of pure infrared thermometers, namely emissivity, stray light, and low resolution, and also has a good S/N ratio for temperature measurement. It also has advantages.

〔Effect of the invention〕

According to the present invention, the emissivity and shape of the temperature-measuring object and the surrounding environment of the temperature-measuring object are not affected at all, so it is effective in measuring the surface temperature and the temperature of a minute part.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view and measurement system diagram of a temperature measuring device according to the present invention, FIG. 2 is an explanatory diagram of the principle of a positron annihilation experiment, and FIG. 3 is a γ-γ angle correlation strength curve diagram. FIG. 4 is a diagram showing the relationship 'f between the coincidence value of annihilation γ-rays and the temperature of the salt-measuring object, and FIG. 5 is a diagram showing the engineering-influence spectrum of annihilation γ-rays. 1...Temperature measured object, 2...γ ray detector, 3...γ
Line detection element piece cooler, 4... Preamplifier, 5... Main amplifier, 6... Analog to digital converter, 7...
Multi-channel Oshima analyzer, 8... Measurement/control computer, 9... Drive device control system, 10... Sample drive device, 11... Positron source, 12... Focusing lens, 1
3... High voltage source, 14... Sample, 15.16...
Slit, 17...disappearance No. 1 Figure 2 Figure 2 $3 Surroundings 4 eyes 1 degree (°C)

Claims (1)

[Claims] 1. A temperature measuring device which is characterized in that, in the temperature measurement method of an object, positrons are incident on the object to be temperature measured and the temperature is measured by the annihilation gamma rays of the positrons.