KC761B: the new Gamma Spectrometer from DEEPACE

Abstract: in this article, we present an interesting new apparatus dedicated to gamma spectrometry and dosimetry measurements. It is a device based on a CsI(Tl) scintillator coupled to solid-state photomultipliers: SiPM. In addition to the scintillation sensor, the instrument has a PIN diode sensitive to beta radiation.


The instrument we present in this post is the new gamma spectrometer produced by Deepace. This is the KC761B model which is an improvement over the previous model, the KC761. The instrument is based on a scintillation sensor (CsI(Tl) crystal coupled to SiPM) which allows an energy resolution of 7.5% and a measurement range with a lower limit of approximately 8 – 10 keV. The instrument is also equipped with a semiconductor sensor (PIN diode), located on the back of the instrument, sensitive to both beta and (with some modifications) alpha radiation.

The device can be powered either by a battery (3 AA of 1.5 V) or externally with a 5V source via a USB type C interface, such as a good quality mobile phone charger. The instrument is equipped with Bluetooth connectivity and can transmit data to a mobile app, for viewing and storing data. Data can also be stored on a memory card. The stored gamma spectrum can be viewed and studied with the well-known SandiaLabs InterSpec application.

The instrument is equipped with a functional display, intuitive keys and context menus, it has LEDs and audible notification alarms.

The first impression is extremely positive: we have a professional tool with great attention to detail, complete with all features and with high performance!

Product Highlights

  • 7.5% FWHM resolution @662keV
  • Extended low energy response to 9keV
  • Sensitive 10cps/0.1μGy/hour
  • Low energy drift in working temperature range ±(2%+10keV) and ±(1%+5)keV uncertainty in ordinary temperature
  • Long-term storage ability

Product Features 

  • Primary sensor using CsI (2.54cm³) scintillator and SiPM, and auxiliary sensor using PIN tube (9mm²).
  • Powered by 3*(AA/LR6) or 3*HRM6 batteries for up to 10 days of continuous use.
  • Support USB (type-C) and POE power supply, a Type-C port can be used to charge the battery.
  • Weight 300g and includes a display that can directly show the energy spectrum and other data with no need to connect to a cell phone.
  • Wide range of interfaces, Bluetooth and RJ45 ports (supports POE power) and microSD card slot for easy data transfer.
  • IP65 waterproof.

Product Functions

  • Radiation measurement with Multi-Channel analyzer
  • Dose display based on energy compensation(up to 100μGy/h)
  • Manual radioactive isotope identification

Where to find the Spectrometer KC761B

Website of the producer DEEPACE
Webpage of the instrument KC761B
Documentation User Manual


The instrument arrived complete with a manual and some minor accessories, shipping was quick and the package was carefully packaged, with adequate protection for the device.

Fig 1 – Unboxing the package

The quality certificate of the energy resolution of the sensor is highly appreciated: it is an excellent 7%!

Fig 2 – The gamma spectrometer and the energy resolution quality certificate

On the front side, the instrument has a display for viewing the gamma spectrum and the dosimeter data and some keys for switching on/off and configuring the instrument. Below the display, there are some context-sensitive function keys. Also on the front side, there are two LEDs for pulses and alarm indication, and the speaker on the bottom. On the back side, there is the battery compartment and the protection window of the PIN detector, located on the back of the instrument. The main sensor, however, is placed on the front side, just above the display.

Fig 3 – the front side and the back side of the device

On the side, protected by a rubber gasket, is the interface connection compartment. We have the slot for microSD memory cards, a socket for an audio jack that carries the output pulses, a USB type-C interface for power and an RJ45 connector for the Ethernet connection (supports POE).

Fig 4 – The interface compartment, protected by a waterproof gasket

In the following image, we show the schematic drawing of the spectrometer with an indication of the main characteristics.

Fig 5 – Schematic of the instrument with its main features

The Device

In the introduction we briefly described the main characteristics of this new gamma spectrometer, now let’s try to give some more details. The scintillation sensor is placed in the upper part, behind a plastic cover that eliminates light but does not constitute an obstacle for gamma radiation. The secondary PIN sensor is located in the rear part, sensitive to beta and alpha radiation. The PIN sensor is protected by a shield that protects the sensor from light. Beta radiation passes through this screen with little attenuation, while alpha radiation is completely blocked. To experiment with the detection of alpha radiation it is therefore necessary to remove this protection, but we will talk about this in one of the next articles.

Fig 6 – The two radiation sensors

The KC761B instrument has two main operating modes: the spectrometer mode and the dosimeter mode. In spectrometer mode, the gamma spectrum of the source appears on the graphic display, along with detailed information about the spectrum and count rate. At the top of the display the radiation dose is shown and also auxiliary information such as pressure and battery status are shown.

Fig 7 – In spectrum modality

In dosimeter mode, the time trend of the dose is shown on the display, while a thumbnail of the gamma spectrum is shown at the top of the screen.

Fig 8 – In dosimeter modality

First test with Cs137

for the first test of the instrument, we used the classic 1uCi Cs137 source, with its X/gamma peaks at 32 KeV and 661.7 KeV. The gamma spectrum appeared on the display after a few moments with the two peaks identifiable. The linearity and calibration of the sensor are good because the measured peak energy values ​​practically coincide with the exact values. The Compton part of the spectrum is rather low due to the size of the crystal but this is positive because it improves the readability of the spectrum. The spectrum can be displayed in both linear and logarithmic scales, as shown in the image below. The first test was passed brilliantly!

Fig 9 – Acquiring the gamma spectrum of a 1uCi Cesium 137 source


We have made a quick description of the new KC761B gamma spectrometer. The first impression is excellent and the first gamma spectrum acquired shows excellent sensitivity and more than good energy resolution. In future articles, we will focus in more detail on the main features of the tool. Stay tuned”!

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MEASALL KC761B: un nuovo Spettrometro Gamma

Abstract: in questo articolo presentiamo un nuovo interessante apparato dedicato a misure di spettrometria gamma e di dosimetria. si tratta di un device basato su di uno scintillatore CsI(Tl) accoppiato a fotomoltiplicatori a stato solido: SiPM. Oltre al sensore a scintillazione, lo strumento dispone di un diodo PIN sensibile alla radiazione beta.