status on the cross check analysis for the e + +e - flux estimation villi scalzotto – luigi cossio...

Status on the cross check analysis

for the e++e-

flux estimation

Villi Scalzotto – Luigi Cossio – Michele PalatielloUdine, MAGIC Collaboration Meeting 2012 – June,10th-16th

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Outline

This is the status of a CROSS CHECK analysis of DANIELA BORLA TRIDON's results on the e+e- spectrum

• Quick introduction• Description of the method• Data set informations• CRAB Test of the method• Electron Flux estimation• Discussion

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• At TeV energies, CR-electrons carry informations about nearby sources, due to energy losses via synchrotron radiation and IC-scattering.

Lifetime (propagation distance) is limited

(105lyr 1kpc) Spectrum is isotropic and steeper than hadronic CRs

(~ E-3.3 vs E-2.7)• Direct measurements at HE is then difficult, but a

chance for Cherenkov telescope:- larger coll. area than satellites (~ 105 m2)

- sufficient energy resol. to resolve the spectrum, such to discriminate among different models

CR-Electrons

OriginElectrons lose energy by:• Ionization• Synchrotron• Inverse Compton• Bremsstrahlung

Possible contributions to HE electrons flux:• Secondary electrons generated in CR interactions

with ISM• Supernova explosion (sharp cutoff in the

spectrum)• Distant sources uniformly distributed• Pulsars• Dark matter

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MAGIC & THIS PHYSICAL CASE

Drag picture to placeholder or click icon to add

INTENT:use

MAGICto support or not

ATIC/FERMI/HESS result

PRO: No dedicated time

AGAINST:Lower sensitivity

Large MCProtons simulation needed to

match MCProtons to RealData

MAGIC

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Villi ScalzottoFERMIATICHESS

Results by other experiments

HOW TO COUNT ELECTRONS?

Drag picture to placeholder or click icon to addGAMMAS and ELECTRONS

morphologically equivalent for MAGIC

BUT ELECTRONS are DIFFUSEALPHA parameter not useful!

All the real datacontain electrons

(both ON and OFF!)

The normalizationof the Alpha plot

allows toobtain the same

amount of electrons

in ON and in OFF:

USE OF HADRONNESS ASSIGNAL PLOT

electrons

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HadronnessTheta2

0 10 0.3

• "ON" Data (with gamma rays from a pointlike source)• Non leptonic cosmic rays (p, He, ecc.) renorm.• "OFF" Data (with diffuse Electrons (and diffuse gammas)

renormalizedHadronnessTheta2

0 10 0.3

• MC Protons simulation (+He + diffuse gammas)• Real Data from a dark patch (thus diffuse electrons + non leptonic cosmic

rays)

THE METHOD

STD ANALYSIS

HADPHA METHOD

Hadpha stands for the

Hadronness parameter used as "Alpha" for the signal plot

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No ALPHA/THETA2 plot

As signal plot

NO ALPHA/THETA2 cut!

ELECTRONS are mostly gammalikeHADRONS are mostly hadronlike

…GAMMAS…are mostly gammalike!

Hadronness plotused to find

signal!

Hadronness:our new “Alpha”

“ON” : MAGIC OFF (with electrons and no gamma contamination)

“OFF”: SIMULATION OF THE BACKGROUND(no electrons in the background)

?

THE HADPHA METHOD

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Datasets needed (all in STEREO):

Real DataCRAB ON data (7.5h)

OFF data (14h)

SimulationMC electrons (~4e5 after stereo trigger)

MC pointlike gammas (~1.6e5 after stereo trigger)MC protons (~1.4e6 after stereo trigger)

In the future:Helium, diffuse gammas, more and more protons…

mostly given by Daniela Borla Tridon,extension thanks to Luigi Cossio and Michele

Palatiello

DATASET

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1FGL J2347.3+0710

RA 23h47m19.9s DEC +07d10m26s

• Galactic long: 96.29 lat: -52.35 • z =N/A

• 6-10-11-13-31/10_2010, 01-25

/11_2010• Zdmin=21.5

Zdmax=30

• Data selection: bad rate (manually checked) and

cloudiness

Total effective time after cuts: 8.84h

3c454RA 22h51m34.7s DEC +18d48m40s

• Galactic long: 87.35 lat -35.65

• z =1.75• 6-8-10-11/12_2009

• Zdmin=15 Zdmax=30

• Data selection: bad rate (manually checked) and

cloudiness

Total effective time after cuts: 2.93 h

TOTAL ~ 14h

BL Lac

RA 22h00m39.3723s DEC +42d02m08.495s • Galactic long: 92.58

lat -10.44• z=0,068

• 15-17/6_2010

• Zdmin=26 Zdmax=31

• Data selection: bad rate (manually checked) and

cloudiness

Total effective time after cuts: 2.12 h

REAL "OFF" DATA

11REAL "OFF" DATA

Zenith angle distributions of the dataset

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• RA 05h34m32.0s DEC +22d00m52s• Gal long 184.557593 lat -5.784197• 8-9-10-11-12-14/11_2010• Zdmin= 7 Zdmax=19• Data selection: bad rate (manually checked) and

cloudiness

Total effective time after cuts: 7,57

CRAB DATA

CRAB ON STEREO DATA SAMPLE:

13 MC SIMULATIONSimulated events (@ 2012):

ELECTRONSZenith 5-35 degrees

70 GeV – 7 TeV (and 30 TeV)ViewCone: 4.5 deg, PowerLaw: -2

# = O(8.107)

PROTONSZenith ~ 0-38 gradiVarious populations:

from (30,70,70) GeV to (30,20,30) TeVViewCone: 5/6 deg, PowerLaw: -1.78/-2

# = O(2.109)

Events surviving the triggering of the stereo system:

Electrons: O(4.105) (~0.4%) evtsProtons: O(1.4.106) (~0.07%) evts

Cleaning M1:6/3 time M2: 9/4.5 time

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In addition:

HELIUMZenith 8-38 deg70 GeV - 20 TeV

ViewCone: 5/6 deg, PowerLaw: -2# = O(4.108) Post Trigger = 1.1.105 (0.03%)

DIFFUSE GAMMAS

Zenith 5-30 deg10 GeV - 30 TeV

ViewCone: 0 deg, PowerLaw: -1.6# = O(3.107) Post Trigger = 1.8.106 (6%)

POINTLIKE GAMMASZenith 5-35 deg10 GeV - 30 TeV

ViewCone: 1.5 deg, PowerLaw: -1.6# = O(2.106) Post Trigger = 1.6.105 (8%)

NOT YET USED FOR THIS ANALYSIS

MC SIMULATION

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RF Electrons study: Train:BKG:

BL Lac 2.12h + 3c454 2.93hMC:

electrons (Daniela + Luigi)

Cuts NTree: 100

RF.trainRatio: 0.95Leakage1>0.15NumIslands>1

Energy Estimation: STD LUTSby MC RFtest sample

RF Crab Test:Train:BKG:

BL Lac 0.56h + 3c454 0.51hMC:

pointlike gammas

USED RF matrix

PARAMETERS:MaxHeight (stereo reconstructed)

Size (M1 and M2)Length (M1 & M2)

Impact par. (M1 & M2)TimeGrad (M1 & M2)

(MHillasTimeFit_*.fP1Grad)MaxHeight (M1 & M2)

Width (M1 & M2)

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Leakage{1,2} < 0.2

Dist{1,2} <300 mm

NumIslands{1,2}<2

Size1>100-150 Size2>200-250

10-12<Impact{1,2}[m]<250-300

MuonRingCenterDist<20 Quality cutsThese cuts have been applied at the electronflux level in order to obtain a better match between MCProtons and RealData

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PARAMETER DISTRIBUTIONS after the quality cuts

Comparison between Real Data and MC protons after the quality cuts.The MC sample is corrected considering the different power law.

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PARAMETER DISTRIBUTIONS after the quality cuts

Parameters as function of the energy.In case of M2, the agreement is quite good.

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PARAMETER DISTRIBUTIONS after the quality cuts

Case of M1.

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PARAMETER DISTRIBUTIONS after the quality cuts

Quite ok.Perhaps there is a small mismatch for the distributions of L,W,M3Long.

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Crab Nebula test

CRAB DATA

To test the performances of the Hadpha Method we use it to estimate a flux by a standard gamma source (Crab).

The method will be obviously less performing than the usual Theta2 Method.

But the spectrum of a strong gamma source should be obtained.

Standard RF, hadronness plot as significance plot

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CRAB TESTTheta VS Hadpha

• EffArea after cuts is lower for Theta Method because it includes the hadronness plot.

• But remember the sensitivity of the Hadpha method is lower!

Theta2 Method

Hadpha Method

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CRAB TESTTheta VS Hadpha

Theta2 Method

Hadpha Method

Good ON/OFF match!

We are using Real Data both for ON and OFF.We do expect this match is not that good in the electron case!

0.4-0.8 seems a good normalization range

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CRAB TESTTheta VS Hadpha

Theta2 Method

Hadpha MethodThe points are consistent within errors.

But there is still a slight underestimation to be understood.

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HADPHA METHOD SENSITIVITY

Theta2 Method

Hadpha Method

As expected, the sensitivity (in Crab units for 50hrs) is worse (~factor 4 for differential sensitivity).

The lowest points for Hadpha are not trustable (see later).

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Theta2 Method

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Hadpha Method

In this method it's very peculiar the selection of

the normalization region

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11<Zd<30 // 20<Zd<30

Azimuth bins: 1 / 9

Energy Bins: 20 / 25 / 30

Hadpha Efficency: 0.55 – 0.75

Normalization region: [0.4/0.45 --- 0.7/0.85] Electronflux

optionsDifferent flux have been extracted by varying some options in a reasonable range

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Different Hadpha normalization region possible…

Discrepancy at the highest values

Perhaps it's enough to apply a quality cut

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Discrepancies at the lowest energy values (as in Daniela's work). Due to mismatch btw simulation and real data.

The matching improves with the energy.

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Signal persists at higher energies, above 1 TeV, but these number of excesses would give huge values in the spectrum.

Lack of statistic?

To investigate.

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??

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e++e-

DIFFERENTIAL SPECTRUM

HadEff = 0.7-0.8HadEff = 0.55-06

E3dN/dE spectra are highly sensitive to the variation of some options in the input card

Main variations due to Zd range, Hadpha Efficiency and the normalization region

We superimpose the different result. We divided it into 2 samples, with lower and higher Hadpha Efficiency

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e++e-

E3Spectrum

FERMIHESSMAGIC CROSS CHECK

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e++e-

E3Spectrum

HadEff = 0.7-0.8HadEff = 0.55-06

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Public resultShown at ICRC'11ICRC proceeding

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• There is a mismatch at high hadronness values to be better understood (in disagreement with Daniela's result) - We used the reweighting

• The method is sensitive to the Zd selection and the normalization region

• Crab Test with diffused electrons to better understand the behaviour of the ViewAngleCone

• Behaviour at high energies? Why do the values seems to increase?

• E3dE/dN distribution is highly amplifying the fluctuations. It's a very precise work to deal with..

• The fluctuations obtained by varying the electron flux options could give an estimation of our systematics due to the analysis

Technicalconsiderations

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• Results are consisent with Daniela's work, but the E3dN/dE spectrum looks a bit higher.

• Range 150<E<1000 GeV. Problems at higher energies.

• We have reported an overlap of spectra. No PowerLaw estimated yet.

• We cannot exclude the presence of a flux higher than expected and measured by Fermi.

• Analysis is finally working (in the past several problems with this crosscheck!)

• Need to fine tune some disagreement (large hadronness mismatch and high energy values). Larger MC production could help.

Conclusions

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BACKUPs

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•Consistency considerations in the mono case:

•Electrons are diffuse:

we need to integrate over the solid angle(we assume an “effective” FOV

of 0.4deg X 0.4deg = 1.5*10-4 sr)

•At 500 GeV:

CRAB = 2 10-13 cm-2 s-1 GeV-1

ELECT (Fermi) = 114/E3(GeV) m-2 s-1 GeV-1 sr-

1

= 9 10-11 * 1.5 10-4cm-2 s-1 GeV-1 sr-1

= 1.35 10-14 cm-2 s-1 GeV-1

Elect.Flux ~ 7% Crab!

Observation time: 50*(10/7)2 = 100 h

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MC ProtonsM1 vs M2

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MC ProtonsM1 vs M2

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Real DataM1 vs M2

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Real DataM1 vs M2

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Some BACKUP slides by Daniela Borla's talk

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Gamma sample (M1: PSF 11.44mm - M2: PSF 12.66mm

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