Extreme Energy Events: an extended multi purpose cosmic ray observatory I. Gnesi on behalf of the EEE Collaboration TAUP 2019, Toyama
• Introduction • scopes and structure • the EEE station • MRPC technology • telescopes and Data Taking • performance and upgrade • Physics items • overview • Long Distance Correlation (2 telescopes cluster correlation) • Long Distance Correlation (extended Multi-telescope correlation) • The Polar Quest Expedition • Summary and Conclusions
Scopes & Structure 56 telescopes at high schools + 2 telescopes at CERN + 4 at INFN Units Total: 62 telescopes + ≈ 50 institutes on the waiting list strong outreach impact >100 high schools involved
Multigap RPC Technology
a EEE Telescope 144 readout channels TDCs @ 100 ps (can be operated to 25 ps) GPS @10-20 ns resolution
a EEE Telescope some EEE telescopes : the typical distance between chambers is 50 cm 1 st coordinate: #strip few installations are equipped with sliding 2 nd coordinate: structures in order to adjust ΔTime (Left-Right) the acceptance as needed adiacent hist are clustered
Data Taking & Recon Data are synchronized to the CNAF (INFN computing center) for reconstruction DQM Analysis 5 runs since 2014 almost 100 billions candidate muon tracks observed
Performance and upgrade Performance survey of ~ 40 telescopes during Runs 2 & 3 • Good efficiency (>90%) • High Time resolution (240 ps) • Good spatial resolution (< 1cm) JINST 13(2018) P08026
Physics Results EAS long ditance correlations / supershowers Upward muons studies EAS Forbush, solar physics, CR climate related topics subTeV anisotropies
LONG DISTANCE CORRELATIONS
Results: LONG DISTANCE CORRELATIONS LDC Correlations among Correlations among Extensive Air Showers multiple secondary muons in at large distances several telescopes and (10-1000 km) at large distances
Results: LDC among Extensive Air Showers LDC at large distances EAS correlations at distances larger than few km Possible physical mechanisms could justify the existence of LDC • EAS originating from cosmics emitted by the same source limited by low energy the presence of magnetic fields high energy primaries have to be stable on long scales energy difference among the correlated primaries time displacement too long at the arrival • EAS originating from cosmics generated by the interaction of a primary cosmic with the interstellar medium • EAS generated by the photodisintegration of primary cosmic rays in the solar field GZ effect
Results: EAS 1 LDC LDC among Extensive Air Showers EAS 2 at large distances FIRST ANALYSIS STRATEGY telescope 1 telescope 2 Correlations between telescope pairs (extensive air showers) telescope 3 looking for SINGLE TRACKS in each telescope telescope 4 R MAX spurious ~ 2 x 100/day x 100/day x 1 ms ~ 10 -9 - 10 -10 Hz ( < 0.03 per year ) R MIN spurious ~ 2 x 2/day x 2/day x 1 ms ~ 10 -11 - 10 -12 Hz ( < 3 per 10000 years ) Analyzed coincidences between the 45 telescope clusters hosting at least two telescopes 3968 days of time exposure 96 observed events against 77.8 estimated background
Results: LDC Eur. Phys. J. Plus (2018) 133: 34 5 candidate events with a p-value < 0.05
Results: EAS 1 LDC LDC among Extensive Air Showers EAS 2 at large distances SECOND ANALYSIS STRATEGY Correlations between single telescopes (extensive air showers) looking for MULTIPLE TRACKS in each telescope telescope 1 telescope 2 R spurious ~ 2 x 160/day x 160/day x 1 ms ~ 8 10 -7 Hz ( ~ 30 per year ) Distribution of track multiplicity for all telescopes and whole statistics 2014-2018 (multiplicity >2) 6 orders of magnitude from telescope multiplicity 3 to 12
Results: Pre - selection of multi-track events: LDC Chi2 < 10: Parallelism constraint (scalar product with the seed track > 0.8) Data set: No. of telescopes: 42 telescopes + 5 clusters No. of Events: 30 millions of coincident events (in +/- 2 seconds window) Period: 2013 → 2018 Analysis cuts: Telescope distance > 5 km Ntracks > 3 on both telescopes Results: excess of events: 40 Expected bckg: 23.4 p-value: 10 -3
The PolarQEEEst expedition: remapping the CR flux
PolarQuEEEst A trip covering 47 degrees in latitude to remap the CR flux vs lat to study seasonal variations at high lats in parallel with geographical mapping with drones microplastics survey
3 scintillator-based detectors with HPTDC readout (100 ps) Nanuq boat Oslo (Nesodden High School) Bra (NW Italy) PolarQuEEEst
PolarQuEEEst Seasonal effect as measured since fall 2018 to spring 2019 Flux Max observed in 3rd week of January 2019 To be completed in a few days from now
PolarQuEEEst EEE Collaboration 2017 A.H. Compton Phys. Rev. 43 (1933) 387
PolarQuEEEst The first EEE cluster @ Svalbard Since May 2019 POLA-01/03/04 are taking data in the area of the Scientific base of Ny-Ålesund (78°56ʹN), Svalbard The intent is to measure EAS flow at the sea level at high latitude
Summary and Outlook Extreme Energy Events is an extended observatory 60 tracking, high T res stations > 10 o lat and long coverage > 5 years exposition expanding! Several topics: solar physics, climate related, EAS, anisotropies Search for Long Distance Correlations / Supershowers observed correlated showers: 5 events @ p-value < 5% (single tracks) 40 events excess -> p-value < 10 -3 (multitracks) PolarQuEEEst mission: remapped the lat dependance of secondary muons 35-82 o New EEE cluster @ NyAlesund (78o north - Svalbard) for studying EAS at high lats on North Emisphere
Backup slides
Results: LDC among LDC a high number of telescopes (Supershowers?) No solid physical mechanism expected to produce multi-particle correlations over a huge area Thus searching for the unexpected Strategy: Consider all possible correlations between 2, 3, ... N telescopes Compare them to expected spurious rate between N telescopes Long exposition needed of course
Performance and upgrade 13 new telescopes (2018-2019) - 39 new MRPCs + 11 spares Total of 50 chambers 6 gaps/250 um technology New Eco gas mixtures studies several mix tested HFO/SF6 HFO/CO2 CO2/SF6 RPC 2017
Results: Complete scan of all available statistics from RUN 5 LDC (October 2018-June 2019, 244 days) Extraction of the multiplicity spectrum (number of coincident events as a function of the number of telescopes) Highest multiplicity events observed: 5 events with 12 telescopes Roughly a factor 10 decrease for every additional telescope Good agreement between raw data and spurious expected trend over 9 orders of magnitude
PolarQuEEEst
Recommend
More recommend
