Main features of cosmic ray induced air showers measured by the - PowerPoint PPT Presentation

Main features of cosmic ray induced air showers measured by the CODALEMA experiment Lilian MARTIN 1,3 , R. Dallier 1,3 , A. Escudie 1 , D. García-Fernández 1 , F. Gaté 1* , A. Lecacheux 2 and B. Revenu 1,3 . 1 SUBATECH, Nantes 2 LESIA, Paris-Meudon 3 USN, Nançay *now at LAPP, Annecy

Motjvatjons of CODALEMA ● Goals: Study the propertjes of the radio electric fjeld – produced in extensive air showers Promote the radio detectjon technique as an – competjtjve alternatjve to SD and FD techniques Contribute to cosmic ray physics within the – CODALEMA energy range ● Context: Installed since 2002 at the Nançay radio – astronomy observatory Several generatjons of antennas, LNA, triggers, – daq and arrays developed... Radio electric transients produced by the geomagnetjc and charge excess mechanisms L.M. ICRC July 2017 2

The CODALEMA instruments Surface: ~ 1 km 2 57 autonomous statjons (B.Revenu et al. [CRI109]) 13 scintjllators 10+5 cabled antennas (A.Lecacheux et al. [CRI103]) 1 tripole antenna (R.Dallier et al. [CRI104]) 7 LF antennas (A.Escudie et al. [CRI102], D.García- 0 500 m Fernández et al. [CRI118]) L.M. ICRC July 2017 3

The autonomous statjon EW and NS horizontal polarizatjons Wide band – [20 – 200] MHz LONAMOS LNA 1 Gs/s – 2.5 μs Self triggering – On board processing L.M. ICRC July 2017 4 GPS tjming

Event reconstructjon in the arrays Blue: early tjmes Red/Green: late tjmes SA ● Typical rates (in a month) : SC : 40 000 evts – SA : 1 200 000 evts (loose trigger) – Coincidences : 60 evts ! – ● Arbitrary small sample of events for this preliminary analysis : Refmect roughly the observed variety in – multjplicitjes, signal amplitudes, shower axis and locatjons SC Not representatjve of the array acceptances – SA and SC arrival directjons agree – L.M. ICRC July 2017 5

Convolutjon of the antenna response Systematjc comparisons with model predictjons : SELFAS* ● Convolutjon : ( Model predictjons → ADC values ) vs Data ● Calculated/measured global transfer functjon of the detectjon chain ● (including the antenna response) Convolutjon + noise SELFAS* simulatjon NS signal EW signal *V.Marin et al., Astropartjcle Physics, Elsevier, 2012, 35, pp.733-741. L.M. ICRC July 2017 6

DATA Is the sensitjvity preserved ? Model : SELFAS ADC : SELFAS convol. Sorted by distance to core Sorted by distance to core Sorted by arrival tjme FM notch FM notch Spectrum and amplitude variatjons are preserved ! L.M. ICRC July 2017 7

Extractjng cosmic ray features Inspired by the method used on AERA data by F.Gaté et al., ARENA 2016, Groningen, June 7-10, 2016. ● SELFAS+CONEX simulatjon ● Interpolate amplitudes ● Calculate χ 2 from amplitude with a virtual antenna F(x,y) difgerences array using E=10 17 eV and ( A ant −α F ( x ant − X core , y ant − Y core )) 2 (θ,φ) exp 2 = ∑ χ ● Convolutjon with 2 σ ant ant the antenna ● Loop over a range of core response H(f,θ,φ) locatjon ( X core , Y core ) and scaling energy factor α ● Combinatjon of ( X core , Y core ) and α + χ 2 map with the lowest χ 2 (= χ 2 min ) is the most probable set of values. ● Process a set of SELFAS simulatjons (typ. 50 p, 10 Fe) per event to sample the X max range ● Compare the χ 2 values versus X max χ 2 vs X max min min ● The lowest χ 2 determines the overall most probable ( X core , Y core ), E=α x10 17 eV and X max L.M. ICRC July 2017 8

Some examples + + + Amplitude footprint + + + χ 2 vs core + + locatjon χ 2 vs X max Lateral distributjon functjon •Data +SELFAS Few antennas give access to the CR propertjes ! L.M. ICRC July 2017 9

Polarization patuerns solve ambiguitjes NS signal Polarizatjon patuern footprint Data SELFAS EW signal Local minimum in the χ 2 values versus X max distributjon. Polarizatjon patuerns support only one solutjon. min Both EW and NS amplitudes must be matched separately ! L.M. ICRC July 2017 10

Comparison with the scintjllators (Xc,Yc) radio Shower core ofuen outside of the SC array: E partjcle underestjmated ! Betuer agreement using (Xc,Yc) radio for the E partjcle estjmatjon + r e g n U . M 7 1 C R C I D F r e g u A ― No error bars on E radio yet , no real atmosphere for X max Preliminary analysis seems on the right directjon but stjll lots of (careful) work to do ! L.M. ICRC July 2017 11

Conclusions and Outlook ● CODALEMA is routjnely observing high-energy cosmic rays in the 10 16 – 10 18 eV range. ● CODALEMA data compare well with SELFAS simulatjons: shower core locatjons, X max and energies can be estjmated using the radio signals ● Further improvements : Careful estjmatjons of systematjcs, error bars and resolutjons – Analysis extended to the full CODALEMA set of data (especially at lower E) – Analysis method (comparison with simulatjons) extended to the two – polarizatjons and the full spectrum Sensitjvity and resolutjon estjmatjon for a sparser array – ● Analysis in progress in parallel with other R&D developments: 3-polarizatjon antenna, standalone and phased triggers, LF antennas... – L.M. ICRC July 2017 12

Spares L.M. ICRC July 2017 13

Trigger and Acquisitjon systems Autonomous statjons ( SA ) Scintjllators ( SC ) Central Acquisitjon System selectjon T3 evt. request monitoring storage LNA SA - multj-level triggering strategy: T1 TRIGGER ● T1 on trigger board: fjlter, threshold discriminatjon, selectjon combinatjon of channels, coarse tjming... T2 PC ● T2 on local PC: tjming, pulse shape discriminatjon, ADC selectjon digitatjon polarizatjon, spectral content... evt. build. ● T3 on central acq. syst.: relatjve tjming between GPS tjming statjons, directjon of arrival, occurrence frequency… SC – partjcle trigger selectjon: ● Individual threshold (15 mV) Analog T1 trigger : no permanent digitjzatjon ● Multjplicity selectjon (5 or more over 13 SC) of the signals and a controlled energy budget (~20W per statjon). ● Trigger GPS tjming ● Trigger broadcast over the network L.M. ICRC July 2017 14

Convolutjon of the antenna response Electric fjeld patuern is not simple, Global transfer functjon : ● ● dependence to the (v,B) angle → H(f,θ,φ) = H ant. (f,θ,φ) H ana. (f) H digit. (f) – compare to realistjc simulatjons ! Calculated or/and measured – H ant. : antenna transfer functjons Directjon ? ● H ana. : analog chain H digit : digital chain Deconvolutjon : data → E fjeld vs Model – ● F -1 (H. F (E(t,θ,φ))) = ADC(t) Convolutjon : Model → ADC vs Data – Convolutjon + noise SELFAS* simulatjon NS signal EW signal *V.Marin et al., Astropartjcle Physics, Elsevier, 2012, 35, pp.733-741. L.M. ICRC July 2017 15

Extractjng cosmic ray features (II) + + + + + + + + L.M. ICRC July 2017 16