From fd8d8cf852ae44496e4fbe343806b01d3703172e Mon Sep 17 00:00:00 2001
From: James Devine <devine.jd@gmail.com>
Date: Fri, 20 Aug 2021 22:57:30 +0200
Subject: [PATCH]

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+%title: Cosmic Pi - A short intro
+%author: James Devine
+%date: 2021-08-21
+
+-> # Cosmic Rays <-
+
+When we started, we had a crazy idea.
+Let's replicate CERN and put it in a box.
+And make it open source, hardware and software.
+
+--------------------------------------------------
+-> # Muons <-
+==============
+
+* High energy cosmic rays hit the atmosphere.
+* They decay into lower energy particles.
+* Muons can be detected at sea level.
+* With a scintillator, you can 'see' muons.
+
+-------------------------------------------------
+-> # Detector Technology  <-
+
+When we started our project (2014), everyone was using GM tubes.
+This is the cold-war tech you see in movies for radiation detectors.
+We wanted to use current electronics from CERN detectors. 
+
+1. Scintillator material (Muon -> Photons)
+2. Silicon Photomultiplier - SiPM (Photons -> Electrons)
+3. Front end (Electrons -> Digital signal)
+4. Raspberry Pi (Digital signal -> Internet)
+
+-------------------------------------------------
+
+-> # An embedded system  <-
+
+Our version 1 was a simple PCB on top of a Raspberry Pi.
+
+It didn't work. 
+
+-------------------------------------------------
+
+-> # Challenges  <-
+
+A working SiPM based muon detector needs:
+
+* Controllable 30-70V Power supply (step up from 5V USB)
+* Analogue amplifier stages (single photon detection)
+* Trigger (screen out common mode noise)
+* Timing system (ns resolution to be useful)
+* ADC (we don't use it yet!)
+* Other sensors (GPS, Accelerometer, Magnetometer, Humidity)
+
+-------------------------------------------------
+
+-> # Timing Resolution  <-
+
+c = 3e8m/s
+timing bucket = 65ns
+spatial resolution = 20m
+
+This is about what is easily achievable with off the shelf electronic parts.
+Good enough for our application.
+
+-------------------------------------------------
+
+-> # Design Philosophy: IoT  <-
+
+The architecture of the system is critical to success:
+
+* Hard Realtime - Arduino (minimum latency) - C
+* Near Realtime - Raspberry Pi (lowish latency) - Python
+* Archive/Presentation - Raspberry Pi/PC. (buffers) - Python
+
+This is a very common architecture.
+Many systems have this type of requirement. 
+
+-------------------------------------------------
+
+-> # An internet telescope  <-
+
+It took us a few years to make working hardware.
+And then to build the infrastructure needed to harvest!
+
+* Each detector has an MQTT client (lightweight IoT protocol)
+* Single (or multiple) MQTT brokers (messaging bus)
+* Server listens to bus and collects muon data via Python
+* Build database + visualisation with InfluxDB and Grafana
+
+-------------------------------------------------
+
+-> # What can we do with it?  <-
+
+Cosmic rays are implicated in our climate system.
+They can cause cloud nucleation.
+Clouds are very important for our climate.
+
+Two important questions: 
+
+1) How many cosmic rays are there right now?
+2) How many cosmic rays were there before we measured them?
+
+-------------------------------------------------
+
+-> # We are now building up our dataset: <-
+
+* Detector location (Lat/Long)
+* Event time (ns precision)
+* Detector orientation (Acceleration in X, Y and Z)
+* Detector magnetic field (X, Y, Z)
+* Air Pressure
+* Humidity 
+* Temperature
+
+-------------------------------------------------
+
+Let me know if you are interested in our dataset!
+cosmicpi.detector at gmail.com
+
+-------------------------------------------------
+
+-> # Live demo? Yes please!  <-
+
+MQTT: data.cosmicpi.org (port 1883)
+cosmicpi
+MuonsFROMSp8ce
+
+Web: https://data.cosmicpi.org
+
+Blog: https://cosmicpi.org
+
+(a better server is in the post!)
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