1

R&D working group report

SAC May 2009

Klaus Helbing, Wuppertal & Hagar Landsman, Madison

●

Goals and tasks

●

Working group structure

●

Status of R&D

refraction, attenuation, background

–

Acoustics

–

air shower radio

–

in-ice radio

●

Conclusions for design of extension

●

Road forward

---

2

Common goals

●

Most general:

–

Extend IceCube and use unique facility and

environment/infrastructure at SP:

Only place to combine optical & radio &

acoustics & air showers

i.e. imitate the IceTop – InIce relation

●

Primary motivation:

–

GZK neutrinos

–

Expand acceptance of IceCube for EeV neutrinos

by orders of magnitude

●

Also:

–

determine EHE neutrino cross section

–

air shower physics (inclined, composition, EHE)

---

3

Tasks of R&D working group

●

work out task distribution amongst

participating institutions

●

establish Letter Of Intent (LOI)

●

define interfaces and common infrastructure

for different sensors (in/on ice, methods, ...)

●

establish milestones for an intermediate

scale detector (~ 5 GZK-

ν

's/year)

●

establish a road map towards a full scale

detector (~ 50 GZK-

ν

's/year; O(1000) km

2

)

●

coordinated planning of funding proposals

---

4

Structure of R&D working group

●

First common meeting (1-day) at fall meeting 2008

●

Formation of WG at last collaboration meeting

phone calls on common issues, converging plans

●

Existing sub-groups continue with dedicated phone

calls (focus: specific instruments):

–

radio (Dave Besson)

●

in-ice

●

air shower

–

acoustic (Timo Karg)

–

optical high energy extension (HE, Albrecht K.)

●

New IC-members and affiliated groups contribute

(e.g. Hawaii and Ohio)

●

Upcoming R&D workshop in June

---

5

Relation to standard (optical) IceCube

●

Benefit from IceCube knowledge and

access to South Pole site

●

Unique possibilities of combined

observations both in-ice and on-ice

●

Vision of “guaranteed” neutrino signal ↔

momentum from potential IC discovery

●

Keep

–

engineering work force

–

students with inclination towards hardware

–

entrepreneurial aspects of early

Amanda/IceCube days

---

6

Status of ongoing site studies

with ...

●

SPATS

: South Pole Acoustic Test Setup

●

RICE

: Radio Ice Cherenkov Experiment

●

AURA

: Askaryan Underice Radio Array

●

NARC

: Neutrino Array Radio Calibration

●

Surface radio antennas

(stand alone)

---

7

Status Acoustics

SPATS

---

8

Speed of sound

●

Also shear waves

are relevant!

–

helps with

reconstruction

●

Precision

measurement

ready for journal

publication in

~ weeks

---

9

Acoustic attenuation

Amplitude

1

st

/2

nd

peak

Energy

time domain

●

Ball park: 300m ± 100 m

Expectation was kilometers

●

Unclear whether attenuation is short

because of absorption or scattering

---

10

Acoustic noise (DC)

Low continuous noise level

---

11

Acoustic noise, transients

●

Transients

correlate with

–

Rod wells for drilling

–

freeze in of IceCube

holes

●

No correlation

found with “dry”

rod well

–

blind analysis proof

---

12

C

a

b

l

e

(

S

P

A

S

E

)

125

m

AMANDA DAQ

Antennas

Status air shower radio

Test array:

4 antennas

read out with

RICE DAQ

---

13

Surface RFI (DC)

Low continuous noise level

---

14

Transient surface RFI

- uncalibrated -

GHz

NoEvent

Event

GHz

0.

1.

0.

1.

2.

2.

RFI

difference

Event - NoEvent

narrow frequency band of RFI emission

compared to broad band air shower signal

RFI

---

15

Pinger Data Reconstruction

Pulser Starts

MAPO 1

SPASE 1

SPASE 1

---

16

Pinger Data Reconstruction

MAPO 1

SPASE 1

SPASE 1

l

imin

a

RMS of reconstruction ~ 3 m

---

17

Shallow (~300m)

Deep (~1400 m)

junction

box

Counting

house

Status in-ice radio

●

AURA cluster:

–

Digital Radio Module (DRM) – similar to DOM

–

4 antennas, 1 Antenna Calibration Unit (ACU)

–

IceCube sphere, DOM main board (waveforms)

●

5 clusters: 2 in 06/07; 3 in 08/09 (with NARC)

●

2 channels (“antennas”) down to 100MHz

●

15/20 channels are working

---

18

Status in ice radio: Index of refraction

●

Changing index helps to

reduce surface noise

pickup

●

... but shadowing for

shallow deployment

●

No birefringence

---

19

Radio attenuation

temperature region for shallow deployment

R=1.0 : worst case scenario

---

20

Forced

Trigger

Trigger - details

In ice RFI transients with AURA

Angular resolution:

few degrees

---

21

Status summary:

Attenuation

●

Mostly known

–

great progress in acoustics with last season

but unfavorable result

–

known from radio reflection of bed rock,

direct on-site measurements would be nice

confirmation

–

Negligible for air shower radio

---

22

Status summary: “

Refraction

”

●

Refraction, signal speed, depth

dependence:

no evident show stopper but impact

on detector designs

–

good knowledge in acoustics but needs

additional studies for shallow holes

–

in radio uncertainties can still influence

detector design

–

E-field needs further attention to understand

signal strength, B-field configuration wrt veto

coverage of air shower radio.

---

23

Status summary:

Noise

●

Noise/EMI/background:

significant

uncertainties wrt transients

potential cost driver (electronics)

–

Acoustic: constant level of noise favorable

(compared to sea), most transients

from known

sources

–

In-ice Radio: deserves attention

●

RICE:

–

favorable in winter, challenge in summer

–

transient

background rate O(1/minute) in multiplicity

●

air showers could be (additional) transient

background

–

Air shower radio (on-ice antennas) could be

instrumental to get rid of EMI in-ice ... for itself

looks promising, work in progress.

---

24

Current implications from site exploration

●

GZK is main science motivation

long attenuation length for radio signals in ice

⇒

Askaryan radio detector in ice main

instrumentation and design driver

●

Pursue integrated approach of air shower radio

detection

together with neutrino detection for

–

additional (EHE) vetoing

→ increased overlap with optical

–

EMI reduction and monitoring

–

air showers may provide test beam for in ice

–

... and of course air shower physics

–

use joint infrastructure

---

25

Role of acoustics

●

Reevaluation of hybrid option needed in view of

shorter than expected attenuation length

●

Finish site exploration e.g. understand attenuation

mechanism

●

In case optimistic scenario prevails

–

scattering accounts for short attenuation

reduces previously diverging vertical demands

–

shallow co-deployment in narrow holes feasible

–

extra cost reasonably small fraction

...

then

–

Hand full of coincidences that no one else in the

world can do – independent reco + signal

–

Add independent evidence for neutrinos to radio

signals

---

26

Drill options for large array

Findings from 2 drilling workshops held in Madison 2008

Current line of thoughts:

●

down to

200m

depth

at reasonable cost

●

Dry holes much easier

than wet holes.

---

27

Road forward

●

Use last holes/seasons for

–

prototype sensor co-deployment

–

tests of digitization strategies

–

instrumentation for further site studies

e.g. retrievable sensors and radio pingers

–

find coincidences of air shower radio with IceTop

●

Aim for dedicated (dry) holes to test

–

Deployment methods

–

Couplings of sensors with holes

●

Assume maximum drilling depth of up to 200m (cost)

–

acoustic scattering might help reduce previously

diverging vertical demands

---

28

●

Clarify role of non-IceCube members 2009

●

Start „Letter of Intent“ (LOI) at R&D workshop in June and

sign in fall 2009 to demonstrate:

–

serious intent of signing groups (FAs)

–

scientific importance

–

long term time scenario and milestones

●

Finish basic exploration of ice properties (season 09/10)

●

Start extensive MC studies (fall 09)

●

Track down number of different detector options (2010)

●

Write „Proposal“ for submission to FA‘s early 2011

–

expand letter of intent based on MC and hardware studies

–

scalable design plan and 2 phase structure

–

work out realistic budget plan

Near term time line

---

29

Hole 36, -250 m

Hole 57, -288 m

Immediate future with AURA

●

More RFI studies

●

new stronger transmitter

⇒ first inter-cluster calibration source

---

30

Radio attenuation: Plans for

direct on-site measurements

AURA

or

AURA

AURA

Options:

2. Frozen-In Tx and Rx

+ good coupling; – fixed position

3. IceCube holes pre-deployment

+ many depths; – water coupling

Previous pinging with RICE

direct signal path

signal path with total reflection

---

31

●

Ice attenuation (shallow, horizontal)

●

Coincidences with IceCube/IceTop

●

South pole RFI map vs. time

●

Possibly produce limit on GZK neutrinos:

–

Sensitivity calibration

–

Life time

–

Simulation

To-Do list radio

---

32

●

Attenuation (if scattering) strongly frequency

dependent

–

Test with broadband pinger

–

Confirm attenuation in perpendicular direction

●

No transients below ~300 m

–

No sources? – Unlikely

–

Mechanism quieting deep sources (relevant to radio?)

–

Lower pinger to deeper depths (~1000 m)

●

New set of pinger runs in 2009/2010!

●

Collect data needed to publish ice properties

Season 09/10 plans for acoustic

---

33

Detector design considerations

●

Sensors:

–

Frequency range and band width

–

Antennas type

●

Geometry:

–

Shadowing effect

→ Deep deployment

–

Ice Temperature

→ Shallow deployment

–

Drilling cost and time

→ Shallow deployment

–

Hole diameter can limit

antenna design

–

Wet/dry hole

Unique signature of Askaryan:

short pulse, linearly polarized

- Capture polarization?

- Low freq has wider signal

cone but more noise

- Narrow holes effect design

dense shallow versus sparse deep

---

34

Case study IceRay

– fully digitized waveforms, 50 km

2

–

Comparison: High density, shallow (50 m) versus sparse, deep (200m )

3-9 GZKs per year (“standard flux”), 0.3-2 coincidences with IceCube

2

by factors

---

35

Example for technology choices

Pulse shaping and triggering

versus waveform capture

shaped pulse

waveform

Short Bipolar Pulse

“Antenna-like” Transient

If only envelope gets sent to surface:

●

Digitization speed can be lowered

➔ towards demands of air shower radio and acoustic

●

no interference with several antennas in a hole

➔ use loop through signal cable

Only feasible if RFI is well behaved

---

36

Data acquisition considerations

fully digitized waveform array

Pros:

+ good timing, full frequency info

+ Method proven by ANITA and RICE

Cons:

– Expensive, more complicated units

– power consumption

Challenges:

Handling large amount of data

Pulse shaping & envelope trigger

Pros:

+ cheaper units → large array

+ Simpler detector

Cons:

– Limited information

Challenges:

information sufficient to reject

background and detect GZKs ?

---

37

Look-back buffer read-out for

detector components (here surface)

---

38

Sensor String Configuration (here: in ice radio)

CM Chokes

(Sets Dipole length)

“Bottle Brush”

Clip-on Antenna Elements

(Allows Reel Deployment)

TDA Node 1

TDA Node 2

“Common Mode” TDA

Node:

- Signal Cable Shield = Antenna Element

- Envelope BW minimizes crosstalk

- Multi-sensors on one cable possible

- Azimuthal asymmetry is avoided

~1” diameter bump in cable

~500 mW power consumption

Hole

RF IN

ENV.

OUT

Gain

Envelope

Circuit

PWR

TDA OUTPUTS

Multi-Pair Cable

TDA Rev2

---

39

Technology choices

●

DAQ and triggering strategy

–

pulse shaping versus waveforms

–

simple local threshold versus local clusters

with phased array type of trigger

●

Energy distribution

–

centralized with cables

–

local with solar panels, wind, peltier effect

●

Signal propagation to central hub

–

cable versus wifi (Auger style)

●

Surface antennas in self trigger mode

versus trigger from IceTop and in ice radio

---

40

Conclusions & Outlook

●

Site exploration

–

very prolific (several publications in pipeline)

–

Short attenuation length in acoustics

→ Askaryan radio primary driver

–

Hybrid option being reevaluated

●

Upcoming seasons to clarify

–

deployment options (depth, dry/wet)

–

choice of pulse shaping, trigger, digitization

●

Institutional responsibilities to be worked

out at upcoming R&D meeting

●

... head out to extend IceCube and IceTop

by factors at the EHE frontier

---

41

Thank you!

---

42

Backup

●

Backup

---

43

Use IceCube’s resources: holes, comm. and power

• Each Cluster contains:

–

Digital Radio Module (DRM) – Electronics

–

4 Antennas

–

1 Antenna Calibration Unit (ACU)

●

Signal conditioning and amplification happen

at the front end

●

Signal is digitized and triggers formed in DRM

●

A cluster uses standard IceCube sphere, DOM

main board and surface cable lines.

junction

Counting

house

AURA Radio Cluster

A

skaryan Under ice Radio A

rray

---

44

AURA Radio Cluster

What’s new in the last season

●

An array of 5 clusters:

2 clusters 2006-2007

+3 clusters 2008-2009

(part of the of the NARC initiative)

●

2 channels (“antennas”) down to 100MHz

●

15/20 channels are working

●

Stronger and/or more sophisticated in ice

pulsers (support CW and pulses)

●

IceCube-like DAQ (based on pdaq)

●

Strong surface pulser

Shallow (~300m)

Deep (~1400 m)

---

45

From Utrecht premeeting

Possible near term timeline:2008-2009-2010

-

Working group and collaboration building -> in progress

-

Write „Letter of Intent“ and sign in spring 2009 to demonstrate:

serious intention of signing groups to in- and out-side world (FA)

scientific importance in comparison to other topics

expected improvement to previous experiments

time scenario and milestones (Hawaii, identify man power)

- Finish basic exploration of ice properties (existing hardware, new deploy?)

-

Agree on deployment scheme already here (?)

-

Start extensive MC studies of different detector options (using above)

-

Start sensor and electronic prototyping

-

Track down number of different detector options based on above

results (earlier?)

- Write „Proposal“ for submission to FA‘s end 2010 (realistic ?)

expand letter of intent to give detailed information

based on extensive MC and hardware studies

still goes with flexible design plan and 2 phase structure

works out realistic budget plan

---

46

Askaryan Signal

Cherenkov angle=55.8

o

Electric Field angular distributionElectric Field frequency spectrum

A

s

t

r

o

-

ph

/

9

9

0

1

2

7

8

A

l

v

a

r

e

z

-

M

un

i

z,

V

a

z

qu

e

z,

Z

a

s

1

9

9

9

---

47

Example Transient

(from snowmobile ignition)

Ignition noise transients from idling snowmobile

Snowmobile was approximately 100m distance from ICL.

Snowmobile was perpendicular with West tower.

Signals as acquired by ic-scope-ag1

Time Delay=20ns W-E, consistent with Angle-of-Arrival (AOA)

Snowmobile

(transient source)

tower

tower

View of snowmobile

from ICL Door

Delta t =20ns

---

48

Transient sensor array

Kael Hanson

Perry Sandstorm

Many “simple” sensors to provide a snap shot of an Askaryan pulse.

Wide dynamic range, low power, simple output

---

49

Case study: Transient Detector Footprints

500m x 500m

sensor

20 km

spacing shown

2

0

k

m

“Kilocube”

100km

2

IceCube

IceRay

18,36

“Kilocube”

# of Sensors vs. Density:

333

1000

1200

333

333

3600

500

500

1600

1000

1000

Sensors

Y

Spacing

(meters)

X

Spacing

(meters)

---

50

Downward Rejection

via Priority, Coincidence

TDA (B)

A

B

A

B

A

B

d

~40m

Lowest Detectable

Neutrino

Trajectory

(93 degree zenith)

Surface

Transients

Accept

Time Difference Of Arrival (TDOA)

Highest Detectable

Neutrino Trajectory

(36 degree zenith)

Surface Processor

---

51

SATRA Functional Blocks

(Sensor Array for Transient Radio

Astrophysics)

---

52

Radio Transient Sensor Instrumentation

Baseline Configuration

~150m

Surface

Firn

Ice

~190m

Active Antennas

Surface

Processor

Assembly

(SPA)

4” Dry

10MHz Clock

Data (RS485)

Slow Ctrl

SPA of

Next Hole

1

2

Row

DAQ

Envelopes

surface

TDOA =

T

ime-

D

ifference-

O

f-

A

rrival

TOT =

T

ime-

O

ver-

T

hreshold

Elevation ≈

TDOA

Between TDAs (z)

Azimuth ≈

TDOA

Between Holes (d)

Amplitude ≈

TOT

of Envelopes

?

Elevation is determined in real time for each hit at each hole.

?

Azimuth and event signature uses elevation and amplitude

data from all holes hit.

?

Its all in the timing.

“z”

“d”

---

53

Sensor Array System-Level R&D

●

Source modeling

●

Nominal array sizes needed for event detection and/or limits

●

Array geometry optimization

–

Vertical, Horizontal spacing

–

Number of sensors per string

–

Size of Array

●

Sensitivity Analysis

–

Antenna bandwidth

–

Envelope/discriminator bandwidth

–

Noise; KT, RFI, CR

●

Optimized data format for transmission, filtering, storage

●

Event simulation and filtering

●

Data processing requirements for online filtering

●

DAQ for each row and combiner from all row-DAQs

---

54

Example data from each hole

Masterclock

LSB= 10ns

From Time-Digital-Converter

LSB=250ps

Range=500ns

8bits

14bits

14bits

8bits

Address

TDA1

TDA1

TDA2

TDA2

TOT

14bits

8bits

TDA 3,4, etc

Compare TOT

(amplitudes)

for

“hit quality”

Compare TOAs for

Elevation Angle

---

55

Sensor String Baseline Configuration

CM Chokes

(Sets Dipole length)

“Bottle Brush”

Clip-on Antenna Elements

(Allows Reel Deployment)

TDA Node 1

TDA Node 2

“Common Mode” TDA

Node:

- Signal Cable Shield = Antenna Element

- Envelope BW minimizes crosstalk

- Multi-sensors on one cable possible

- Azimuthal asymmetry is avoided

~1” diameter bump in cable

~500 mW power consumption

Hole

RF IN

ENV.

OUT

Gain

Envelope

Circuit

PWR

TDA OUTPUTS

Multi-Pair Cable

TDA Rev2

---

56

Sensor String Development

separable activities/disciplines by color

●

TDA PCB

–

Circuit topology

–

Parts selection

–

Schematic Capture

–

PCB layout, potting, mechanical attachment

–

Spice optimization of antenna match

●

Common Mode Antenna

–

XFTD modeling of elevation response

–

NEC modeling of elevation response

●

Cable

–

Spice or Qucs simulation of envelope transmission

–

String fabrication and deployment

---

57

SPA

(Ele

B

vat

a

ion

s

b

e

y h

l

i

i

-r

n

es

e

TDO

C

A,

o

Am

n

pli

f

tu

i

d

g

e

u

by

r

TO

a

T)

tion

Discriminator

Discriminator

Upper

Lower

TDA

Threshold

STOP CH2

TOT

Time-Digital

Converter (TDC)

4-fold stops/ch

65ps bin size

Min 200ns window

ALU

Hit Processor

Hit Buffer

Elevation

& Coinc.

Fine Time

Data

Coarse Time

(x10) Master clock

Serializer

Get Data

Slow Control

Pair

Adjacent

SPAs

---

58

SPA Development

separable activities/disciplines by color

•

Surface Cable and Interface

•

Discriminator

•

TDC (or simple elevation gate for ’09-’10

expmt)

•

Hit Processor (µProcessor or FPGA)

•

PLL & Course-Time Counter

•

Data Format and Buffer

•

DC-DC Converter/ Head-end PSU requirements

●

Enclosure and Integration

---

59

SATRA South Pole Testing

●

Proof of Concept for Envelope Detection

’08-’09 (done)

–

Goals:

Show feasibility of TDOA technique for background rejection using envelope signals from TDA

–

Setup:

Two TDAs connected to Horizontally-separated antennas on ICL Towers.

–

Enables:

Continued transient background monitoring with programmable oscilloscopes

●

Real-time elevation gating with vertically-separated TDAs

’09-’10

–

Goals:

Background Rate vs. (elevation & threshold)

–

Setup:

single test string in multiple IceCube firn and/or rod well holes, simplified SPA. Measure

sensitivity to surface and AURA transmitters

–

Enables:

comparison of candidate TDA / antenna configurations, verification of envelope discriminator

and basic elevation gating.

●

Small test array (3km x 1km); (~10x3 holes)

’11-’12

–

Goal:

(Rate & amplitude) vs (elevation & azimuth & threshold) DAQ verification

–

Setup:

Upgraded RAM Drill, 30 strings, 30 full-function SPAs, 30 surface links, 3 “Row” DAQs

–

Enables

: Verification of TDC and course timing circuitry, Optimization of SPA comms, initial sensitivity

calibration. Optimization of RAM drill. DAQ and filter testing, Optimize TDA-TDA and Hole-Hole spacing

●

Large test array (3km x 2km); (~10x6 holes) ’

12-’13

–

Goals:

Verify changes to RAM drill and Instrumentation; grid spacing should conform to final geometry

–

Apparatus:

Upgraded RAM drills, 60 strings, 60SPAs, 60 surface links, 6 Row DAQs

–

Enables:

verification of configurations and procedures for large-scale drilling and deployment, Establish

Flux Limits and possible event detection.

●

SATRA KiloCube (20km x 20km); (400-1600 holes)

‘13-’16

–

Goals:

Detect significant number of GZK events

–

Apparatus:

$15-20M

–

Enables:

Event detection and confirmation by spatiotemporal signature.

---

60

Envelope / TDA Proof-of-Concept Testing

South-Pole 08-09

Ignition noise transients from idling snowmobile

Snowmobile was approximately 100m distance from ICL.

Snowmobile was perpendicular with West tower.

Signals as acquired by ic-scope-ag1

Time Delay=20ns W-E, consistent with Angle-of-Arrival (AOA)

Snowmobile

(transient source)

tower

tower

View of snowmobile

from ICL Door

Delta t =20ns

---

61

Sensor experiment for ’09-’10

Rate vs. (Threshold, Elevation)

●

Goals:

–

Test Common-Mode antenna/TDA design

–

Optimize envelope/discriminator parameters for rejection of

background transients by virtue of their elevation

–

Get low-threshold data regarding SP background transients

●

Basic vertical string with two Rev2 TDAs

–

Temporary, self-contained apparatus (e.g. battery powered)

–

Can be moved from hole-hole (e.g. IC firn holes before drilling)

●

Simplified Surface Processor (SPA)

–

Acquires background rates vs. (threshold, elevation)

–

Simplified design allows low thresholds with ~MHz hit rates

–

Threshold scan is repeated at each elevation increment.

–

Complete threshold/elevation scan should take a few hours.

---

62

Simplified SPA -Elevation Scan for ’09-’10

Variable Delay Range≈ “elevation range”

Mono ~10ns

Mono ~10ns

Variable Delay

Mono 100ns

Elevation

Setting

Rate

Output

0

Threshold

Setting

2

1

3

4

Rate Output

1

2

3

4

5

5

A

B

Envelope

From

Hole

40m

Resolution

Setting

Pulse width≈ “elevation resolution”

TDOA

---

63

Askaryan pulses from air

shower core