Overview of the Fourth Flight of the ANITA Experiment Jiwoo Nam (National Taiwan University) for The ANITA Collaboration
The ANITA Collaboration Univ. College London Univ. of Delaware Ohio State Univ. Univ. of Chicago Washington Univ. St. Louis Univ. of Kansas Cal-Poly National Taiwan Univ. JPL Univ. of California, LA Univ. of Hawaii 11 Institutes, ~50 collaborators in a 18 hour time zone
The ANITA Experiment The ANITA (ANtarctic Impulsive Transient Antenna) is; - a NASA long-duration balloon payload with - an array of radio antennas (180-1200MHz) • UHE Neutrino Detection (Primary Goal) • UHE Cosmic Ray Detection • Askaryan signals in Antarctic ice. • EAS with Geo-magnetic radiation • Excellent sensitivity in 10 19 - 5x10 20 eV. • Large field of view • Large volumes of ice • Partially coherent emission in ANITA’s • Excellent transparency of the Antarctic ice freq. band. (RF attenuation length: ~ 1km.)
ANITA’s 3 rd signal Up-coming shower? A nu-tau signature? 117, 071101 (2016) A strong H-pol non-inverted signal seen! - Expected background events: 4x10 -4 For details; - 27.4 deg below horizon, E = 0.6 0.40 EeV Andrew Romero-Wolf’s talk Chord length: 5450 km (20000km water equivalent) NU142, Monday 13:30 1600km SM interaction length @ 1 EeV Difficult to be explained by SM (need to be factor 3-5 of cross-section )
Prior ANITA Flights ANITA-I (2006-2007) 35 days 32 Antennas Both H-pol/V-pol trigger (via LCP/RCP) No neutrino candidate seen Observation of 16 CR events Observation of 1 up-coming event ANITA-II (2008-2009) 30 days 40 Antennas V-pol trigger only 1 neutrino candidate observed Additional 2 CR events ANITA-III (2014-2015) 22 days 48 Antennas H-pol/V-pol trigger Data analysis in progress Each flight increased the sensitivity with improved instruments
ANITA’s signatures ANITA CR CR shower 3) CR 2) 4) decay 1) Antarctic ice sheet 1~4km Askaryan effect Origin RF production Polarization RF Direction Polarity 1) Neutrinos Askaryan V ‐ pol Below Horizon Normal 2) CR ‐ reflected Geo ‐ synchrotron H ‐ pol Below Horizon Inverted 3) CR ‐ direct Geo ‐ synchrotron H ‐ pol Above Horizon Normal 4) Tau Neutrino? Geo ‐ synchrotron H ‐ pol Below Horizon Normal
ANITA-4 Instrument GPS antennas + TDRSS & Iridium antennas Omni-directional solar array (top) Two 8 horn antenna clusters (top) ANITA electronics 16 horn antenna cluster (middle) 16 horn antenna cluster (bottom) Omni-directional solar array (bottom) Credit P. Gorham
Trigger/ Digitizer Data Stream 1) Frontend (see next slide) By O. Banerjee 2) Tunable notch filter (see next slide) 3) 90 o hybrid coupler & trigger ANITA-3 trigger: H-pol or V-pol ANITA-4 trigger: LCP & RCP (linearly polarization only )
ANITA-4 Frontend NTU LNA ANITA-4 Frontend ANITA-3: Band-pass Filter (180-1200MHz) ANITA-4: only Low-pass Noise Temp. vs Freq Reduce transmission loss and noise ANITA-3 Customized (utilized) LNAs ANITA-4 K ANITA-3: only on 32 channels ANITA-4: all 96 channels A big improvement of noise figure (30-40K) freq(MHz) 20% improvement of energy threshold (by B. Fox and L. Batten)
Tunable Universal Filter Frontend (TUFF) ANITA-4 power (dBm/MHz) ANITA-3 power (dBm/MHz) freq. (MHz ) freq. (MHz ) by Ben Strutt ANITA 3: -sector masking fraction Unexpected EMI due to newly deployed military ANITA-3 satellites CW noise at 260 MHz and 360 MHz masking -sectors to minimize effect Masking fraction but overall acceptance reduced ANITA-4: use TUFF ANITA-4 Each channel has 3 independent tunable-, switchable- notch filters (~50MHz width) CW effect under control except near McMurdo Time (M-D) factor ~2.5 improvement for acceptance Figures by O. Banerjee
ANITA-4 Flight Credit S. Prohira HiCal launch HiCal Credit S. Prohira Credit S. Prohira Launched on December 2 nd 2016 at Williams Field, Antarctica Landed on December 30 2016 near South Pole (232 km away) 28 days at float A spiral pattern of trajectory: keep away from McMurdo Station (highest noise source) Two follow-up payloads (HiCal) were also launched
ANITA-4 Recovery Credit C. Miki Credit C. Miki A partial recovery done on Jan 10 th 2016 - All Data disks were fully recovered - Small- and important- items (AMP etc) Full recovery is planned in November 2017
ANITA-4 Performance ANITA-4 was in pristine condition for Live time vs. flight time most of the flight. ANITA-3 Recorded ~100M events Maintained 94% live on average 27.3 days of live time:1.46 times 1.46 time than ANITA-3 (18.7 days) 2.5 times for acceptance (TUFF) 1.45 times for live time ~ 3.6 times improvement in exposure ANITA-4 All figures by O. Banerjee
Validation and Calibration Two ground pulsers in McMurdo and WAIS were used for -System Validation -Trigger characterization -Amplitude / Timing calibration -Test Angular reconstruction Angular reconstruction obtained by interferometry technique shows an excellent pointing capability; =0.5 deg, =0.15 deg (Andrew Ludwig)
Example events (very preliminary) H-pol Many candidate events were found in telemetry data during operation/monitoring shifts Detailed characterizations will be done in following data analysis Here, two examples found when ANITA was in deep field V-pol Top: H-pol dominant Bottom: V-pol dominant
Improvements in Data Analysis Energy estimation of CR events: spectral slope analysis Advanced digital filtering, such as CW noise subtraction 1. Template search method based on improved understanding 2. of signals and the system response Binned approach to optimize cuts depending on RF noise 3. environment Steady improvement in MC simulation
Summary & Plan ANITA successfully completed the fourth flight with improved performance; - 20% lower energy threshold - Factor 3.6 increased exposure Data analysis of ANITA-3 and ANITA-4 in progress - well positioned for neutrino discovery! - hundreds of CR events expected! - search for partners to the up-coming event!
Backup Slides
The ANITA Collaboration Univ. College London Univ. of Delaware Ohio State Univ. Univ. of Chicago Washington Univ. St. Louis Univ. of Kansas Cal-Ploy National Taiwan Univ. JPL Univ. of California, LA Univ. of Hawaii 11 Institutes, ~50 collaborators in a 18 hour time zone
GZK Neutrino: CR spectrum Guaranteed UHE Neutrinos Presence of UHE Cosmic Rays requires UHE neutrinos GZK Cutoff Process p + cmb → + → n+ + n → lower energy protons → GZK neutrino) Looks like there is the GZK Cut-off Universe of EHE remainspuzzled, until GZK neutrinos are confirmed Lack of neutrinos: UHECRs not hadrons? Lorentz invariance wrong? New physics?
New Concept for Neutrino Detection Askaryan Effect (1962) Particle induces shower → Contained ~20% negative charge excess → Produces Cherenkov radiation Coherent, MHz – GHz frequency range, Linearly polarized and detectable at distances Blue: ~0.01GHz yellow: 2GHz Gurgen Askaryan (1928-1997) RF Cherenkov neutrino Shower ~10m length (20% e - excess) 20 m Shower RF field strength profile (SLAC, 2002) It has been confirmed experimentally for various media (sand, rock salt and ice.)
Ice Attenuation Measurements ~70 m Tx Rx Pulser Input ~940 meters @Taylor Dome Bedrock (2004 South Pole, S. Barwick et al.) RF attenuation length ~1km - 2004 South Pole, - 2006 Taylor Dome - 2010 South Pole
SLAC Beam Test (2006 June) 10 ns Askaryan pulse Absolute gain calibration with real Askaryan pulse Mini-Antarctica with 10 tons of ice target 28.5 GeV electron beam (10 9 electrons) First measurement of Askaryan effect in Ice PRL 99, 171101 (2007)
ANITA UHECR Events Geomagnetic field Unfolded waveforms correlation 16 UHECR Events : 14 reflected + 2 direct from ANITA-I 2 events from ANITA-II H-pol trigger was off (optimized for neutrino) PRL 105, 151101 (2010)
Laboratory Confirmation of The geo-synchrotron radio pulse T-510 experiment @ SLAC, Jan 2014 Expected emission field map Experimental setup 1000 G magnetic coils PRL 116 (2016)
Energy and Flux of CRs Observed point ( c ) : largest systematics However, spectral analysis can measure c 42-50% error in energy measurement • APP 77 (2017)
Neutrino signals vs. EAS signals ANITA V-pol predominated after refraction Neutrino Detection RF Cherenkov by Askaryan Effect Low Fresnel coeff. for transverse RF neutrino electric waves at the air-ice boundary. Cherenkov H-pol signal suppressed Shower ~10m Predominately V-pol length (20% e - excess) Geomagnetic Field EAS Detection ANITA H-pol predominate RF signal by Synchrotron geosynchrotron emission Emission V-pol component is further (H-pol.) suppressed in the reflection Predominately H-pol
Trigger/ Digitizer Data Stream By O. Banerjee
Trigger/ Digitizer Data Stream
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