阅读说明：本技术 脉冲中子发射时间探测器 (Pulse neutron emission time detector ) 是由 唐琦 宋仔峰 刘品阳 刘中杰 肖云青 易涛 余波 于 2021-09-23 设计创作，主要内容包括：本发明公开了一种脉冲中子发射时间探测器,包括光纤束,所述光纤束的前端连接有闪烁体,后端连接有光电倍增管,光电倍增管的外部环套有避光壳,所述光纤束的后端安装有夹持环,该夹持环的周向外部连接有压盖,所述压盖与避光壳螺纹拧接,以使所述夹持环抱紧所述光纤束,并迫使光纤束后端与光电倍增管持续耦合；所述压盖和避光壳的外部设有铅屏蔽套,所述光纤束朝远离光电倍增管的方向延伸,以使所述闪烁体远离光电倍增管。本发明的有益效果是：大幅降低了x射线和伽马射线在光电倍增管中的噪声信号,显著地提升了信噪比。(The invention discloses a pulse neutron emission time detector, which comprises an optical fiber bundle, wherein the front end of the optical fiber bundle is connected with a scintillator, the rear end of the optical fiber bundle is connected with a photomultiplier, a light shielding shell is sleeved outside the photomultiplier in a surrounding manner, the rear end of the optical fiber bundle is provided with a clamping ring, the circumferential outside of the clamping ring is connected with a gland, and the gland is screwed with the light shielding shell in a threaded manner, so that the optical fiber bundle is embraced by the clamping ring, and the rear end of the optical fiber bundle is forced to be continuously coupled with the photomultiplier; the gland is equipped with the lead shielding cover with the outside of keeping away from the light shell, the fiber bundle extends towards the direction of keeping away from photomultiplier, so that the scintillation body is kept away from photomultiplier. The invention has the beneficial effects that: the noise signals of the x-ray and the gamma ray in the photomultiplier are greatly reduced, and the signal to noise ratio is remarkably improved.)

1. The utility model provides a pulse neutron emission time detector, includes fiber bundle (1), the front end of fiber bundle (1) is connected with scintillator (9), and the rear end is connected with photomultiplier (7), its characterized in that: the outside of the photomultiplier (7) is sleeved with a light shielding shell (4), the rear end of the optical fiber bundle (1) is provided with a clamping ring (2), the circumferential outside of the clamping ring (2) is connected with a gland (3), the gland (3) is screwed with the light shielding shell (4) in a threaded manner, so that the clamping ring (2) holds the optical fiber bundle (1) tightly, and the rear end of the optical fiber bundle (1) is forced to be continuously coupled with the photomultiplier (7);

the outside of gland (3) and light-avoiding shell (4) is equipped with lead shielding cover (5), fiber bundle (1) extends towards the direction of keeping away from photomultiplier (7), so that photomultiplier (7) are kept away from in scintillation body (9).

2. The pulsed neutron emission time detector of claim 1, wherein: the outside of grip ring (2) is equipped with along its axial symmetric distribution's first toper anchor ring face (2a) and second toper anchor ring face (2b), gland (3) have with first toper anchor ring face (2a) the first hole (3a) that suit, it is equipped with second hole (4a) that suit with second toper anchor ring face (2b) to keep away light shell (4) front end.

3. The pulsed neutron emission time detector of claim 2, wherein: the clamping ring (2) is provided with a first weakening notch (2d) in an annular distribution manner on the first conical ring surface (2a), a second weakening notch (2c) in an annular distribution manner on the second conical ring surface (2b), and the first weakening notch (2d) and the second weakening notch (2c) are arranged in a staggered manner.

4. The pulsed neutron emission time detector of claim 1, wherein: an optical filter (6) is connected between the rear end of the optical fiber bundle (1) and the photomultiplier (7) in an abutting mode.

5. The pulsed neutron emission time detector of claim 4, wherein: the light shielding shell (4) comprises a first connecting section (41) and a second connecting section (42) which are in threaded connection, wherein the second connecting section (42) is sleeved outside the photomultiplier (7), the first connecting section (41) is sleeved outside the optical filter (6) and the clamping ring (2), and the first connecting section (41) is provided with a limiting step (4b) at a position close to the optical filter (6).

6. The pulsed neutron emission time detector of claim 1, wherein: the lead shielding sleeve is characterized in that an outer fixing sleeve (8) is arranged outside the lead shielding sleeve (5), and the outer fixing sleeve (8) is composed of a first fixing section (8a) and a second fixing section (8b) which are in threaded connection.

7. The pulsed neutron emission time detector of claim 1, wherein: the light shading shell (4) is made of an aluminum shell.

8. The pulsed neutron emission time detector of claim 1, wherein: and a lead shielding layer (10) is wrapped outside the scintillator (9).

9. The pulsed neutron emission time detector of claim 1, wherein: the photomultiplier (7) is a microchannel plate type photomultiplier.

10. The pulsed neutron emission time detector of claim 1, wherein: the length of the optical fiber bundle (1) is more than or equal to 1 m.

Technical Field

The invention belongs to the technical field of neutron detection, and particularly relates to a pulse neutron emission time detector.

Background

The scintillation detector made up of the combination of scintillator, light collecting component and photoelectric converter is a common radiation detector, when the particle enters the scintillator, the atom or molecule of the scintillator is excited to produce fluorescence, the light collecting component makes the fluorescence emit to the photoelectric converter and emit photoelectron, then the photoelectron can be converted into electric signal to output directly or after multiplication.

When pulsed neutrons are used as a radiation source, a scintillator is required to convert a neutron signal into an optical signal, and since pulsed neutron sources are generally accompanied by other radiation such as x-rays and gamma rays, and PMTs (photomultiplier tubes) respond to both x-rays and gamma rays, the generated noise signal affects the time interpretation of a measurement signal.

Disclosure of Invention

In view of this, the present invention provides a pulse neutron emission time detector, which can greatly reduce noise signals of x-rays and gamma-rays in a photomultiplier tube, and improve a signal-to-noise ratio.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the utility model provides a pulse neutron emission time detector, includes the fiber bundle, the front end of fiber bundle is connected with the scintillator, and the rear end is connected with photomultiplier, and its key lies in: the outer part of the photomultiplier is annularly sleeved with a light shielding shell, the rear end of the optical fiber bundle is provided with a clamping ring, the circumferential outer part of the clamping ring is connected with a gland, and the gland is screwed with the light shielding shell so that the clamping ring embraces the optical fiber bundle and forces the rear end of the optical fiber bundle to be continuously coupled with the photomultiplier; the gland is equipped with the lead shielding cover with the outside of keeping away from the light shell, the fiber bundle extends towards the direction of keeping away from photomultiplier, so that the scintillation body is kept away from photomultiplier.

By adopting the structure, the scintillator and the photomultiplier are separately designed, the photomultiplier can be separately shielded by using thick lead, signals in the scintillator are not influenced, the noise signals of x rays and gamma rays in the PMT are greatly reduced under the condition of not increasing the volume of the probe, and the signal-to-noise ratio is improved. Meanwhile, the optical fiber bundle is fixed through the gland and the clamping ring, and the optical fiber bundle fixing device has the technical advantages of convenience in assembly, good reliability and high stability.

Preferably, the method comprises the following steps: the outside of grip ring is equipped with along its axial symmetric distribution's first toper anchor ring face and second toper anchor ring face, the gland has the first hole that suits with first toper anchor ring face, it is equipped with the second hole that suits with second toper anchor ring face to keep away light shell front end. The clamping ring is provided with a first weakening notch in an annular distribution mode on the first conical ring surface, a second weakening notch in an annular distribution mode on the second conical ring surface, and the first weakening notch and the second weakening notch are arranged in a staggered mode. By adopting the structure, the optical fiber bundle can be held tightly, and the coupling between the optical fiber bundle and the PMT can be ensured not to be loosened.

Preferably, the method comprises the following steps: and an optical filter is abutted between the rear end of the optical fiber beam and the photomultiplier. With the structure, light can be attenuated to proper intensity when the signal intensity is too strong.

Preferably, the method comprises the following steps: the light-resistant shell comprises a first connecting section and a second connecting section which are connected in a threaded manner, wherein the second connecting section is annularly sleeved outside the photomultiplier, the first connecting section is annularly sleeved outside the optical filter and the clamping ring, and the first connecting section is provided with a limiting step at a position close to the optical filter. By adopting the structure, the detector is convenient to assemble.

Preferably, the method comprises the following steps: the outer part of the scintillator is wrapped with a lead shielding layer. With the above structure, x-rays can be shielded.

Compared with the prior art, the invention has the beneficial effects that:

1. the probe at the front end of the detector occupies small space and can be placed at a position close to the neutron source, so that the measurement solid angle of the detector is improved.

2. By adopting the design that the scintillator and the Photomultiplier (PMT) are separated, the photomultiplier can be singly shielded by using thick lead, signals in the scintillator are not influenced, and on the premise of not increasing the volume of the probe, noise signals of x rays and gamma rays in the photomultiplier are greatly reduced, and the signal-to-noise ratio is remarkably improved.

Drawings

FIG. 1 is a cross-sectional view of a pulsed neutron emission time detector;

FIG. 2 is a schematic view of a clamp ring;

FIG. 3 is a cross-sectional view of the gland;

FIG. 4 is a sectional view of a light-shielding case;

fig. 5 is a schematic structural diagram of a pulsed neutron emission time detector.

Detailed Description

The present invention will be further described with reference to the following examples and the accompanying drawings.

As shown in fig. 1 and 5, a pulse neutron emission time detector structurally comprises a scintillator 9, an optical fiber bundle 1 and a photomultiplier tube 7 which are sequentially connected from front to back, wherein the photomultiplier tube 7 is preferably a microchannel plate type photomultiplier tube, an aluminum light shielding shell 4 is arranged outside the photomultiplier tube, a clamping ring 2 is sleeved at the rear end of the optical fiber bundle 1, a gland 3 is connected to the circumferential outside of the clamping ring 2, the gland 3 is screwed with the light shielding shell 4, and a lead shielding sleeve 5 with the thickness of 4cm is arranged outside the gland 3 and the light shielding shell 4.

As shown in fig. 2, 3 and 4, the exterior of the clamping ring 2 is provided with a first tapered ring surface 2a and a second tapered ring surface 2b which are symmetrically distributed along the axial direction, the first tapered ring surface 2a and the second tapered ring surface 2b have opposite and symmetrical inclination directions, the gland 3 is provided with a first inner hole 3a corresponding to the first tapered ring surface 2a, the front end of the light shielding shell 4 is provided with a second inner hole 4a corresponding to the second tapered ring surface 2b, and based on the structural design, when the gland 3 is screwed with the light shielding shell 4, the inclined first inner hole 3a and the second inner hole 4a can force the clamping ring 2 to contract inwards so as to clamp the optical fiber bundle 1.

Referring to fig. 5, the length of the optical fiber bundle 1 is not less than 1m, preferably 1m in this embodiment, the optical fiber bundle 1 extends in a direction away from the photomultiplier tube 7, so that the scintillator 9 at the front end of the optical fiber bundle 1 is away from the photomultiplier tube 7, the scintillator 9 and the photomultiplier tube 7 are separately designed, and the photomultiplier tube 7 is separately shielded by using the lead shielding sleeve 5, so that on the premise of not affecting signals in the scintillator 9 and not increasing the probe volume, noise signals of x-rays and gamma-rays in the photomultiplier tube 7 are greatly reduced, and the signal-to-noise ratio is significantly improved. In addition, the forward extending optical fiber bundle 1 makes the probe head at the front end of the detector occupy a small space and can be placed at a position close to the neutron source, thereby improving the measurement solid angle of the detector.

As shown in fig. 3 again, in order to ensure that the clamping ring 2 can contract inward and clasp the optical fiber bundle 1, a first weakening gap 2d is annularly distributed on the first conical ring surface 2a, a second weakening gap 2c is annularly distributed on the second conical ring surface 2b, and the first weakening gap 2d and the second weakening gap 2c are arranged in a staggered manner.

An optical filter 6 is detachably arranged between the rear end of the optical fiber bundle 1 and the photomultiplier 7, and the optical filter 6 is a neutral density optical filter and can attenuate light to proper intensity when the signal intensity is too strong. In order to conveniently mount and fix the optical filter 6, the light shielding shell 4 is composed of a first connecting section 41 and a second connecting section 42 which are connected in a threaded manner, wherein the second connecting section 42 is sleeved outside the photomultiplier tube 7 in a sleeved manner, the first connecting section 41 is sleeved outside the optical filter 6 and the clamping ring 2 in a sleeved manner, a position of the first connecting section 41 close to the optical filter 6 is provided with a limiting step 4b, and after the first connecting section 41 is screwed on the second connecting section 42, the optical filter 6 is fixed on the end face of the photomultiplier tube 7 by the limiting step 4 b.

In order to fix the rear end of the detector on the corresponding support structure conveniently, an external fixing sleeve 8 is arranged outside the lead shielding sleeve 5, and the external fixing sleeve 8 is composed of a first fixing section 8a and a second fixing section 8b which are connected in a threaded manner.

Referring to fig. 1, in the present embodiment, the thickness of the scintillator 9 is preferably 1-2mm, and the front end of the scintillator 9 is covered with a lead shielding layer 10 with a thickness of 1cm for shielding x-rays.

The working principle of the pulse neutron emission time detector is as follows:

when the detector works, a neutron signal reaching the detector is converted into an optical signal by the scintillator 9 at the front end of the detector, the optical fiber bundle 1 transmits the optical signal to the photomultiplier, the photomultiplier converts the optical signal into an electrical signal, and the electrical signal is transmitted to recording equipment such as an oscilloscope and the like through a cable for signal recording. The detector has a fast time response, the rising time of the detector is about 700ps, and the timing precision of the detector is better than 50 ps.

Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.