Cosmic Array

An array of cosmic ray detectors across a landscape that demonstrates in light and sound how cosmic rays are constantly all around us.

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Each detector in the array is designed to produce deferent coloured light and sound depending on the direction of the cosmic ray (muon) passing through it. Observers will witness in real time, how cosmic rays are all around us, as each detector twinkles with sound and light. Further, as cosmic rays arrive in showers of particles, from time to time, these detectors will trigger in unison. The experience something similar to the sights and sounds of life. Flocks of birds, cicadas, or fireflies, where their actions fade in and out from randomness into unison. Cosmic Rays originate from interstellar space, particles thrown off in the catastrophic death of stars. Ever present throughout the entire evolutionary history of life on our planet. This display reinforces our connection with the immense scale, age and complexity of the universe and the importance of science. Maybe to help grow an appreciation of how tiny our planet is, so precious, rare and fragile, something worth protecting.

This project provides an interesting window into the universe and the natural world around us, leaving the observer to form their own connections and conclusions. Hopefully creating some discussion and maybe some small appreciation of the scale, age and complexity of our universe and how tiny our planet.  Something very precious indeed, rare and fragile, something worth protecting.  Similar ideas inspired by Carl Sagan in his book the Pale Blue Dot in 1994 from an image taken by Voyager 1 spacecraft on February 14, 1990.

Cosmic Rays have been present throughout the entire evolutionary history of life on our planet and so this display reinforces our connection with the universe and the importance of science and understanding the natural world.

When the public came to visit the array, they experience how cosmic rays are all around us and arrive in showers of particles. Each detector randomly twinkles with colours and sounds triggered by cosmic rays. 

The experience not unlike colourful wind chimes.

However, as cosmic rays arrive in showers of particles, some of these detectors will trigger in unison and others randomly.  A similar experience to what can be witnessed in nature like the sounds of Cicadas or the flashing light of Fireflies, where both sound and light fade in and out from randomness into unison.

Each detector in the array produced a bright flash of one of 4 colours (red, green, blue or white). In the same manner, one of 3 musical notes and all 3 notes ( a Chord) together, depending on the trajectory of the muon that passed through two or more Geiger–Müller tubes simultaneously.  A combination of copper radiation shielding and coincidence detection methods were used to filter out local background radiation.

The system used for playing sounds and other IoT functions utilises the latest Raspberry Pi Zero W and the code was developed by Paul Schulz.  The IoT setup was very successful with this arrangement and were able to stream live data to another computer where it was mapped into music using MAX/MSP software.

Information about Cosmic Rays, what they are, their origins and how to detect them are on my website here: (open source)

I'm working on a number of different design approaches to this project as it will need to be more cost effective if I was to build a larger installation of 100 or more detectors. The detectors in the array may be enclosed in a type of bollard lamp post, sphere, something that hangs on a tree or tripod or is put in the ground like a paving block.

A real-time demonstration using 16 Detectors was on display in Adelaide for the Splash Adelaide winter festival on the 2nd and 3rd of September 2017.  The installation was very successful will allot of public interest, questions and discussion about the universe.  The IoT setup was also very successful using Pi Zero W and we were able to stream live data to another computer where it was mapped into music using MAX/MSP software where combined into a beautiful musical soundscape. 

The array was also on display along with other detectors I have made at Maker Faire Adelaide on 2nd November 2017 and was the winner of Best Backyard Science award. Maker Faire Adelaide is the largest Maker Faire in Australia and in the Southern hemisphere. Also the only Maker Faire solely run by volunteers. 

Winner of 2 semifinals in the 2017 Hackaday prize

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Cosmic ray information.pdf

Poster about Cosmic Rays for Maker Faire Adelaide

Adobe Portable Document Format - 1.44 MB - 10/31/2017 at 08:32


XXLX-7875-G (2).zip

PCB Gerber Files V8

x-zip-compressed - 18.29 kB - 09/05/2017 at 03:59


Cosmic Array V8.pcb

PCB Design using ExspressPCB V8

pcb - 28.10 kB - 07/11/2017 at 12:02


Cosmic Array.pcb

PCB Design using ExspressPCB V7

pcb - 29.77 kB - 06/10/2017 at 23:05


  • 3 × Resistor 10M Ohm 0.25W, 1/4W SMD 1206 HV
  • 3 × Capacitor 10pF ±5% 1kV Ceramic NP0 SMD 1206
  • 1 × LM2576S-ADJ Step-Down 3A 5-Pin TO-263-6 SMD D²Pak
  • 1 × Voltage Regulator Positive Fixed 5V 1A SMD DPAK-3
  • 3 × Green LED 2.2V SMD 0805

View all 33 components

  • Reworking embedded computer software

    Paul Schulz06/23/2018 at 01:03 0 comments

    In order to make each detector easier to manage for end users we are looking into alternatives to Emdebian. 

    This isn't an issue with the operation of the detector. Once a system has been setup, the Operating System (OS) can be changed as easily as rebooting and swapping MicroSD cards. 

    One alternative OS is OpenWrt/LEDE, which has recently merge again after a fork. One benefit of OpenWrt/LEDE is that it comes with a web based configuration tool - Luci. As well as a 'registry' style of configuration management (in /etc/config, and managed via the 'uci' tool), the web interface provides an easy way of managing the network connectivity and getting to device onto a network. 

    With the Raspberry Pi Zero W running Openwrt, there are instructions available to allow network connectivity via USB to a connected PC.

    Another useful piece of the puzzle is the build environment that comes with OpenWrt/LEDE. It should be possible to build an ipkg with our cosmic-array software which will improve development, deployment and version control. What this space. 

  • Science - Next month of data (April and some May)

    Paul Schulz05/13/2018 at 09:22 0 comments

    The next month and a bit of data is now available at github.

  • Science - More muon detection data

    Paul Schulz04/03/2018 at 09:45 0 comments

    More muon data has been processed.. the raw data and processing scripts (using the Jupyter Notebook, for running interactive Python) can be found here -

  • Science - Muon detection rates

    Paul Schulz02/18/2018 at 01:41 0 comments

    Muon Detection Rate Data

    One of the muon detectors (cosmic-array-2-3) has been turned on and left running for an extended period of time and the event data collected, and is displayed in the graph below. (Click on the image to see all the details as the axes don't show up on black with the transparent background.)


    • The large break in the data was when I was at Linux.Conf.Au., doing a presentation on the project (and at the embedded miniconf). The other break was when I had to unplug the detector because it was stopping someone in the family going to sleep.
    • The detector has been aligned oriented North-South with the power lead pointing North. 
    • In this detector, the Red(0), Green(1), Blue(2) channels have been wired into the RaspberryPi in the order Red,Blue,Green, which doesn't match the other detectors. Blue and green channels have been swapped.
    • The colours in the graph do not match the channel colours.

    Observations on the data:

    • Channel 2 has a consistent rate of about 130 counts per 2 hours (120 sec) over the entire period.
    • Channels 0 and 1 start at the same rate, but increase together to almost double in the second half of the graph before falling back to around 50% higher than channel 2.
    • A daily cycle of minimums and maximums can almost inferred between 2018-02-01 and 2018-02-08 (if you squint a little bit).

    Data Processing

    This data was collected directly on  RaspberryPi Zero W in the Cosmic Array muon detector (cosmic-array-2-3) and logged to a file in the form of 'timestamp channel', where the timestamp is a Unix timestamp (seconds since 1 Jan 1970) with microseconds.

    1516084564.897229 1
    1516084600.713800 2
    1516084615.300136 1
    1516084617.992265 0
    1516084673.840925 0
    1516084676.053668 0
    1516084686.885977 1

    Using interactive python workbook software,  Jupyter, this data was  read and processed with the Pandas library and plotted with matplotlib.

     All scripts and data are available in the Github repository - PaulSchulz/cosmic-array-science

  • Upgrading a Cosmic Array detector element for standalone use.

    Robert Hart01/28/2018 at 04:06 0 comments

    Upgrading a Cosmic Array detector element for standalone use.

    Recently I upgraded a Cosmic Array detector element for standalone use. This includes replacing the Raspberry Pi Zero W with a full Raspberry Pi 3B for faster processing speed and improved audio. 

    Original unit used in Cosmic Array installation.

    Wiring was improved to reduce noise and GMT cables were replaced with HV Teflon coated RG178 coax to reduce false muon counts. With the addition of external connectors for access to electronics including RPi3 USB, LED Driver, DC Power and direct Audio out from RPi3.

    Inside unit with upgrades
    Operating detector with upgrades 

    In the original concept of this detector I planned to drive acoustic instruments from the output of the detector. But due to budget and time constraints a raspberry pi zero w was chosen to play wave files. Consequently it is design to drive solenoids or contractors directly.  This modification allows the user to  drive anything from large gones to glockenspiel to other electronic or midi devices.     

    Note each LED output driver pulls low to 0V/Ground.  

  • Cosmic Array at the Sydney​ 2018

    Robert Hart01/20/2018 at 03:31 0 comments

    At the Sydney 2018 linux.conf.auPaul Schulz will be giving a presentation about the Cosmic Array and  software development. Paul, has been a key person in development of the sound and wireless networking aspect of the Cosmic Array.

  • Winner for best backyard science @ Maker Faire Adelaide 2017

    Robert Hart11/05/2017 at 10:35 0 comments

    We setup the Cosmic Array in quite a large space at the rear of Maker Faire Adelaide at 8am.

    Left to right - The Cosmic Array, then some units opened up so people can look inside, then my early Drift Hodoscope, then my 81 Pixel Hodoscope which was connected to a computer to play music and regenerative graphic. 

    Although it doesn't look it. It was quite busy as we where located right at the end of the Maker Faire. 

    Above is Paul Schulz, who has developed code for the Cosmic Array and was a great help all day.  He will be doing a presentation at the next - 2018.

    A very busy day lots of questions and was  the Winner for best backyard science.

    Got this award presented by MickMake one of my favorite Youtubers 

  • Preparing for Maker Faire Adelaide 5th Nov

    Robert Hart10/30/2017 at 07:00 0 comments

    I am currently busy preparing for Maker Faire Adelaide this weekend and so I will have the 16 detectors running live, along with other detectors I have made and more details on its operation.  

    Maker Faire Adelaide is the largest Maker Faire in Australia and in the Southern hemisphere. Also the only Maker Faire solely run by volunteers.   So if you are in Adelaide this weekend come and say hi!

  • Si Pin Photodiode solid-state detector first draft.

    Robert Hart10/06/2017 at 04:02 0 comments

    I'm currently exploring a new solid-state detector design using Pin Si Photodiodes, this is still a few months away. But will be a feature of a new cosmic ray detector designs to come.   The main issue with using Geiger–Müller tubes and Photomultiplier scintillators as detectors is mostly cost. But also includes limited life and high voltages between 400 to 1600V DC which must also be low noise and regulated. 

    Solid state devices particularly Si Pin Photodiodes are capable of measuring both ionising radiation (Muons) and some added benefits like energy resolution, low voltage, low power, greater longevity and lower cost. But do have issues and compromises such as: more complexity, noise, and a small aperture size.  

    There are some specialist Photodiodes designed specifically for this application, but these are very expensive and difficult to source in small quantities for example:

    • Manufacture First Sensor Part # 5014450 - has visible light filter 
    • Manufacture First Sensor Part # PS100B-7-CERPINE - has visible light filter 
    • Hamamatsu Part # S3590 - no visible light filter

    Here is an example using the First Sensor 5014450 and an old CD V-700 Geiger Counter check source which is radium 226Ra.  Although successful, the detector is expensive (~$50au) and still only has a relatively small aperture compared with a  Geiger–Müller tube, so multiple detectors would be required.

    There are lower cost of-the-shelf Pin Photodiodes such as the BPW34F which have been featured in many DIY radiation detector projects over the years. However, these have an even smaller aperture.  So many will need to be connected together to increase it.  However, they can not be simply wired in parallel due their combined capacitance.   Here is rough layout that I have began experimenting with using JFETs to buffer each photodiode before amplification. 

  • Splash Adelaide 16 Detector Array

    Robert Hart09/06/2017 at 09:26 0 comments

    The Splash Adelaide installation was very successful will allot of public interest and questions.  The IoT setup also went well and we were able to live stream data to another computer where it was mapped into music using MAX/MSP software.  The sounds in the following video include bell sounds from each detector and also the combined musical soundscape generated in MAX/MSP. 

View all 38 project logs

  • 1
    Considerations for building a cosmic ray detector

    Cosmic Rays are created high in the earth's atmosphere (~30km) and the resulting shower of subatomic particles are what we can detect at sea level.  These particles interact with atmosphere, decay or are difficult to detect, but the muon the heavier cousin of the electron can be detected as it has a charge and can ionise matter as it passes through.   Consequently it can be detected using any ionising radiation detector such as: Cloud chambersElectroscopeGeiger CountersSpark Chambers, Resistive Plate Chambers, and materials called Scintillators which give off light when an ionizing particle passes through them.

    A muon  has a measured mean lifetime of 2.2 microseconds and should only be able to travel a distance of 660 metres even at near the speed of light and so should not be capable of reaching sea level. However, Einstein’s theory of relativity tells us that time ticks slowly when moving at speeds close to that of light. Whilst the mean lifetime of the muon at rest is only a few microseconds it moves at near the speed of light and so its lifetime is increased by a factor of ten or more giving them plenty of time to reach the ground and be detected.

    The problem of using a radiation detector for a cosmic ray observations, is that there is larger amounts of terrestrial radiation as much 73% of background radiation is Alpha, Beta, and Gamma from the natural decay of matter. Although in small quantities it is sufficient to make it difficult to discriminate between a terrestrial or cosmic sources.

    Consequently, at least two detectors are needed placed one above the other, feed into electronics that can monitor coincidence between the two detectors quickly thus, filtering out most terrestrial radiation.

    Cosmic particles travel at nearly the speed of light and so do not ionise very efficiently and hence can travel through matter very easily passing through metal shielding and both detectors without effort, whereas the terrestrial radiation may not. Consequently anything detected in both detectors simultaneously is more likely to be a cosmic event than terrestrial.

    Well almost simultaneously, if a muon is travelling at 0.998c and the detectors where spaced 5cm apart the actual flight time of a muon would be just 0.16ns. However as the detector and electronics response and delay times would be much slower than this, we can say in "real-life" terms it is simultaneous.

    The main idea of coincidence detection in signal processing is that if a detector detects a signal pulse in the midst of random noise pulses inherent in the detector, there is a certain probability, p, that the detected pulse is actually a noise pulse. But if two detectors detect the signal pulse simultaneously, the probability that it is a noise pulse in the detectors is p2. Suppose p = 0.1. Then p2 = 0.01. Thus the chance of a false detection is reduced by the use of coincidence detection.

  • 2
    Geiger–Müller Tubes

    I've had comments regarding the validity of using Geiger–Müller Tubes for a cosmic ray (muon) detector. Pointing out that Photomultipliers and scintillation panels are best, and yes the are far more effective. However, they are also expensive, whereas Geiger–Müller tubes are relatively cheap and easily available to purchase.

    History is full of examples of physicists using Geiger–Müller tubes for cosmic ray observations up to the 80s. Geiger Tube Telescopes (GTT) were used by NASA including many Pioneer spacecraft missions and others. One most notable user was Bruno Benedetto Rossi a famous Italian experimental physicist who made major contributions to particle physics and the study of cosmic rays. At the age of 24, he fabricated his own Cosmic Ray detector using Geiger–Müller tubes and then went on to invent the first practical electronic coincident circuit.

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Enjoy this project?



Frank wrote 08/09/2018 at 04:56 point

Hello Robert,

I am very impressed with your Cosmic Array. VERY IMPRESSIVE and a very great tool to get people interested in Science.

It also is used as an ART object, which is great as it combines "Art" (real art) with science and technology.

My question: Robert, is this a permanent display? Or can it be used in other places than Adelaide, like for instance Ararat (Vic)? I would love to see this Cosmic Array in Ararat's new Arts Center, I am sure it would be a great talking point and raise awareness of Science.

Please email me with your comments.

  Are you sure? yes | no

za1630219 wrote 02/18/2018 at 02:56 point

I'd just like to pop in and say this is a super cool project. I'd love to see it in person, maybe I'll just have to build something of my own!

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Robert Hart wrote 06/10/2017 at 01:56 point

Hi followers, I now receive seed funding for this project for every click of the like button.

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Andrew Bolin wrote 05/08/2017 at 23:22 point

Congratulations on being one of the winners of the concept round. 

Good to see another Aussie on here! If the project goes well, maybe you could consider bringing it up to Sydney for Vivid.

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Robert Hart wrote 05/09/2017 at 07:28 point

Hi Andrew, Thank you, I'm currently building a small array of 20 detectors for the Splash Adelaide Winter festival. Btw I'm originally from Sydney, moved to Adelaide 20 years ago.

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DontStalkME wrote 04/05/2017 at 08:43 point

Could you make it cheaper by using tin-can ion detectors? Or make your own GM tubes? You could get funding by pre-selling the boxes on kickstarter. Then after you get some images you can ship them out. This assumes you are not wanting a permanent installation.

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Robert Hart wrote 04/08/2017 at 22:15 point

Hi DontStalkME, An Ion detector can indeed detect Muons, in fact the very early discoverers of cosmic rays used such detectors. However, they are slow, unstable and are effected by other environmental factors like humidity.  Nevertheless I have developed a solid state detector using a matrix of low cost SiPIN photodiodes. Just haven't published this yet as it is a rat nest gamma detector and not yet in a coincidence detector configeration. 

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biemster wrote 10/23/2016 at 19:03 point

Very nice idea! I've worked for cosmic shower detectors in Holland (HiSparc) and Argentina (Auger). The shower front on earth' surface is usually multiple kilometers wide, what inter-detector spacing are you planning to use?

For HV generation you could consider PWM and a boost converter, something like I did here #ESP8266 Geiger counter. The circuit could easily be adapted to count events on the three tubes on different GPIO's of the uC. That would simplify the schematic quite a bit, and if you choose for the ESP as well you can easily network them together too.

In addition to my inter-detector spacing question, how many stations are you planning?

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Robert Hart wrote 10/24/2016 at 06:31 point

Hi Biemster,  Thank you! This in the very early stages of development, mostly a proof of concept. I've built many cosmic ray detectors, Geiger counters and PMT counters, just for lolz.  I have developed a good power supply but I fear it's a little over the top for this project and if I want to build a 100 lets say it would be difficult to fund as a hobby project.  So yes I've been thinking about a boost switch-mode approach.   I'm also considering a solid-state detector as well, which I've also been working on.  For this project I might just build a few using GM tubes as demonstration pieces and then maybe go for some crowd funding.  3 ideas I have for an installation would be 1) bollard lamp post in a city parkland 2) block paving bricks 3) across a remote desert landscape below a hill.  these detectors would be placed a few metres apart and most likely 100 or more.  

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