Results of the ARAcalTA experiment: measurement of the coherent - - PowerPoint PPT Presentation

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Results of the ARAcalTA experiment: measurement of the coherent radio emission from an electron excess in ice. R. Gaor a , A. Ishihara a , T. Kuwabara a , K. Mase a , M. Relich a , S. Ueyama a S. Yoshida a for the ARA collaboration, M.

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SLIDE 1

Chiba University

Results of the ARAcalTA experiment: measurement of the coherent radio emission from an electron excess in ice.

1

  • R. Gaïora, A. Ishiharaa, T. Kuwabaraa, K. Mase∗a, M. Relicha, S. Ueyamaa S. Yoshidaa

for the ARA collaboration, M. Fukushimab, D. Ikedab, J. N. Matthewsc, H. Sagawab,

  • T. Shibatad, B. K. Shine and G. B. Thomsonc

a Department of Physics, Chiba University, Yayoi-cho 1-33, Inage-ku, Chiba 263-8522, Japan b ICRR, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8522, Japan c Physics And Astronomy, University of Utah, 201 South, Salt Lake City, UT 84112, U.S. d High Energy Accelerator Research Organization (KEK), 2-4 Shirakata-Shirane, Tokai-mura,

Naka-gun, Ibaraki, 319-1195, Japan

e Department of Physics, Hanyang University, 222 Wangsimni-ro Seongdung-gu Seoul, 133-791,

Korea

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SLIDE 2

Introduction

2

ARA Askaryan radiation experiments in lab

  • High Energy Neutrino (E> 100PeV)

radio detector

  • Collects the radio emission from

charge excess in ice

  • Never observed insitu

Several beam experiment were carried

  • ut since 2000.
  • 2000 Salzberg et al. First observation

in silica sand (Phys. Rev. Lett. 86, 2802 )

  • 2005 Gorham et al. Observation in

rock salt (Phys. Rev. D 72, 023002)

  • 2007 Gorham et al. Observation in ice

(Phys. Rev. Lett. 99, 171101 )

  • 2015 Belov et al. Observation with B

field ( arXiv:1507.07296 [astro-ph.IM])

R.Gaïor TeVPa Oct2015

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SLIDE 3

ARAcalTA

Goals

  • Confirm the intensity of Askaryan radiation
  • Check our signal simulation method
  • Check our detector response

Setup

Source: 40MeV Telescope Array Electron light source + block of ice (1m x 0.3m x 0.3m) Detector: ARA antenna (Vpol) + Low noise ampli. + filter + fast sampling osci

Data taking

15 days in Delta Utah (TA site) ~7 days of beam in January 2015 Different runs:

  • with ice target
  • without target
  • only plastic box

3

R.Gaïor TeVPa Oct2015

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SLIDE 4

ARAcalTA

e- beam e- beam

Target

  • ice target (kept a low temp.)
  • plastic structure
  • target angle adjustable
  • target removable

Detector

  • 2 polarization antenna on a pole
  • pole height adjustable up to 7m

above the beam exit

  • Filter (230-430MHz) and LNA at the

exit of the antenna

  • ~40m cable to DAQ

4

R.Gaïor TeVPa Oct2015

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SLIDE 5

Beam configuration

Beam width: ~2-3 ns width Beam charge: 25-60 pC (~2 - 4 x108 e-) 2 monitors: Faraday cup: stop the beam (calorimetric meas.) Wall current monitor: let the beam go through → can calibrate WCM with FC on dedicated runs Faraday cup Wall current monitor FC vs WCM

2ns

5

R.Gaïor TeVPa Oct2015

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SLIDE 6

Results: Polarization/Coherence /Intensity

Data Simulation (Askaryan) Simulation with sys. uncertainty No target

Data 0.92±0.03 Simula2on 1.00±0.01 No&target 0.82±0.03

  • " Polarization angle

" Polarization

■

  • (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

Slope index: 1.86 ± 0.01

  • ■
  • Very polarized signal in all cases (ice target and no target)

(expected for a field from the beam or electron shower)

  • Charge dependence of the radio signal: almost fully coherent
  • Signal with ice target at least 2 times larger than without
  • No specific background from plastic box

6

  • bservation angle [deg.]

10 20 30 40 50

radio energy at 1m [Joule/pC]

  • 10

10

  • 9

10

  • 8

10

ice / 30 deg ice / 60 deg. ice / 45 deg

no target / vert plastic box only thin layer of ice

normalized to 30pC

(observation angle: angle from ice to antenna)

ice

thin ice plastic box

R.Gaïor TeVPa Oct2015

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SLIDE 7

Simulations

7

R.Gaïor TeVPa Oct2015

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SLIDE 8

Simulations chain

  • 1. Particle simulation: Geant4 based,

realistic beam profile and lateral spread

~ Aseg = e 4πRc −[ ˆ u×( ˆ u×~ β)] 1−n~ β · ˆ u

bunch profile

  • 2. Radio simulation: ZHS based

computes the potential vector for electron tracks

β1 r1 β2 r2 β3 r3

Δt1 Δt2 Δt3

  • bserver time

→ E field by time derivation

8

  • 3. Detector simulation:

antenna: Time domain simulation electronics: frequency spectrum measurement

time [ns]

  • 40
  • 20

20 40 60

radio signal [V]

  • 0.3
  • 0.2
  • 0.1

0.1 0.2 0.3

data simulation

validation: emit a pulse with an antenna and measure it with our detector → ΔP/P < 15% Input

  • bunch time profile
  • lateral spread
  • total charge
  • most of particle contained

in ice thickness

R.Gaïor TeVPa Oct2015

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SLIDE 9

Simulation with target

Ice target: simulate a big block of ice

e- shower

Simulation configuration:

  • Simplified: only ice environment

(neglect air contribution and Transition radiation)

  • Refraction accounted afterwards

Ice target

Comparison with data

  • large discrepancy in absolute value
  • different angular dependence

→ Other emission process dominate

9

Observation elevation angle [deg.] 5 10 15 20 25 30 35 40 45

Radio Energy [J]

  • 12

10

  • 11

10

  • 10

10

  • 9

10

ice:30 deg ice: 45 deg ice: 60 deg no target

simulation data

R.Gaïor TeVPa Oct2015

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SLIDE 10

On going improvement

Large discrepancy data/simulation → make our simulation more detailed:

10

Simulation of field source: Implement the real geometry Account for air contribution through ice and for reflected ray → Other process included (esp. transition radiation) → should increase the absolute scale Other effects studied:

  • diffraction from ice

(size of ice block comparable to λ)

  • Index of refraction of the ice

→ can modify the angular dependence

source of E field = change of potential vector

  • from beam appearance point
  • change of index
  • shower development

~ Aseg = e 4πRc −[ ˆ u×( ˆ u×~ β)] 1−n~ β · ˆ u

R.Gaïor TeVPa Oct2015

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SLIDE 11

Simulation with no target

No target

beam exit

Change of potential vector from beam appearance point

11

Comparison with theory

E(ω) = e 4πε0c2R ! v⊥ 1− ⌢ k ⋅ ! v c exp(iωti − ! k ⋅ ! r)

i

∑

  • ■
  • !

v⊥ = ⌢ k ×( ⌢ k × ! v)

  • done by Pavel Motloch

(at U. of Chicago)

Comparison with data

R.Gaïor TeVPa Oct2015

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SLIDE 12

No target run: Comparison with other experiments

TA LINAC used for several radio experiment

  • TA Radar: Radar for UHECR detection (~50MHz)
  • Brussels IceCube group: Radar on plasma in ice for ν detection (~2-3GHz)
  • Konan University: Molecular Bremsstrahlung (12GHz)

12

R.Gaïor TeVPa Oct2015

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SLIDE 13

Conclusions

13

Observation of coherent radiation from electron at UHF

  • Set of data for different configuration:
  • no target - ice block - background check
  • Highly polarized an coherent radio signal observed
  • > emission from electron beam and shower
  • Signal observed with ice larger than no target measurement

Comparison with simulation

  • Askaryan component seems lower than dominant background
  • No target run has already a shift in absolute scale:
  • detector simulation checked
  • comparison with theory checked

Complementary studies

  • No target runs compared with other radio experiment

→ important for their background understanding

  • Ice target run: possibly data of transition radiation at UHF

→ radiation studied for the detection of neutrino shower ( http://arxiv.org/pdf/1509.01584v1.pdf)

R.Gaïor TeVPa Oct2015

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SLIDE 14

Radio signal simulations

Particle simulation: Geant4 based, realistic beam profile and lateral spread

~ Aseg = e 4πRc −[ ˆ u×( ˆ u×~ β)] 1−n~ β · ˆ u

bunch profile particle in ice Shower depth

Radio simulation: ZHS based computes the potential vector for electron tracks

β1 r1 β2 r2 β3 r3

Δt1 Δt2 Δt3

  • bserver time
  • ■
  • Lateral distribution
  • 4.5 cm
  • lateral spread

→ E field by time derivation

14

particle number

particle track

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SLIDE 15

Detector simulations

Antenna: Time domain simulation with XFDTD software (method in http://www.farr-

research.com/biblio.html (note 555))

Electronics: Based on measured gain/phase Detector simulation validation

time [ns]

  • 40
  • 20

20 40 60

radio signal [V]

  • 0.3
  • 0.2
  • 0.1

0.1 0.2 0.3

data simulation

15

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SLIDE 16

ARAcalTA: main runs

  • physics: nominal configuration i.e. block of ice (ice angle 30, 45, 60 deg.)
  • background: replace target by nothing, just plastic case, thin layer of ice...
  • calibration: use bicone antenna and scan height, beam monitoring
  • interference test: vertical and horizontal antenna

α

Full Ice ≠angles Just plastic Thin ice

16

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SLIDE 17

β1 r1 β2 r2 β3 r3

  • bserver time

source time converted to obs time

~ Aseg = e 4πRc −[ ˆ u×( ˆ u×~ β)] 1−n~ β · ˆ u

For each segment vector potential is computed

Δt1 Δt2 Δt3

ZHS

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SLIDE 18

β1 β2 β3

  • bserver time

source time = obs time For each point +/- E field is computed

Δt Δt Δt Δt

r1 r2 r3 r4

  • E±(

x, t) = ± 1 ∆t q c

  • ˆ

r × [ˆ r × β∗] (1 − n β∗ · ˆ r)R

  • +
  • +
  • End point method
  • +
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SLIDE 19

aking all updates one at a time and reflection on angular




  • m blue to magenta we

  • m magenta (5 bunches)





Expected Angular distribution (for different beam conditions)

19

  • the inner structure due to subbunches

are wash out by the beam spread)

  • Absolute timing (w.r.t. to emission time)
  • Similar signal to what is expected in ARA

Expected bipolar pulse

  • Dependance of the signal with beam

spread

  • realistic beam profile reduce the total

expected field

Simulation

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SLIDE 20

Source and Target

Source: TA LINAC

  • source of 40 MeV electron
  • maximum of 109 particles/s
  • bunch of few ns long divided in sub

bunches (every 350 ps)

  • bunch length can be changed

Target: Ice block

  • 100cm x 30cm x 30 cm
  • Installed in a plastic box 1m above the beam

exit

  • can be inclined to choose the exit angle of

radio wave

  • Due to refraction, angle of target will give the

accessible emission angle in ice

  • M. Relich

20

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SLIDE 21

21

Prior Detector calibration

Antenna simulation

  • Pattern simulation +

VSWR

  • Time domain solver XFDTD
  • Work on time domain response simulation

(account for the antenna phase response) Antenna calibration

  • pattern measurement in Anechoic chamber
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SLIDE 22

Simulation

22

response to simulated pulse

Antenna response convolution

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SLIDE 23

Results: ARA antenna

23

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SLIDE 24

24

Time [ns]

40 50 60 70 80 90 100 110 120

Voltage [V]

  • 0.4
  • 0.3
  • 0.2
  • 0.1

0.1 0.2 0.3 0.4

Frequency [MHz]

150 200 250 300 350 400 450 500

Energy [J/MHz]

  • 18

10

  • 17

10

  • 16

10

  • 15

10

  • 14

10

  • 13

10

  • 12

10

x6 for simulation

  • Vpol
  • Vpol

V]

Simulation (normalized)

Data

  • Simulation (normalized)

Data

  • ■