Composition Results from Auger Markus Roth Karlsruhe Institute of - PowerPoint PPT Presentation

OBSERVATORY Composition Results from Auger Markus Roth Karlsruhe Institute of Technology (KIT)

The Pierre Auger Observatory Fluorescence detector • 4 sites: E>10 18 eV • HEAT: E>10 17 eV Surface detector array • 1660 stations • Grid of 1.5 km: 3000 km 2 
 E>10 18.5 eV

dX dX Shower observables 
 ] m Z dE c / g [ h 500 t p e e recorded at Auger d l fi t n o a l r s E ∝ p l 1000 a n i d u t 20 i g ) s n t o Time structure i 18 n L u . dE/dX [PeV/(g/cm )] 40 b 16 r a ( 14 l a X max n 30 g 12 i s r o 10 t c 20 e 8 t e D 6 10 4 2 0 20 40 60 80 100 120 140 160 180 200 Time bins (25 ns) Signal [VEM] Signal [VEM] 4 4 10 10 Lateral distribution 3 3 10 10 S 1000 ∝ E S 1000 2 2 10 10 10 10 1 1 500 500 1000 1000 1500 1500 2000 2000 2500 2500 r [m] 3

dX dX Shower observables 
 ] m Z dE c / g [ h 500 t p e e recorded at Auger d l fi t n o a l r s E ∝ p l 1000 a n i d u t 20 i g ) s n t o Time structure i 18 n L u . dE/dX [PeV/(g/cm )] 40 b 16 r a ( 14 l a X max n 30 g 12 i s r o 10 t c 20 e 8 t e D 6 10 4 2 0 20 40 60 80 100 120 140 160 180 200 Time bins (25 ns) Signal [VEM] Signal [VEM] 4 4 10 10 Lateral distribution 3 3 10 10 S 1000 ∝ E S 1000 2 2 10 10 10 10 1 1 500 500 1000 1000 1500 1500 2000 2000 2500 2500 r [m] 4

Height a.s.l. (km) Primary mass and 
 12 10 8 6 4 2 8 ) 9 Number of charged particles (x10 19 proton, E=10 eV longitudinal shower profiles 7 Auger shower 6 slant depth [g/cm ] 5 500 4 l 3 a 1000 n i d u t 2 i g n o e l L fi 1 o dE/dX [PeV/(g/cm )] 40 r p 0 x 200 300 400 500 600 700 800 900 1000 30 a X m 2 Slant depth (g/cm ) 20 Height a.s.l. (m) 12000 10000 8000 6000 4000 2000 8 10 ) 9 Number of charged particles (x10 19 iron, E=10 eV 7 Auger shower 6 5 4 3 2 1 Mean depth of shower profiles and shower-to-shower fluctuations as 0 200 300 400 500 600 700 800 900 1000 measure of composition 2 Slant depth (g/cm ) 5

Average Shower Maximum 80 proton 850 data ± σ stat 70 ± σ sys proton 60 800 cm 2 ] cm 2 ] 50 σ ( X max ) [ g/ h X max i [ g/ 750 40 iron 30 700 20 EPOS-LHC iron 650 Sibyll2.1 10 QGSJetII-04 0 10 18 10 19 10 20 10 18 10 19 10 20 E [ eV ] E [ eV ] Pierre Auger Collaboration, PRD 90 (2014) 12, 122005 6

HEAT+Coihueco telescopes: extended field of view Coihueco: 2° - 30° FoV in elevation 
 HEAT: 30° - 60° FoV in elevation 60 )] elevation [deg] 2 /Ndf= 89.7/107 2 χ dE/dX [PeV/(g/cm 0.5 HEAT 50 0.4 40 0.3 30 CO 0.2 20 HEAT CO 0.1 10 0 0 400 500 600 700 800 900 1000 1100 1200 190 180 170 160 150 140 130 120 2 azimuth [deg] slant depth [g/cm ] 7

End to end cross-checks with MC simulations Proton, Iron and 50:50 mixture, 
 generated (lines) VS reconstructed (markers) Generated and reconstructed MC data are compatible, 
 with residual bias in the lowest energy bin: 
 correction using half of the 50:50 mixture, 
 plus a symmetric systematic uncertainty accounted 8

X max systematic uncertainties & resolutions h i • ︎ Reconstruction bias (only left) and detector resolution (right) • Offset in time between SD-FD, calibration and telescopes alignment • Analysis • Atmospheric uncertainty in the geometry reconstruction and fluorescence light yield 9

Standard FD vs HEAT+Coihueco Standard VS HeCo dataset 2 Compatible within expected uncorrelated systematic uncertainties ( ∼ 7 g/cm 2 ) 10

Average shower maximum and RMS Dip model (ankle due to pure proton flux) 
 seems to be ruled out Pierre Auger Collaboration, to be presented at ICRC15 11

Statistical moments of ⟨ ln A ⟩ Mean Variance EPOS-LHC QGSJetII-04 12

Average shower maximum Telescope array Auger 850 [gm/cm 2 ] proton Data 850 data ± σ stat QGSJETII − 03 QGSJET − 01c ± σ sys SYBILL 2.1 800 800 <X max > Proton cm 2 ] h X max i [ g/ 750 750 iron Iron 700 700 EPOS-LHC 650 Sibyll2.1 QGSJetII-04 650 18.5 19 19.5 20 10 18 10 19 10 20 Energy log 10 (E/eV) E [ eV ] • EAS simulations are folded with detector 
 • Unbiased estimate of X max and 
 response (det. resolution and bias introduced) higher moments • Maximized statistics • Reduced statistics Telescope Array Collaboration, APP 64 (2014) 49 Pierre Auger Collaboration, PRD 90 (2014) 12, 122005 13

Average shower maximum Telescope array Auger 850 [gm/cm 2 ] proton Data 850 data ± σ stat SYBILL 2.1 ± σ sys 800 800 <X max > Proton cm 2 ] h X max i [ g/ 750 750 iron Iron 700 700 650 Sibyll2.1 650 18.5 19 19.5 20 10 18 10 19 10 20 Energy log 10 (E/eV) E [ eV ] • EAS simulations are folded with detector 
 • Unbiased estimate of X max and 
 response (det. resolution and bias introduced) higher moments • Maximized statistics • Reduced statistics Telescope Array Collaboration, APP 64 (2014) 49 Pierre Auger Collaboration, PRD 90 (2014) 12, 122005 14


 Average shower maximum 820 preliminary TA MD 2014 TA data from 
 800 MD telescopes 
 Auger 2014 TA MD ⊗ ] 780 2 Parameterized 
 [g/cm Auger data 
 760 folded with the 
 〉 max MD acceptance 740 X 〈 720 MD = Middle Drum 
 (site of one telescope station) 700 18.2 18.4 18.6 18.8 19 19.2 19.4 19.6 19.8 20 lg(E/eV) ⟨∆⟩ = (2.9 ± 2.7 (stat.) ± 18 (syst.)) g/cm 2 Pierre Auger and TA Collaborations, Proc. UHECR 2014, arXiv:1503.07540 15

Composition fit of the whole distribution EPOS-LHC proton 600 850 log(E/eV) = 17.8-17.9 data ± σ stat ± σ sys p = 0.769 500 800 p.d.f. [arb. units] cm 2 ] 400 h X max i [ g/ 750 300 iron 700 200 100 650 Sibyll2.1 0 500 600 700 800 900 1000 10 18 10 19 10 20 X max [g/cm 2 ] E [ eV ] Pierre Auger Collaboration, PRD 90 (2014) 12, 122006 16

Data available 
 Composition Fit (X max distribution) only up to 
 < 5x10 19 eV 1 Sibyll 2.1 Fe fraction QGSJET II-4 0.8 EPOS-LHC 0.6 0.4 0.2 0 1 N fraction 0.8 0.6 0.4 0.2 0 
 t 1 He fraction n s 0.8 e u 0.6 n s 0.4 o c 0.2 c i H 0 a 1 r p fraction d 0.8 0.6 0.4 0.2 0 10 0 10 -1 p-value 10 -2 10 -3 10 -4 10 18 10 19 E [eV] Pierre Auger Collaboration, PRD 90 (2014) 12, 122006 17

dX dX Shower observables 
 ] m Z dE c / g [ h 500 t p e e recorded at Auger d l fi t n o a l r s E ∝ p l 1000 a n i d u t 20 i g ) s n t o Time structure i 18 n L u . dE/dX [PeV/(g/cm )] 40 b 16 r a ( 14 l a X max n 30 g 12 i s r o 10 t c 20 e 8 t e D 6 10 4 2 0 20 40 60 80 100 120 140 160 180 200 Time bins (25 ns) Signal [VEM] Signal [VEM] 4 4 10 10 Lateral distribution 3 3 10 10 S 1000 ∝ E S 1000 2 2 10 10 10 10 1 1 500 500 1000 1000 1500 1500 2000 2000 2500 2500 r [m] 18

Shower observables 
 recorded at Auger 20 ) s t Time structure i 18 n u . b 16 r a ( 14 l a n g 12 i s r o 10 t c e 8 t e D 6 4 2 0 20 40 60 80 100 120 140 160 180 200 Time bins (25 ns) Signal [VEM] Signal [VEM] 4 4 10 10 Lateral distribution 3 3 10 10 S 1000 ∝ E S 1000 2 2 10 10 10 10 Pierre Auger Coll., JCAP 1408 (2014) 019 1 1 500 500 1000 1000 1500 1500 2000 2000 2500 2500 r [m] 19

Muon Production Depth 
 distribution (MPD) in a nutshell Inclined events to avoid 
 /dX [a.u.] 40 EM contamination: θ = 59 . 06 ± 0 . 08 � 35 E = 92 ± 3 EeV µ 30 dN 25 20 15 10 5 0 0 200 400 600 800 1000 1200 µ -2 X [g cm ] � Geometric delay of arriving muons: Mapped to muon production depth: ✓ r 2 c · t g = l − ( z − ∆ ) ◆ z = 1 + ∆ − ct g r 2 + ( z − ∆ ) 2 − ( z − ∆ ) 2 p ct g = � 20 � � � �

Mapped to muon production depth: + ∆ ◆ − ct g distribution (MPD) in a nutshell Muon Production Depth 
 ct g ✓ r 2 z = 1 2 /dX [a.u.] 4 0 3 3 3 RD 5 dN µ 3 I NTERN 0 2 5 21 2 0 1 5 1 0 r 2 + ( z − ∆ ) 2 − ( z − ∆ ) 5 0 Figure 2 : Real reconstructed MPD, � = (59.06 Geometric delay of arriving muons: 0 2 function. 0 0 = (92 ± 3) EeV, with the fi t to a Gaisser 4 0 0 6 0 0 8 0 0 c · t g = l − ( z − ∆ ) 1 µ X 0 0 µ 0 (rec) - X chosen. Therefore [g cm 1 2 0 0 a trade off 40 - 2 ] x µ a m 20 reconstruction and X p =

Muon Production Depth Data set: 01/2004 - 12/2012 
 E > 10 19.3 eV (more muons/event) 
 EPOS-LHC Zenith angles [55°,65°] (low EM contamination) 
 30 EeV Distances from the core [1700 m, 4000 m] 
 55°-65° 481 events after quality cuts 
 Systematic uncertainties: 17 g/cm 2 Resolution: 
 100 (80) g/cm 2 at 10 19.3 eV for p (Fe) 
 50 g/cm 2 at 10 20 eV QGSJetII-04: data bracketed by predictions 
 EPOS-LHC: predictions above data 22