Measuring Muon Decay with Red Pitaya: Affordable Cosmic Ray Detection for Education and Research

Bringing Particle Physics into the Classroom

Cosmic rays constantly bombard Earth, producing a shower of secondary particles in our atmosphere. Among them, muons play a central role in modern physics experiments. Measuring the decay of these short-lived particles not only demonstrates fundamental physics principles but also provides an excellent educational opportunity. 

Traditionally, such experiments required expensive laboratory equipment. Today, with the Red Pitaya STEMlab platform, researchers, educators, and students can design affordable, open-source experiments that rival professional setups. In this article, we show how Red Pitaya was used to build a DIY muon decay detector based on a plastic scintillator and a photomultiplier tube (PMT). 

Complete apparatus with the detector and Red Pitaya card

What Is Muon Decay and Why Does It Matter? 

Muons (μ) are unstable elementary particles with a mean lifetime of about 2.2 microseconds. They are produced when cosmic rays collide with atoms in the upper atmosphere. Despite their short lifetime, relativistic effects allow many muons to reach sea level, making them detectable with relatively simple equipment. 

Understanding muon decay introduces students to: 

• Exponential decay laws in particle physics. 

• Special relativity through time dilation effects. 

• Hands-on experimental methods in high-energy physics. 

For educators, it’s a practical way to bring advanced physics concepts into the classroom or lab using accessible tools. 

Building a DIY Cosmic Ray Detector with Red Pitaya

The experiment described here combines low-cost components with Red Pitaya’s powerful data acquisition capabilities: 

• Plastic scintillator (BC412): Converts muon energy into light. 

• Hamamatsu R6233 photomultiplier tube (PMT): Detects the light flashes. 

• Custom readout electronics: Amplifies and filters the signals. 

• Red Pitaya STEMlab 125-14: Captures, analyzes, and processes the pulses. 

Unlike traditional laboratory instruments, Red Pitaya acts as a flexible oscilloscope, spectrum analyzer, and data processor all in one compact board. Its FPGA-based architecture allows precise pulse timing measurements, essential for identifying muon decay events. 

 Internal view of the electronics

How the Experiment Works: Detecting Muon Decay Events

The muon detection process works as follows: 

1. A muon enters the scintillator, slows down, and produces a first light pulse. 

1. After a short delay, the muon decays into an electron and neutrinos. The electron produces a second light pulse. 

1. Red Pitaya records both pulses and measures the time interval between them. 

1. Thousands of such events are collected and processed using software (e.g., ROOT), yielding an exponential distribution that reveals the muon lifetime. 

In this experiment, more than 10,000 muon decay events were successfully captured, giving a measured lifetime of 2.100 ± 0.027 μs—in excellent agreement with theoretical predictions. 

TIA amplifier scheme

Red Pitaya as a Data Acquisition Tool for Physics Experiments

Red Pitaya offers unique advantages for researchers and educators: 

• High sampling rate (125 MS/s, 14-bit ADC): Ideal for fast particle interactions. 

• Compact and affordable: Fits in the palm of your hand, reducing lab costs. 

• Open-source and programmable: Enables full customization of data acquisition and analysis. 

• Versatile applications: Functions as an oscilloscope, logic analyzer, spectrum analyzer, or custom FPGA platform. 

By lowering costs and complexity, Red Pitaya makes cutting-edge experiments accessible to universities, high schools, and DIY science enthusiasts. 

Making Particle Physics Accessible to Everyone

The muon decay measurement described here proves that high-level physics experiments no longer require million-dollar labs. With a simple scintillator-PMT setup and the Red Pitaya STEMlab board, it’s possible to explore fundamental particle physics in an educational or hobbyist setting. 

This approach not only demonstrates the power of open-source science but also inspires the next generation of physicists, engineers, and curious minds to explore the building blocks of our universe. 

This project was created by Lappetito Lodovico and originally published on Physics Open Lab: Muon Decay Measurement with Red Pitaya