ASTRI

ASTRI Mini-Array: Advanced Gamma-Ray Astronomy with Custom Electronics

The ASTRI Mini-Array is an ambitious project led by INAF (Istituto Nazionale di Astrofisica) aimed at building a network of nine dual-mirror Cherenkov telescopes. Installed at the Teide Observatory in Tenerife, at an altitude of ~2400 meters, this array is designed to capture the faint traces of high-energy gamma photons from distant astrophysical sources. The energy range—between 1 and 300 TeV—is one of the least explored windows in gamma-ray astronomy.

By detecting the brief flashes of Cherenkov light produced when these gamma rays initiate atmospheric particle showers, ASTRI can reconstruct the origin, energy, and timing of the original photons. Each telescope is equipped with highly reflective optical mirrors and a fast focal plane camera, capable of resolving events on nanosecond timescales.

ASTRI Install site. The ASTRI Mini-Array is located at the Teide Observatory in Tenerife, at an altitude of ~2400 meters. The high altitude provides a clear view of the night sky, minimizing atmospheric interference.

ASTRI Install site. The ASTRI Mini-Array is located at the Teide Observatory in Tenerife, at an altitude of ~2400 meters. The high altitude provides a clear view of the night sky, minimizing atmospheric interference.

Night view of the ASTRI telescope during a test run. The stars are visible in the background.

Night view of the ASTRI telescope during a test run. The stars are visible in the background.

ASTRI Camera installation. The camera is mounted on the telescope’s focal plane, where it captures the Cherenkov light produced by gamma-ray interactions in the atmosphere.

ASTRI Camera installation. The camera is mounted on the telescope’s focal plane, where it captures the Cherenkov light produced by gamma-ray interactions in the atmosphere.

Detail view of the optical filter used in the ASTRI camera. The filter is designed to transmit Cherenkov light while blocking other wavelengths, ensuring that only the relevant signals are captured.

Detail view of the optical filter used in the ASTRI camera. The filter is designed to transmit Cherenkov light while blocking other wavelengths, ensuring that only the relevant signals are captured.

First image captured from the ASTRI camera after the installation. It is possible to recognize the different crightness of the the sky compared to the ground in the variance plots of the light captured.

First image captured from the ASTRI camera after the installation. It is possible to recognize the different crightness of the the sky compared to the ground in the variance plots of the light captured.

First event captured. The top plots show the ariance in both High Gain and low gain, while the bottom plots show the time distribution of the event. The event is a gamma-ray interaction in the atmosphere, producing a shower of secondary particles that emit Cherenkov light.

First event captured. The top plots show the ariance in both High Gain and low gain, while the bottom plots show the time distribution of the event. The event is a gamma-ray interaction in the atmosphere, producing a shower of secondary particles that emit Cherenkov light.

The Role of Nuclear Instruments

The development of the ASTRI Mini-Array involved a consortium of companies contributing to different aspects of the system. Nuclear Instruments was responsible for the design, testing, and manufacturing of the custom electronic boards used in the camera systems of the telescopes.

These boards play a critical role in the acquisition and digitization of ultra-fast signals produced by the Cherenkov light. Designed to meet the strict timing and noise requirements of high-energy astrophysics, the electronics ensure nanosecond precision while maintaining robust performance in the demanding environmental conditions at high altitude.

Cutting-Edge Engineering

Each board was developed with a deep focus on:

• High-speed signal acquisition, capable of resolving the brief Cherenkov flashes with sub-nanosecond timing.

• Low-noise analog front-ends, essential for detecting weak light pulses from faint cosmic sources.

• Reliable operation in harsh environments, including temperature fluctuations and low air pressure at the observatory’s altitude.

• Scalability and maintainability, supporting the integration of multiple telescopes within the Mini-Array.

Prototypes underwent rigorous laboratory testing and field validation before being finalized for deployment. The successful implementation of these systems marks a significant step forward in enabling ASTRI to perform both gamma-ray detection and cutting-edge stellar interferometry.