A neutron photography electronics system

Abstract

The present invention discloses a neutron photography electronics system, including: a time measurement unit for acquiring a shutter trigger signal; a signal control unit for reading the time information and preliminary position information in the shutter trigger signal, generating a shutter switch signal according to the time information, and determining the corresponding ROI area according to the preliminary position information; the neutron photography unit includes a CMOS sensor, the CMOS sensor acquires a light spot image under the control of the shutter switch signal, and the signal control unit reads the pixels corresponding to the ROI area in the light spot image. The present invention adopts a CMOS sensor readout method, adds time measurement on the basis of position measurement, so that the neutron photography electronics system can achieve fast shutter triggering, precise light spot projection, and high-efficiency readout control, and can take into account the readout rate while maintaining high position and time resolution.

Description

Technical Field

[0001] The present invention relates to the technical field of neutron detection, and in particular to a neutron photography electronics system. Background Art

[0002] With the continuous upgrading of neutron scattering spectrometers and the expansion of their application scale, the demand for large-area position-sensitive neutron detectors will increase in the future. With the increase of neutron flux, the number of detector readout channels or pixel units also increases sharply, and there is a conflict between the high-precision position measurement and readout count rate in the signal readout link. The pixel sensor has high position accuracy but the readout count rate is not ideal. Summary of the invention

[0003] The embodiment of the present invention provides a neutron photography electronics system to solve the problem of unsatisfactory readout count rate of pixel sensors in the prior art.

[0004] In one aspect, an embodiment of the present invention provides a neutron radiography electronics system, comprising:

[0005] A time measurement unit, used for obtaining a shutter trigger signal;

[0006] A signal control unit, used to read the time information and preliminary position information in the shutter trigger signal, generate a shutter switch signal according to the time information, and determine a corresponding ROI area according to the preliminary position information;

[0007] The neutron photography unit comprises a CMOS sensor. The CMOS sensor acquires a light spot image under the control of a shutter switch signal. A signal control unit reads pixels corresponding to a ROI area in the light spot image.

[0008] A neutron photography electronics system in the present invention has the following advantages:

[0009] By adopting the CMOS sensor readout method, time measurement is added on the basis of position measurement, so that the neutron photography electronics system can achieve fast shutter triggering, precise light spot projection, and high-efficiency readout control, and can take into account the readout rate while maintaining high position and time resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1A functional module diagram of a neutron photography electronics system provided by an embodiment of the present invention;

[0012] Figure 2 A working state diagram of a COMS sensor provided by an embodiment of the present invention;

[0013] Figure 3 A schematic diagram of a ROI region provided in an embodiment of the present invention;

[0014] Figure 4 An internal logic block diagram of an FPGA provided by an embodiment of the present invention;

[0015] Figure 5 A logic block diagram of a CMOS data processing module provided by an embodiment of the present invention;

[0016] Figure 6 A logic block diagram of a sequence adjustment module provided in an embodiment of the present invention;

[0017] Figure 7 A flowchart of the neutron radiography electronics system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Figure 1 A functional module diagram of a neutron photography electronics system provided in an embodiment of the present invention. An embodiment of the present invention provides a neutron photography electronics system, including:

[0020] A time measurement unit, used for obtaining a shutter trigger signal;

[0021] A signal control unit, used to read the time information and preliminary position information in the shutter trigger signal, generate a shutter switch signal according to the time information, and determine a corresponding ROI area according to the preliminary position information;

[0022] The neutron photography unit comprises a CMOS sensor. The CMOS sensor acquires a light spot image under the control of a shutter switch signal. A signal control unit reads pixels corresponding to a ROI area in the light spot image.

[0023] For example, Figure 1The system includes a front-end signal readout part, a digital signal readout part and a data transmission part, wherein the front-end signal readout part includes a time measurement unit and a neutron radiography unit, the digital signal readout part includes a signal control unit, and the data transmission part may include a network card of the signal control unit and a host computer. The signal control unit may use an FPGA (field programmable gate array) chip, the network card may use a Gigabit Ethernet card, and the host computer is used to send control instructions and receive data, wherein the received data includes pixel data read by the signal control unit.

[0024] After the neutrons are emitted, they bombard the phosphor scintillator screen and react with the neutron-sensitive nuclides in the scintillator screen, thereby generating a shutter trigger signal. The shutter trigger signal lasts from generation to decay and disappearance within 1 μs. Therefore, the system of the present invention needs to complete the measurement and readout of time and position within this extremely short time.

[0025] After the time measurement unit screens and identifies the shutter trigger signal input from the external interface, it can complete the triggering and reading of neutron events with a response in nanoseconds. The readout signal contains precise time information, preliminary position information and energy information.

[0026] Furthermore, the time measurement unit also screens the shutter trigger signal input from the external interface to select valid signals. Specifically, since the light spots in the preliminary position information are large and inconsistent after neutron scattering, the full-screen and overly large light spots need to be removed. Therefore, the time measurement unit in the present invention uses a threshold readout method to ensure valid signals.

[0027] The light spot formed by the neutron bombardment of the scintillation screen (i.e., the shutter trigger signal obtained by the time measurement unit) is projected onto the glass screen of the CMOS (Complementary Metal Oxide Semiconductor) sensor for photography.

[0028] In an embodiment of the present invention, the CMOS sensor first enters the training mode after powering on, and after the training is completed, all channels are synchronized and locked, and enter the normal working mode under the control of the driving clock. In the normal working mode, the CMOS sensor first performs initialization settings according to the command sent by the host computer, including initialization settings of the working mode, the photographing mode, the window mode, etc., and then after acquiring the spot image, the signal control unit writes the ROI area into the register of the CMOS sensor, and then takes pictures and reads out by receiving the shutter switch signal.

[0029] Furthermore, in the time information determined by the signal control unit, the fast signal is used as the shutter opening signal, and the slow signal is used as the shutter closing signal. Moreover, the CMOS sensor used in the embodiment of the present invention has a ROI (Region Of Interest) function. When the CMOS sensor acquires a spot image containing the full frame, the spot image is temporarily stored in a register. When the signal control unit writes the ROI area information into the register, the CMOS sensor will read and output the pixels corresponding to the ROI area in the spot image.

[0030] The working status of CMOS sensor is as follows: Figure 2 As shown in the figure, it enters the training mode after power-on, continuously sends 0X32A, synchronizes and locks the channel. After the drive clock arrives, the sequence is uploaded through the serial peripheral interface (SPI), and the light spot is captured after enabling. Then the image data is written to the register, read out after the writing is completed, and the sequence is disabled through SPI. Return to the training mode and wait for the next work.

[0031] Furthermore, the signal control unit uses the centroid method to determine the ROI area corresponding to the preliminary position information. Specifically, for a light spot of a certain area, it is necessary to find the geometric center point within the range where the light spot is located, that is, the centroid. The geometric center point is more accurate than the entire light spot and must be inside the light spot. After obtaining the centroid position of the light spot, it can be used as the ROI area and transmitted to the signal control unit. After mapping, the readout area of ​​the CMOS sensor can be controlled. The position of the ROI area in the light spot image is as follows: Figure 3 shown.

[0032] The internal logic block diagram of the signal control unit is as follows: Figure 4 As shown, the coordinate signals in the X direction and Y direction input from the external interface are processed separately. In the centroid method and time extraction module, the centroid method is used to calculate the precise position of the ROI area and extract and save the time information. The main data output channels of the CMOS sensor include 12 data channels and 1 synchronization channel, all of which are differential signals, received through the low-voltage differential signal (LVDS) interface. After passing through the differential to single-ended and delay modules, it is converted from serial to parallel through ISERDESE2 to obtain 10-bit parallel data, as shown in FIG. Figure 5 The first half of the data is the A array, and the second half of the data is the reverse B array. The pixel data is reordered in the CMOS data processing module, as shown in Figure 6As shown. The data is input into the sequence adjustment module, and the pixel data of the odd and even digits of the AB array are adjusted in blocks to obtain sequential pixel data. Before the final data is transmitted to the host computer, the signal control unit also integrates the position and time information to remove redundant data, streamline the data content, and only retain the pixel information and its corresponding channel to reduce the pressure of back-end transmission. The pixel data is transmitted to the host computer via the GTP protocol (GPRS tunnel protocol).

[0033] For the overall process of capturing and reading, see Figure 7 The embodiment of the present invention adopts the method of shooting first and then setting the ROI area, which can effectively prevent the neutron fluorescence time from being missed.

[0034] The neutron photography electronics system using the above structure has been experimentally verified to have achieved performance indicators of time resolution of 10ns / 20μs, position resolution of 200μm, and counting rate of 50kHz, and can read out data quickly.

[0035] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0036] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A neutron radiography electronics system, characterized in that: include: A time measurement unit, used for obtaining a shutter trigger signal; After being emitted, the neutrons bombard the phosphor scintillator screen, react with the neutron-sensitive nuclides in the scintillator screen, and generate the shutter trigger signal; A signal control unit, used to read the time information and preliminary position information in the shutter trigger signal, generate a shutter switch signal according to the time information, and determine a corresponding ROI area according to the preliminary position information; The neutron photography unit includes a CMOS sensor. The light spot formed by neutron bombardment of the scintillation screen is projected onto the CMOS sensor. The CMOS sensor acquires the light spot image under the control of the shutter switch signal. The signal control unit reads the pixels corresponding to the ROI area in the light spot image.

2. A neutron radiography electronics system according to claim 1, characterized in that: The time measurement unit also screens the shutter trigger signal to select a valid signal.

3. A neutron radiography electronics system according to claim 1, characterized in that: Also includes: Host computer, used to send control instructions and receive data.

4. A neutron radiography electronics system according to claim 3, characterized in that: In the normal working mode, the CMOS sensor is first initialized according to the command sent by the host computer, and then the signal control unit writes the ROI area into the register of the CMOS sensor after acquiring the spot image.

5. A neutron radiography electronics system according to claim 4, characterized in that: After the CMOS sensor is powered on, it first enters a training mode. After the training is completed, all channels are synchronized and locked, and it enters a normal working mode under the control of a driving clock.

6. A neutron radiography electronics system according to claim 1, characterized in that: The signal control unit determines the ROI area corresponding to the preliminary position information by using a centroid method.

7. A neutron radiography electronics system according to claim 1, characterized in that: The signal control unit also integrates the time information and the extracted pixels to remove redundant data.

8. A neutron radiography electronics system according to claim 1, characterized in that: The signal control unit uses the fast signal of the time information as a shutter opening signal, and the slow signal as a shutter closing signal.

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