Gamma Spectroscopy with KC761B

Abstract: in this article, we continue the presentation of the new KC761B device. In the previous post, we described the apparatus in general terms. Now we mainly focus on the gamma spectrometer functionality.


The Deepace KC761B instrument is both a dosimeter and a gamma spectrometer. The switch between the two modalities is done via the buttons on the front of the instrument. When turned on, the instrument is already, by default, in gamma spectrometer mode. During event acquisition, the gamma spectrum of the source under examination is shown on the front display.

KC761B stand-alone

In stand-alone mode, the instrument is used as a portable gamma spectrometer. The source under examination is placed in front of the measurement window, the gamma spectrum is displayed on the front display. Depending on the activity of the source, it will be necessary to wait a more or less long time for the spectrum to present a stable trend. the sensor is, however, rather efficient; therefore, the spectrum stabilizes within a few minutes. The following images show some gamma spectra acquired with the instrument.

Fig 1 – Measurement setup

The instrument easily acquires the spectrum of Americium 241 and excellently resolves the main peak at 60KeV and the secondary peaks around 20KeV, as shown in the following graph.

Fig 2 – Am241 gamma spectrum

The classic Cesium 137 source produces the gamma peak at 660KeV and the X-ray peak at 32KeV. The spectrum can be displayed in both linear and logarithmic scales, as shown in the following graphs:

Fig 3 – Linear scale Cs137 gamma spectrum

Fig 4 – Log scale Cs137 gamma spectrum

A significant test is the acquisition of the gamma spectrum of a Thorium 232 source. This spectrum is characterized by numerous peaks of both low and high energy. The following graph shows the spectrum acquired with the instrument, where you can notice the multiple energy peaks corresponding to the various emissions of the Th232 nuclide, highlighted in the graph by the dotted lines.

Fig 5 – Th232 gamma spectrum

KC761B connected to KCMA app

The instrument is equipped with Bluetooth connectivity and can be connected to a mobile phone with the KCMA App installed. This application allows you to view the gamma spectrum of the source under examination on the mobile screen. The application makes numerous commands available for managing the instrument and for improved visualization of the gamma spectrum, the spectrum data can also be stored on files in the form of a CSV file.

Fig 6 – Measurement setup with a mobile phone

Fig 7 – Cesium 137 gamma spectrum shown in the KCMA app

Gamma spectra analyses with InterSpec

The CSV file of the gamma spectrum, obtained from the KCMA app or stored on an SD card directly from the instrument, can be easily viewed on a computer with the InterSpec application, a free-to-use professional software. With this software you can analyze the gamma spectrum in depth, for example, you can modify the linearization coefficients, compare the spectrum with the known emissions of radionuclides and make a quantitative assessment of the activity of the source. The following graphs show some spectra obtained with the KC761B instrument and subsequently processed with InterSpec.

Fig 8 – Am 241 gamma spectrum

Fig 9 – Cs 137 gamma spectrum

Fig 10 – Na 22 gamma spectrum

Fig 11 – Th 232 gamma spectrum


The KC761B instrument is a feature-rich gamma spectrometer. The energy resolution of the sensor is excellent and the detection efficiency is also good, allowing even high energy peaks to be easily detected. The instrument can be used stand-alone, for example for field use, but it can also be connected with the KCMA application on a mobile phone, and the spectra can be stored for subsequent in-depth processing, for example with the InterSpec application.

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Abstract: in questo articolo continuiamo la presentazione del nuovo device KC761B. Nel post precedente abbiamo descritto l'apparato termini generali. Ora ci focalizziamo principalmente sulla funzionalità di spettrometro gamma.