Multi Channel Analyzer for Gamma Spectroscopy With Arduino & Theremino (2024)

Multi Channel Analyzer for Gamma Spectroscopy With Arduino & Theremino (1)

By stoppi71 in WorkshopScience





Introduction: Multi Channel Analyzer for Gamma Spectroscopy With Arduino & Theremino


I'd like to show you my homemade multi-channel-analyzer for gamma spectroscopy using a.) the freeware theremino and b.) an arduino.

First of all I have to say some words about gamma spectroscopy at all. To detect radioactive decays you need a detector like a geiger-Counter. For gamma-spectroscopy you have to take a photomultiplier combined with a scintillation crystal made of sodium Iodide. You can get both things on ebay for less than 100 USD.

The gamma-rays from the radioactive source is going through the scintillation crystal and produce very faint light-flashes. Those light-flashes are recorded by the photomultiplier, who converts them is small voltage-pulses at the Output. For this the photomultiplier and the Crystal have to be in a absolutely light-tight housing. I use shrinkable tubing for that.

The Job of the multi-channel-analyzer (MCA) is to measure the height of those pulses coming from the photomultiplier. This is because every gamma-photon produces a voltage-pulse with a height depending on it's energy. The higher the energy of the gamma-photon, the higher the voltage pulse.

When the pulse-height has been measured, the number pulses with this recorded amplitude can be increased by one. At the end you get a spectrum of number of pulses versus pulse-height, which is characteristic for each radioactive element. For example cesium-137 emits gama-rays with an energy of 662 keV. They will produce pulses with a certain pulse-height. With a MCA you'll get a spectrum with a peak at a certain voltage corresponding to the pulse-height. Therefore you can identify radioactive sources with a MCA.

You don't get just the so called photo-peak, but also characteristic structures like the compton-edge, which is produced by the scattered electrons.

Step 1: High Voltage Power Supply

For the photomultiplier you'll need a high-voltage power supply. Most of the PMT (photomultiplier-Tubes) Need voltages between 800 V and 1500 V. I use a negative voltage, because then you'll get the signal from the PMT in an easier way.

There are a lot of different methods producing the high-voltage. In my case I use a cheap CCFL-Inverter combined with a simple electronic stabilization.

Step 2: The MCA Freeware Theremino

With the MCA-Freeware theremino ( you're able to record gamma-spectra in a very easy way. You'll just need the detector (photomultiplier + scintillation-crystal), the high voltage power supply an a cheap USB-Sound Card (




Step 3: The DIY-MCA With Arduino

Though the Freeware Theremino is a nice and well functioning Software I tried to realize an MCA with an arduino. The principle is quite simple:

First the storage capacitor of the Peak-detector is discharged. Then I close the Switch of the Peak-detector and wait until I get a pulse from the monoflop. Then I open the Switch and read in the voltage of the capacitor, which is equal to the maximum voltage of the incoming pulse. After this I refresh the graphics by adding one at the matching column.

To see whether the reading of the peak-voltage is fast enough, I inserted a test-pulse immediately after a variable delay and after I've read the voltage of the storage-capacitor. This confirmed my guess that without a delay I really measure the Peak-voltage and the capacitor isn't noticeably unloaded.

To make another test I fed my MCA with pulses with just one and not varying amplitude. You can see the result in the picture. I got a real spectrum with just one line as it should be.


  • Arduino_MCA.ino


Step 4: The Peak Detector

For the MCA you need a circuit, which stores the height of an incoming pulse. I use a very simply method with a transistor, a diode and a capacitor. In the pictures you can see the pulses from the photomultiplier and the voltage of the peak-detector. The voltage of the peak-detector gets exponentially lower with time because the capacitor looses his charge over the resistor.

Step 5: The Complete Device

The complete device consists of the following In- and outputs:

  • signal In: Here the signals from the photomultiplier are coming in
  • gain: to vary the signal-heights
  • offset: to vary the offset of the pulses
  • signal out: to check the Signal with an oscilloscope
  • comparator-level: to vary the level from which a signal is sent to the monoflop
  • to counter: the significantly longer signal from the monoflop for external counters or something else

Step 6: Results

Here are some spectra taken with a Thorium-mantle (), an autunite and a cesium-spark-gap-tube. You can clearly see the photopeak at 662 keV...

Maybe you'd like to take a look at my YouTube-channel:

more physics projects:

Multi Channel Analyzer for Gamma Spectroscopy With Arduino & Theremino (9)

Participated in the
Explore Science Contest 2017

Multi Channel Analyzer for Gamma Spectroscopy With Arduino & Theremino (2024)


What is the purpose of multi channel analyzer? ›

A multichannel analyzer (MCA) is an instrument used in laboratory and field applications to analyze an input signal consisting of voltage pulses.

Which detector is ideal for gamma ray spectrometry? ›

The best gamma ray energy resolution is obtained with HgI2 detectors less than 4 mm in thickness. A similar situation exists with CdTe and limits detector thicknesses to about 2−4 mm.

What is the difference between single channel analyzer and multi channel analyzer? ›

However the single channel analyzer will only exam these detections for one set level of energy at a time and then must be manually adjusted to look at the detections of another energy. The multi channel analyzer will sort the detections by their energy level as they are detected.

How does a gamma ray spectrometer work? ›

Gamma rays emitted from a radioactive source that are absorbed in the HPGe detector produce electrical pulses, and the pulse amplitude is proportional to the energy deposited in the detector, which allows for measurement of gamma ray energies.

How does multi-channel work? ›

Multi-channel refers to the use of several media channels for spreading marketing messages. This can include email, social media, print, mobile, display ads, television, and more. Leveraging multiple channels allows brands to interact with their customers across multiple touchpoints for a more comprehensive campaign.

Why should you use multiple channels? ›

By using multiple channels, marketers can target a wider audience and increase the probability of reaching customers in the most convenient way for them. Customers usually interact with multiple touchpoints before converting––they may discover, research, and finally purchase on different mediums.

Which instrument has the highest efficiency detecting gamma radiation? ›

For instance, sodium-iodide (NaI) scintillation detectors have a higher efficiency for gamma radiation than the GM probes and therefore they are more sensitiveefficient.

Why is it difficult to detect gamma radiation? ›

Unlike optical light and x-rays, gamma rays cannot be captured and reflected by mirrors. Gamma-ray wavelengths are so short that they can pass through the space within the atoms of a detector.

What is the difference between gamma-ray spectroscopy and spectrometry? ›

Gamma-ray spectroscopy is the qualitative study of the energy spectra of gamma-ray sources, such as in the nuclear industry, geochemical investigation, and astrophysics. Gamma-ray spectrometry, on the other hand, is the method used to acquire a quantitative spectrum measurement.

What is multi-channel analysis? ›

Multichannel analytics or multichannel reporting is a business process that combines data from multiple sources or channels into a single location. For example, if you own three online stores, then you can aggregate the data of each store into one single place through the help of a multichannel analytic tool.

What is a multichannel detector? ›

The multichannel detector is divided into a number of horizontal strips, corresponding to the output from each fiber. In this manner, multiple spectra can be measured simultaneously.

What is multi-channel testing? ›

Multi-channel testing is a user research method that involves evaluating the user experience and functionality of a product across multiple channels.

Why is gamma spectroscopy important? ›

Gamma spectrometry is used to detect, identify and quantify gamma-emitting radionuclides (e.g., 131I, 60Co, 134Cs and 137Cs). It allows simultaneous analysis of multiple radionuclides, often with little or no sample preparation, and is therefore a basic technique used for radionuclide monitoring.

What device detects gamma rays? ›

Gamma-ray detectors can be placed in two broad classes: spectrometers and imagers. The first class would typically be called spectrometers or photometers in optical astronomy.

What is the difference between spectrometry and spectroscopy? ›

Essentially, spectroscopy is the study of radiated energy and matter to determine their interaction, and it does not create results on its own. Spectrometry is the application of spectroscopy so that there are quantifiable results that can then be assessed.

Why use a multi-channel approach? ›

A multichannel strategy can help you reach your people where they are, keep all your marketing work in one convenient place, and increase your ROI over time. Best of all? They're not as expensive or complicated as you think. And you don't have to use all the channels on day one!

What is the benefit of multi-channel distribution? ›

You'll reach a wider audience

Selling through multiple sales channels not only helps you reach a wider audience, but it also provides an opportunity to diversify your product line and serve multiple demographics.

What is a multi-channel amplifier used for? ›

Multi-Channel Amplifiers

For example, different volume levels in different rooms, turning rooms on and off remotely and allowing different audio sources to be played in different rooms simultaneously.

Top Articles
Latest Posts
Article information

Author: Virgilio Hermann JD

Last Updated:

Views: 6476

Rating: 4 / 5 (41 voted)

Reviews: 88% of readers found this page helpful

Author information

Name: Virgilio Hermann JD

Birthday: 1997-12-21

Address: 6946 Schoen Cove, Sipesshire, MO 55944

Phone: +3763365785260

Job: Accounting Engineer

Hobby: Web surfing, Rafting, Dowsing, Stand-up comedy, Ghost hunting, Swimming, Amateur radio

Introduction: My name is Virgilio Hermann JD, I am a fine, gifted, beautiful, encouraging, kind, talented, zealous person who loves writing and wants to share my knowledge and understanding with you.