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EAS arrays: ARGO-YBJ and HAWC

EAS arrays: ARGO-YBJ and HAWC. G. Di Sciascio disciascio@roma2.infn.it INFN – Sezione di Roma “Tor Vergata”. ARGO and Beyond – Roma Tor Vergata July 20, 2011. http://lhaaso.sciencesconf.org/. Third Workshop for Air Shower Detection at High Altitudes

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EAS arrays: ARGO-YBJ and HAWC

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  1. EAS arrays: ARGO-YBJ and HAWC G. Di Sciascio disciascio@roma2.infn.it INFN – Sezione di Roma “Tor Vergata” ARGO and Beyond – Roma Tor Vergata July 20, 2011 ARGO-YBJ and Beyond, Roma July 20, 2011

  2. http://lhaaso.sciencesconf.org/ Third Workshop for Air Shower Detection at High Altitudes In the recent years, the interest on astroparticle physics experiments using air shower detection techniques at high altitudes has strongly increased. The ARGO-YBJ experiment has been publishing exciting observational results, the HAWC water tank array and muon detectors in the ASγ array are currently under construction and the R&D for the LHAASO project is already well advanced. To discuss the current results and the design for new experiments, we will hold a 3rd Workshop for Air Shower Detection at High Altitudes at the Nuclear Physics Institute of Orsay, (IPNO), close to Paris   October 6-7, 2011 ARGO-YBJ and Beyond, Roma July 20, 2011

  3. The Yangbajing Cosmic Ray Laboratory ARGO Tibet ASγ The ARGO-YBJ experiment Longitude 90° 31’ 50” East Latitude 30° 06’ 38” North 90 Km North from Lhasa (Tibet) Anunconventional EAS-array exploiting the full coverage approach at very high altitude to detect small air showers at an energy threshold of a few hundred GeV. 4300 m above the sea level ~ 600 g/cm2 ARGO-YBJ and Beyond, Roma July 20, 2011

  4. NumberofFiredStrips The basicconcepts …for an unconventional air shower detector • HIGH ALTITUDE SITE (YBJ - Tibet, 4300 m a.s.l, ~ 600 g/cm2) • FULL COVERAGE (RPC technology, 92% covering factor) • HIGH SEGMENTATION OF THE READOUT (small space-time pixels) Real event Space pixels: 146,880 strips (7×62 cm2) Time pixels: 18,360 pads (56×62 cm2) … in order to: • image the shower front • get a energy threshold of a few hundreds of GeV ARGO-YBJ and Beyond, Roma July 20, 2011

  5. The basicconcepts E  1000 TeV …extending the dynamical range • ANALOG READ-OUT → PeV (3672 1.40 × 1.25 m2 “big pads”) Saturation ! Big Pad for charge read-out Strip Big Pad Time pixel (56 × 62 cm2) #18360 Space (digital) pixel (6.7 × 62 cm2) #146880 ARGO-YBJ and Beyond, Roma July 20, 2011

  6. Multicore EAS & Large pT ARGO-YBJ and Beyond, Roma July 20, 2011

  7. The basicconcepts Astrop. Phys. 30 (2008) 85 ApJ 699 (2009) 1281 …lowering the energy threshold • SCALER MODE → GeV Recording the counting rates (Nhit ≥1, ≥2, ≥3, ≥4) for each cluster at fixed time intervals (every 0.5 s) lowers the energy threshold down to ≈ 1 GeV. Poor information on the arrival direction and spatial distribution of the detected particles. • Object: • flaring phenomena (high energy tail of GRBs, solar flares) • detector and environment monitor ARGO-YBJ and Beyond, Roma July 20, 2011

  8. ARGO-YBJ: a multi-purpose experiment • Sky survey -20º  δ  80º above 300 GeV(-sources) • High exposure for flaring activity (-sources, GRBs, solar flares) • CR physics 1 TeV  104 TeV • CR p/p flux ratio at TeV energies • Solar and heliospheric physics (p + He) spectrum at low energies Knee region p-air and p-p cross sections Anisotropies Multicore events by 2 independent operational modes: • scaler mode (counting rate, > 1 GeV) • shower mode (full reconstruction, > 300 GeV) ARGO-YBJ and Beyond, Roma July 20, 2011

  9. time resolution ~1-2 ns (pad) space resolution = strip CentralCarpet: 130 Clusters 1560 RPCs 124800 Strips 99 m 74 m 8 Strips (6.5 x 62 cm2) for each Pad 10 Pads (56 x 62 cm2) for each RPC 1 CLUSTER = 12 RPCs (5.7  7.6 m2) Gas Mixture: Ar/ Iso/TFE = 15/10/75 HV = 7200 V 78 m 111 m Single layer of Resistive Plate Chambers (RPCs) with a full coverage (92% active surface) of a large area (5600 m2) + sampling guard ring (6700 m2 in total) Experimental Hall & Detector Layout RPC ARGO-YBJ and Beyond, Roma July 20, 2011

  10. Angular resolution Energy calibration Moon shadow analysis (1) Physical Review D 84 (2011) 022003 • A tool to evaluate the performance of the detector • Pointing accuracy • Angular resolution • Absolute energy calibration The energy scale uncertainty is estimated to be smaller than 13% in the energy range 1 – 30 (TeV/Z). Npad> 100, 71 s.d. ARGO-YBJ and Beyond, Roma July 20, 2011

  11. Moon shadow analysis (2) Physical Review D 84 (2011) 022003 • Npad>100: 10 s.d./month • A tool to monitor the stability of the data and reconstruction • Right figures: one point per month ! • Position stable at a level of 0.1° • Angular resolution stable at a level of 10% ARGO-YBJ and Beyond, Roma July 20, 2011

  12. Complementarity of TeV Gamma-Ray Detectors Imaging Air Cherenkov Telescopes Extensive Air Shower Arrays IACTs EAS arrays ARGO-YBJ and Beyond, Roma July 20, 2011

  13. Current Status • In observation since July 2006 (commissioning phase) • Stable data taking since November 2007 • Theaverage duty cycle ~ 85% • Trigger rate ~3.5 kHz@ 20 pad threshold • Dead time 4% • 220 GB/day transferred to IHEP/CNAF data centers ARGO-YBJ and Beyond, Roma July 20, 2011

  14. Mrk421 ARGO-YBJ RXTE 2 – 12 keV • Mrk421 is characterized by a strong flaring activity both in X-rays and in TeVγ–rays. • Lack of continuous long-term monitoring at VHE. >1TeV >1TeV ARGO-YBJ and Beyond, Roma July 20, 2011

  15. Mrk421: X-ray / TeV flares RXTE 2 – 12 keV June 2008 July 2006 16-18 Feb. 2010 ~6 σ ~6 σ G. Aielli et al, ApJL 714 (2010) L208 ARGO-YBJ and Beyond, Roma July 20, 2011

  16. Mrk421 in 2010 The SEDs become harder during the flares in respect to the long-term SED Feb. 16 Apr. 28 ARGO-YBJ and Beyond, Roma July 20, 2011

  17. Mrk421 long-term monitoring ApJ 734 (2011) 110 • ARGO-YBJ cumulative light curve (>TeV) compared with Swift and Rossi/RXTE data. • Good correlation between TeV/X-ray data. • Active and quite periods are observed. RXTE/ASM 2-12 keV Swift/BAT 15-50 keV ARGO-YBJ TeV Active periods ARGO-YBJ and Beyond, Roma July 20, 2011

  18. Galactic plane and Cygnus region MGRO J2031+41 ARGO-YBJ MGRO J1908+06 MGRO J2019+37 ARGO-YBJ and Beyond, Roma July 20, 2011

  19. CR Physics highlights Nucl. Phys. B 212-213 (2011) 301 ARGO Horandel p+He EAS-TOP + MACRO Phys. Rev. D 80 (2009) 092004 CREAM p+He Heavy DM CREAM He Secondary production CREAM p 5% at 1.4 TeV at 90% c.l. 6% at 5 TeV at 90% c.l. ARGO-YBJ and Beyond, Roma July 20, 2011

  20. Large scale CR anisotropy vs energy 0.9 TeV 1.5 TeV 2.4 TeV 3.6 TeV ARGO-YBJ 2011 7.2 TeV 18.3 TeV The tail-in broad structure appears to dissolve to smaller angular scale spots. ARGO-YBJ and Beyond, Roma July 20, 2011

  21. 90° 65° 30° 210° Intermediate scale CR anisotropies Focus on >4 s.d. significant regions Cygnus region Sub-structures? New-structures? Median energy 1 TeV Zenith angle < 50° 3 years data ~2.2 1011 events GALACTIC ANTI-CENTER ARGO-YBJ and Beyond, Roma July 20, 2011

  22. Energy and angular scale 0.9 TeV The correlation of energy and angular scale of the anisotropy might provide a hint on the distance scale of the cause. 1.5 TeV 2.4 TeV 3.6 TeV 7.2 TeV 18.3 TeV ARGO-YBJ and Beyond, Roma July 20, 2011

  23. From Milagro to HAWC • The High Altitude Water Cherenkov Observatory • Redeploy Milagro detectors at Volcán Sierra Negra, México • Increase altitude from 2630 m to 4100 m • Increase area from 2,400 m2 (bottom layer of pond) to 20,000 m2 • Segment the Cherenkov medium: separate tanks instead of a single pond • Better angular resolution and background rejection, lower energy threshold • Achieve 10-15 x sensitivity of Milagro • Detect Crab at 5σ in 6 hours instead of 3 months • Cost: ~$10M ARGO-YBJ and Beyond, Roma July 20, 2011

  24. ARGO-YBJ and Beyond, Roma July 20, 2011

  25. ~ 135 m ~ 150 m ARGO-YBJ and Beyond, Roma July 20, 2011

  26. Sensitivity ARGO-YBJ and Beyond, Roma July 20, 2011

  27. Energy threshold and effective area ARGO-YBJ N > 20 HAWC Milagro ARGO-YBJ and Beyond, Roma July 20, 2011

  28. Lowering the energy threshold Primary Energy (GeV) Low Energy Threshold Requires Detection of Gamma Rays in EAS ARGO-YBJ and Beyond, Roma July 20, 2011

  29. Angular Resolution ICRC 2009 0863 ARGO-YBJ and Beyond, Roma July 20, 2011

  30. Algorithm looks for high-amplitude hits more than 40 m from the reconstructed core location Milagro bottom layer Hadron Rejection γ p ARGO-YBJ and Beyond, Roma July 20, 2011

  31. Gamma-Hadron separation ARGO-YBJ and Beyond, Roma July 20, 2011

  32. Sensitivity to Crab-like Point Sources ARGO-YBJ 1 yr / 5 yr 1 CRAB 0.1 CRAB 0.01 CRAB ARGO-YBJ and Beyond, Roma July 20, 2011

  33. LHAASO sensitivity ARGO-YBJ and Beyond, Roma July 20, 2011

  34. HAWC Construction Schedule ARGO-YBJ and Beyond, Roma July 20, 2011

  35. Some conclusions… ARGO-YBJ planned up to 2012 HAWC: full operation 2014 - 2015 ? LHAASO: full operation 2019 ? • There is room for an extension of the ARGO-YBJ data taking for at least 2-3 years improving the reconstruction algorithms • Monitoring of the Northern sky (cumulative sensitivity ≈20% Crab units) . • CR physics at the knee with the analog read-out. • Study of the CR anisotropy at higher energies. • Solar activity monitoring through the 24th solar cycle . • Can we envisage a ARGO-YBJ Phase-2 in view of a future merging into LHAASO ? • Array around the building to detect e.m. + muons . • New detectors inside the building to detect neutrons, hadrons, etc… • New ideas are needed… ARGO-YBJ and Beyond, Roma July 20, 2011

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