Detecting Cosmic Rays with LOFAR - LOFAR Community Science Workshop 2019
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Detecting Cosmic Rays
with LOFAR
LOFAR Community Science Workshop 2019
Katie Mulrey for the CR KSP
A. Bonardi, S. Buitink, A. Corstanje, H. Falcke, B. M. Hare,
J. R. Hörandel, T. Huege, G. Krampah, P. Mitra, K. Mulrey*, A. Nelles,
H. Pandya, J. P. Rachen, L. Rossetto, P. Schellart, O. Scholten,
S. ter Veen S. Thoudam, T. N. G. Trinh, T. Winchen
1 *kmulrey@vub.be
Cosmic Rays and
Multi-Messenger Astronomy
ν
p
γ
Gamma rays: point to sources, can be
absorbed, multiple emission mechanisms
Neutrinos: point to sources, not
absorbed, weak interaction
Cosmic rays: charged and deflected,
info in composition, easy to detect
Cosmic ray all-particle spectrum
Galactic
transition?
extra
galactic
G. Matthiae et al. New J. Phys 12 (2010) 2
Cosmic ray energy & composition
Galactic: SNR Extragalactic: AGN
Hillas criterion:
Emax ∝ Z e B r
Max Energy
EFe, max= 26 x Ep,max
• Below 1019 eV, can’t point
IceCube Masterclass 2019
directly to sources
• Use composition to understand
origin
• Transition to heavier composition
indicates the maximum source
energy is reached
3
Composition: Measuring Xmax
Xmax is an observable that gives radio detection
information about composition nearly 100% duty cycle
LOFAR, AERA, Tunka
T. Huege. Physics Reports, 620:1-52,2016 fluorescence light
dark nights (
Cosmic ray radio emission
Geomagnetic Charge Excess
Radiation Pattern:
• Direction
• Magnetic Field
• Energy
• Xmax
• Atmosphere
5
Radio Detection Experiments
LOFAR
(576)
energy=1017 eV
zenith=45
6
Cosmic Ray Detection at LOFAR
• LOFAR Radboud Array
• scintillator detectors
• Provides trigger for
antenna readout
300 m
offline analysis
trigger
buffer
2 ms read-out
• RFI cleaning
• direction reconstruction
• antenna pattern unfolding
• calibration
P. Schellart et al., A&A 560, 98 (2013)
6 LBA stations (6 x 48 antennas)
+ stations outside Superterp 7
Stokes Parameters
Geomagnetic Charge Excess
vxvxB vxvxB
vxB + vxB
Pim Schellart et al.,
JCAP 10 14 (2014)
I Q U V
O. Scholten et al., PRD 94 1030101 (2016)
8
ucted from the arrival times of the
nnas), and for each antenna polar-
Stokes Parameters
he form of the Stokes parameters:
V. The orientation of the polar-
tructed from Stokes Q and U.
tween June 2011 and September
corded a total of 762 air show-
intensity pattern on the Charge Excess
complexGeomagnetic
G. Trinh et al PRD 95 083004 (2017)
measured showers can be well re-
vxvxB vxvxB
ricate details by state of the art
codes [22, 23]. These codes aug-
nte Carlo air shower simulations
alculated from first principles vxB +at vxB
11, 24]. In this analysis we use
CORSIKA [25] with QGSJETII
m !
or
s the hadronic interaction models.
y that the exact shape of the pat- r s t
d e
istance to the shower maximum,
u n Pim Schellart et al.,
Th
JCAP 10 14 (2014)
bsolute field strength scales with
y of the primary particle.
owers cannot be correctly repro-
Of these, 27 air showers have a
se ratio below ten in amplitude
et a reliable reconstruction. For
wers three additional I observations Q U V
he showers occur within two hours
orded by the Royal Dutch Meteo-
MI). Moreover, their polarization
antly from that of a ‘normal’ fair-
his can be seen in Fig. 1. For air-
O. Scholten et al., PRD 94 1030101 (2016)
8
g thunderstorm conditions the po-Event Analysis
Radiation from
track endpoints
CoREAS simulation
• no assumptions
about emission
SB et al. PRD 90 082003 (2014).
• independent of
LOFAR data hadronic models
• 200-450 antennas / T. Huege et al. AIP Conf.Proc. 1535 (2013) no.1, 128
event
• Total power within
55ns of peak
emission 9Event Analysis
• Simulate proton and iron showers Preliminary
Proton
• Power scales with energy2
See talk by
• Calculate reduced X2 for each A. Corstanje
simulation
• Parabola fit determines event Xmax
• Resolution < 20 g/cm2
• Best fit (2016): 80% light particles Iron
(p+He) at 1017 -1017.5 eV 10GDAS Atmospheric
Corrections
• GDAS provides atmosphere
measurements (temp, humidity,
pressure)
• Any location (1˚x1˚), time (3-hourly)
• Integrated into simulations
• For extreme conditions,
can shift Xmax up to 15 g/cm2
A. Corstanje Astropart.Phys. 89 (2017)
P. Mitra et al. PoS ICRC2017 (2018) 325 12Calibration
13Calibration
14Calibration
Buffer boards!
LFmap
5Calibration
sky model
K. Mulrey et al. Astropart.Phys 111 (2019) 1-11.
16LORA expansion
• Current cosmic-ray trigger is based on 20 Current LORA
scintillators on the superterp
• Expand by adding 20 scintillators at
neighboring
• Expected 45% increase in events
Installation began
spring 2018
17Low Energy Extension: Hybrid Trigger
Buitink et al., 2016
Proton
Iron
All CR primaries must have
same probability
of triggering to remove bias
Current trigger
18Hybrid Trigger
Particle trigger
- High rate with low trigger threshold Cosmic ray
- Composition bias at low energies +
+ Guaranteed cosmic ray good radio signal
+
Radio trigger RFI rejection
- Flooded with RFI +
+ Ensures a usable CR signal Reduced trigger
threshold
19Hybrid Trigger
CR detectable with radio
Trigger rate (Hz)
Event with high RFI
Min # detectors triggered
Bias-free detection
down to 1016.2 eV Current detection
criteria
Need access to existing radio trigger
info in real time to form trigger
20G. Matthiae et al. New J. Phys 12 (2010)
Can we access the highest energy particles?
!22
21Goldstone
VLA
Westerbork
Lovell
ATCA
Kalyazin
LOFAR
Parkes
!23 22T. Winchen !24 23
T. Winchen
2425
Summary
• LOFAR measures air showers
with highest precision in radio
• Xmax reconstruction resolution
competitive with fluorescence
• New atmospheric
modelling & calibration
• Multiple Extensions
(hybrid trigger + LORA)
• Lunar detection very promising
(overlap with ground experiments!)
27Backup
Calorimetric Energy Estimate
Radio emission from cosmic rays
provides a calorimetric energy
measurement without
uncertainties from hadronic
models
Glaser et al. JCAP 1609 (2016)
Integrate fluence
of radio footprint
RD
11T. Winchen
nalysis a number of physical param-
and stored. These include the esti-
Thunderstorm events
e air shower (as reconstructed from
r data), the arrival direction of the
structed from the arrival times of the
LOPES:
ntennas), Amplification
and for in thunderstorms
each antenna polar-
S.B. et al. A&A 467, 385 (2007)
in the form of the Stokes parameters:
and V. The orientation of the polar-
onstructed
LOFAR:from Stokes Q and U.
measure atmospheric E-field
between June 2011Schellart
and September
et al. PRL 114, 165001 (2015)
recorded a total of 762 air show-
Trinh et
ted complex intensity pattern onal.
thePRD 93, 023003 (2016)
ll measured showers can be well re-
intricate details by state of the art
on codes [22, 23]. These codes aug-
Monte Carlo air shower simulations
n calculated from first principles at
el [11, 24]. In this analysis we use
n of CORSIKA [25] with QGSJETII
7] as the hadronic interaction models.
usly that the exact shape of the pat-
e distance to the shower maximum,
e absolute field strength scales with
ergy of the primary particle.
showers cannot be correctly repro-Hillas Plot J. Aguilar, ULB
You can also read
