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IFIC ANALYSIS (5L PS WITH BBFIT)
PHONE CALL
AWG
09 June 2010
Juan Pablo Gómez, Paco Salesa, Salvatore Mangano
OUTLINE
PLS ANALYSIS WITH 5LINES DATA SUMMARY
 Optimized sample
 Detector performance
 Searching method
 Sensitivity
 Systematic effects
 Results
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5Lines Analysis
Juan Pablo Gómez-González
SAMPLE EVENT SELECTION
Optimum cuts  chi2 < 1.8, bchi2 > 1.8, elevation < -10 & nhit > 5 & nlines > 1
Data
Atm. Neutrinos
Atm. Muons
background
314
225
52
277
• Last mc production
(make use of mixed noise files to
simulate optical background)
• Updated calibration tables
(from previous official production)
No significant changes in
the relevant results
Good data-mc agreement
in the chi2 region
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5Lines Analysis
Juan Pablo Gómez-González
DETECTOR PERFORMANCE
Effective area
Angular resolution
Bbfit reconstruction strategy
Remember: The aim was to have results for the summer conferences
Optimum results (more restrictive limits)  work on reconstruction method
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5Lines Analysis
Juan Pablo Gómez-González
SEARCH ALGORITHM
Method which analytically maximize the likelihood (3 free parameters)
Doesn’t needs to make very precise fits to the angular resolution
Do we have a perfect knowledge of our detector?
 We can be more conservative and use a method which can recover the actual ang. resolution
Performance of the clustering method
This searching algorithm has been
tested during more than 2 years
Last six months
 3 different mc production
 2 different calibration sets
(requested from the coll.)
Same performance shown
Very stable and robust method
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5Lines Analysis
No bugs discovered in this analysis
Juan Pablo Gómez-González
SENSITIVITY
Differential neutrino flux limits
Fixed source search
All sky survey
We look to certain directions of the sky
A blind search is performed
The crucial variable is the
quality parameter of the
reconstruction
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Optimum cuts  balance between best sensitivity and purest sample (to discard
misreconstructed tracks)
5Lines Analysis
Juan Pablo Gómez-González
ACCEPTANCE SYSTEMATIC
• We consider that uncertainties on
Absorption length, and PMT quantum
and collection efficiency are the same
for neutrinos and muons
• OM angular acceptance effect is
negligible for neutrinos
• Not perfect data-mc agreement
30% of systematic on neutrino
acceptance
Convolution with a gaussian
( = 1,  = 0.3)
We get a ~10% factor worse sensitivity
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5Lines Analysis
Juan Pablo Gómez-González
SYSTEMATICS COMPUTATION
Two cases tested:
• 50% degraded angular resolution
•10% degraded angular resolution
Hit times smeared by 1.6 ns
RMS data 2  RMS mc 2
Angular resolution change less than 5%.
This is not the only systematic we can have
in the angular resolution
Small difference with a 10% factor worse ang. res.
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5Lines Analysis
Juan Pablo Gómez-González
SYSTEMATICS COMPUTATION
We put together a 30% systematic
on the detector acceptance and10%
factor for the angular resolution
We get a 10-15% factor
worse sensitivity
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5Lines Analysis
Juan Pablo Gómez-González
AFTER UNBLINDING...
To claim a discovery if a p-value lower than the corresponding 5sigma is found:
• In the candidate list (after correcting by the trial factor from the number of sources)
OR
• In the all sky search
3 sigma will be considered as a hint
p_value 

BIC obs
dP / d ( BIC )
BICobs
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5Lines Analysis
Juan Pablo Gómez-González
CONCLUSSIONS
Optimized by sensitivity cuts give a sample containing 314 data events
Detector performance given by BBfit reconstruction strategy
Stable clustering method deeply tested
Limits to the differential neutrino flux presented
Computation of the systematic
Documented in an Internal note and web page
Ready for unblinding
Thanks for your attention
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5Lines Analysis
Juan Pablo Gómez-González