Transcript Antennae Project
Surface Wave Propagation
Preliminary work developing a method for surface wave detection Amy Zheng Andrew Johnanneson
Ultrahigh Energy Neutrino Detection
• • Askaryan effect [1]
v
emit radiation due to the
phase
Detection is difficult due to internally reflected waves dying off quickly [2]
Surface Waves as an Detection Tool
• • Radiation from Askaryan cascade is trapped in Air dielectric layer between ice and firn [2] In tandem with existing experiments RICE [3] and ANITA [4]
Why Use Surface Waves?
• • • • Surface waves travel between two mediums [5] ▫ ▫ Amplitudes fall at the rate 2 2 1
r
~800 times more efficient than bulk waves If detection is viable, expanding existing experiments would be far less expensive Surface waves may carry information about neutrinos and their interactions with ice better than the current method
Procedure
• • 1 sending + 2 receiving antennas displayed waveshape Physically moved antennas to determine wavelength and thus index of refraction
Example Antenna Placements
• “Surface” • “Air” • “In”
Translating to refractive index
n
c v
phase
c f
n
Definition of Refractive Index 1
B n
2
C
2
n
Sellmeier Equation (1) (2)
Refractive Index of Air
Single or Half λ 1,2 1 0,8 0,6 0,4 0,2 0 1000 MHz 1500 MHz Calculated (2) 1000MHz & 1500MHz n= 1.000273[6]
Refractive Index of Water (rms)
Single or Half λ 2 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0 Surface Surface Surface Surface Surface Half Surface In In 750 MHz 1000 MHz 1500 MHz Surface Half Half Surface Half In Calculated (2) n~1.3333[7]
Refractive Index of NaCl (rms)
Single or Half λ 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0 Surface Surface Surface In Surface In In Air In 1000 MHz 1500 MHz Calculated (2) n~1.544[8]
Refractive Index of Granulated Fused Silica (sand) Single or Half λ 2 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 0,2 0 1000 MHz 1500 MHz Surface Surface Surface In Surface In In Air In Calculated (2)1000MHz n= 1.73251 [9] Calculated (2) 1500MHz n= 1.73317
Refractive Index of Granulated Fused Silica (sand) Multiple λ 0,6 0,4 0,2 0 1,4 1,2 1 0,8 1000 MHz 1500 MHz Surface Surface Surface In Surface In In Air In Calculated (2) 1000MHz n= 1.73251 [9] Calculated (2) 1500MHz n= 1.73317
Measurement Complications
• • • • • • • Mechanical water waves appeared to alter EM waveform Imprecise measurements due to hand & eye observation Sand and water tend to collect in the connectors Angular error from planar disparity Waveforms disappeared & reappeared on and off Waveforms constantly shift amplitude Background EM noise & reflections often interfered
Future Steps
• • • Experiment using ice as a medium Change antenna size; more precision Change experimental scale
References
• • • • • • • • • • • [1] G.A. Askaryan, Sov. Phys. JETP 14, 441 (1961) [2]J.P. Ralston, Phys. Rev. D 71, 011503 (2005) [3] RICE Collaboration, I. Kravchenko et al., Astropart. Phys. 19, 15 (2003); S. Razzaque, Sseunarine, D.Z. Besson, D.W. McKay, J.P. Ralston, and D. Seckel, Phys. Rev. D 65, 103002 (2002); Phys. Rev. D 69, 047101 (2004).
[4] For information on ANITA, see http://www.phys.hawaii.edu/anita/.
[5] J. P. Ralston “An Experiment to Detect Surface Waves on Polar Ice” (2005) [6] Philip E. Ciddor. Refractive index of air: new equations for the visible and near infrared, Appl. Optics 35, 1566-1573 (1996) doi:10.1364/AO.35.001566
[7]P. Schiebener, J. Straub, J.M.H. Levelt Sengers and J.S. Gallagher, J. Phys. Chem. Ref. Data 19, 677, (1990) [8] Faughn, Jerry S., Raymond A. Serway. College Physics, 6th Edition. Toronto: Brooks/Cole, 2003: 692.
[9] I. H. Malitson. Interspecimen Comparison of the Refractive Index of Fused Silica, J. Opt. Soc. Am. 55, 1205-1208 (1965) doi:10.1364/JOSA.55.001205
[misc] Colloquium Notes from John P. Ralston Refractive index calculations for relative reference only: ▫ n found for granulated fused silica was found using Sellmeier constants for solid fused silica; granulation affects density.
▫ Calculated n for water is for λ of 589.29 nm ▫ Calculated n for NaCl is for λ of 589 nm
Acknowledgements
• • • Dave Besson Marie Piasecki Carolyn Bandle