CN109709515A - A kind of source localization method based on three sensors - Google Patents

Abstract

The invention discloses a kind of source localization method based on three sensors, belong to weak signal identification field, it is therefore intended that solve under field environment, when radioactive source distance farther out when, the signal of detector can be weaker, is easy the problem of being influenced by environmental exact details.This method comprises the following steps: three detectors being arranged into a column, the spacing between two neighboring detector is d, and three detectors are successively denoted as the first detector, the second detector, third detector from right to left；By calculating, detector can be obtained to the distance and bearing angle of radioactive source, and then realize the accurate positionin to radioactive source.Improvement based on method, it is only necessary to, can be by the way that the position and angle of 3 detectors of source distance is calculated, to realize the positioning to source with 3 same sources of detector measurement.Present inventive concept is ingenious, reasonable design, easy operation, and experiment accuracy of measurement is high, application value with higher and preferable application prospect.

Description

A kind of source localization method based on three sensors

Technical field

The present invention relates to radiation detection field, especially weak signals to identify field, specially a kind of to be based on three sensors Source localization method.

Background technique

Under field environment, influence of the source signal vulnerable to environmental exact details, large volume detector is more easily known within a short period of time Other source signal, but single large volume detector can not carry out fast source positioning.

For this purpose, there is an urgent need to a kind of new methods, to solve the above problems.

Summary of the invention

Goal of the invention of the invention is: under field environment, influence of the source signal vulnerable to environmental exact details, and large volume detector Source signal is more easily identified within a short period of time, but single large volume detector can not carry out fast source positioning.For this problem, A kind of source localization method based on three sensors is provided.The present invention can effectively solve the problem that the above problem, and single measurement can be real The quick positioning of radioactive source under existing environmental exact details, and the absolute activity in source is provided simultaneously.

To achieve the goals above, the present invention adopts the following technical scheme:

A kind of source localization method based on three sensors, includes the following steps:

(1) three detectors are arranged into a column, the spacing between two neighboring detector be d, by three detectors from A dextrad left side is successively denoted as the first detector, the second detector, third detector；

The formed angle side of being between straight line where line and three detectors between (2) second detectors and radioactive source Parallactic angle θ, the radiation intensity that the first detector, the second detector, third detector detect are followed successively by I₁, I and I₂, by first Detector, the second detector, third detector to radioactive source distance be successively denoted as r₁, r and r₂；

(3) calculating r is carried out using following formula 1,

Using following 2 computer azimuth angle θ of formula,

The γ emissivity A of radioactive source is obtained using following formula (3),

In formula (3), η_{It is intrinsic}For the intrinsic detection efficient of measurement detector, S is the spy of measurement detector face radioactive source Survey the area in section.

Improvement based on method, the present invention only need to realize the positioning to source with 3 same sources of detector measurement It is measured with source strength.Present inventive concept is ingenious, reasonable design, easy operation, and experiment accuracy of measurement is high, with higher to apply valence Value and preferable application prospect.

Detailed description of the invention

Examples of the present invention will be described by way of reference to the accompanying drawings, in which:

Fig. 1 is 3 probe position schematic diagrams.

Specific embodiment

All features disclosed in this specification or disclosed all methods or in the process the step of, in addition to mutually exclusive Feature and/or step other than, can combine in any way.

Any feature disclosed in this specification unless specifically stated can be equivalent or with similar purpose by other Alternative features are replaced.That is, unless specifically stated, each feature is an example in a series of equivalent or similar characteristics ?.

1 source of embodiment positions (3 detector)

(1) explorer count and source radiation activity, source range finder distance, detector shape and detection efficient itself etc. be all Have an impact.When the distance of source range finder farther out when, it is point source that radioactive source, which can be approximately considered,.Detector meter under ideal conditions Number has to be determined by formula (4) formula,

In formula:

I --- the counting rate in the detector unit time；

The γ emissivity in A --- source；

The sectional area of S --- detector；

Distance of r --- the detector to source；

η_{It is intrinsic}--- the intrinsic detection efficient of detector.

Detector as existing 3 is arranged into a column, their spacing are d, as shown in Figure 1.

According to the intensity I of detector signal and distance r square inversely (point source and distance is approximate farther out), they Counting have following relationship:

Solving equations (5) can obtain distance r and azimuth cosine cos θ, as follows:

Formula (6,7) are substituted into (a) formula and (b) formula in formula (5), r can be found out₁And r₂, it is as follows:

It can thus be appreciated that, it is only necessary to it, can be by the way that source distance 3 detections be calculated with 3 same sources of detector measurement The position of device and angle, to realize the positioning to source.

By formula (7) and figure it is found that azimuth angle theta has 2 solutions (to be located at the two of detector line within the scope of 0 °~360 ° Side, symmetrical).In actual measurement, detector finds source during exercise, is detected by the direction of motion of detector and 3 The azimuth of radioactive source can be limited within the scope of 180 ° by the strength relationship of device.It therefore can be only according to the intensity of 3 detectors One determines azimuth angle theta.

By orientation distance r, r₁And r₂, signal strength I, I of detector₁And I₂And formula (3) can calculate 3 differences Source radiation activity value A, A₁And A₂.This 3 activity values should be equal in principle, but due to various errors and approximation, meeting between them There is certain difference.In order to obtain accurate source radiation activity value, 3 activity values can be subjected to arithmetic average, reduce activity value And the deviation of true value.

(2) positioning accuracy

1, azimuth positioning accuracy

By (6) formula and (7) formula, the included angle cosine value of source and detector can be obtained, as follows:

Formula (10) differential can obtain, as follows:

It enablesThen have:

Formula (12) further differential, can obtain:

D (θ)=K (AdI+BdI₁+CdI₂) (13)；

In formula (13), A, B, C are coefficient, as follows:

2, source Distance positioning precision

According to formula (6) formula, the positioning relative uncertainty degree U in source and intermediate detector distance r_relIt (r) can be by total differential It obtains,

In formula (17),

U_rel(r) --- the relative uncertainty degree of source orientation distance；

U_rel(d) --- the relative uncertainty degree of detector spacing；

U_rel(I) --- the relative uncertainty degree that intermediate detector counts；

U_rel(I₁) --- the relative uncertainty degree that detector 1 counts；

U_rel(I₂) --- the relative uncertainty degree that detector 2 counts.

By formula (17) it is found that the positioning uncertainty of r is formed by two, the uncertainty of detector spacing d is plus 3 spies Survey the operation between the uncertainty of device intensity.Detector spacing d can be controlled relatively accurately.The counting of 3 detectors is not true Surely spending general evolution can estimate, but denominator is an a small amount of square, it is easy to bring larger shadow to the uncertainty of r It rings.In actual experiment, when θ corner connection is 0 ° nearly, the experimental data of 3 detectors will appear (I/I for discovery really₁+I/I₂- 2) small In 0 the case where.At this moment not only uncertainty is very big, but also does not give the real solution of r.

Denominator makes uncertainty very big close to 0 when solving the problems, such as 0 ° nearly because of θ corner connection, in the design for searching source policy In can by detector around intermediate detector rotate horizontally 90 ° so that radioactive source angle is near 90 °.Simultaneously according to I, I₁And I₂It is big Small relationship can suitably move detector to source direction, so that r reduces, can also reduce the positioning uncertainty of r.

(3) positioning result and analysis

1, in order to verify source locating scheme, multiple groups experiment is devised.It mainly include following groups confirmatory experiment: 1) voltage input With constant at a distance from central detector, the angle in change source and detector column；2) angle of voltage input is constant, changes in the distance of source The position of heart detector.Experiment is 1.5 inches, a height of 1.5 inches of LaBr using diameter₃Scintillator detector.γ is put The source of penetrating is¹³⁷Cs and²⁴¹Am.The γ emissivity in two sources is weaker, and 2 π emissivity are respectively 2.56E+04s^-1And 3.18E+04s^-1。

2, result and analysis

2.1 different angle positioning analysis

In experiment, Fig. 1 is seen in the spatial position of detector and radioactive source.The position r of source distance center detector is fixed as 1m, The spacing d of detector is 25cm, and source is¹³⁷Cs and²⁴¹Am is located at 90 °, 75 °, 60 °, 45 °, 30 °, 15 ° and 0 °, measurement knot Fruit sees Tables 1 and 2.When angle, θ larger (close to 90 °), differ smaller with actual angle by formula (10) calculated angle, When angle is smaller, the angle of calculating obtained differs larger with reality and even occurs the case where cos θ is greater than 1 sometimes.It calculates To source also have large error at a distance from detector.

Table 1 is used¹³⁷The angle and distance that the source Cs the data obtained is calculated

d	25	25	25	25	25	25	25
								I	2.09	1.83	1.90	1.80	1.90	1.87	1.93
I1	1.80	2.14	2.03	2.63	2.77	3.27	3.06
								I2	1.66	1.30	1.42	1.27	1.09	1.24	1.36
r	54.49	69.79	67.71	111.65	53.51	120.33	151.23
								r1	58.68	64.54	65.53	92.32	44.39	91.02	120.26
r2	61.19	82.63	78.26	132.89	70.75	148.07	180.36
								cos(θ)	0.06	0.38	0.27	0.82	0.57	1.13	1.19
θ	86.83	67.58	74.32	35.08	55.44	#NUM！	#NUM！
								θr	90	75	60	45	30	15	0
θ-θr	-3.17	-7.42	14.32	-9.92	25.44	—	—
								(r-rr)/rr	- 46%	- 30%	- 32%	12%	- 46%	20%	51%

Note: in table 1, the reference value r of actual range_rFor 1m；" #NUM in table！" indicate that cos θ is greater than 1, do not give angle Value.Or r, r₁And r₂Calculated value be imaginary number.

Table 1 gives use¹³⁷Positioning result at the fixed 1m in the source Cs when different angle, this method can realize 3 detectors pair The function that radioactive source is positioned.But by orientation distance and angle it can also be seen that, the result of uncertainty and theory analysis Unanimously, but deviation is bigger than normal, the reason is that radioactive source is weaker.

Table 2 is used²⁴¹The angle and distance that the source Am the data obtained is calculated

d	25	25	25	25	25	25	25
								I	6.64	6.28	6.68	6.42	6.32	6.22	6.57
I1	6.38	7.16	7.89	9.41	10.06	11.35	11.28
								I2	5.66	5.84	5.62	4.94	4.64	4.29	4.57
r	76.09	#NUM！	195.62	#NUM！	#NUM！	#NUM！	249.76
								r1	77.69	#NUM！	179.88	#NUM！	#NUM！	#NUM！	190.57
r2	82.43	#NUM！	213.14	#NUM！	#NUM！	#NUM！	299.49
								cos(θ)	0.10	#NUM！	0.67	#NUM！	#NUM！	#NUM！	2.14
θr	90	75	60	45	30	15	0
								θ	84.27	#NUM！	48.07	#NUM！	#NUM！	#NUM！	#NUM！
θ-θr	-5.73	—	-11.93	—	—	—	—
								(r-rr)/rr	- 24%	—	96%	—	—	—	150%

Note 1: the reference value r of actual range_rFor 1m；

Note 2: " #NUM in table！" indicate that cos θ is greater than 1, do not give angle value.Or r, r₁And r₂Calculated value be void Number.

Table 2 gives use²⁴¹Positioning result at the fixed 1m in the source Am when different angle, with¹³⁷The source Cs acquired results are similar.It is real It tests orientation distance that result provides and angle has no small error, this is consistent with the theoretical analysis result of uncertainty, and 1/ (I/I₁+I/I₂- 2) difference of 3 explorer counts of factor pair is very sensitive.¹³⁷The source Cs and²⁴¹Am is strong almost the same in a steady stream, still Capacity volume variance is larger.?¹³⁷The background in the source Cs 661keV energy area is lower, and²⁴¹The background in the source Am 59.5keV energy area is higher by very It is more.The fluctuation absolute value of 59.5keV energy area background is larger, so as to cause²⁴¹The uncertainty of the source Am full energy peak peak area increases. It is finally embodied in table 2 and situation more without real solution occurs than table 1.The approach for improving uncertainty is only improved I, I₂And I₃ Measurement accuracy, that is, increase detector detection efficient.

2.2 different distance positioning analysis

For different distance, experiment has chosen 15 ° and 60 ° of two specific angles, and source is placed on the intermediate spy of distance respectively Survey the place of device 70cm and 100cm.In terms of angle, 60 degree of response is preferable, and 15 degree the feelings that cosine value is greater than 1 occur Condition.

Table 3 is used¹³⁷Cs and²⁴¹The source Am distance and angle that at 60 °, measurement is obtained

137Cs	d	I2	I	I1	r2	r	r1	cosθ	θ
										70cm(1)	25	2.50	3.87	5.29	83.07	66.77	57.14	0.54	57.03
70cm(2)	25	2.67	3.90	5.10	90.16	74.60	65.20	0.52	58.71
										100cm	25	1.47	1.94	2.41	115.59	100.67	90.33	0.52	58.93
241Am	d	I2	I	I1	r2	r	r1	cosθ	θ
										70cm(1)	25	8.07	12.11	15.99	85.49	69.82	60.75	0.52	58.81
70cm(2)	25	8.23	12.31	16.25	85.97	70.30	61.19	0.52	58.78
										100cm	25	4.79	5.77	7.38	#NUM！	#NUM！	#NUM！	#NUM！	#NUM！

Table 4 is used¹³⁷Cs and²⁴¹The source Am distance and angle that at 15 °, measurement is obtained

137Cs	d	I2	I	I1	r2	r	r1	cosθ	θ
										70cm(1)	25	2.15	3.83	8.56	98.12	73.46	49.13	0.98	10.86
70cm(2)	25	2.17	3.71	8.54	123.01	94.15	62.03	1.20	#NUM！
										100cm(1)	25	1.23	1.86	3.29	156.32	127.11	95.53	1.20	#NUM！
100cm(2)	25	1.22	1.94	3.22	101.20	80.23	62.31	0.79	37.59
										100cm(3)	25	1.12	1.90	3.15	85.36	65.71	50.98	0.71	44.51
100cm(4)	25	1.16	1.85	3.16	104.21	82.41	63.02	0.84	33.29
										100cm(5)	50	0.69	1.72	6.41	127.99	81.06	41.96	0.90	25.61
100cm(6)	50	0.65	1.82	6.29	113.76	68.13	36.61	0.85	31.64
										100cm(7)	50	0.71	1.72	6.20	130.99	84.01	44.24	0.90	25.22
241Am	d	I2	I	I1	r2	r	r1	cosθ	θ
										70cm(1)	25	7.00	12.11	28.12	116.20	88.36	57.99	1.01	#NUM！
70cm(2)	25	6.88	12.27	28.42	101.90	76.31	50.14	1.03	#NUM！
										100cm	25	3.81	5.93	10.52	127.44	102.15	76.68	1.15	#NUM！

Table 3 and table 4 are set forth¹³⁷Cs and²⁴¹Distance and angle positioning result of the source Am in 60 ° and 15 °.Distance is Positioning accuracy when 70cm is significantly better than positioning accuracy when 100cm, and main cause is apart from small, and the counting of detector increases, In the case where background is constant, the fluctuation of corresponding explorer count becomes smaller, that is, I, I₂And I₃Uncertainty of measurement become smaller, To improve positioning accuracy.

On the whole, the positioning in source may be implemented in this localization method substantially, but positioning accuracy has after distance increases Larger decline.

The analysis of 2.3 source strengths

After source distance r is determined by formula (6), formula (4) is converted to obtain formula (18), can be used for detecting unknown The γ emissivity A in source.The intrinsic detection efficient η of detector_{It is intrinsic}It can be calculated by simulation softwards such as MCNP.Further combined with power spectrum Nucleic is identified, with reference to the Characteristic γ ray emission probability of the nucleic, the activity in the source can be calculated:

According to formula (18), the uncertainty of source radiation activity mostlys come from the uncertainty and distance r of explorer count I Positioning accuracy.The uncertainty of explorer count can control within 3% in actual measurement, but by positioning uncertainty Theory analysis and experiment measurement result can know that the uncertainty of source strength mostlys come from the positioning accuracy of r.

The invention is not limited to specific embodiments above-mentioned.The present invention, which expands to, any in the present specification to be disclosed New feature or any new combination, and disclose any new method or process the step of or any new combination.

Claims (1)

1. a kind of source localization method based on three sensors, which comprises the steps of:

(1) three detectors are arranged into a column, the spacing between two neighboring detector is d, by three detectors from dextrad A left side is successively denoted as the first detector, the second detector, third detector；

Formed angle is azimuth between straight line where line and three detectors between (2) second detectors and radioactive source θ, the radiation intensity that the first detector, the second detector, third detector detect are followed successively by I₁, I and I₂, by the first detection Device, the second detector, third detector to radioactive source distance be successively denoted as r₁, r and r₂；

(3) calculating r is carried out using following formula 1,

Using following 2 computer azimuth angle θ of formula,

The γ emissivity A of radioactive source is obtained using following formula (3),

In formula (3), η_{It is intrinsic}For the intrinsic detection efficient of measurement detector, S is that the detection of measurement detector face radioactive source is cut The area in face.