LABDOS01 - Scientific, semiconductor-based ionizing radiation spectrometer

LABDOS01 is an open-source spectrometer-dosimeter based on a silicon PIN diode and is intended for scientific research and experimental purposes. Power and communication are secured by a USB-C port or JST-GH connector. The device can be used statically (located in a specific place e.g. laboratory or base) or in mobile applications (such as cars or UAVs). The spectrometer is housed in a 3D printed box, which brings basic mechanical resistance and allows future development of user enclosures and integrations.

LABDOS01 aims to make an open-source, accessible, high-quality, reliable, and simple measuring device - a radiation energy spectrometer for the scientific community.

LABDOS01 can function on its own but requires an external power supply. A computer is only needed to visualize the recorded data. The device is not intended for outdoor use (it is not waterproof). Instead of that, it is intended to be used as an experimental device with the same internals as its application-specific variants like:

• GEODOS01 - Outdoor and stand-alone ionizing radiation detector
• AIRDOS02 - Airborne cosmic radiation dosimeter with GPS
• SPACEDOS02 - PIN diode dosimeter for manned spacecraft
• SPACEDOS01 - CubeSat cosmic radiation dosimeter and spectrometer

LABDOS01 is therefore the all-in-one solution for generic semiconductor-based ionizing radiation measurement. It should be used as a universal experiment testing device before using an application-specific design. Concerning the development of the detectors, Universal Scientific Technologies s.r.o. has established long-term cooperation with the Nuclear Physics Institute of the CAS (Department of Radiation Dosimetry), in the framework of project CRREAT.

The detailed manual is available at UST docs website

Where to get it?

LABDOS01 is commercially available from Universal Scientific Technologies s.r.o., write an email to sale@ust.cz or shop at Tindie store. The device is designed as open-source hardware and software and is released under the GPLv3 license. The device was initially developed and maintained by UST (Universal Scientific Technologies s.r.o.) company, which sells it commercially and offers technical support.

Parameters

• Silicon PIN diode detector with 44 mm³ detection volume
• Effective number of energy channels 470 ±3
• Deposited energy ranges from 60 keV to 7 MeV
• Energy measurement resolution 15 ±2 keV (depending on calibration method and type of particles)
• Power supply 5V (by using the USB port or JST-GH connectors)
• Integration time depends on firmware setup 10 seconds is the default
• Deadtime 1 second in case of writing to SDcard, 100 ms in case of data output to USB
• Interface - USB 2.0, USB-C connector or 3.3V UART link on JST-GH connector (Pixhawk telemetry port).
• Dimensions - 96 x 56 x 19 mm
• Weight - 76 grams

Applications

• AeroSpace or Terrestrial Radiation Monitoring
• Aircraft Onboard Radiation Monitoring
• Scientific High Altitude Balloons, e.g. Pfotzer Maximum measurement
• Educational Toolkit, cosmic ray monitoring
• Radiation Mapping in 3D together with GNSS and UAV
• Space Weather Monitoring e.g. on high-altitude observatories
• Open science
• Citizen science

The device uses USTSIPIN02 which is the core of a range of UST dosimeters specialized to the specific application like AIRDOS or SPACEDOS or GEODOS.

Usage examples

Dosemeter for frequent-flyers

The LABDOS could be easily used as a cosmic radiation dosemeter on board aircraft. In this use case, the LABDOS measures the secondary cosmic radiation generated in the atmosphere or the aircraft fuselage. There is a calculation of the dose rate in silicon for the example flight.

The measured data could be compared with a CARI numerical model, as could be seen in the following graph.

The sum is photons+electrons+protons+positrons. The difference between the sum value and the total value is mainly caused by muons. If we consider some shielding (the LABDOS sensor is covered by 35 um of copper foil) the agreement is clear. It is also visible that the measured data contains more information on the fluctuations, which is missing in the numerical model.

Connection

Simply plug the LABDOS01A into your computer or tablet USB port using a USB-C cable. The device should appear as a virtual serial line. On a Linux computer, the device should connect without any external drivers. For computers with Windows, you will need to install a driver for FTDI USB converter.

This usage case is especially suitable for interactive testing of silicon-based detector setups. E.g. experiments on accelerators, short-term flights, or balloon or UAV experiments where an external logging unit is available.

Output data format

The output message types are described in the following paragraphs. The exact format of each message depends on application-specific firmware. The firmware could be tuned to specific usage cases by modifying the Arduino code. The firmware itself could be updated using the bootloader. The baud rate used by the USB port by default is 115200.

Initial messages

#Cvak...
#Hmmm...
#Filesize,2173540
#Filename,3.txt

The initial messages are sent as soon as the processor is restarted, and reading it correctly indicates that the connection is well set up. Filesize and Filename are information about a file in case a proper SD card is inserted.

About message

As can be seen in the following example, when LABDOS is turned on, a string is sent that uniquely identifies the device.

$DOS,LABDOS01A,L02,256,379276a,1290c00806a200914056a000a0000086

• $DOS - is the first character of the message string
• LABDOS01A - Name of the device. In this case, it is LABDOS
• L02- FW version
• 256 - ADC DC offset
• 379276a - Hash of identifying the commit of firmware
• 1290c00806a200914056a000a0000086 - Unique serial number of LABDOS dosemeters

Data message

$HIST,0,7.94,517,1,13297,48790,2914,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0```

• $HIST - Marking a message with spectrums (histograms)
• count - Measuring number since restart or power-up; Restart can be handled by toggling of DTR signal on an asynchronous interface
• time - Time in seconds from power-up
• suppress - Number of filtered (omitted) ionizing radiation events, prevention of double detections caused by asynchronous sampling
• flux - Number of detected particles per measuring interval (6.88 s)
• energetic channels - All remaining values indicate a certain energy channel from the smallest to the largest deposited energy; The 4th value is 1st channel without noise

Data logging

The data is sent according to a very simple protocol, which is sent in text form. Another option is logging into the integrated SDcard, see the "Stand-alone use" section.

Linux/Android

The device should appear as a virtual serial line without any external drivers. Many serial logging tools could be used to log the LABDOS output, for example, picocom or minicom. Look to LABDOS01A/sw for details.

Windows

For computers with Windows, you will need to install a driver for FTDI USB converter. Then you could use the putty which is a program that can be used for logging. One of the tutorials on how to set up data logging using Putty is here for example.

Stand-alone use

The device contains an SD card, which could be used do data logging in stand-alone use. In that case, the LABDOS01 needs an external power supply. That mode could be used for short-term demonstrating of SPACEDOS, AIRDOS, or GEODOS variants of that device.

Note: Only industrial SLC or SLC mode SD cards with properly implemented SPI interface are supported.

FAQ

How to reset the LABDOS connected over the USB serial link?

The reset could be requested by toggling the DTR signal. The exact implementation of how the DTR UART signal could be accessed depends on the implementation of serial communication software. For example in picocom is asserted by Ctrl+A and Ctrl+P.

How to split Individual file Records of Energy Spectra from the LABDOS01 SDcard log file

The LABDOS01 device performs measurements of energy spectra and stores them in a single file on an SD card, typically named "0.TXT". It is desirable to split the file into individual records to efficiently process and analyze this data. For this purpose, the csplit command can be used, allowing for the automated splitting of the logging file into smaller parts based on a specified line containing a desired pattern.

Description: The csplit command is used to split the logging file of the LABDOS01 device, which contains partial records of energy spectra, into individual measurements. This command enables automated and efficient division of the input file into smaller sections based on a specified line with the desired pattern.

Usage:

1. Create a folder for the output files:

   mkdir split
   

2. Use the csplit command to split the logging file "0.TXT" into individual records:

   csplit -f split/0_ 0.TXT '/\$DOS,LABDOS01/' {*}
   

   The csplit command utilizes the regular expression /\$DOS,LABDOS01/ to identify the line that separates the individual energy spectra records. The output files will be stored in the "split" folder with the prefix "0_" and assigned sequential numbers.

   Upon executing this command, output files containing the individual energy spectra records from the "0.TXT" logging file will be created. These files can be further processed or analyzed independently.

Inline variant of command with creation of output folder and composing each subrecord file

mkdir -p split && cat *.TXT > compose.txt && csplit -b "%04d.dos" -f split/ compose.txt '/$DOS,LABDOS01/' {*}