Composition and working principle of scintillation detector
Scintillation detectors usually consist of scintillators, photoelectric sensors (such as photomultiplier tube-PMT, multi-pixel photon counter-MPPC, photodiode-PD, etc.), power supply circuits and signal processing circuits (amplification, comparison, shaping). The schematic diagram is shown in Fig. 1. Rays (α, β, gamma, X, neutrons) is incident in the scintillator and interact to ionize and excite the atoms and molecules of the scintillator; when the ionized and excited atoms and molecules de-excite, part of the ionization and excitation energy is released in the form of light radiation and emit fluorescent photons; fluorescent photons converted into electrons and amplified (or not amplified) by photoelectric sensors, then output the current pulse signal; after amplification, this pulse signal can output exponential analog signals, or continue to output the standard TTL signal after being discriminated and shaping.
The parameters in the detector have been set to the best state. Just input low voltage from the outside and connect the output signal to the subsequent signal processing circuit or counter.
Fig. 1 Scintillation detection schematic block diagram
Application of scintillation detector
Scintillation detectors have been widely used in medical diagnosis, analysis (X-ray analysis, precision measurement analysis), industrial measurement (oil/coal exploration, industrial non-destructive testing), environmental monitoring (PM2.5 detection, environmental radioactive pollution detection), safety inspection and other fields. After years of accumulation and development, the technology has gradually matured.
Due to its advantages of miniaturization, high reliability, long lifetime and non-susceptible to magnetic field, MPPC-based scintillation detectors have gradually attracted public attention and begun to play an increasingly important role in many radiation detection application fields. In some fields, there is a tendency to gradually replace photomultiplier tubes (PMT).
The following is an introduction to several MPPC based scintillation detectors and their specific application scenarios:
1. CM404 Series - Coalfield Logging
CM404 series products (Fig. 2) are counting type scintillation detectors, which integrate scintillator, MPPC, power supply and signal processing circuits. They use a low-voltage power supply to supply power and output positive TTL signals. It has a temperature compensation function, which can maintain good output stability in a wide range of ambient temperature; In addition, this series of products have been carried out targeted structural and shape design for the application of coalfield logging to ensure the vibration resistance of the products.
Fig. 2 CM404 series products
(CM404-01: φ20mm×106.5mm, weight 80g; CM404-02: φ21.4mm×203mm, weight 250g)
At present, they are mainly used in the scenarios of natural gamma-ray counting, environmental gamma-ray counting. In coalfield logging applications, when the detector moves underground, it can record a curve of natural gamma intensity change, so that the depth and thickness of coal seams can be studied, natural radioactive deposits can be found, rock formations can be analyzed, lithology can be judged, etc.
2. CM442 - Portable Radiation Detector
CM442 is a counting type scintillation detector (Fig. 3), which integrates scintillator, MPPC, power supply and signal processing circuits. It can be powered by a +3.3V power supply (which can be directly powered by lithium batteries), outputs positive TTL signals, and has temperature compensation functions.
This product is developed for the application of portable radiation detectors to count rays with energy higher than 30keV, so as to detect and monitor the dose levels of X and gamma-rays in irradiation sites and guide relevant personnel to do radiation protection well. Small in size (φ30mm×96mm) and light in weight (125g), that makes it easy to carry.
Fig. 3 CM442 product
3. MPPC array module - radiation imaging
MPPC array modules are suitable for various radiation imaging applications, such as security imaging, medical imaging, etc. We support one-dimensional and two-dimensional array customization, which can match different sizes and types of scintillators, select different connector interfaces, and design single-channel or multi-channel power supply and other circuit requirements. As shown in Table 1, there are several MPPC array modules made to meet the needs of different customers.
Table 1 MPPC array module products
1×16 line array MPPC+ scintillator
Through the pins, it can be connected to the subsequent circuit to provide power supply for each channel and lead to the output signal of each channel.
1×16 line array MPPC+ scintillator
A mounted connector is on the back of the circuit.
1×32 line array MPPC
A mounted connector and a temperature sensor are on the back of the circuit.
In addition to the above products, there is also a single-point MPPC+
scintillator product (Fig. 4).
Fig. 4 CM414 products
Beijing Hamamatsu Photon Technique Inc. (BHP) has mature application technologies of MPPC. The MPPC scintillation detector products developed are novel in design and reliable in performance. We have completed test equipments, strict quality control, and mature mass production experiences. According to different requirements of customers, we customize different module of MPPC+ scintillators+ circuit units, provide a variety of combinations of product size, MPPC mode, scintillator, output signal type, etc.
In addition to the application scenarios introduced above, MPPC scintillation detectors can also play an important role in nuclear medical imaging, X-ray imaging, non-destructive testing, industrial CT, environmental monitoring, safety inspection, high-energy physics and other fields. BHP can provide customized solutions according to their requirements.