David Saltzberg, 24 Nov. 02 ANITA meeting Slide 1 Review of Accelerator Measurements of RF shower emission l Outline äMini review of RF detection (emphasis on tricky points) - Antenna response to signal - Noise äMeasurements of Askaryan Effect

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 2 Basic Anatomy of an Antenna +Receiver E E E field Z 0 = 377  /n balun coax cable R r =50 or 75  (typical) V Balun impedance matches AND isolates outside of cable shield from radiator, BUT is difficult to make broad-band R r =“radiation resistance”= impedance looking into back of balun

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 3 Electric fields and Antennas l View I: Electric fields & Effective height äE field measured in V/m äAntenna described by effective height, h eff, where äCareful, V is the “open circuit” voltage, i.e. if antenna is looking into infinite impedance. For a matched load, divide by 2

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 4 Electric fields and Antennas l View 2: Pointing Flux and Effective Aperture äS = E 2 /Z (E is instantaneous E(t)…careful factors of 2), where Z 0 =377  in free space (W/m 2 ) - P=A*S - In media, Z 0 = 377  * äPower delivered by antenna into a matched load is called “effective aperture”. (assuming no ohmic losses) - Careful, note difference in defintion wrt h eff l If load is known, can go between two views:

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 5 Noise l R.F.I. : Radio Frequency Interference, typically manmade. äIf impulsive, could mimic signals without increasing system temperature äEven if not impulsive, can raise system temperature äIf narrow band, can be removed by notch filtering (online) or by making a cut on signal duration (offline). äEven “broadband” RFI can usually be removed offline by cutting on duration äDo not expect EXTREMELY broadband ( MHz) and short duration from RFI. äEven if not impulsive, can raise system temperature

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 6 Noise l Thermal noise äBroadband and is ultimate background since can look like signal äIf antenna aperture is filled by source at temperature T, expect power delivered to matched load to be P=k B *T*B, where B=bandwidth äGives V fluctuating as Gaussian with V rms =sqrt(P*R) where R is input impedance of detector (typ. 50  ). This is a bit more complex when bandwidth≠100% ä290K filling aperture, connected to matched load: - P=-174 dBm/Hz - V rms =0.45 nV/sqrt(Hz) if 50  system

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 7 Recommended Reading l J. Kraus, “Antennas, 2 nd ed”, esp. chapter 2 l C. Balanis, “Antenna Theory” l ARRL “The Antenna Book” l M. Schwartz, “Information Transmission, Modulation, and Noise” (you can skip the part on vacuum tubes!) l Horowitz & Hill (amplifiers, noise…)

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 8 Lunacee II and III (July 2000 and June 2002) Askaryan Experiments at SLAC: SLAC/FFTB 30 GeV e - < 1mm bunch size 1-3%X 0 radiators up to eV in  ’s Only photons leave the vacuum window  no TR 30 GeV e - e - &  e - to dump =4 GeV radiators 30 GeV linac FFTB

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 9 Lunacee II and III l SLAC, Final Focus Testbeam äAl Odian contacted us after seeing Lunacee-I preprint äBremsstrahlung photons from 28 GeV electrons äVery small beamsize (<<1mm) äReal charge excess develops äphoton beam so no Transition Radiation

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 10 Two SLAC runs July 2000 June 2002

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 11 Target Geometry Lunacee II Lunacee III, similar geometry but built with salt bricks

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 12 Bandlimitted pulses l E.g., 1.7 to 2.6 GHz l With radiator out, saw mV/m fields. l In general,  t ~ 1/BW l # cycles ~ 1/ frac. BW

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 13 Absolute field emission check l Also took data in 2002 run to check coherence out to ~12 GHz. To be analyzed V/m/MHz at 1m

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 14 Coherence

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 15 Shower profile

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 16 Shock wave Speed of radio propagation in sand=0.6 c Measured speed = (1.0  0.1)c  CR shock wave Shock wave at Cos -1 (1/  n)  ~51 O ``Snelled’’ to 29 O

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 17 Polarization Tracking

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 18 T.I.R. l Anita needs to see signals that are transmitted from ice to vacuum (chance of total internal reflection) l Tested at Lunacee-II, from sand to air, and saw a 36 dB suppression l Antarctica’s firn layer should help somewhat. l Still will be loss due to Fresnel Coeff.

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 19 Transition Radiation l TR is made whenever a charged particle crosses a dielectric boundary l Closely related to CR and all the coherence arguments of Askaryan hold l In Lunacee –I sent a 15 MeV electron beam through a foil. Found X10 disagreement with prediction. Perhaps because we were not monitoring beam at its last stage l Lunacee –III created an electron beam from the SLAC photon beam using a lead brick & aluminum plate. Calcuated E field (0.28 V/m) was consistent with observed (0.31 V/m).

David Saltzberg, 24 Nov. 02 ANITA meeting Slide 20 Summary & ideas l Askaryan effect is established (or why would you be here?) l Other tools we may need äUser module to provide parameterized E-fields to MC simulations äBetter parameterization of angular distribution of emission (including airy peaks) äAntenna design code äDigital signal processing code äApply to understanding transmissivity of Firn (hard to do experimentally?)