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

Studies of the microwave emission 
 of extensive air showers with GIGAS and MIDAS 
 at the Pierre Auger Observatory a b c R. Gaïor , for the Pierre Auger Collaboration , M. Richardson 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 35 th ICRC 12-20 July 2017 Busan Korea

Motivations: Detection of MBR 
 (Molecular Bremsstrahlung Radiation) • Signal from a EM shower observed in • Experimental effort 
 microwave frequency [1] Accelerator: AMY / MAYBE 
 CR exp in situ : CROME / AMBER / MIDAS / EASIER • Interpreted as Molecular Bremsstrahlung • No observation of MBR from particle shower 
 Radiation ( MBR ) so far • Emitted isotropically • Detailed calculation of the MBR lowered the • like Fluorescence with 100% duty cycle expected intensity by a factor 70 to 200 [2,3] [1] Gorham et al Phys. Rev D78 (2008) 032007 2 [2] Al Samarai et al, Astropart. Phys. 67 (2015) 26 [3] Al Samarai et al, Phys. Rev. D93 (2016) 052004 35 th ICRC 12-20 July 2017 Busan Korea

Microwave detection at 
 the Pierre Auger Observatory Two complementary radio detectors* The Pierre Auger Observatory 
 Ideal to probe new techniques GIGAS MIDAS 3 * a third one AMBER exists but is not presented here 35 th ICRC 12-20 July 2017 Busan Korea

GIGAS 4 35 th ICRC 12-20 July 2017 Busan Korea

GIGAS 
 GHz Identification of Giant Air Shower • Radio surface detector α • Triggered by SD station EASIER GIGAS antenna • in regular Auger data set • 3 implementations GIGAS61 ★ GIGAS61 
 C-band (3.4 - 4.2 GHz) / G~9dBi / 90° HPBW / EASIER box T sys ~100K 
 SD electronics ~50 antennas / 6 years 
 GIGADuck-C box PMT —>Observed EAS with this setup but at small distance to shower axis GIGADuck-L ! PMT PMT ★ GIGADuck-C 
 C-band / G~ 15dBi / 30° HPBW / T sys ~50 - 60K 
 7 antennas / 2 years Water Cherenkov Detector ★ GIGADuck-L 
 L-band (1 - 1.4 GHz) / G~ 15dBi / 30° HPBW / 
 T sys ~100 -150K 
 7 antennas / 6 months 40 MHz FADC 5 35 th ICRC 12-20 July 2017 Busan Korea

GIGADuck GIGADuck-L GIGADuck-C k B · T sys F signal = √ A e ff ( θ , φ ) · τ · ∆ ν GIGAS 6 35 th ICRC 12-20 July 2017 Busan Korea

particle trigger GIGAS : Event search Reconstruction Quality Cut out Lightning event background sample signal sample Energy > 5EeV R > 3000 m θ < 60° R < 2000 m Radio selection define a threshold with background sample radio signal > threshold ± 250 ns around the particle arrival time 7 35 th ICRC 12-20 July 2017 Busan Korea

EASIER : Event study Table of observed event (all with GIGAS61) 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 • 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 [1] CROME: R. Š mida et al. , Phys. Rev. Lett. 113 (2014) 221101 8 [2] ANITA: S. Hoover et al. Phys. Rev.Lett. 105 (2010) 151101 35 th ICRC 12-20 July 2017 Busan Korea

MIDAS 9 9 35 th ICRC 12-20 July 2017 Busan Korea

MIDAS : MIcrowave Detection of Air Showers 
 See ref [1] Sensor simulated event Trigger strategy • Inspired from Fluorescence Detector 53 C-band LNBf • First Level Trigger 
 Time over threshold • Second level trigger 
 4-fold FLT in time Detector calibration and simulation simulated pattern Effective area = 9.1 m 2 
 • counting room roof (central pixel) +5 V +18 V FEED BIAS-T Power IMPEDANCE FILTER ADAPTER Detector 4 GHz 1 GHz System temperature = 65K 
 • DC Pulse (measured with sun flux) To ADC 10 [1] J. Alvarez-Muñiz et al. , Nucl. Instrum. Meth. A 719 (2013) 70–80. 
 35 th ICRC 12-20 July 2017 Busan Korea

MIDAS : Event search Data set Data set: SLT 09/2012 —> 09/2014 Remove noisy period (rate > 0.5Hz) Time coincidence with Auger SD ± 300 μ s —> Effective livetime of MIDAS : 
 T MIDAS - T Auger [s] 372 days (8.2 × 10 5 events) Event search results N obs = 1 event N exp(bkg) =0.3 event 
 (R exp . T MIDAS ) R exp = 2 · R SD · R MIDAS · τ with R SD = 9x10 ≠ 4 Hz an · · SD event: 2.5 EeV and R MIDAS = 1 . 8x10 ≠ 2 Hz Distance: 53 km 11 35 th ICRC 12-20 July 2017 Busan Korea

MIDAS : Limits on MBR intensity • Simulation of SD events Gorham et al. [1] Log 10 (I f,ref ) [W / m 2 / Hz] • GH profile Excluded region • MBR emission according [1] • 95% CL limits ◆ 2 ✓ N ◆ α ✓ d ρ I f = I f,ref R N ref ρ 0 d: beam to antenna distance ◆ α R: shower to antenna distance I f,ref : Intensity observed in lab N ref : Nr of particle in lab. exp. Excludes the interpretation in terms of MBR of original beam test [1] Further improvement would require a change of technology 12 [1] Gorham et al Phys. Rev D78 (2008) 032007 35 th ICRC 12-20 July 2017 Busan Korea

Conclusions 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: S et 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 13 35 th ICRC 12-20 July 2017 Busan Korea

Thanks for your attention 14

Back up 15

GIGAS : Temperature measurement setup 1 SKY oscilloscope T B = 4K detector power power detector GROUND oscilloscope T B = 270K setup 2 T elec = T hot − YT cold where Y = P hot Y − 1 P cold 16 [1] Gorham et al Phys. Rev D78 (2008) 032007 35 th ICRC 12-20 July 2017 Busan Korea

GIGADuck Improved design: lower the threshold of sensitivity • higher gain: increase A eff two versions: C-band (3.4-4.2 GHz) & L-band (1-1.5GHz) • geometry change (FOV overlap) improve SNR + increase coincidence probability 17

GIGADuck-C : Temperature measurement System temperature with the sun flux for GIGADuck-C 18 [1] Gorham et al Phys. Rev D78 (2008) 032007 35 th ICRC 12-20 July 2017 Busan Korea

GIGADuck-C : Temperature measurement 19 [1] Gorham et al Phys. Rev D78 (2008) 032007 35 th ICRC 12-20 July 2017 Busan Korea

GIGADuck-L : Calibration and monitoring data In lab calibration • 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 20 [1] Gorham et al Phys. Rev D78 (2008) 032007 35 th ICRC 12-20 July 2017 Busan Korea

MIDAS : Pixel patterns 21 [1] Gorham et al Phys. Rev D78 (2008) 032007 35 th ICRC 12-20 July 2017 Busan Korea

Radio emission mechanism: VHF band (30-80MHz ) Geomagnetic effect Geomagnetic effect Askaryan effect Experimental characteristics • Observed in VHF band (30-80MHz) 
 (AERA, Codalema … ) • Short pulse (~20 ns) • beamed emission (steep decrease with distance to shower axis) Askaryan effect 
 Geosynchrotron 
 • dense array (100s of meter charge excess Acceleration of charge spacing) —>coherent radiation in earth magnetic � � 22 � � � � � �

Radio emission mechanism: Microwave Gorham et al PRD 2008 78 032007 Experimental characteristics • in microwave (1-6GHz) • isotropic 
 (large distance observation) • unpolarised Molecular Bremsstrahlung 
 • several efforts in lab (AMY, ionization electron in MAYBE) and in situ 
 molecules field (CROME, MIDAS) —> currently not confirmed 23