The Tale of IceCube and GRB080319B or the Mystic Magic of TestDAQ Alexander Kappes UW-Madison...

The Tale of IceCube and GRB080319Bor the Mystic Magic of TestDAQ

Alexander Kappes

UW-Madison

IceCube Collaboration Meeting

May 3, 2008, Madison

May 3, 2008 Alexander Kappes, IceCube Meeting, Madison 2

The Event: GRB080319B

Triggered Swift on March 19, 06:12:49 UTC

Position: RA = 217.9º, Dec = +36.3º

T90 > 60 s (main emission within first 60 s)

Brightest (optical) GRB ever observed: Fluence (15-150 keV; 60 s) = 8110-6 erg/cm2

Isotropic energy = 1.31054 erg

Optical afterglow saturated several UVOT pixels

Redshift z = 0.94 (DA = 1.6 Gpc, light travel time 7.5 Gyr)

Remark: 3 other bursts on that day (normally 2 per week)+ all in northern sky; IceCube data for 2


GRB080319B: Swift Instruments

XRT (X-ray) UVOT (ultra violet)


GRB080319B: Optical Brightness

Visible to the naked eye for ~10 s !!!

Animated GIF:http://grb.fuw.edu.pl/pi/index.html


And what about IceCube?

... but fortunately the detector was actually running (weekly runs): (Francis: “we were running in maintenance mode”)

IC9 TestDAQ run (~6 min) ( this talk)(last run until 110685 was started)

Full 2 hour AMANDA TWR run ( see following talk by Martijn) (running outside of ANVIL control)

GRB080319B occurred 06:12:49 UTC (main burst ~60 s)


IceCube Data (IC9)

GRB time: 08-03-19 – 06:12:49 GRB duration:

main burst 06:12:49 – 06:13:49

Run containing GRB: SPS-TESTDAQ02_run0002484_1-LocalCoincidence-02-2006-Config-IceCube9-InIce-Amanda-V6-Weekly

duration: 08-03-19 – 06:09:14.6 (first event, 214 s before main burst)08-03-19 – 06:15:51.2 (last event, 122 s after end of main

burst) # events: 40492 102 Hz (after standard multiplicity 8 trigger)

Konus data (-ray)IceCube data

GRB direction


Estimated Events in IceCube

Standard fireball model (Guetta et al) IC9 point source effective area @ dec = 35º (© Chad Finley)

(averaged over azimuth; angular cut loosened from 2.5º to 5º)

Expected # of obs. events ~0.1, but large fluctuations in neutrino flux possible

gamma spectrum neutrino spectrum

IC9 eff. area # events in IC9


Background Calculation

Precision of background estimate crucial:with 0.1 expected signal events we have

~10% chance to observe 1 event~0.5% chance to observe 2 events . . .

1 event in on-time window (60 s) significant @ 4 requires calculated background to be 610-5

Options: For background estimate purely from data

we need at least 1 event in given time period T

T > 60s / 610-5 ≈ 12 days

Fit function to low statistics background map from Testdaq data statistics even in total map very low, systematics,

doesn’t work with unbinnned likelihood

Use of MC not enough statistics, systematics

. . . and use IC9 2006 dataset (137 days). . . and use IC9 2006 dataset (137 days)


IC9 TestDAQ vs. 2006 RealDAQ Data

IC9 TestDAQ data is taken with same settings as in 2006 (e.g. OM voltages)

However, there are differences: Simplified time window for local coincidences (800 ns) in TestDAQ

(signal travel time not corrected) TestDAQ reads out only one ATWD (slightly more deadtime) . . . ?

Requires careful comparisonsRequires careful comparisons


Data Processing

TestDAQ: fat-reader with SMT 8 and LC-Span 1

“Simulation” of 2006 online muon filter:

zenith (linefit || dipolefit) > 70º && Nchan ≥ 10

std-processing (Level1 + 2) as for IC22

2006 IC9 data (thanks to Martin Merck): Same data as for 2006 atm. muon and point source analysis

std-processing (Level1 + 2) as for IC22

Required some tweaking as not all entries in database filled in 2006

(e.g. some droop correction values not set)

FilterMask not contained in current Level2 files

differences at low cut levels in following plots


IC9 TestDAQ - 2006 RealDAQ Comparison

Mainly down-goingmuons from HE-filter

(special 1 hour IC9 TestDAQ run 1 week after GRB)


IC9 TestDAQ - 2006 RealDAQ Comparison

37% signal efficiency


Analysis Method

Unbinned loglikelihood method (similar to Chad’s point source analysis)

Track information in PDFs: Relative position to GRB together with full paraboloid error ellipse Relative time to GRB

Optimization of quality cuts on Ndir and paraboloid error(already used in IC9 point source analysis)

ontime


Signal Simulation

Generation of muon neutrinos from direction of GRB with modified neutrino-generator (Chad Finley)

allows specification of direction and time period

generates neutrinos randomly within time period

Sample source events (Poisson sampling) from generated neutrinos weighted with calculated GRB spectrum


Current Limitations

Only 26 out of 137 days of 2006 data for background

Ndir cut on Pandel track removes high energy events in future cut on MPE Ndir

Differences between TestDAQ and RealDAQ


Background Map for PDF (preliminary)

GRB position

Ndir 6, paraErr ≤ 6


MDF Calculation (preliminary)

Cuts: Ndir 6, paraErr ≤ 6 Significance = 2.510-3 (3), Power = 0.5

Expected signal events = 0.16 MDF = 6.8 Probability to discover signal ~7%

10,000 randomizedbackground samples

Likelihoodrequired mean

# signal evts

sig

nal

eve

nts


MDF Optimization (preliminary)

Optimize MDF varying cuts on

Ndir_C and paraboloid error

Best MDF:

Ndir 6, paraErr ≤ 6


To Do List and Time Schedule

Process data/MC to level3 (MPE)

Investigate differences between TestDAQ and RealDAQ

Varify stability of GRB TesDAQ run

Check that paraboloid error gives reasonable error estimate

also for IC9

Do checks on absolute timing and pointing

Systematics (differences TestDAQ - RealDAQ, uncertainty on

background estimation etc.)

Time schedule: Unblinding proposal until end of May

The Tale of IceCube and GRB080319B or the Mystic Magic of TestDAQ Alexander Kappes UW-Madison...

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