Latest updates and results from the Fluorescence detector Array of Single-pixel Telescopes (FAST)
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Fraser Bradfield et al., UHECR 2024
![Example events - Auger event 1
25
[Auger event display here]](https://image.slidesharecdn.com/uhecr2024fast-250422060319-3a661ec5/85/Latest-updates-and-results-from-the-Fluorescence-detector-Array-of-Single-pixel-Telescopes-FAST-25-320.jpg){kind=tracking}
![Xmax parameterisation
• From Blaess, 2018
• Parameterizations of EPOS, QGSJetII.04 and Sybil Xmax
distributions for 4 primary mass groups (p, He, CNO, Fe)
• When Xmax is generated, choose mass group based on
fractions provided (typically [0.25, 0.25, 0.25, 0.25]), then
based on mass group chosen and energy randomly sample
Xmax from appropriate distribution.
43](https://image.slidesharecdn.com/uhecr2024fast-250422060319-3a661ec5/85/Latest-updates-and-results-from-the-Fluorescence-detector-Array-of-Single-pixel-Telescopes-FAST-43-320.jpg){kind=tracking}
Latest updates and results from the Fluorescence detector Array of Single-pixel Telescopes (FAST)
- 1. Latest updates and results from the Fluorescence detector Array of Single-pixel Telescopes (FAST) Fraser Bradfield, J. Albury, J. Bellido, L. Chytka, J. Farmer, T. Fujii, P. Hamal, P. Horvath, M. Hrabovsky, V. Jilek, K. Cerny, J. Kmec, J. Kvita, M. Malacari, D. Mandat, M. Mastrodicasa, J. Matthews, S. Michal, H. Nagasawa, H. Namba, M. Niechciol, L. Nozka, M. Palatka, M. Pech, P. Privitera, S. Sakurai, F. Salamida, P. Schovanek, R. Smida, D. Stanik, Z. Svozillikova, A. Taketa, K. Terauchi, S. Tomas, P. Travnicek and M. Vacula (The FAST Collaboration) UHECR 2024, Malargüe, Pierre Auger Observatory
- 2. The Fluorescence Detector Array of Single-pixel Telescopes 12 telescopes/ station Aiming for 100％ trigger efficiency above 1019.5 eV Goal： • Uncover origin of UHECRs • Use same detector in both hemispheres • Detection area - 150,000 km2 Design：Low-cost, easily deployable, autonomous fluorescence telescopes 1.6 m Four 20 cm PMTs 30°x30° Segmented mirror UV filter 2 Coleman, 2021
- 3. FAST reconstruction １）Directly compare data traces to those from simulations ２）The parameters (E, Xmax, 𝜃, 𝜙, 𝑥, 𝑦)of the simulation which give the best matching traces to data are chosen Top-down reconstruction How？Maximize likelihood function Probability of observing signal 𝑥𝑖 in time bin 𝑖 of PMT 𝑘 given shower parameters Ԧ 𝑎= (E, Xmax, 𝜃, 𝜙, 𝑥, 𝑦) Data MC 3
- 4. First generation prototypes “FAST@TA” 4 “FAST@Auger” 3 prototypes (installed 2016, 2017, 2018) Observation time: ~540 hrs TA CLF 2 prototypes (installed 2019, 2022) Observation time: ~2970 hrs Only one in operation
- 5. Coincidence events FAST@TA FAST@Auger Analysis period 2 telescopes（2018/03 – 2018/10） 3 telescopes（2018/10 – 2023/02） 1 telescope（2022/07 – 2022/10） Observation time 2 telescopes ~ 65 hrs 3 telescopes ~ 182 hrs 1 telescope ~ 122 hrs Trigger condition External trigger from TA BRM FD External trigger from Auger LL Bay 4 Coincidence events 438 236 Signal detection algorithm: 5 For event observed by TA/Auger in FOV of FAST: • Smooth original trace ‘𝑇’ with a finite impulse response (FIR) filter → get waveform ‘𝐹’ • For the ith bin of 𝐹, 𝐹𝑖, calculate PMT has signal if the max SNR over all bins > 2 F3100 bkgrd3100
- 6. Data/MC comparison FAST@Auger Data MC Energy Energy • Data = TA/Auger reconstructed values (E > 1018 eV) • MC Conditions • Xmax dist.：EPOS (500-1200 gcm-2) • Energy dist.： 𝐸-1 (1018-1020 eV) • 𝜃 dist.： sin𝜃cos𝜃 (0-80 deg) • FAST@TA • Core pos：Circle at (0,0) r＝35 km • FAST@Augerで6万シャワ • Core pos： Circle at (0,0) r＝12 km • Trigger cond.：2 PMTs with SNR>6 • MC histograms rescaled to match area of data histograms FAST@TA 6 Rp Rp Data MC
- 7. Azimuth Zenith Azimuth Zenith FAST@TA FAST@Auger Data/MC comparison 7 Data MC Zenith • Data = TA/Auger reconstructed values (E > 1018 eV) • MC Conditions • Xmax dist.：EPOS (500-1200 gcm-2) • Energy dist.： 𝐸-1 (1018-1020 eV) • 𝜃 dist.： sin𝜃cos𝜃 (0-80 deg) • FAST@TA • Core pos：Circle at (0,0) r＝35 km • FAST@Augerで6万シャワ • Core pos： Circle at (0,0) r＝12 km • Trigger cond.：2 PMTs with SNR>6 • MC histograms rescaled to match area of data histograms
- 8. CoreX CoreY CoreX CoreY FAST@TA FAST@Auger Data/MC comparison 8 Data MC • Data = TA/Auger reconstructed values (E > 1018 eV) • MC Conditions • Xmax dist.：EPOS (500-1200 gcm-2) • Energy dist.： 𝐸-1 (1018-1020 eV) • 𝜃 dist.： sin𝜃cos𝜃 (0-80 deg) • FAST@TA • Core pos：Circle at (0,0) r＝35 km • FAST@Augerで6万シャワ • Core pos： Circle at (0,0) r＝12 km • Trigger cond.：2 PMTs with SNR>6 • MC histograms rescaled to match area of data histograms
- 9. Reconstruction results 9 Reconstruction setup • Recon. (E, Xmax, 𝜃, 𝜙, 𝑥, 𝑦) ＋fit time offset • Use the TA/Auger reconstructed values as first guess • Cuts： • Successful minimization of likelihood • Best fit time offset between (100,500) FAST@TA FAST@Auger y=x (red line)
- 10. Reconstruction results 10 FAST@TA FAST@Auger Proper labels Reconstruction setup • Recon. (E, Xmax, 𝜃, 𝜙, 𝑥, 𝑦) ＋fit time offset • Use the TA/Auger reconstructed values as first guess • Cuts： • Successful minimization of likelihood • Best fit time offset between (100,500) y=x (red line)
- 11. Possible reasons for difference Filter efficiency degradation Atmospheric changes Baseline fluctuations PMT response (deterioration/structure) • On average, signal in data is lower than expected from Auger/TA first guess FAST@Auger Source of Xmax bias 11 FAST@TA
- 12. FAST@TA PMT uniformity measurements To check telescope performance, measured response of FAST@TA PMTs on site Mar. 2024 using PMT scanner 12 ~60% (std-dev) non-uniformity was observed. This is not accounted for in simulations... Color difference between camera panels FAST 1 FAST 2 FAST 3 Reflectors
- 13. Energy spectrum First energy spectrum from FAST • Calculated from the reconstructed energy values and exposure determined with simulations used for data/MC comparison • The FAST@TA and FAST@Auger results agree within statistical uncertainty 13 E.g. FAST@Auger exposure (~122 hrs)
- 14. Elongation rate – Comparison with EPOS Construct Xmax rails for FAST Simulation conditions: • Xmax dist.：EPOS (500-1200 gcm-2) • Energy dist.： 𝐸-1 (1018-1020 eV) • 𝜃 dist.： sin𝜃cos𝜃 (0-80 deg) Fitting proton & iron showers separately between 17 < log(E/eV) < 20 14 Proton Iron Reconstruct only Xmax & E (geometry fixed) • Initial Xmax and E varied by 30g/cm2 and 10% • Cuts: • One PMT with SNR>6 • Successful minimization • Relative uncertainty in E & Xmax both < 0.5 Core pos. 14
- 15. Elongation rate • Proton and iron rails estimated from FAST MC • Around 1017.5-1018.5 eV the composition estimated by FAST tends toward iron • FAST@TA and FAST@Auger results agree within statistical uncertainty 15
- 16. Designed to operate “in-the-field” without connection to Auger/TA - “FAST-Field telescope” - Comms. with telescopes at LL via 5 GHz Wifi Improvements: - Mirrors (simplified production, 9→4 segments) - Enclosure (smaller, self sufficient power system) - Camera (new electronics and PMTs) Testing at Ondrejov - FOV measured ✓ - Solar power test ✓ - Pedestal ✓ - Amplifier ✓ Second generation prototypes 16
- 17. FAST mini-array 17 Stereo observation with FAST: - Install 4 second gen. telescopes at Auger to form triangle with current prototypes Spacing estimation: - Estimated # of events FAST mini- array will detect in one year as function of station spacing - Start with ~11km spacing (validate stereo observation with high quality events) then move to ~16km to increase statistics Current 2 tels. Second gen prototypes
- 18. FAST mini-array 18 Stereo observation with FAST: - Install 4 second gen. telescopes at Auger to form triangle with current prototypes Spacing estimation: - Estimated # of events FAST mini- array will detect in one year as function of station spacing - Start with ~11km spacing (validate stereo observation with high quality events) then move to ~16km to increase statistics Current 2 tels. Second gen prototypes 2025: Move in 2026!
- 19. FAST mini-array – site inspection 19 Soil composition: Solid, earthy soil (no stones) Can use ground screws for installation Soil inspection ✓ LL Soil inspection ✓ AYELEN PUQUEN LL 2025 2026
- 20. Summary & future 20 • FAST - low cost, easily deployable, autonomous fluorescence telescopes for detecting UHECRs • Over 650 coincidences between FAST and Auger/TA • Simulations seem to reproduce data • Estimated the elongation rate and energy spectrum using ~600 events • FAST mini-array will test second gen prototypes with stereo observation • Site inspection complete. Initial station spacing ~11km • Include PMT non-uniformity measurements etc. in simulation (check FAST@Auger PMTs) • Finish testing in Ondrejov, ship telescopes to Auger, install, test → stereo observation early 2025
- 21. 21
- 22. Backup
- 23. Example events - TA event 1 23 cv
- 24. 24 Example events - TA event 2
- 25. Example events - Auger event 1 25 [Auger event display here]
- 26. Exposure calculation 26 FAST@TA FAST@Auger Calculated using MC data set used in previous data/MC comparison 247 hrs 122 hrs
- 27. 27 Reconstruction results - extra Best fit time bin FAST@TA FAST@Auger
- 28. 28 Zenith Reconstruction results - extra FAST@TA FAST@Auger
- 29. 29 Azimuth Reconstruction results - extra FAST@TA FAST@Auger
- 30. 30 Core X Reconstruction results - extra FAST@TA FAST@Auger
- 31. Reconstruction results - extra 31 FAST@TA FAST@Auger Core Y
- 32. Xmax bias – signal difference 32 FAST@TA FAST@Auger
- 33. Xmax bias – signal difference 33 Difference Ratio FAST@TA
- 34. Xmax bias – signal difference 34 Difference Ratio FAST@Auger
- 35. Gaisser Hillas reconstruction 35 Need geometry! Most likely only obtainable with stereo observation
- 36. • XY scanner • 1 mm by stepping motor • Control by serial communication • LED flasher • Wavelength (400 nm) • Spot size: 1 cm circle • Pulse width: 10us • Trigger: 100 Hz • Intensity: set to 8000 (*) • Oscilloscope • PicoScope 3400D-MSO • External trigger from flasher • PC 36 PMT scan - measurement setup
- 37. PMT scan – PMT alignment angle 37
- 38. FAST Field telescope PSF 38 9 segment – old design 4 segment – new design *(not to scale)
- 39. 39 Signal detection – coincidence Energy vs. Rp
- 40. Signal detection – baseline estimation 40
- 41. Machine learning for FAST mini-array 41 Core pos. Inputs: Pulse timing/height/integral from each PMT Training: 300,000 showers Xmax 500 - 1200 g cm-2 E 1 - 100 EeV θ 0 - 80° ϕ 0 - 360° Testing: 10,000 showers Layer structure: 72/72/36/18/6 Core pos: Circle at (0,0), r = 5773 m Rec. cuts: Rec. energy > 1018 eV All three stations triggered FAST preliminary FAST preliminary • Simple NN shows reasonable performance as first guess
- 42. Simulation flow Use old version of Auger Offline software as simulation backbone. Have written specific modules for FAST. Typical simulation… • FASTProfileSimulatorCG • FASTEventGeneratorCG • ShowerLightSimulatorKG • FASTSimulator • FASTEventFileExporter 42
- 43. Xmax parameterisation • From Blaess, 2018 • Parameterizations of EPOS, QGSJetII.04 and Sybil Xmax distributions for 4 primary mass groups (p, He, CNO, Fe) • When Xmax is generated, choose mass group based on fractions provided (typically [0.25, 0.25, 0.25, 0.25]), then based on mass group chosen and energy randomly sample Xmax from appropriate distribution. 43