Light-1 and RAAD
Introduction:
The Rapid Acquisition Atmospheric Detector (RAAD) is a detector designed and built for the detection of a phenomena called Terrestrial Gamma-Ray Flashes (TGFs).
TGFs are sub-millisecond bursts of Gamma Rays with energies that can reach up to several tens of MeV. Seriously fast and powerful, and they are produced here in our atmosphere!! Thus, they are very interesting for us to study.
These TGFs have been found to be associated with thunderstorms and lightning activity. They are attenuated by the atmosphere, thus the best way to observe them is from above where there is less air to attenuate them. And so, it was proposed to put RAAD on a CubeSat and launch it to space to conduct a study on TGFs.
RAAD is an acronym that was also chosen for its similarity to the Arabic word “Ra’ad” ( رعد ) which means thunder. It seemed fitting as both thunder and TGFs were biproducts of lightning.
RAAD was a project that started by a team from NYUAD. After it won the UAE Space Agency's MiniSat Competition in 2018, it was granted a chance to fly to space in a CubeSat that was later named Light-1.
Light-1 was launched to space on the 21st of December 2021, and was deployed from the International Space Station on the 3rd of February in 2022.
Detector Design:
As Gamma Rays cannot be seen by eyes or cameras, the way to detect them is to use scintillators. Scintillators detect particles by absorbing part of the particle's energy as it passes through the crystal, and then emit that energy back in the form of visible light. PhotoSensors are attached to these scintillators to capture that light and turn it into readable signals that can be recorded and studied.
RAAD is composed of two detectors. The first detector is made of a 2 x 2 array of low background Cerium Bromide scintillating crystals coupled with 4 Multi-pixel Photon Counters. The second detector is made of 2 Cerium Bromide crystals and 2 Lanthanum BromoChloride crystals, all of which are optically connected with 4 PhotoMultiplier Tubes. Thus, RAAD is made up of 8 detection units in total.
As the scintillator crystals are sensitive to photons and charged particles alike, a VETO layer of plastic scintillators is added around the crystals. VETO can detect charged particles but not Gamma Rays, thus it can be used to filter out unwanted data. In this picture we find the 8 VETO channels wrapped around the crystal array of one of RAAD's Detectors.
In this picture, from left to right, we find the electronics board of one of the RAAD detectors, a Multi-Pixel Photon Counter unit, a PhotoMultiplier Tube, and the combination of Scintillator crystal array with VETO. The two different photosensing components of each of the two RAAD detectors are clearly different in size. They are the reason one detector takes up 1U of the 3Us of the CubeSat, while the other takes up around 0.7U.
A picture of Dr. Adriano peacefully working on RAAD during the pandemic.
The exploded 3D model of the Multi-Pixel Photon Counter unit showing how the components are aligned.
The 3D Model of the two RAAD detectors integrated into the Light-1 Bus system.
Light-1 was launched to space on the 21st of December, 2021. It was launched from the Kennedy Space Center on a SpaceX rocket.
Destination: International Space Station!
On the 3rd of February, 2022, Light-1 was deployed into orbit via JAXA's Japanese Experiment Module (JEM) with an initial altitude of 400 km.
Panos, Lolowa, and Tengiz worked on analyzing the data received from Light-1. Panos created a new GEANT4 simulation for the detectors, and built a solid code for obtaining, decoding, and analyzing the data.
On the 18th of July, 2023 - The Light-1 team presented the updates of the mission and the state of the data analyzed before the UAE Space Agency.
