LunaticsLunatics - those who search for lunar ticks - those who search for lunar ticks

Developments in Nanosecond Pulse Developments in Nanosecond Pulse Detection Methods & TechnologyDetection Methods & Technology

UHE Neutrino Detection using the Lunar Cherenkov Technique UHE Neutrino Detection using the Lunar Cherenkov Technique

Prof Ron EkersProf Ron EkersDr Paul RobertsDr Paul RobertsDr Chris PhillipsDr Chris Phillips

Rebecca McFaddenRebecca McFadden(PHD)(PHD)

Prof Ray PrthoeroeProf Ray PrthoeroeClancy James (PhD)Clancy James (PhD)

A/Prof Steven TingayA/Prof Steven TingayDr Ramesh BhatDr Ramesh Bhat

OutlineOutline

Lunar Cherenkov Technique

Characterisitics of Cherenkov Radio Pulse

Current ATCA Experiment

ATCA Upgrade

Future Experiments - SKA

UHE Neutrino Detection using the Lunar Cherenkov Techniqueneutrino

photon

shower

Image courtesy of R EkersImage courtesy of R Ekers

Technique first proposed by Dagkesamanskii & Zhelezynkh (1989)

and first applied by Hankins, Ekers and O'Sullivan (1996)

using the Parkes radio telescope

Characteristics of Radio Pulse and Characteristics of Radio Pulse and Experimental RequirementsExperimental Requirements

100% linearly polarised

Broadband (0-3+GHz), continuous emission

(See #0341 Clancy James for more details)

Very narrow unmodulated pulse (1-2ns)

Dispersed by ionosphere

Blurred by instrumental effects

Require:

Broad receiver bandwidth for ns time resolution

High speed sampling

Real time trigger to avoid excessive storage requirements

Real time dedispersion to maximise SNR for trigeer

Advantages of using an Array of Small Radio Telescopes

A rray geometry allows RFI discrimination based on the signal direction of arrival.

The system temperature is dominated by thermal emission from the moon so there is little improvement in signal to noise ratio to be gained by larger apertures.With many small dishes, their spatial separation can be used to ensure that thermal emission from the moon is incoherent between elements thus increasing the signal to noise ratio.

At frequencies in the 1-2GHz range, the primary beam produced by a 22m aperture (such as the Compact Array) can see the entire moon. Beamwidth is inversely proportional to aperture size, therefore a larger dish will see less than the entire moon and any minimal improvement in sensitivity from the larger aperture will be offset by decreased coverage of the moon.

Current ATCA Experiment using Current ATCA Experiment using FPGA based Sampler BoardFPGA based Sampler Board

3 Antennas fitted with custom built hardware

1.2 GHz-1.8 GHz (600MHz) RF signal taken directly from antenna

Dedispersion on fixed analogue dedispersion filter

Real time trigger in FPGA

Ethernet connection to control room

Baseband recording for offline processing

Overall System Design Overall System Design for May 2007 Observing Term for May 2007 Observing Term

Baseband Baseband BufferBuffer

1 Gbit Ethernet Link (TCP/IP)

Offline Processing

System Detail at Each AntennaSystem Detail at Each Antenna

3 – 8 ns (night – day)

LNA1.5 Ghz

LNA2.3 Ghz

LNA2.3 Ghz

LNA1.5 GHz

Polarisation and BandSplitter

L-Band RF SplitterModule (F10)

S-Band Splitter(C23)

L-Band Splitter(C22)

S-Band RF SplitterModule (F11)

1.2 – 2.5 Ghz Horn

Pol APol BPol A

Pol B

Analog Dedispersion Filters

2.048 Gs/s

8 bit ADC

Buffer

Ethernet Connection

Coincidence Test and Threshold Detect

5.1 σ4096 samples, 2μs

8 bit ADC

CABB Sampler BoardATNF BCC Interface 100Mb/s

Standard ATCA Receiving Path

Customised Hardware

Differential Delay StatisticsDifferential Delay Statistics

Restricting data set to night-time hours (8pm-6am):Restricting data set to night-time hours (8pm-6am):

Average TEC of Average TEC of 7.06 VTECU7.06 VTECU (May 2006) and (May 2006) and 7.01 VTECU 7.01 VTECU (May 2007)(May 2007)

Over the 600MHz bandwidth (1.2-1.8 Ghz) this corresponds to an average Over the 600MHz bandwidth (1.2-1.8 Ghz) this corresponds to an average differential delay of differential delay of 5ns5ns (May 2006) and (May 2006) and 4.39ns4.39ns (May 2007) (May 2007)

Δt = 0.00134 TEC (1/fΔt = 0.00134 TEC (1/flolo

2 –2 – 1/f 1/fhihi

2 2 ))

TEC data from NASA’s Crustal Dynamics Data Information System TEC data from NASA’s Crustal Dynamics Data Information System

Signal dedispersion is performed in analog microwave filters Signal dedispersion is performed in analog microwave filters with a fixed dispersion characteristic.with a fixed dispersion characteristic.

These filters were designed using a new method of planar These filters were designed using a new method of planar microwave filter design based on inverse scattering .microwave filter design based on inverse scattering .

This results in a filter with a continuously changing profile, in This results in a filter with a continuously changing profile, in this case a microstrip line with continuously varying width. this case a microstrip line with continuously varying width.

The width modulations on the microstrip line produce The width modulations on the microstrip line produce cascades of reflections which sum to produce the desired cascades of reflections which sum to produce the desired

frequency response.frequency response.

Histogram of VTEC for May 2006

Field Programmable Gate Array Field Programmable Gate Array

Semiconductor device containing programmable logic components

Can be programmed to duplicate logic functions (such as AND, OR, NOT, XOR)

Or more complex functions such as decoders or simple math functions (DSP applications: filtering, transforms, modulation)

A Hardware Description Language (HDL) can be used to define the FPGA's behaviour

High level design tools may be used to raise the level of abstraction in the design process

Introduction to ATCA UpgradeIntroduction to ATCA Upgrade

Upgrade planned to increase current 600MHz bandwidth to 2 GHz – Compact Array Broad Band Upgrade (CABB)

Due to bandwidth and data storage limitations, the only way to exploit this new bandwidth is by implementing real time detection algorithms

These algorithms can be programmed into more complex FPGA boards currently being built by the ATNF for the CABB Upgrade

Additional Processing Power from FPGA UpgradeAdditional Processing Power from FPGA Upgrade

Wavefront

D

Path = D sin

Delay = D/c sin

Wavefront 2

We can form multiple Beams to We can form multiple Beams to Cover the Limb of the MoonCover the Limb of the Moon

It will also be possible to implement real time dedispersion algorithms in this hardware and we have It will also be possible to implement real time dedispersion algorithms in this hardware and we have developed a technique for obtaining measurements of the ionospheric TEC which are both developed a technique for obtaining measurements of the ionospheric TEC which are both

instantaneous and line-of-sight to the lunar observations. instantaneous and line-of-sight to the lunar observations. The ionospheric TEC can be deduced from Faraday Rotation measurements of a polarised source The ionospheric TEC can be deduced from Faraday Rotation measurements of a polarised source

combined with geomagnetic field models, which are more stable than ionospheric models when the combined with geomagnetic field models, which are more stable than ionospheric models when the direction of signal propagation is parallel to the geomagnetic field vector.direction of signal propagation is parallel to the geomagnetic field vector.

We propose to use this technique, with the polarised thermal radio emission from the lunar limb as our We propose to use this technique, with the polarised thermal radio emission from the lunar limb as our polarised source, to obtain instantaneous and line-of-sight TEC measurements.polarised source, to obtain instantaneous and line-of-sight TEC measurements.

Work conducted by the Lunatic team will form a pathway for UHE neutrino detection using the Work conducted by the Lunatic team will form a pathway for UHE neutrino detection using the proposed SKA radio telescope.proposed SKA radio telescope.

The Square Kilometre Array will be 100 times more sensitive than the best present day radio The Square Kilometre Array will be 100 times more sensitive than the best present day radio instruments.instruments.

The current designs proposed for the SKA consist of large numbers (~104) small dishes (6-12m) to The current designs proposed for the SKA consist of large numbers (~104) small dishes (6-12m) to achieve a square kilometre of collecting area in the 1-3GHz range.achieve a square kilometre of collecting area in the 1-3GHz range.

Lunar UHE Neutrino Astrophysics with Lunar UHE Neutrino Astrophysics with the Square Kilometre Array (LUNASKA)the Square Kilometre Array (LUNASKA)