Ice Shear Measurement using the deep AMANDA strings

and IceCube flashers

Kurt Woschnagg, UCBLake Geneva, 4/24/07

http://wiki.icecube.wisc.edu/index.php/Ice_shear_measurement

shear model

Ice temperature profilefrom AMANDA thermistors

Fill in IceCube data (5 strings)

× 9 years

AMANDA strings 11-13:► extend to 2350 m

► deployed Jan 1998

Note: flow is really 10 m at surface

IceCube strings 48/57/58:► Surround 11/12/13► Newly deployed → (~)vertical► All DOMs have working flashers→ measure individual DOM-OM distances vs depth

d1 d2

d3

(x1,y1)(x2,y2)

(x3,y3)

Known: x1, y1, x2, y2, x3, y3, v

Unknown: x, y, t0

d1 = (x1-x)2 + (y1-y)2 = v(T1 - t0)

d2 = (x2-x)2 + (y2-y)2 = v(T2 - t0)

d3 = (x3-x)2 + (y3-y)2 = v(T3 - t0)

(x,y)

√ √ √

T

flash time

prompt time

time [ns]

flashing

receiving

T0-less analysis through triangulation

1. Merge TWR events with TestDAQ data (flasher pulse) 2. Assume reasonable T0 start values for AMANDA OMs 3. Make travel time histograms for all receivers 4. Fit leading edges (=prompt times+scattering) and

convert to distances (may require ice simulations)5. Triangulate: solve 3 equations for receiver OM's

(x,y,T0) 6. Plot fitted (x,y) vs depth

→ is there a trend? → is it along the flow direction?

→ at least upper limit on ice shear

Note: this measurement can possibly also be done with muon tomography [Martino Olivo/Carsten Rott]

Analysis Strategy

Requirements Flashers on 48, 57, 58 operational

(only with TestDAQ for now) TWRdaq operational Deep OMs alive Deep OMs read out by TWR

(6 electrical, 18 optical) IceCube/TWR time synch to a few ns IceCube/TWR data merging

fusing should work (Steve M., Gustav W.)

Will AMANDA trigger?

Will AMANDA trigger? well…

How vertical were strings 11-13 in 1998?

[Analysis and plots by Varun Gopalakrishna (UW)]

11 12

Run Plan• Pilot runs

Determine suitable brightnessProvide data to develop analysis code– flash DOMs 33 and 48 on 48/57/58– two different intensities per flasher– 10 min/run → 2 hours

• Data runs– flash every DOM 40-54 on 48/57/58– flash a few DOMs 20-30 on 48/57/58– each run 5-10 min → 5-10 hours

• Pilot runs delayed by AMANDA illness– Fixed now

• Pilot runs to be taken soon

• Want to get data taking out of the way before physics runs start

Status