RU2038617C1 - Anisotropic-sensitivity gamma-ray sensing element - Google Patents

Abstract

FIELD: nuclear physics; detectors affording determination of ionizing radiation direction; gamma-astronomy. SUBSTANCE: gamma-ray sensing element has axisymmetric gamma-ray detector surrounded by radiation shield placed in axisymmetric manner relative to it. External surface of radiation shield of isotropic detector on gamma-ray side is formed due to rotation of curve r(φ) = -1/μ ln[E(φ)] about symmetry axis of gamma-ray sensing element, where r(φ)- is thickness of radiation shield on gamma-ray side along direction to gamma emitter; φ- is angle between symmetry axis of gamma-ray sensing element and direction to gamma emitter; μ- is linear coefficient of gamma-ray attenuation for radiation shield material on gamma emitter side; E(φ)- is sensing element directivity pattern determined, for example, from equation E(φ) = aφ+b,. EFFECT: provision for ensuring desired accuracy in taking bearings of gamma emitter in arbitrarily chosen range of bearing angles and/or improved accuracy in range of low angles. 4 dwg

Description

 The invention relates to nuclear physics, in particular to detectors that determine the directivity of ionizing radiation, as well as to gamma-ray astronomy.

A known device is a detector in the collimator for emitting radiation coming into the detector from a certain direction, which is a scintillation detector surrounded by radiation protection having a cylindrical hole in the front [1]
Its disadvantage is the inability to determine the direction to the radiation source without mechanical scanning.

A prototype of the invention that does not require scanning to determine the direction of arrival of gamma rays is a gamma sensor with anisotropic sensitivity [2]
The design of the gamma sensor is an axisymmetric gamma-ray detector surrounded by an axisymmetric radiation shielding coaxially with it, the outer and inner surfaces of which from the direction-finding gamma-ray emitter are made in the form of planes perpendicular to the axis of symmetry of the sensor, and the scintillator is made in the form of a disk that is surrounded lateral radiation protection.

 However, such a design does not provide the specified direction finding accuracy in an arbitrarily selected range of direction finding angles, for example, the same accuracy in the entire range of direction finding angles and higher accuracy in the region of small angles, due to the fact that the dependence of the sensitivity of the gamma sensor due to the above design features is proportional to the cosine the angle between the axis of symmetry of the gamma sensor and the direction to the gamma emitter.

 The invention is intended to determine the direction to a point gamma emitter with a given accuracy in an arbitrarily selected range of direction finding angles, for example, the same accuracy in the entire range of direction finding angles and higher accuracy in the region of small angles, which is not provided by either an analog or a prototype.

 A specific version of the statement of this problem is illustrated by the following example. Several identical metal balls in the fluid flow supplied through the pipe 1 and flowing through the pipe 2, move along the Pitot tube 3 in a liquid medium (Fig. 1). It is necessary to determine the location of one of them at separate consecutive moments of time on trajectory 4. The selected ball (ball indicator) cannot be marked in any way, except for its activation, for example, by slow neutrons, since in all other cases its physical characteristics change ( weight, surface structure, magnetization, etc.) affecting the nature of its behavior in a liquid or its interaction with other balls. Given the fact that in this problem the diameter of the pitot tube, the distance between its direct and reverse bend, and the dimensions of the inventive gamma sensor 5 are much smaller than the distance from the sensor 5 to the pitot tube 3, the position of the ball indicator is completely determined by the angle. In this case, the inventive gamma sensor must provide a given direction finding accuracy in an arbitrarily selected range of direction finding angles and higher accuracy in the region of small angles (φ is the angle between the axis of symmetry 6, gamma sensor 5 and the direction of the gamma emitter to the ball indicator).

где R(φ) расстояние от оси симметрии датчика до внешней поверхности радиационной защиты со стороны гамма-излучателя;
d(φ) толщина радиационной защиты со стороны гамма-излучателя, вдоль направления на гамма-излучатель;
φ- угол между осью симметрии датчика и направлением на гамма-излучатель;
μ- линейный коэффициент ослабления гамма-излучения для материала радиационной защиты со стороны гамма-излучателя;
ε(φ) диаграмма направленности датчика, определяемая, например, из зависимости
ε(φ)= аφ+ b, где a

b=1
Специально выбранная форма внешней поверхности радиационной защиты изотропного детектора со стороны гамма-излучателя позволяет получить диаграмму направленности датчика (зависимости чувствительности датчика от угла между осью симметрии и направлением на гамма-излучатель), представленную на фиг. 2 (прямая 1), т.е.In the proposed gamma sensor containing an axisymmetric gamma radiation detector; an axisymmetric radiation shielding coaxial with the detector, which surrounds the detector, the inner surface of the protection from the direction of the gamma-ray transmitter being emitted is made in the form of a plane perpendicular to the axis of symmetry of the sensor, an isotropic detector is used, and the outer surface of the detector's protection from the gamma-ray side is formed by rotation around the axis of symmetry curve sensor

where R (φ) is the distance from the axis of symmetry of the sensor to the outer surface of the radiation protection from the side of the gamma emitter;
d (φ) thickness of radiation protection from the side of the gamma emitter, along the direction to the gamma emitter;
φ is the angle between the axis of symmetry of the sensor and the direction to the gamma emitter;
μ is the linear attenuation coefficient of gamma radiation for radiation protection material from the side of the gamma emitter;
ε (φ) sensor radiation pattern, determined, for example, from the dependence
ε (φ) = aφ + b, where a

b = 1
A specially selected shape of the outer surface of the radiation protection of the isotropic detector from the side of the gamma emitter allows you to get the radiation pattern of the sensor (the dependence of the sensitivity of the sensor on the angle between the axis of symmetry and the direction to the gamma emitter), shown in Fig. 2 (line 1), i.e.

. (1) При этом погрешность определения угла φ
Δφ

, (2) или с учетом формулы (1)
Δφ.=

, (3) т.е. Δφ не зависит от φ точность определения угла постоянна во всем диапазоне углов пеленгации (фиг. 3, прямая 1).ε (φ) = 1

. (1) Moreover, the error in determining the angle φ
Δφ

, (2) or taking into account the formula (1)
Δφ. =

, (3) i.e. Δφ does not depend on φ, the accuracy of determining the angle is constant over the entire range of direction-finding angles (Fig. 3, line 1).

. (5) Таким образом (фиг. 3, кривая 2)

∞
Следовательно, изобретение обеспечивает более высокую точность определения направления на гамма-излучатель в области малых углов.At the same time, for the prototype device (Fig. 2, curve 2)
ε (φ) cosφ, (4) or taking into account formula (2):
Δφ

. (5) Thus (Fig. 3, curve 2)

∞
Therefore, the invention provides higher accuracy in determining the direction of the gamma emitter in the field of small angles.

угла пеленгации φ от величины этого угла для гамма-датчика-прототипа (кривая 2) и для предлагаемого гамма-датчика (прямая 1); на фиг. 4 предлагаемый гамма-датчик.In FIG. 1 is a diagram illustrating the task; in FIG. 2 graphs of the sensitivity of the gamma sensor prototype (curve 2) and the proposed gamma sensor (line 1) on the angle between the axis of symmetry of the gamma sensor and the direction to the gamma emitter; in FIG. 3 graphs of the relative error

direction finding angle φ of the magnitude of this angle for the gamma sensor prototype (curve 2) and for the proposed gamma sensor (line 1); in FIG. 4 proposed gamma sensors.

где R(φ) расстояние от оси симметрии датчика до внешней поверхности радиационной защиты со стороны гамма-излучателя;
d(φ) толщина радиационной защиты со стороны гамма-излучателя вдоль направления на гамма-излучатель;
φ- угол между осью симметрии датчика и направлением на гамма-излучатель;
μ- линейный коэффициент ослабления гамма-излучения для материала радиационной защиты со стороны гамма-излучателя;
ε(φ) диаграмма направленности датчика, определяемая из зависимости ε(φ)= аφ+ b, где a

b=1
Гамма-датчик действует следующим образом.The gamma sensor (Fig. 4) contains an isotropic gamma radiation detector 7 and its axisymmetric radiation protection 8 and 9, coaxial with the axis of symmetry of the sensor 10, while the radiation protection 8 from the side of the gamma emitter 11 has an outer surface 12 and an inner surface 13. In this case, the shortest distance from the axis of symmetry 10 to a given point A of the outer surface 12 is a radius R, and the perpendicular dropped from point A to the inner surface 13 is the thickness d of the radiation protection 8. The inner surface 13 is a plane perpendicular to the axis of symmetry of the sensor 10, and the outer surface 12 is formed by rotation around the axis of symmetry of the sensor 10 of the curve

where R (φ) is the distance from the axis of symmetry of the sensor to the outer surface of the radiation protection from the side of the gamma emitter;
d (φ) the thickness of the radiation protection from the side of the gamma emitter along the direction to the gamma emitter;
φ is the angle between the axis of symmetry of the sensor and the direction to the gamma emitter;
μ is the linear attenuation coefficient of gamma radiation for radiation protection material from the side of the gamma emitter;
ε (φ) is the radiation pattern of the sensor, determined from the dependence ε (φ) = aφ + b, where a

b = 1
The gamma sensor operates as follows.

 When moving the gamma emitter 11 from the position φ = 0 to the position φ ≠ 0 according to the graph of the sensitivity of the gamma sensor on the angle φ between the axis of symmetry and the direction to the gamma emitter (Fig. 2), determine the angle φ that defines the current position time gamma emitter 5 on the trajectory of its movement. Moreover, the accuracy of determining the angle φ does not depend on the angle φ itself and has a finite value for all φ up to φ = 0.

Claims (1)

GAMMA SENSOR WITH ANISOTROPIC SENSITIVITY, containing an axisymmetric gamma radiation detector surrounded by an axisymmetric radiation shielding coaxial with it, one surface of which is internal, characterized in that an isotropic detector is used as a gamma radiation detector, and the external surface of protection is on the gamma side the emitter is formed by rotation around the axis of symmetry of the gamma sensor curve described by the equation

where r (φ) is the thickness of the radiation protection from the side of the gamma emitter along the direction to the gamma emitter;
φ is the angle between the axis of symmetry of the sensor and the direction to the gamma emitter;
m linear gamma attenuation coefficient for the protection material from the gamma emitter;
E (φ) sensor radiation pattern.

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