Experimental calibra/on of the ARA radio neutrino telescope with an - - PowerPoint PPT Presentation

14th, July, 2017, ICRC2017

Experimental calibra/on of the ARA radio neutrino telescope with an electron beam in ice

• R. Gaior, A. Ishihara, T. Kuwabara, K. Mase, M. Relich, S. Ueyama, S. Yoshida

for the ARA collaboraFon,

• M. Fukushima, D. Ikeda, J. N. MaLhews, H. Sagawa, T. Shibata, B. K. Shin and G. B. Thomson
• K. Mase

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14th, July, 2017, ICRC2017

■ The ARA calibra/on with the TA-ELS (ARAcalTA)

Performed in January, 2015 at TA site, Utah Purpose: BeLer understanding of the radio emissions and the detector calibraFon

We measured ² PolarizaFon ² Angular distribuFon ² Coherence

Antenna tower Extendable: 2-12m Ice target Vpol antenna Hpol antenna 40 MeV electron beam line TA LINAC

Bicone ARA antenna 150-850 MHz

LNA + filter (230-430 MHz)

• K. Mase

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• 14th, July, 2017, ICRC2017

■ TA LINAC

Measured bunch structure ~10 bunches 2 ns 2×108 electrons → Enough signal strength Correlation → Monitor of electron number Cover wide range → Coherence

ü 40 MeV electron beam ü Typical electron number per bunch train: 2×108 → 30 PeV EM shower ü Pulse frequency: 2.86 GHz → pulse interval: 350 ps ü Bunch train width was opFmized to ~2 ns ü Beam lateral spread: ~4.5 cm ü Trigger signal available ü Electron number can be monitored (~3%)

• K. Mase

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■ Ice target and the configura/ons

l 100 x 30 x 30 cm3 l Easily rotatable structure l Easily movable on a rail l Plastic holder for the ice has a hole underneath for the beam 40 MeV electron beam line l Main data sets l With ice (30°, 45°, 60°) l No target

Thermometer Dry ice (on side)

1 m α=60° α=30°

Cherenkov angle in ice (56°)

• R. Gaior, 1135,

ICRC2015 14th, July, 2017, ICRC2017

• bservation

angle

40 MeV electrons

emission angle

emission angle [deg.]

ice inclination angle (α)

Ice target

• K. Mase

4 Electrons stop after running 20 cm in ice due to an ionization loss → Wide angle distribution

14th, July, 2017, ICRC2017

■ Expected radio emissions

ü Several radio emissions are expected ü Askaryan radiation

ü In ice ü Wide angular distribution due to the short tracks ü Peak at more horizontal direction than the Cherenkov angle (56°)

ü Transition radiation

ü At air/ice boundary ü Peak at Cherenkov angle (56°)

ü Sudden appearance radiation

ü When beam appears ü Forward emission (Cherenkov angle is ~1°) ü More in Krijn’s talk on Tuesday

Electron Light Source facility

20 cm hole metal ice beam pipe

40 MeV electrons

Askaryan radiation Transition radiation Sudden appearance signal

• K. Mase

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• Obs. angle 0° (no target) at 1 m

Middle point Endpoints

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• K. Mase

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■ Simula/on

• Bunch structure

2 ns Lateral distribution 4.5 cm Electron Light Source facility 20 cm hole metal ice beam pipe

40 MeV electrons

Emission in ice Emission in air Electron beam (Geant4) E-field calculation Ray trace

Based on the classical EM theory (Lienard-Wiechert potentials) Middle point method (PRD 81, 123009 (2010)) Endpoints method (PRE84, 056602 (2011))

Thanks to Anne Zilles for sharing her code for the implementation

Including accelerator configurations

E-field

tables made

20 cm

E-field [V/m]

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■ Detector simula/on

＋ ＋ =

E-field Antenna response (T-domain) filter + LNA response

• K. Mase

7 2 ns

• R. Gaior, 1135, ICRC2015

Time [ns] Time [ns] Frequency [GHz] E-field [V/m] Antenna height [m] Gain [dB]

Time [s] Voltage [V] 5 ns 230-430 MHz Verify the understanding the emission mechanisms and detector responses, comparing with data

• Obs. angle 0° (no target) at 1 m

Time [ns]

40 60 80 100 120 140

Voltage [V]

• 0.3
• 0.2
• 0.1

0.1 0.2 0.3

Time [ns]

40 60 80 100 120 140

Voltage [V]

• 0.3
• 0.2
• 0.1

0.1 0.2 0.3

■ Comparisons of waveform and the frequency spectrum

ü Reasonable agreements between data and simulation after correcting the cable attenuation ü Less Hpol signal → high polarization ü Some indications of noise

Vpol Hpol Vpol

Configuration: Ice 60°, obs. angle: 15° Simulation

Data

• Simulation

Data

• Simulation

Data

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• K. Mase

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Group review

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■ Cable / connector aYenua/on correc/on

Faraday Cup (for the electron charge measurement) TA short cables / connectors (~3m, up to 500 MHz) Long cables (40m, high frequency adapted)

TA LINAC

• scilloscope

Counting house 40 MeV electrons

• K. Mase

Long (45 m) Short (3 m) Short + Long (40 m)

Original Long (45 m) Short (3 m) Short + Long (40 m) Charge loss 9.9 % 23.5% 45.7%

² Found out the TA short cable attenuate signal significantly ² Electron number for data was underestimated by 46% ² The emission power is proportional to the charge square → correction of x2.1 (1.462) ² Original bunch structure turned out to be more narrower

Time [ns] Voltage [V]

Time [ns] 40 60 80 100 120 140 Voltage [V]

• 0.3
• 0.2
• 0.1

0.1 0.2 0.3

Data Simulation

Time [ns]

■ Polariza/on

Polarization Polarization angle

Data (Ice target) Simulation (Ice target) Data (No target) ü All signals shows relatively high vertical polarization ü Smaller polarization for the no target configuration ü Less polarized signals for the outside of the main peak → indication of the noise contamination Ice target 0.92±0.03 SimulaFon 1.00±0.01 No target 0.82±0.03

Highly polarized Configuration: Ice 60°, obs. angle 15°, Vpol Time development of polarization

Polarization Time [ns]

Data Simulation

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Voltage [V]

(electron number)

10

Log

7.6 7.8 8 8.2 8.4 8.6

(radio energy [J])

10

Log

• 11.8
• 11.6
• 11.4
• 11.2
• 11
• 10.8
• 10.6
• 10.4
• 10.2

Time [ns] 20 40 60 80 100 120 140 160 180 200 Voltage [V]

• 0.3
• 0.2
• 0.1

0.1 0.2 0.3

Data Simulation

Voltage [V] Time [ns]

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■ Coherence

Slope index: 1.86 ± 0.01 ü High coherence, but not full → Possibly due to the noise ü Similar values for all the configurations (Even Hpol too) Data ü High coherence around the all main pulse ü Noises seem to show the high coherence Configuration: Ice 30°, obs. angle 0°, Vpol Time development of coherence

Time [ns] Slope index

• K. Mase

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■ Angular distribu/on

ü Noise were filtered using a time window (±5 ns) with respect to the peak in a waveform ü Reasonable agreement after applying the noise cut (otherwise the shapes do not agree, data is ~60% higher)

Electron Light Source facility

ice

40 MeV electrons

Observation angle

Preliminary

distance corrected, but antenna gain not corrected

• K. Mase

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θc(30°) θc(45°) θc(60°)

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■ Summary

l We have performed an experiment at Utah using the TA-ELS for the better understanding of radio emissions and the ARA antennas l Highly polarized and coherent signals were observed l Radio signals observed from the beam appearance l More signals observed when using an ice block l Agreements improved after correcting the cable attenuation l More detail simulation constructed to take the reflection and refraction into account l Need to understand the noise a little better l Like to understand how much Askaryan signals are contained using simulation

• K. Mase

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Backups

• K. Mase

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2 km

² Aims to detect high energy neutrinos above 30 PeV using Askaryan radiaFon

² 37 staFons (3 staFons deployed so far) ² Each staFon has 4 strings at 200 m depth ² Each string has 2 Vpol + 2Hpol broadband antennas (~200–800 MHz)

² Total surface area ~100 km2 ² ~10 IceCube @ 1 EeV

Astroparticle Physics 35 (2012) 457–477

■ Askaryan Radio Array (ARA)

• K. Mase

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Group review

• K. Mase

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[dBi] Angle [deg.] Bunch number

Ratio

■ Systema/c uncertain/es

Bunch after cable correction

Widest case Shortest case

1 ns

Original Long (45 m) Short (3 m) Short + Long (40 m)

Item Data Simula/on StaFsFcal error ±7% ±10% Stability ±19%

• Antenna response

uncertainty

• 17% +14%

Bunch width

• 14% +17%

Sum ±20% ±24% Time [ns]

1 ns

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■ Waveform agreements (no target)

0 m 3.5 m 7.4 m ü Timing is matched with a cross correlation ü Time difference between data and simulation is explained by cable delay etc. ü Agreements are reasonable ü Prepulse seen Data Simulation Δt = 137.5 ns Δt = 138.9 ns Δt = 139.7 ns

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■ Residual signal (no target)

0 m 3.5 m 7.4 m ü Similar shape ü Similar amplitude ü Time correlates with signal → generated at source? Prior to the signal? ü 10 ns earlier (3 m below the cover box) ü From the end of the beam pipe? ü No distance dependence? Data - Simulation

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■ Spectrum agreements (no target)

0 m 3.5 m 7.4 m ü Similar behaviors ü Difference becomes larger at high height because the signal is weaker and the effect of additional component is larger Data Simulation

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■ Residual spectrum (no target)

0 m 3.5 m 7.4 m ü Quite similar shape ü Flat spectrum →White noise?

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■ The ARA sensi/vity

ARA37 (3yr)

ARA Test Bed limit ARA2 limit

• K. Mase

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■ Reproducibility

Vpol Hpol The reproducibility was checked with data with the same configuration

2015/01/14 Run1 (ice 60 deg., 0m) 2015/01/14 Run4 (ice 60 deg., 0m)

The difference in the amplitude is 5% → 10% in power (Vol)

• K. Mase

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14th, July, 2017, ICRC2017

■ Stability and far field confirmation

ü The stability with the same configuraFon: 5% in amplitude ü The antenna mast was intenFonally rotated by ~15 deg. ü The signal amplitude decreased proporFonally with the distance

• change. → Far field confirmaFon

(3.0 ns Fme delay → 11% distant → 12% amplitude decrease) ü Time difference from the expectaFon was checked for each configuraFon. ü The spread is 1.9 ns → 9° rotaFon → 6% in amplitude ü The overall systemaFc uncertainty in power: 16% 15 degrees

2015/01/14 Run1 2015/01/14 Run3 (3.0 ns delay corrected)

Configuration: Ice 60°, obs. angle: 0°, Vpol

• K. Mase

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■ The ARA system

DAQ box

• ptical fiber

(~200 m) DAQ at surface LNA

in-ice

~40 dB band-pass filter Antennas

calibrate these detectors V-pol antenna

Bicone 150-850 MHz

• H-pol antenna

Quad-slot cylinder 200-850 MHz Gain similar to dipole (+2 dBi)

• ~40 dB
• K. Mase

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■ Schema/c of the ARA system

DAQ box FOAM DTM

• ptical fiber signal

transfer system

Antenna

• ptical fiber

(200m) band-pass filter DAQ at surface LNA

DTM FOAM in-ice

~40 dB

• K. Mase

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■ Antennas

V-pol antenna

Bicone 150-850 MHz

• H-pol antenna

Quad-slot cylinder 200-850 MHz Gain similar to dipole (+2 dBi)

• K. Mase

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