PoS(ICRC2019)980 6 − 10 × 7 . 1 http://pos.sissa.it/ = Φ 2 E † eV. Data from the operation of the ARIANNA 18 for the ARIANNA Collaboration ∗ at a energy of 10 1 − sr 1 − s 2 − [email protected] pilot array will inform the design ofcapable the of next probing generation of all radio but neutrino theshown detectors, most that which such will pessimistic be detectors models will of have the anpoint GZK important sources. neutrino role to flux. play It in will the multi-messenger also detection be of GeVcm Speaker. for collaboration list see PoS(ICRC2019)1177 The seven-station test-bed for theHexagonal ARIANNA Radio Array ultra-high (HRA), energy was (UHE) completedIn during neutrino the the telescope, 2014-2015 more the Antarctic than summer four season. silience years and since, stability, the surviving ARIANNA multipleuptime pilot Antarctic during array winters the has summer while demonstrated months, operating remarkablebe while with re- the capable a ARIANNA and typical data cost/power 90% acquisition efficient.array system has will A proven be to combined presented. analysisciency of of The 79%, 4.5 providing neutrino an years updated search limit of for yielded data the diffuse no from UHE candidate neutrino the flux events, pilot of with a signal effi- † ∗ Copyright owned by the author(s) under the terms of the Creative Commons c 36th International Cosmic Ray Conference -ICRC2019- July 24th - August 1st, 2019 Madison, WI, U.S.A. Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). University of California, Irvine, USA E-mail: Christopher Persichilli Performance of the ARIANNA pilot array,implications and for the next generation ofdetectors UHE neutrino PoS(ICRC2019)980 σ eV 20 ). 1 Christopher Persichilli attenuation lengths for radio frequencies in ) km thermal trigger rates at a trigger threshold of 4 1 1 ( ) O ]. In addition to constraining the diffuse cosmogenic 6 mHz ( O amplitude, which allows for real-time data transfer. Events which are not ]. Each event trigger records a 128 ns record at 2 GSa/s. The SST employs a 7 RMS V ]. Such designs can economically instrument large volumes at modest cost, and will 3 , 2 ], prompted renewed interest in the role of in multi-messenger astronomy. Theo- Each station is a self-contained and autonomous detector, powered by individual solar panels, In December 2015 the battery systems on all HRA stations were upgraded, leading to improved The ARIANNA pilot Hexagonal Radio Array (HRA) consists of seven sta- The current pilot array stations are based on the Synchronous Sampling plus Triggering (SST) The intriguing correlation of neutrinos measured in IceCube with the blazar, TXS 0506+056 Determining the source, or combination of sources, which contribute to the measured flux of 5 , ], is at the heart of one of the most fundamental unsolved problems in astronomy. Radio-based 4GHz wireless ethernet and Iridium satellite communication systems. This design allows for the . 4 1 multi-stage coincidence trigger. The firstthreshold stage crossing requires on a a single 5ns inputtrigger coincidence channel. within between The a high second 30ns and stage requires low same window, that signal. taking two or advantage This more of schema channels above that achieves thermal parallel a pairs of LPDA’s see largely the and able to transfer event2 data to the USdeployment of in ARIANNA stations near in real-time at any throughfor location infrastructure a with development. ice combination of of sufficient quality, long without the range need livetime and stability for the array.stations When the have been array is shown to configured to achieve sustained maximize operational livetime, ARIANNA efficiencies of 90% (figure tions installed at the Moore’sLPDA Bay antennas site installed on just below the theice/seawater Ross snow boundary Ice surface, below Shelf. pointing Moore’s downward Each Bay intowhich station acts significantly the contains increases Ice as the a Shelf. a effective set volume The highlysitivity of of efficient the across four detector, mirror the and at entire provides upward fairly radioextremely uniform sky. frequencies, radio sen- The quiet Moore’s environment, Bay owing sitebeing to close also enough shielding has to from the McMurdo nearby unique Station mountain to advantages take of ranges, advantage an while of surface also logistics. 2. The ARIANNA detector chip developed [ neutrino flux, the sensitivity ofminous radio-based transient neutrino events detectors to allows astrophysical forpotential neutrinos to exciting study from contributions source lu- to objects via multi-messenger light, astronomy gravitational waves, and and the neutrinos. be a valuable tool for the detection of UHE neutrinos. [ detectors, such as ARIANNA, leverage the ries of UHE cosmic ray productionneutrinos, predict a and deep UHE relationship charged between cosmic gamma-rays, astrophysical rays [ ultra-high energy (UHE) cosmic rays, which have been measured with energies in excess of 10 Performance of ARIANNA 1. Introduction [ cold ice to searchshowers for [ the characteristic Askaryan pulses generated by neutrino induced particle PoS(ICRC2019)980 ], using 2017-06 9 5

e v o b a

2017-04 n u Livetime Excluded from Analysis Sun above horizon S ]. Two versions 10 Christopher Persichilli 2017-02 Time 2016-12 2016-10 . Since the HRA stations rely on solar 4 ] with a GZK energy spectrum [ 2016-08 8

1.0 0.8 0.6 0.4 0.2 0.0 Fraction of Day of Fraction range from 0 (no correlation) to 1 (identically 2 χ 90%. Shaded regions show fractions of the day that the sun Monte Carlo [ . > 2019 RMS V above the horizon. ◦ ShelfMC 2018 used to compare a specific reference template to the measured signal on Time 2017 χ 2016 Uncorrected Corrected Excluded from Analysis (left) Cumulative livetime for all SST based HRA stations since deployment. The corrected curve 2015 level above the thermal noise σ

6 4 2 0 8 The time-domain signal is produced by generating waveform templates which incorporate In order to generate a population of simulated neutrinos for analysis, one billion neutrino A template matching procedure is used to distinguish signal from background. A Pearson

10 Cumulative Livetime (station years) (station Livetime Cumulative the response of the antennas and amplifiers, according to the procedure in [ interactions were simulated in the correlation coefficient 3. Simulation of Neutrino Signal a detector configuration matching the currently deployedThis ARIANNA HRA produced stations a in sample Moore’s Bay. of approximatelyat 1.3 a million 4 events which triggered the simulated station of the ARIANNA amplifiers (100differences and in their 200 impulse series) response. are Tostructed account in for for use each these type in differences, of separate the amplifier, and templates pilotThe the are stations array, simulated con- which which event contain have each geometry type slight is areneutrino, analyzed used which separately. to is scaled select to the the correctsimulated most amplitude signal appropriate and is template added converted to to for the finite each bandwidth samethe simulated thermal data triggered noise. format, events. and The processed by the exact same analysis, as 4. Analysis of Triggered Events each channel of a triggered event. Values of is above the horizon, and more than 5 power, they shut down duringHRA the station. winter Configurations and are doafter-which tuned stations not typically to accrue show maximize livetimes livetime. livetime after (right) the The end livetime of per the day field for season an (red band), Figure 1: represents the livetime used for analysis, as discussed in section Performance of ARIANNA transferred in real-time can be transferredinternal storage. on demand at a later date, or physically recovered from PoS(ICRC2019)980 2 1 0 0 0 0 1 1 1 100 . 4 is the maximum , 2016 during the th than for a low SNR PTP Christopher Persichilli V . The expected number ave ), which excludes times χ 1 , 2014) through February th . Notice that larger values of SNR 3 SNR , where σ 10 2 / PTP Signal region, 77.60% efficiency Amp Saturation V vs SNR. Stations with series 100 amps (left)

cutoff, the tail of the cumulative distribution

ave

0.0 1.0 0.8 0.6 0.4 0.2 e v is the root-mean-squared voltage of min-bias a χ σ ave and SNR in which we will define a signal region 3 χ 1 0 2 ave 0 0 0 χ 1 1 1 ], which was observed by the HRA. 100 , since lower SNR leads to worse cross-correlation to the reference 11 ave χ for each channel, we combine the results into a single parameter per χ SNR 10 essentially imposes a condition that pairs of antennas see similar signals, which is ave Signal region, 80.89% efficiency Amp Saturation , which is the greater of the two averages between co-polarized pairs of LPDA’s. High Distribution of simulated neutrino signal in χ ave χ

Events are binned according to a sliding 0.2 decade window in log We can define a lower bound for a neutrino signal region within this parameter space such that The data for this analysis includes all triggered events collected from the current SST based By also considering the signal amplitude, it is possible to leverage the general behavior that a We create a 2D parameter space using

0.2 0.0 0.8 0.6 0.4 1.0 e v a , 2019. The total livetime for this analysis is 7.96 station years (figure . th when the Moore’s Bay site wasoperation occupied, as or well HiCal ANITA’s as pulser some [ periods on Dec 11-13 and series 200 amps (right) are analyzed separately, as discussed in section Figure 2: the expected number of background events willversions be of 0.5 the across ARIANNA all amplifiers stations (100 for the andwith entire 200 different data series) amplifier set. are models employed Two in will thehardware be pilot response. analyzed array. Stations separately, in order to account for differences in pilot array stations from after their deployment (beginning December 8 SNR correspond to larger values in 5 of background events in a binthe is fraction taken of to neutrino be events the inbackground total the ratio. number bin, of In expected which events effectively order (0.5) produces to weighted a the by curve calculate of the constant signal to 2 template. The blue vertical line represents aThe 800mv red cutoff line where represents the the amplifiers lower would be bound strongly of non-linear. the signal region, which is discussed in section Performance of ARIANNA similar). After calculating event, values of expected for neutrino signals. high signal-to-noise ratio (SNR) event is likely to have a greater value of event. In this text, thepeak SNR to of peak an amplitude event will acrossnoise be events. all defined channels, as and for this analysis. The distribution of the simulated neutrino signal in this space is shown in figure PoS(ICRC2019)980 1 0 4 3 2 0 0 0 0 0 1 1 1 1 1 100 . No candidate 4 Christopher Persichilli . ave χ 1.0 SNR . An expected number of 0.5 10 3 0.8 Signal region, 77.60% efficiency Amp Saturation . The blue horizontal line represents a 800mv 3 0.6 events in the bin (the single highest value event

1.0 0.8 0.6 0.4 0.2 0.0

e e v v a a ave χ 4 . No triggered events remain in the signal region. 0.4 4 1 0 3 2 vs SNR. Stations with series 100 amps (left) and series 200 0 0 0 0 1 1 1 1 ave χ 0.2 100 event distribution values to fit fit to tail bin boundary target probability 0.0 1 2 3 2 5 4 3 1 0 0 0 0 0 1

0 0 0 1 1 1 1

1 1 1 Number above in bin in above Number SNR 10 - SNR distribution of the measured data set is presented in Fig. Signal region, 80.89% efficiency Amp Saturation ave An illustration of the procedure for calculating the signal region boundary for a particular slid- χ Distribution of triggered events in

In the absence of observed events in the signal region, a model independent 90% confidence The

0.2 0.0 0.8 0.6 0.4 1.0 e v a amps (right) are analyzed separately, as discussed in section Figure 4: upper limit on the diffuse neutrino flux is given by, where a noticeable pile-up effectof is the observed signal due region, to which amp is clipping. discussed in The section red line represents the lower bound 5. Diffuse Flux Limits is excluded from thebackground fit event probability, in yielding order the signal to region limit lower bound the value of effect of outliers), and extrapolatedneutrino to events were intersect observed the in the desired signal region. background events within the full data set results in a neutrino signal efficiency of 79%. Figure 3: ing SNR bin. A power law is fit to the 300 highest Performance of ARIANNA is fit to a power law,resulting and curve extrapolated is to then the smoothed desiredand number by a of a background second graphical events order illustration in Savitzky-Golay the of filter. bin. this Some The process technical details are shown in figure PoS(ICRC2019)980 0 2 0 (5.1) 1 9 1 ]. 0 1 15 8 1 0 Christopher Persichilli 1 is the effective volume of 7 1 0 Ω 1 ) i e f f t neutrino energy [eV] V i 6 ε 1 ( 0 i ARIANNA pilot array sensitivity ARIA (130 stations) sensitivity Fang & Metzger (30 days) 10 Mpc IceCube sensitivity (to GW170817) Auger sensitivity (average, to GW170817) 1 ∑ ) E Ω ( is the water equivalent interaction length 5 1 are, respectively, the total livetime and the e f f 0 L 1 2 5 4 3 2 1 0 1 EL 0 0 0 0 0 0 ε

0 0 1 1 1 1 1 1

1 1

] m c / V e G [ F E e c n e u l f l a r t c e p 90 s ], for the shown limits and spectra). EV

2 2 14 and 5 FC log i t 1 ] have reduced cost and power consumption, while d 1 7 0 1 . l a ln10

ARA ], and 0 t 1 e

0 e ANITA I - III ≤ z 12 1 n i ) e H 1 is the bin width in decades,

, E ) ( 9 3 = 0 ± Φ 1 (

2 R E C E E Auger H . (right) Sensitivity of the ARIANNA pilot array to transient sources. Figures U

8 log t 5 i 0 f

d 1 t s e 10% protons in UHECRs, van Vliet et al. allowed from UHECRs, van Vliet et al. Best fit UHECR, Heinze et al. B 44 is the Feldman Cousins 90% confidence upper limit per decade-wide bin, . 7 0 2 1 . = neutrino energy [GeV] 5 ] (see references therein, as well as [ IceCube 90 6 trigger threshold in amplitude. Future detectors will make use of more advanced 13 0 1 ARIANNA HRA (this work) ARIA: 130 stations, 5 years σ FC ] and initial ARIANNA stations [ (left) Diffuse flux limit for the ARIANNA HRA on a sliding decade wide energy bin. For details 16 5 0 7 8 9 4 5 6 1 0 1 1 1 where We have demonstrated that a template matching procedure is capable of rejecting all observed The operation of the ARIANNA pilot array at Moore’s Bay, since it’s completion in December 0 0 0 0 0 0

0 0

1 1 1 1 1 1

1 1

] r s s m c V e G [ is the neutrino energy, E

1 1 2 2 calculated using the cross section in [ E a single ARIANNA station averaged over all flavors, improving reliability and livetime.eration Practical of experience the gained ARIANNA throughexperimental pilot the designs. array deployment will and op- provide crucial insight for the development of future backgrounds over the operation of79% the at HRA, a while 4 maintaining a combined signal efficiency of 6. Discussion and Outlook triggering and analysis techniques in ordereffective to volume push per the station. sensitivity In threshold addition, lower,tic and the environments increase development the offers of new the wind potential powerstations to systems through for the significantly Antarc- winter, increase without the the need livetime for of investment remote in power autonomous infrastructure [ Figure 5: of the calculation see section adopted from [ 2014, has provided a robust prooftor. of concept Iterative for improvements an in autonomous, data radio-basedtotypes UHE acquisition [ neutrino and detec- power systems since the first ARIANNA pro- Performance of ARIANNA analysis efficiency for each station.shown The in result figure of this calculation for the ARIANNA pilot array is PoS(ICRC2019)980 . , Soviet (2007) , ]. 99 17 , Sissa Medialab, Christopher Persichilli Physical Review Letters . , ), which is effectively the entire upward 5 ], and the projected flux limit is shown in 13 (1965) 658. 21 (2018) eaat1378 6 ]. In particular, a precise measurement of neutrino 17 Science , Multimessenger observations of a flaring blazar coincident with Observations of the askaryan effect in ice The cosmic ray energy spectrum measured using the pierre auger observatory Coherent Radio Emission from Cosmic Showers in Air and in Dense Media . DOI collaboration, for comparison. This design expands on the basic ARIANNA station layout by including Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017) UGER 5 Journal of Experimental and Theoretical Physics high-energy neutrino IceCube-170922a Aug., 2017, in Since each ARIANNA station serves as a autonomous and self-contained detector, this plat- We are grateful to the U.S. National Science Foundation-Office of Polar Programs, the U.S. We acknowledge funding from the German research foundation (DFG) under grants GL 914/1- Using the knowledge gained through the operation of the ARIANNA pilot array, it is possible [4] The IceCube Collaboration, et al., [2] G. A. Askar’yan, [3] ANITA collaboration, [1]A form can be deployed atallow various for sites the in easy order installation toformation attain of for full high-gain precise sky antennas event coverage. reconstruction in [ any Near-surface detectors polarization, providing increased in- National Science Foundation-Physics Division (grantarray NSF-1607719) at for Moore’s Bay. granting In the particular, we ARIANNA staff, are grateful without for which the the excellent scientific support of mission the in McMurdo Antarctica region would not be possible. 1 and NE 2031/2-1 and thefrom Taiwan Ministry the of Swedish Science Government and strategic Technology.from HB program the acknowledge Stand support Uppsala Up university for Vice-Chancellor’s travel Energy. grantlenberg Foundation) (sponsored EU and by acknowledge the the C.F. support Liljewalch Knut travel scholarships. andfrom Alice DB the and Wal- ANo MEPhI acknowledge Academic support Excellence2013 Project program (Contract of No. Russia, 02.a03.21.0005) via agreement and 14.12.31.0006 the from Megagrant 24.06.2013. References figure a 15m vertically orientedthe string sensitivity of of dipoles, the as detector, as wellevent well properties, as as which other the will ability design be to vitally changes perform important which a in improve precise a both first reconstruction detection of of neutrino UHE neutrinos [ arrival direction will enable real-time alertsmulti-messenger to follow up. be Additionally, sent the out large effective to volumethem of the highly radio-based sensitive community, detectors to allowing makes explosive for events, e.g. directed therable sensitivity to of the Auger ARIANNA for pilot objects array within issky. compa- the This field of uniform view sensitivity, (figure which comessignificant benefit as in a the property hopeful of detection Moore’s of bay’s rare ice/sea transient boundary, events. is of 7. Acknowledgements to make informed projections offor the an sensitivity optimized of surface array a (ARIA) future is full-scale discussed detector. in [ A proposed design Performance of ARIANNA PoS(ICRC2019)980 , 62 . Physical , . (2010) 85 Progress in Particle A prototype station Hical 2: An , Targeting ultra-high Christopher Persichilli 624 Astroparticle Physics (2019) , (2019) . ]. . . 1410.7369 (2019) 60 . 918 (2019) . (2015) [ (2016) 082003 7 Advances in Space Research Nuclear Instruments and Methods in Physics Research , 93 , A wind-turbine for autonomous stations for radio Neutrino direction and energy resolution of askaryan , Ph.D. thesis, University of California, Irvine, 2018. (2018) eaat2890 . Neutrinos from propagation of ultrahigh energy protons PoS(ICRC2019)968 (these proceedings) , Phys. Rev. D Science , . , Neutrino emission from the direction of the blazar TXS 0506+056 prior Design and Performance of the ARIANNA Hexagonal Radio Array Time-domain response of the ARIANNA detector ]. Opening a new window onto the universe with IceCube (2018) 73 (2011) 102 Performance of two stations and first results in the search . 83 Calculation of high energy neutrino-nucleon cross sections and uncertainties using Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Performance and Simulation of the ARIANNA Pilot Array, with Implications for Future , (2001) 1406.0820 [ PoS(ICRC2019)899 (these proceedings) 64 IEEE Transactions on Nuclear Science , , for ultrahigh energy neutrinos for arianna: A detector for cosmic neutrinos Review D instrument designed for calibration of themeasurements anita experiment and for antarctic surface reflectivity energy neutrinos with the arianna experiment detection of neutrinos experiment Section A: Accelerators, Spectrometers, Detectors and Associated Equipment detectors Systems the martin-stirling-thorne-watt parton distribution functions andPhysical implications Review for D future experiments Ultra-high Energy Spectrometers, Detectors and Associated Equipment and Nuclear Physics (2015) 139 to the IceCube-170922a alert [7] ARIANNA collaboration, [6] M. Ahlers and F. Halzen, [8] C. Persichilli, [9] R. Engel, D. Seckel and T. Stanev, [5] The IceCube Collaboration, [14] ARA collaboration, [15] A. Nelles for the ARIANNA collaboration, [16] L. Gerhardt, S. Klein, T. Stezelberger, S. Barwick, K. Dookayka, J. Hanson et al., [17] C. Glaser for the ARIANNA collaboration, [12] A. Connolly et al., [13] A. Anker, S. Barwick, H. Bernhoff, D. Besson, N. Bingefors, G. Gaswint et al., [11] S. Prohira, A. Novikov, D. Besson, K. Ratzlaff, J. Stockham, M. Stockham et al., [10] ARIANNA collaboration, Performance of ARIANNA