The Tale of IceCube and GRB080319B or the Mystic Magic of TestDAQ Alexander Kappes UW-Madison IceCube Collaboration Meeting May 3, 2008, Madison

May 3, 2008Alexander Kappes, IceCube Meeting, Madison2 The Event: GRB080319B  Triggered Swift on March 19, 06:12:49 UTC  Position: RA = º, Dec = º  T90 > 60 s (main emission within first 60 s)  Brightest (optical) GRB ever observed: Fluence ( keV; 60 s) = 81  erg/cm 2 Isotropic energy = 1.3  erg  Optical afterglow saturated several UVOT pixels  Redshift z = 0.94 (D A = 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

May 3, 2008Alexander Kappes, IceCube Meeting, Madison3 GRB080319B: Swift Instruments XRT (X-ray)UVOT (ultra violet)

May 3, 2008Alexander Kappes, IceCube Meeting, Madison4 GRB080319B: Optical Brightness Visible to the naked eye for ~10 s !!! Animated GIF:

May 3, 2008Alexander Kappes, IceCube Meeting, Madison5 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 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)

May 3, 2008Alexander Kappes, IceCube Meeting, Madison6 IceCube Data (IC9)  GRB time: – 06:12:49  GRB duration: main burst 06:12:49 – 06:13:49  Run containing GRB: SPS-TESTDAQ02_run _1-LocalCoincidence Config-IceCube9-InIce-Amanda-V6-Weekly duration: – 06:09:14.6 (first event, 214 s before main burst) – 06:15:51.2 (last event, 122 s after end of main burst) # events:  102 Hz (after standard multiplicity 8 trigger) Konus data (  -ray) IceCube data GRB direction

May 3, 2008Alexander Kappes, IceCube Meeting, Madison7 Estimated Events in IceCube  Standard fireball model (Guetta et al)  IC9 point source effective 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

May 3, 2008Alexander Kappes, IceCube Meeting, Madison8 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) 4  requires calculated background to be 6   Options: For background estimate purely from data we need at least 1 event in given time period T  T > 60s / 6  ≈ 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 IC dataset (137 days)

May 3, 2008Alexander Kappes, IceCube Meeting, Madison9 IC9 TestDAQ vs 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 comparisons

May 3, 2008Alexander Kappes, IceCube Meeting, Madison10 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

May 3, 2008Alexander Kappes, IceCube Meeting, Madison11 IC9 TestDAQ RealDAQ Comparison Mainly down-going muons from HE-filter (special 1 hour IC9 TestDAQ run 1 week after GRB)

May 3, 2008Alexander Kappes, IceCube Meeting, Madison12 IC9 TestDAQ RealDAQ Comparison 69% signal efficiency

May 3, 2008Alexander Kappes, IceCube Meeting, Madison13 IC9 TestDAQ RealDAQ Comparison 66% signal efficiency

May 3, 2008Alexander Kappes, IceCube Meeting, Madison14 IC9 TestDAQ RealDAQ Comparison 53% signal efficiency

May 3, 2008Alexander Kappes, IceCube Meeting, Madison15 IC9 TestDAQ RealDAQ Comparison 37% signal efficiency

May 3, 2008Alexander Kappes, IceCube Meeting, Madison16 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) on time

May 3, 2008Alexander Kappes, IceCube Meeting, Madison17 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

May 3, 2008Alexander Kappes, IceCube Meeting, Madison18 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

May 3, 2008Alexander Kappes, IceCube Meeting, Madison19 Background Map for PDF (preliminary) GRB position Ndir  6, paraErr ≤ 6

May 3, 2008Alexander Kappes, IceCube Meeting, Madison20 MDF Calculation (preliminary)  Cuts: Ndir  6, paraErr ≤ 6  Significance = 2.5  (3  ), Power = 0.5  Expected signal events = 0.16  MDF = 6.8  Probability to discover signal ~7% 10,000 randomized background samples Likelihood required mean # signal evts signal events

May 3, 2008Alexander Kappes, IceCube Meeting, Madison21 MDF Optimization (preliminary)  Optimize MDF varying cuts on Ndir_C and paraboloid error  Best MDF: Ndir  6, paraErr ≤ 6

May 3, 2008Alexander Kappes, IceCube Meeting, Madison22 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

May 3, 2008Alexander Kappes, IceCube Meeting, Madison23 Likelihood Function  Likelihood function (similar to point source analysis):  Likelihood ratio: Remark: “Standard” Likelihood function optimizes also n b = N - n s because of possible contamination of N with bkg events signal events (maximized) bkg events (calculated) signal PDF bkg PDF

May 3, 2008Alexander Kappes, IceCube Meeting, Madison24 Signal PDF  Possible offset of GRB-window start time taken into account  Extension of “flat area” to negative times (precursor)?  energy spectrum quite different: needs separate analysis!? Two dimensional Gaussian on time