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Studies of the microwave emission of extensive air showers with - - PowerPoint PPT Presentation

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Studies of the microwave emission of extensive air showers with GIGAS and MIDAS at the Pierre Auger Observatory a b c R. Gaor , for the Pierre Auger Collaboration , M. Richardson a Laboratoire de Physique Nuclaire et de Hautes

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Studies of the microwave emission 


  • f extensive air showers with GIGAS and MIDAS 


at the Pierre Auger Observatory

  • R. Gaïor

a

, for the Pierre Auger Collaboration

b

, M. Richardson

c

a

Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Universités Paris 6 et Paris 7, CNRS-IN2P3,

Paris, France


b

Observatorio Pierre Auger, Av. San Martín Norte 304, 5613 Malargüe, Argentina

c

Vanderbilt University

E-mail: auger_spokespersons@fnal.gov Full author list: http://www.auger.org/archive/authors_icrc_2017.html

35thICRC 12-20 July 2017 Busan Korea

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Motivations: Detection of MBR 


(Molecular Bremsstrahlung Radiation)

2

  • Signal from a EM shower observed in

microwave frequency [1]

  • Interpreted as Molecular Bremsstrahlung

Radiation (MBR)

  • Emitted isotropically
  • like Fluorescence with 100% duty cycle
  • Experimental effort 


Accelerator: AMY / MAYBE
 CR exp in situ : CROME / AMBER / MIDAS / EASIER

  • No observation of MBR from particle shower


so far

  • Detailed calculation of the MBR lowered the

expected intensity by a factor 70 to 200 [2,3]

[1] Gorham et al Phys. Rev D78 (2008) 032007 [2] Al Samarai et al, Astropart. Phys. 67 (2015) 26 [3] Al Samarai et al, Phys. Rev. D93 (2016) 052004

35thICRC 12-20 July 2017 Busan Korea

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Microwave detection at 
 the Pierre Auger Observatory

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Two complementary radio detectors*

GIGAS MIDAS

The Pierre Auger Observatory
 Ideal to probe new techniques

* a third one AMBER exists but is not presented here

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SLIDE 4

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GIGAS

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SLIDE 5

GIGAS


GHz Identification of Giant Air Shower

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  • Radio surface detector
  • Triggered by SD station
  • in regular Auger data set
  • 3 implementations

★ GIGAS61 


C-band (3.4 - 4.2 GHz) / G~9dBi / 90° HPBW / Tsys~100K
 ~50 antennas / 6 years
 —>Observed EAS with this setup but at small distance to shower axis

★ GIGADuck-C


C-band / G~ 15dBi / 30° HPBW / Tsys ~50 - 60K
 7 antennas / 2 years

★ GIGADuck-L


L-band (1 - 1.4 GHz) / G~ 15dBi / 30° HPBW / 
 Tsys ~100 -150K
 7 antennas / 6 months

40 MHz FADC

EASIER antenna SD electronics box EASIER box α PMT PMT

PMT

Water Cherenkov Detector GIGAS61 GIGADuck-C GIGADuck-L !

GIGAS

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SLIDE 6

GIGADuck

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Fsignal = kB · Tsys Aeff(θ, φ) · √ τ · ∆ν

GIGADuck-L GIGADuck-C GIGAS

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SLIDE 7

GIGAS : Event search

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Reconstruction Quality Cut out Lightning event R > 3000 m Energy > 5EeV θ < 60° R < 2000 m

background sample signal sample

define a threshold with background sample radio signal > threshold ± 250 ns around the particle arrival time

Radio selection

particle trigger

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SLIDE 8

EASIER : Event study

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  • All signals found at distance to shower axis < 240m
  • No signal observed in GIGADuck setup 


with this analysis → features of a coherent emission 


(see VHF bandwidth / CROME experiment [1] / ANITA [2])

→ next step is to produce limits on MBR with the 
 non-observed events

Event date 2011/06/30 2012/09/05 2013/01/03 2013/06/04 2013/07/16 2013/09/26 2015/02/03 Energy [EeV] 16 6 27 19.5 42 6.2 28 Distance [m] 112 103 237 133 181 208 176 (θ,φ) (29.6, 17) (48, 167) (55, 34) (53, 1.2) (40, 155) (59, 49) (54, 1) Radio maximum 13 7.7 12.3 6.9 63 8.5 9.4

Table of observed event (all with GIGAS61)

[1] CROME: R. Šmida et al., Phys. Rev. Lett. 113 (2014) 221101 [2] ANITA: S. Hoover et al. Phys. Rev.Lett. 105 (2010) 151101

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MIDAS

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SLIDE 10

MIDAS : MIcrowave Detection of Air Showers


See ref [1]

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  • Inspired from

Fluorescence Detector

  • First Level Trigger


Time over threshold

  • Second level trigger


4-fold FLT in time

Power Detector

+18 V +5 V

1 GHz counting room

FEED

BIAS-T roof

DC Pulse

4 GHz

To ADC

FILTER IMPEDANCE ADAPTER

Sensor

Trigger strategy Detector calibration and simulation

  • Effective area = 9.1 m2


(central pixel)

  • System temperature = 65K


(measured with sun flux)

[1] J. Alvarez-Muñiz et al., Nucl. Instrum. Meth. A 719 (2013) 70–80.


simulated pattern simulated event

53 C-band LNBf

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SLIDE 11

MIDAS : Event search

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Data set Event search results

Nobs = 1 event

SD event: 2.5 EeV Distance: 53 km

Data set: SLT 09/2012 —> 09/2014 Remove noisy period (rate > 0.5Hz) Time coincidence with Auger SD ± 300μs

—> Effective livetime of MIDAS :
 372 days (8.2×105 events)

TMIDAS - TAuger [s]

Nexp(bkg) =0.3 event
 (Rexp . TMIDAS)

Rexp = 2 · RSD · RMIDAS · τ · · and RMIDAS = 1.8x10≠2 Hz

with RSD = 9x10≠4 Hz an

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SLIDE 12

MIDAS : Limits on MBR intensity

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Gorham et al.[1]

Excludes the interpretation in terms of MBR of original beam test [1] Further improvement would require a change of technology

If = If,ref ρ ρ0 ✓d R ◆2 ✓ N Nref ◆α

  • Simulation of SD events
  • GH profile
  • MBR emission according [1]
  • 95% CL limits

[1] Gorham et al Phys. Rev D78 (2008) 032007

d: beam to antenna distance R: shower to antenna distance If,ref: Intensity observed in lab Nref: Nr of particle in lab. exp.

Excluded region

◆α

Log10 (If,ref) [W / m2 / Hz]

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Conclusions

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2 complementary experimental efforts for the MBR search 
 at the Pierre Auger Observatory

GIGAS: 3 radio surface detector arrays implemented
 results: Detection of 7 events but close to the shower axis


Status: Last installed array in Dec 2016, Decommissioning foreseen for Nov. 2017
 Future: Further search of event and results/limits.


MIDAS: Microwave telescope for EAS
 results: Set stringent limits on MBR emission by UHECR


Status: Data taking ended. (Sept 2012 - Sept 2015)

Results understood together as a coherent emission from EAS at GHz

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Thanks for your attention

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Back up

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GIGAS : Temperature measurement

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[1] Gorham et al Phys. Rev D78 (2008) 032007

setup 1 setup 2

SKY TB = 4K GROUND TB = 270K

power detector

  • scilloscope

power detector

  • scilloscope

Telec = Thot − YTcold Y − 1 where Y = Phot Pcold

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SLIDE 17

GIGADuck

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Improved design: lower the threshold of sensitivity

  • higher gain: increase Aeff

two versions: C-band (3.4-4.2 GHz) & L-band (1-1.5GHz)

  • geometry change (FOV overlap)

improve SNR + increase coincidence probability

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GIGADuck-C : Temperature measurement

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[1] Gorham et al Phys. Rev D78 (2008) 032007

System temperature with the sun flux for GIGADuck-C

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GIGADuck-C : Temperature measurement

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[1] Gorham et al Phys. Rev D78 (2008) 032007

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GIGADuck-L : Calibration and monitoring data

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[1] Gorham et al Phys. Rev D78 (2008) 032007

  • Calibration with sun biased by other modulations
  • Modulation aligned with Local Sidereal Time


(Could be positioning satellites)

  • Direct calibration is used to estimate the noise

temperature

In lab calibration

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SLIDE 21

MIDAS : Pixel patterns

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[1] Gorham et al Phys. Rev D78 (2008) 032007

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SLIDE 22

Radio emission mechanism: VHF band (30-80MHz)

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Geomagnetic effect

  • Geomagnetic effect

Askaryan effect

  • Observed in VHF band (30-80MHz)


(AERA, Codalema … )

  • Short pulse (~20 ns)
  • beamed emission (steep decrease

with distance to shower axis)

  • dense array (100s of meter

spacing)

Geosynchrotron


Acceleration of charge in earth magnetic

Experimental characteristics

Askaryan effect


charge excess —>coherent radiation

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SLIDE 23

Radio emission mechanism: Microwave

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  • in microwave (1-6GHz)
  • isotropic 


(large distance observation)

  • unpolarised
  • several efforts in lab (AMY,

MAYBE) and in situ
 (CROME, MIDAS)

Experimental characteristics

—> currently not confirmed

Molecular Bremsstrahlung


ionization electron in molecules field

Gorham et al PRD 2008 78 032007