PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTION H Yepes -Ramirez IFIC (CSIC – Universitat de València) ANTARES Collaboration Meeting Strasbourg,

PROGRESS ON WATER PROPERTIES ON PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTIONTRACKS RECONSTRUCTION

PROGRESS ON WATER PROPERTIES ON PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTIONTRACKS RECONSTRUCTION

H Yepes -Ramirez H Yepes -Ramirez IFIC (CSIC – Universitat de València)IFIC (CSIC – Universitat de València)

ANTARES Collaboration Meeting

Strasbourg, November 21st-25th, 2011

OUTLINEOUTLINEOUTLINEOUTLINE

ANTARES Collaboration Meeting ANTARES Collaboration Meeting Strasbourg, Strasbourg, NovNov 21 21stst-25-25thth2

Brief reminder of light propagation Brief reminder of light propagation in sea water: in sea water: ANTARES Monte Carlo

model

Simulation: Simulation: data selection, absorption and scattering length inputs and codes

Selected resultsSelected results

Conclusions and outlookConclusions and outlook

Brief reminder of light propagation Brief reminder of light propagation in sea water: in sea water: ANTARES Monte Carlo

model

Simulation: Simulation: data selection, absorption and scattering length inputs and codes

Selected resultsSelected results

Conclusions and outlookConclusions and outlook

Brief reminder of light Brief reminder of light propagation in sea waterpropagation in sea water


3




Scattering phase function (Scattering phase function ())

Morel and Loisel approach

Molecular scattering (Rayleigh) Isotropic (<cos>=0)

= contribution of Rayleigh scattering

Particle scattering (Mie) Strong forward peaked (<cos>Mie=0.924)

effscatabs

effatt

111

Attenuation Length (COLIMATED BEAM)

Effective Attenuation Length (ISOTROPIC SOURCE)

Absorption lengthAbsorption length Scattering LengthScattering Length

scatabsatt 111

Mie

scatscateffscat

cos)1(1cos1

924.0cos Mie

Scattering length wavelength dependence

(Kopelevich parameterization)

][550

312.0550

34.1550

0017.0 13.07.13.4

mvvb ls

scat

b1

b = scattering coefficient.

vs, vl = scattering centers.<Cos> = Average cosine of the global distribution

Petzold values for particle scattering

)()1()()( *** MieRay

SimulationSimulationSimulationSimulation

5



DATA/MonteCarlo SELECTION:Data 2008 – 2010 data from the official SeaTray production May 2011 (5997 runs).

• First run: 31051, Last run: 54244. Subsample from Point Sources data from Juan Pablo analysis (2007-2010).

• Lifetime: 618.96 days.

MonteCarlo (no run-by-run) SoS prepared (C. Bogazzi) with the previous subsample (5997 data runs).

• Mupage for muons + Geasim for neutrinos.

• Statistics hugely increased from CM Moscow (two runs per water model: 2 , 2 -, 2 ), right now:Water Model data

sc0.0075 aa09 abs55 sca53 eta0.17 90 40 312 5997

sc0.01 aa09 abs55 sca41 eta0.17 82 34 312 5997

sc0.02 aa09 abs55 sca22 eta0.17 81 35 312 5997

sc0.01 aa09 abs55 sca41 eta0.11 74 39 312 5997

sc0.02 aa09 abs55 sca22 eta0.02 78 39 312 5997

sc0.0075 aa09 abs63 sca53 eta0.17 82 37 312 5997

sc0.01 aa09 abs63 sca41 eta0.17 80 38 312 5997

sc0.02 aa09 abs63 sca22 eta0.17 79 38 312 5997

sc0.01 aa09 abs63 sca41 eta0.11 80 36 312 5997

sc0.02 aa09 abs63 sca22 eta0.02 81 39 312 5997

sc = scattering centers; aa = om angular acceptance; abs = absorption; sca = scattering; eta = fraction of Rayleigh scattering.



Water models are selected based on:

• Three models with the same value and different scattering spectrum for a given absorption length.

• Three models with different values, but is computed in such a way that the three models will have the same effective scattering length at 470 nm, for a given absorption length.

• OM Angular acceptance of June 2009 (Genova Meeting 2009).



GENGENWATER MODEL:

•Photon tables production (water tables) Water tables (hbook files) + Description files (ASCII files).

HITHITOM PARAMETERS:

• Hit probability computation from the water tables for a given OM parameters Hit tables (hbook files) + Description files (ASCII files).

KM3KM3SIMULATED EVENTS: GEOMETRY + KINEMATICS

• Physics events reading and OM hits production based on event geometry and hit probability tables Detector events: Signal hits (muons, not tracks from hadronic showers), physical background.

GEASIMGEASIM

MCEWMCEW

TETE

RECORECO

SIMULATIONS OF ATMOSPHERIC NEUTRINO INTERACTIONS.

• Process (and evaluation) tracks from particles coming from the hadronic showers (also muons from KM3).

TRANSLATION OF INFO ASCII FILES INTO ROOT FORMAT.

FORMAT CONVERSION TO “LOOK LIKE DATA”: electronics smearing effects (calibration, ARS response) and optical background.

RECONSTRUCTION: Reconstruction of track direction (AAfit) and ntuples information arrangement as number of hits, zenith distribution…(AntDST).

Simulation chain:



Main options and software versions in muons and neutrinos simulation:

CODE/INPUT OPTIONS/VERSIONS

GEN v3r7

HIT v3r7

KM3 v3r7

DETECTOR r12_c00_s01

GEASIM v4r10

MCEW 2011-01-27

TriggerEfficiency Gaussian ARS threshold file: threshold_gaus_0.33_0.08_0.1.txt

SoS file: noise_basic_harold_new.root (based on data subsample)

-n 10000000 –t 104.858 –C3 – p 0.035

-t 104.858 Frame time in ms. To determine the number of background hits to be generated in case the summary data are used.

-C3 Hit generator type: 3, Gaussian, according observed charge distribution, with time-dependent contribution of after pulses.

May 2011 version

Aafit v0r9

AntDST v1r2p3



• It is not a run-by-run simulation.

• 5997 data runs (2008-2010).

• 312 mupage muon runs.

• 90 neutrino + 40 anti-neutrino Geasim files.

• TE May 2011.

• Down-going neutrinos not used in this MC.

• Run-by-run simulation.

• 5997 data runs (2008-2010).

• 5941 mupage muon runs.

• 5898 neutrino + 5900 anti-neutrino Geasim files.

• TE September 2010.

• Down-going neutrinos are used in the run-by-run MC. >-5.2 removes some events close to the horizon (my sample), > -5.4 relax this zone (SEE NEXT SLIDE)

Sanity check with the official production (sc0.0075 aa09 abs55 sca53 eta0.17):

My production Official production



• A restrictive cut at > -5.2 removes neutrinos and muons near the horizon (and some muons below the horizon). This may have a large impact on this analysis due to the smaller statistics (concerning the run-by-run MC statistics).

• If we relax the cut to > -5.4 the agreement to data is better within the different available samples (typical cut on point sources analysis before run-by-run MC).

±[31-43]% [-1, -0.1]

±25% [>0.2] ±45% [-0.1, +0.1]

Selected ResultsSelected ResultsSelected ResultsSelected Results

Selected resultsSelected resultsSelected resultsSelected results


Lessons learnt since the CM in Moscow:

• Lower effective scattering lengths could not be an good approach.

• Higher absorption lengths should not be discarded.

• Determination of the effective scattering length seems to be more critical than the estimation of absorption length.



DATA/MC rates for zenith angle distribution:

• Lowest effective scattering lengths could be discarded (< 100 m)

• Contribution of Rayleigh scattering seems to be lower Comparison improves.

• sca = 41 m && = 0.11 && abs = 55 m fit better to data, overall at neutrino region

• The “hole” close to the horizon could be filled by means of the use of down-going neutrinos, improving the comparison.



DATA/MC rates for zenith angle distribution:

• Higher absorption lengths should not be discarded.

• Lowest effective scattering lengths can be discarded (< 100 m)

• Contribution of Rayleigh scattering seems to be lower.

Two models with higher absorption length, equal effective scattering length and different contribution of eta and scattering length show nice agreement to data



Influence of abs on reconstructed tracks:

1.Strategy For a couple of water models with different abs but same scattering parameters, estimate the difference on the reconstructed track rate.

2.Previous systematic studies in ANTARES (J.A et al / Astroparticle Physics 34, 2010, 179-184, Pag. 182) “The uncertainty of the light absorption length in water is assumed to be ±10% over the whole wavelength spectrum and yields a variation of ±20% on the number of expected events”.

CASE

1



CASE

2CA

SE 3



CASE

4CA

SE 5



THE UNKNOWLEDGE ABOUT ABSORPTION LENGTH FOR

DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT

≈ 18% ON AVERAGE ON THE RECONSTRUCTED MUON RATE

Case 1:

_rate ≈ 0 %

Case 2:

_rate ≈ 15 %

Case 3:

_rate ≈ 15 %

Case 4:

_rate ≈ 15 %

Case 5:

_rate ≈ 15 %



THE UNKNOWLEDGE ABOUT ABSORPTION LENGTH

FOR DIFFERENT WATER OPTICAL PARAMETERS HAS

AN IMPACT ≈ 15% ON THE RECONSTRUCTED NEUTRINO

RATE



INFLUENCE OF sca,eff ON RECONSTRUCTED TRACKS:

1.Strategy Two optical parameters fixed (absorption, eta) and one free parameter (scattering length), for both absorption lengths.





THE UNKNOWLEDGE ABOUT EFFECTIVE SCATTERING LENGTH FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT BETWEEN 15-25% ON THE

RECONSTRUCTED MUON-NEUTRINO RATE DEPENDING OF THE ZENITH ANGLE



THE UNKNOWLEDGE ABOUT EFFECTIVE SCATTERING LENGTH FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT BETWEEN 15-25% ON THE

RECONSTRUCTED MUON-NEUTRINO RATE DEPENDING OF THE ZENITH ANGLE



INFLUENCE OF ON RECONSTRUCTED TRACKS:1.Strategy One optical parameters fixed (absorption) and two free parameters (scattering length and eta), for both absorption lengths.





THE UNKNOWLEDGE ABOUT RAYLEIGH SCATTERING FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT LESS THAN 18 % ON THE RECONSTRUCTED

MUON-NEUTRINO RATE



THE UNKNOWLEDGE ABOUT RAYLEIGH SCATTERING FOR DIFFERENT WATER OPTICAL PARAMETERS HAS AN IMPACT LESS THAN 18% ON THE RECONSTRUCTED

MUON-NEUTRINO RATE

Conclusions and outlookConclusions and outlookConclusions and outlookConclusions and outlook

CONCLUSIONS AND OUTLOOKCONCLUSIONS AND OUTLOOKCONCLUSIONS AND OUTLOOKCONCLUSIONS AND OUTLOOK


1. Current study shows that, for the current physics conditions simulated in the ANTARES KM3 code the uncertainty on water parameters could be summarized as follow:

2. The effective scattering length seems to be the most relevant parameter for muons.

3. Neutrino tracks reconstruction is very sensitive to the absorption length and Rayleigh scattering.

4. An extensive study to effective areas and angular resolution will be performed.

5. An internal note will be prepared soon with a dedicated description of the analysis.

Parameter (for muon tracks) abs [%] sca_eff [%] [%]

Absorption length < 18

Effective scattering length < 25

Rayleigh scattering < 18

Parameter (for neutrino tracks) abs [%] sca_eff [%] [%]

Absorption length < 15

Effective scattering length < 25

Rayleigh scattering < 18

BackupBackupBackupBackup

31

BACKUPBACKUPBACKUPBACKUP
































Documents

PROGRESS ON WATER PROPERTIES ON TRACKS RECONSTRUCTION H Yepes -Ramirez IFIC (CSIC – Universitat de València) ANTARES Collaboration Meeting Strasbourg,