KR101523319B1 - A METHOD FOR ILLIMINATING INTERNAL NOISE OF LaBr3 SCINTILLATING DETECTOR - Google Patents

Abstract

The invention 10cm as, more particularly, LaBr ₃ scintillation detector background removal method of solving the aforementioned conventional problems and to present to achieve the objects invention relates to a process to remove the portable LaBr ₃ scintillation detector background is to measure the background spectrum LaBr ₃ into a scintillation detector and a correction crew in the lead shield of the thickness is measured background spectrum and the measured energy spectrum of the calibration crew to it. Calculate the energy calibration function based on the measured spectrum. LaBr ₃ and a sample (sample) spectrum measured by scintillation detector, using a peak of 242KeV, 295KeV, 352KeV, 609KeV or 1764KeV in the spectrum and calculates the energy correction function. The following converts the spectral channels into energy intervals. The spectrum transformed into the energy section is calculated as an integral spectrum, and the energy spectrum measured for each channel is converted into a spectrum having a constant energy interval, This is a flash detector background removal method in which the background spectrum is subtracted for each channel to obtain a sample measurement spectrum from which the influence of internal contamination has been removed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a LaBr3 scintillation detector,

The present invention for removing LaBr ₃ bromide carbon taneom (Lanthanum Bromide) scintillation detector relates to internal contamination effect removal method, and more particularly in the background (internal contamination) due to collapse of the Lanthanum (Lanthanum) of the _three scintillation detectors LaBr ≪ / RTI >

The scintillator using LaBr ₃ is composed of a scintillator which emits a gamma ray emitted from a subject when it detects radiation, and a photomultiplier which converts the light emitted from the scintillator into a pulsed electrical signal. Roneun scintillator 111 for the flash is detected, for example, _{Bi 4 Ge 3 O 12 (BGO} ), Gd 2 Si0 5: Ce (GS0), Lu 2 SiO 5: Ce (LSO), LuYSi0 5: Ce ( LYSO), LaBr ₃ : Ce, LaCl ₃ : Ce, NaI, CsI: Na, BaF ₂ , CsF and PbWO ₄ .

The lanthanum used in the present invention is a radioisotope ¹³⁸ La having a half-life of 1.05 × ^{10 11} years, and 66.4% of ¹³⁸ La is β-decayed to be barium- ¹³⁸ ( ¹³⁸ Ba), resulting in emission of 1435.79 KeV of gamma rays. % Is? -Decomposed to become cerium- ¹³⁸ ( ¹³⁸ Ce), and a gamma ray of 788.7 KeV is emitted.

The gamma rays emitted in the low radiation fields are clearly visible in the spectrum due to the background signal due to the pollutants, which hinders the accurate radiation identification of the measurement object.

In addition, since LaBr ₃ detects flash light, there is a problem that it is difficult to identify whether the amount of radiation is due to a channel movement due to temperature or the amount of radiation generated by the background in the detector.

The invention as this, a half-life to the β + decay barium -138 ⁽¹³⁸ Ba) by the gamma rays and, β- collapse of 1435.79KeV cerium -138 ⁽¹³⁸ Ce) that is released as a complement to the above-described disadvantages The background spectrum generated by the 788.7 KeV gamma ray emitted is subtracted for each channel in the sample measurement spectrum so that the spectrum of the background measurement can be obtained.

LaBr ₃ scintillation detector background removal method of solving the aforementioned conventional problems, and the present invention for achieving the above object,

To measure the background spectrum, a LaBr ₃ scintillation detector and a calibrated source are placed in a 10 cm thick lead shield and the background spectrum measurement and the energy calibration source spectrum are measured.

Calculate the energy calibration function based on the measured spectrum.

The equation for calculating the calibration function at this time is E _B = a ₀ + a ₁ C _B + a ₂ C _B ² , E _B is the channel, and C _B is the energy (KeV).

LaBr ₃ and a sample (sample) spectrum measured by scintillation detector, using a peak of 242KeV, 295KeV, 352KeV, 609KeV or 1764KeV in the spectrum and calculates the energy correction function.

The energy correction function (E) at this time becomes E = a ₀ + a ₁ C + a ₂ C ² .

The following haebomyeon converting the spectral channel energy interval, assuming that some spectrum channel x _i coefficients y _i in, y _i = f (x _i) that are correction function at this time is E _i = a ₁ + a ₂ C _i + a ₃ C _i ² . If we calculate this as an integral spectrum, YC = ln (), and if we calculate it as a channel that increases with a constant energy interval, then k = F (C). Here, the integration coefficient Y _k in the channel having the energy _k is obtained by interpolating the cubic equation using the low energy side 2 and the high energy side 2 of the integral coefficients of the peripheral channel, and then converting the integral spectrum obtained by the calculation into the differential spectrum So that the energy interval changes into a constant spectrum. At this time, the conversion equation becomes Y _k = exp (Y _{k +1} ) -exp (Y _k ).

The energy spectra measured for each channel are converted into a spectrum having a channel having a constant energy interval. If the background spectrum is removed for each channel in the sample measurement spectrum, the sample measurement spectrum from which the influence of the internal pollution is removed can be obtained.

According to this aspect of the invention, LaBr ₃ scintillation detector internal contamination effect removal method of the present invention has the effect of being able to avoid errors in the measurement that may result from the contamination of the internal during radioactive contamination survey.

The present invention is capable of removing the influence of internal pollution of all the LaBr ₃ spectra with an energy-corrected internal pollution influence spectrum, so that it is possible to promptly identify the radiation pollution.

1 is a view showing that the influence of the internal LaBr ₃ scintillation detector contamination detection.
2 is a table in which a 2.5-channel interval is converted into a Gaussian function having 3-channel intervals according to an embodiment of the present invention.
3 is a table in which an x-value is converted from 2.5 channels to 3.0 channels.
FIG. 4 is a view showing a background spectrum and a measurement spectrum for a sample as a channel measurement and a background channel measurement screen in a laboratory.
5 is a diagram of a channel spectrum converted into an energy interval using an energy correction function.
FIG. 6 is a graph showing a spectrum of a sample from which a predetermined background is removed in FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is LaBr ₃ scintillation detector is affected by the background of the figure shows the detected that the β + decay half-life corresponding to the 788.7KeV gamma rays emitted as a gamma ray and, β- collapse of 1435.79KeV discharged background are not removed while the The background is detected and it can be seen that it is difficult to identify the radiation of the measurement object.

Therefore, in order to remove such a background, FIG. 2 converts the data obtained by converting a 2.5 channel section into a Gauss function having a 3-channel section into a statistical Gaussian function based on a center position of 60 KeV. In FIG. 3, when the x value of FIG. 2 is detected by the table obtained by converting 2.5 channel section with 3.0 channel section and the integral spectrum (Y) of each channel is detected, it is found that the left and right symmetry values are the same based on the center position 60 KeV There is a number.

In order to confirm this, a background spectrum and a measurement spectrum for a sample are shown as a laboratory channel measurement and a background channel measurement screen in FIG. 4, which shows that accurate radiation recognition is difficult due to background spectrum.

FIG. 5 shows that when the channel spectrum of FIG. 4 is converted into the energy interval using the energy correction function, the spectrum and the background spectrum of the sample overlap each other.

FIG. 6 shows a spectrum of a sample from which a predetermined background is removed in FIG. 5, showing that there is no obstacle to the identification of radiation.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of course, this is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the equivalents as well as the claims that follow.

Claims (1)

To measure the background spectrum, a LaBr ₃ scintillation detector and a calibration source are placed in a 10 cm thick lead shield, background spectrum measurement and energy calibration source spectra are measured,
Calculating an energy correction function based on the measured spectrum of the calibrated source,
Calculating an energy calibration function using peaks of 242 KeV, 295 KeV, 352 KeV, 609 KeV, or 1764 KeV in the measured sample spectrum;
Converting the spectral channel into an energy interval, converting the spectral channel into a spectrum having a channel having a constant energy interval, and subtracting a background spectrum for each channel from the sample measurement spectrum, and
Obtaining a sample measurement spectrum from which the background has been removed
LaBr ₃ scintillation detector background removal method that includes.

Images