Science in space: the CSES mission @ TIFPA

May 11, 2026

Space@TIFPA

Francesco M. Follega^(1,2) for CSES-Limadou

(1) Department of Physics, University of Trento

(2) Trento Institute of Fundamental Physics and Applications (TIFPA-INFN)

S. Perciballi

The CSES scientific mission

​

​

​

The CSES mission is a scientific collaboration between Italy and China. The satellites (Polar + Sun Synchronous orbit - 500 km) carries a suite of instruments for the detection of electromagnetic fields, particles and plasma in space.

​

Scientific goals:

• Investigate the ionosphere and gather world-wide data;
• Measure the particles and plasma perturbations in the ionosphere and magnetosphere: natural sources (EQs) and anthropic emitters;
• Study solar-terrestrial interactions and solar physics: CMEs, SEPs, solar flares;
• Study and extend low energy spectrum of cosmic rays.

S. Bartocci et al 2024 ApJ 976 239

​

M. Martucci et al 2023 ApJL 945 L39

Space Weather

10.1029/2022SW003191

​

https://doi.org/10.1016/j.nuclphysbps.2013.09.002

Scientific partners

Industrial partners

2

F.M.Follega - 11/05/2026

HEPD-01 on board the CSES-01 satellite

​

​

​

HEPD-01

CAD model

Limadou HEPD-01 integrated on CSES-01

Acceptances for

contained particles

Peak ~ 400 cm² sr

HEPD-01 is designed to measure fluxes of charged particles: electrons (3-100 MeV) and protons (30-200 MeV) and light nuclei at low energy

Publication reference:

“The HEPD particle detector of the CSES satellite mission for investigating seismo-associated perturbations of the Van Allen belts”, Published on SCIENCE CHINA�"Scientific Goals and In-orbit Performance of the High-energy Particle Detector on Board the CSES". Published on APJS

3

F.M.Follega - 11/05/2026

Search for particle burst with CSES-01 payloads

​

​

​

• Analysis of low-energy (from 100 keV) electrons of CSES
• Data collection, preparation, background estimation in invariant phase-space
• Selection of exceptional events and building/clustering of particle bursts
• Anomalous cluster analysis with ML-algorithms (DB scan)

Particle bursts search at low energies

Publication reference:�"Search for Electron Bursts in the Inner Van Allen Belts with the CSES and NOAA POES Satellites". Published on Remote Sensing (2023)�“The HEPD particle detector of the CSES satellite mission for investigating seismo-associated perturbations of the Van Allen belts”, Published on SCIENCE CHINA

​

drift

bounce

gyration

Three periodic motions of trapped particles

R. Battiston, V. Vitale / Nuclear Physics B (Proc. Suppl.) 243–244 (2013) 249–257

Time correlation EQ-PB

4

F.M.Follega - 11/05/2026

Gamma Ray burst physics … The BOAT

​

​

​

Publication reference:�"Observation of Anomalous Electron Fluxes Induced by GRB221009A on CSES-01 Low- energy Charged Particle Detector". Published on APJ Letters (2023)

Geant4 simulation of HEPP-L channel

Sens.2023,15,411

Anomaly detection and stat. analysis

The GRB221009A was detected by the low energy particle detector HEPP-L on board CSES-01 with framework developed for the Particle Burst search in HEPD-02. The signal was then matched with High Energy Burst Searcher (HEBS/GECAM-C) on board SATech-01.

5

F.M.Follega - 11/05/2026

Gamma Ray burst analysis with HEPD-01

​

​

​

First GRB catalogue for HEPD-01, in the MeV gap (0.3–50 MeV). Demonstrates HEPD-01 capability beyond its design → groundwork for HEPD-02 dedicated GRB mode. New blind search method applied.

This analysis framework allowed for the identification of Gamma Ray Burst as significative outliers in the particle rate��→ 12 GRBs a posteriori matched with other instruments

→ fluences, T90 and Tpeak have been estimated��→ HEPD-01 GRB catalogue over the full data taking

​

bkg estimation (parametric approach)

bkg subtraction

Publication reference:

Gamma-Ray Burst Observations by the High-Energy Particle Detector on board the China Seismo-Electromagnetic Satellite between 2019 and 2021, Published on APJ (2025)�"The Catalogue of Gamma-Ray Burst Observations by HEPD-01 in the 0.3–50 MeV Energy Range". Published on APJ (2025)

(*)

“short outliers” analysis (1-2 min)

“long outliers” analysis (1-2 days)

Effective area estimation

6

F.M.Follega - 11/05/2026

Research activity with HEPD-01 - Mapping the SAA

​

​

Publication reference:

“New results on protons inside the South Atlantic Anomaly, at energies between 40 and 250 MeV in the period 2018–2020, from the CSES-01…” Published on PRD

“Mapping the South Atlantic Anomaly via charged particle measurement by the HEPD-01 detector on board the CSES-01 satellite”, Published on PRD

Shift of SAA centroid

Proton integral flux above threshold

Detailed particle-based mapping of the SAA above 200 MeV protons. Reference dataset for geomagnetic field evolution, space weather modeling, and space mission radiation safety. Measured northwest drift of SAA centroid and validated NASA AP9–AE9 models in poorly energy range (in this part of the 25 solar cycle).

Validation of state of the art models AP9/AE9

Synergy with COSI people for bkg estimation due to SAA passages

7

F.M.Follega - 11/05/2026

Low energy cosmic ray modulation with HEPD-01

​

​

​

​

Publication reference:�"Time Dependence of 50-250 MeV Galactic Cosmic-Ray Protons between Solar Cycles 24 and 25". Published on APJL (2023)

Modulation study of the protons flux in the range between 50-250 MeV (consistent with models and other detector measurement). Thanks to the HEPD-01 e/p separation power, its fluxes can be utilized to adjust modulation models for moderate to low solar activity conditions in the heliosphere

dE/dx approach to separate e/p:�

• Energy reconstruction allows for y_i ∝A_i/x
• Geographical selection based on rigidity cut-off

Energy dependence over time (CR) allows to improve modulation models

8

F.M.Follega - 11/05/2026

Time correlation and multi-payload analysis

​

​

​

​

​

The time correlation group in the CSES-Limadou collaboration search for space-time correlation between CSES observations and external phenomena: i.e. strong earthquakes, lightnings and VLF transmitters.

Correlation PB - transmitters (i.e NWC)

PB - lightnings (WWLLN 2019 - 2022)

Particle Wave Interaction (PB - VLF)

PB/VLF - EQ correlation

LSTM AE DNN

Publication reference:�"Search for Electron Bursts in the Inner Van Allen Belts with the CSES and NOAA POES Satellites", Published on Remote Sensing (2023)

“CSESpy: A Unified Framework for Data Analysis of the Payloads on Board the CSES Satellite”, Published on Remote Sensing (2025)

“Data-Driven Deep Learning Model for Detecting Ionospheric Electric Field Perturbations and Seismic Correlation” Published on Remote Sensing (2026)

​

9

F.M.Follega - 11/05/2026

The launch of the second satellite CSES-02

​

​

Jiuquan Satellite Launch Center (Inner Mongolia)

10

F.M.Follega - 11/05/2026

Multi Satellite era of the CSES mission

​

​

Operation area between lat [-65,65]

Full coverage at extreme latitudes

The new phase of the mission started with the launch of the second satellite: multi-payload and multi-satellite studies now possible

• A new particle detectors suite for CSES-02 with improved detectors (i.e. HEPD-02) with energy range from tens of KeV to hundreds of MeV (three orders of magnitude);
• Improved version of EFD-02 (developed by INFN) working in conjunction with EFD-01 for electromagnetic field detection;
• Another point of observation and improved coverage and latitude span with sensitivity to GRB;

​

Complementary Orbit with CSES-01

• Same Orbit Plane but shifted by 180°;
• Return cycle: 5 days→2.5 days

EFD-02

HEPD-02

11

F.M.Follega - 11/05/2026

HEPD-02 and EFD-02

​

​

DOI: 10.1007/s11214-026-01274-x

DOI: 10.1007/s11214-025-01167-5

12

F.M.Follega - 11/05/2026

Research activity in Limadou - HEPD-02 tracker evolution

​

​

​

Both HEPD-01 and HEPD-02 are designed to reconstruct the particle identify and the arrival direction thanks to a silicon tracker, both with two different technologies

• 2 planes of double sided Si microstrip detectors produced @ FBK:�- thickness 300 μm and total surface 880 cm² �- Alternated floating and readout strips with a pitch of 182 μm�
• This system has a spatial resolution of 50 μm;�
• The tracker provides useful information (dE/dx) to identify particles

References:�Scientific Goals and In-orbit Performance of the High-energy Particle Detector on Board the CSES, The APJ (2019)

“The High-Energy Particle Detector on Board the CSES-02 Satellite”, Space Science Reviews (2026)

Limadou HEPD-01

Limadou HEPD-02

First MAPS in space, chips developed for ALICE experiment

• 29.24 μm x 26.88 μm pixels (~ 4-5 μm single-hit resolution)
• ALTAI chip: 512x1024 pixels -> 10 chips per stave;
• three tracking planes for an active area of 15 x 15 cm2 each
• Low material budget ~ 0.015 X0
• TDAQ board developed

13

F.M.Follega - 11/05/2026

Performance of the HEPD-02 tracker

​

​

​

​

​

Position Reconstruction and cluster size - Vertical beam

​

Angular Reconstruction - Vertical beam

~0.7 deg offset compatible with our manual alignment

Preliminary

14

F.M.Follega - 11/05/2026

Other handles HEPD-02 in particle identification with the new tracker

​

​

​

​

​

​

​

MSC with tracker�- discriminate low energy e-/high energy p(interacting)

Low energy e-

High energy p

Courtesy of D. Giordano

Nuclei fragments (boosted) or pion star

(isotropic)

anti-D/anti-p

from the top

vertex reconstruction

(from sec. tracks)

Incoming heavy nucleus

15

F.M.Follega - 11/05/2026

New GRB capabilities with HEPD-02

​

New physics case fully enabled:

​

• Dedicated GRB triggers for HEPD-02
• Ev. acquisition/counting mode;
• Time resolution ~ 5 ms

GRB trigger algorithm tested and designed in Trento @ LINAC

16

F.M.Follega - 11/05/2026

Preliminary gamma ray transients candidates detected in flight

​

GRB20250902A

GRB20250702A

Interesting candidates of gamma transients identified during commissioning (ANALYSIS STILL ONGOING/PRELIMINARY)

GRB20250804B

GRB20250830C

GRB20251016B

PRELIMINARY

PRELIMINARY

PRELIMINARY

PRELIMINARY

PRELIMINARY

17

F.M.Follega - 11/05/2026

First HEPD-02 in-flight data - Improved trigger logic

TR1and

Max. observed rate ~3.2 MHz

TR1&TR2

First events collected in space by HEPD-02

After the launch of HEPD-02 on board CSES-02 the first data are coming (almost 1 year up to now). Several improvements already clear with HEPD-02 w.r.t. Its predecessor.

HEPD-01

HEPD-02

TR2&BOT

New trigger logic:�- up to 6 concurrents masks

-128 configurables orbital zones

- possibility to prescale triggers�- Avoided saturation and full-lat span

Each lon/lat with different data aq. configuration

18

F.M.Follega - 11/05/2026

First HEPD-02 in-flight data

In the first data we have already evidence of light nuclei signal (He) and of heavier nuclei recorded by the HEPD-02 during the first few months after commissioning

Helium signal in a few months of HEPD-02 data

Signal from heavier nuclei as in Carbon and Oxygen

Satellite always operational over the full latitude span

19

F.M.Follega - 11/05/2026

Space Weather events during HEPD-02 data taking

​

Article in preparation for sub…

The GLE Of November 11, 2025

​

The January 2026 geomagnetic storm

​

​

Under submission on SW AGU

20

F.M.Follega - 11/05/2026

New technologies studied/applied in the context of the CSES mission

Trained on HEPD-02 Simulation

Simulation @CNAF

+

Impact positions

and

track residuals

HEPD-02 deep learning reconstruction chain

Deep learning event reconstruction:�

• Limadou HEPD-01 and HEPD-02 are among the few space experiments with a full DL evReco chain�
• Currently experimenting with state of the art models as Transformers (self-attentnion used in LLM, i.e. chatGPT or Claude AI)

R&D silici spazio

Space-Ready Silicon Tracking Technologies

• Develop and mature MAPS/FD-MAPS and LGAD technologies for future high-energy cosmic-ray spectrometers in space.

- Moving from 180 nm to 65 nm technology enables a more compact chip design.

- Reduced power consumption, a key advantage for space missions with strict power and thermal constraints.

21

F.M.Follega - 11/05/2026

Interesting times ahead…

The addition of the second satellite to the CSES mission enriches the data coverage of the mission and extends the lifetime and scientific reach of the mission and of the CSES-Limadou collaboration:

​

• Improved satellite platform and possibility to acquire data on the full latitude span (higher duty cycle).�
• Improved instruments on CSES-02:

- HEPD-02: improved tracking and PID capabilities, improved trigger logic (intelligent trigger and GRB algorithm)

- EFD-02: payload designed by INFN with several improvements which improves EFD-01

​

Already interesting results in less then one year:��- Two SW events detected;�- Preliminary heavy nuclei and GRBs identified;�- improved overall performance;

​

​

​

GRB20251016B

PRELIMINARY

New possibility of multi-payload and multi-satellite observations��Stay tuned…..

Under submission on SW AGU

Preliminary data

22

F.M.Follega - 11/05/2026

Research activity in Limadou - Quest for antimatter with HEPD-02

​

​

​

​

​

Example of annihilation process in TR2.

pion star

(isotropic)

anti-D/anti-p

from the top

HEPD-02 may be sensitive to anti-deuterons (anti-protons) in the range between 10 MeV/n and 30 MeV/n.

vertex reconstruction

(from sec. tracks)

Antideuteron spectra from J. Heisig et al, DarkRayNet: Emulation of cosmic-ray antideuteron fluxes from dark matter �Sensitivieties of AMS-02 from F. Giovacchini et al. Cosmic Rays Antideuteron Sensitivity for AMS-02 experiment�Sensitivieties of GAPS from The GAPS experiment: low-energy antinuclei measurements for dark matter searches

​

preliminary

preliminary

23

F.M.Follega - 11/05/2026

Research activity in Limadou - Helium and electrons with HEPD-01

​

​

Helium with HEPD-01

24

F.M.Follega - 11/05/2026