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Anisotropy of Cosmic Rays.
Origins, experiments, data analysis problems & methods. Vladimir.Kulikovskiy@GE.INFN.IT


! CR anisotropy origins over view. ! Latest and some important experiments that measure anisotropy
! Comparison table ! Some results and methods

Icecube ! Tibet, Argo
!

! ANTARES problems and methods.


CR
!

Till 1018eV CR assumed to have Galactic origin. Origin: acceleration in expanding shock waves from SN (SNR). Loss direction to origin in the Galactic magnetic field (~10 G or 1nT, thickness 200-300pc) For 100TeV proton:
"9

!

!

!
Rg
yro

pc 100 ! 1012 q = = qcB q ! 3 ! 108 ! 10

= 3 ! 1014 m = 0.01 pc


Origins
! Solar anisotropy (local coordinates) 10-4 !I v = (! + 2 ) cos" c ! Earth motion around Sun (29km/s). Fits well the data. I
! Careful atmospheric and detector corrections.

! Galactic anisotropy (equatorial coordinates) 10

-3

! Compton-Getting effect (motion of solar system through ISM,

around the GC is 220km/s ) ! Local Interstellar Magnetic Field + Heliosphere (argued because heliosphere can't inf luence CRs >10TeV, but anisotropy obser ved) ! Discrete distribution of CR sources - Erlykin A. D., Wolfendale A. W.,2006, Astroparticle Phys., 25, 183 ( doi:10.1016/j.astropartphys.2006.01.003) ! Diffusion of CR in the Galaxy - Candia J.,Mollerach S., Roulet E., J. 2003, Cosmol. Astropart. Phys., 5, 3.


«2D» experiments
Name Tibet Air Shower Array Position 90.522o E, 30.102o N; 4300 m above sea level 30.11 N, 4300m a.s.l. Gran Sasso, 2000m Caucasus, 1700m (40deg N, 113 deg W), atmospheric depth of 860 gm/cm2 Energy 4,6.2,12,50, 300 TeV Gamma /CR mix Time 1997-1999 TibetII, 1999-2001 TibetIII (bigger HD array). 4 years 1 year Statistics 7x109 in ~1000 days Rate Ang. Res. 0.9 for 3Te V Method Equi-zenith

ARGO-YBJ

0.7, 1.5,3.9 TeV 100-400TeV

mix

6.5 x1010 in 2008 1.5*10
9

Equi-zenith

EAS-TOP

mix

Jan 1992 ­ Dec 1999 1431 days

EW

BaksanCarpet HiRes

10-100TeV 106 TeV

mix Mix December, 1999, through April, 2006

(low) 12,000 5
0

EW Direct integration


«3D» experiments
Name Position Energy Gamma/CR Time Statistics Rate Ang . Res. Method MACRO Gran Sasso, 800 meters underground 2630 m, 36 N >10TeV CR 1991-2000 2145 days 6 years 4.4*10
7

16/min

Like Kamiokande + quality criteria, average in another way. <1 FB + harmonics fit, Direct integration

Milagro

3 TeV

mix/ possible differentiati on CR?

1.5*1011 events in 6 years 2*10
8

1700 Hz

SK-I

1000m underground , Japan 1000m underground , Japan South Pole

10TeV +-order

6years (1662.0 days)

1.8 Hz

2

o

Sidereal time normalization and average to eliminate azimuth anisotropy.
o

Kamiokande ­II, III IceCube

12 TeV

CR?

6years

6*10

7

0.33 Hz

30

Vertical muons, detector stab. in time, time normalization. Azimuth correction for different zenith belts. Like Kamiokande + quality criteria, average in another way. Comparison with RBR MC for time/space detector eff. correct?

20TeV

March 2008-May 2009 324 days CR 1991-2000 2145 days 2008-2010 ~700days? (587 after QC)

15*10

9

3

o

MACRO

Gran Sasso, 800 meters underground 2500m depth

>10TeV

4.4*10

7

16/min

ANTARES

60-70Te V

CR

3*108 (all trig.) 1.1*108 3N, -6.5

5-10Hz (~2Hz)


IceCube.
!

the sidereal variation is not affected by diurnal variations because the whole sky is fully visible to the detector at any given time and because there is only one day and one night per year. remaining challenge for this analysis is accounting for the detector asymmetr y, and unequal time cover- age in the data due to the detector run selection

!


IceCube with others.
Large scale

Medium scale


CR energy detected by ANTARES
! !

Underground experiments in the northern hemisphere with similar statistics is SK. SK and ANTARES has similar overburden, but SK has lower threshold than ANTARES. Rates are similar. Primar y energy in SK ~10TeV, ANTARES ~70TeV.

Mean ~68TeV

CORSIKA (QGSJET01c for hadronic interaction description) polygonato with rigidity dependent knee (also called "Horandel parameterization") All particle spectrum (mass groups: p, He, N, Mg, Fe) . Energy between 1- 105 TeV/nucleon. zenith angle between 0-85 trigger efficiency : -C2 Thanks to Annarita for the plot. HT=3 3N+T3

CR energy.

lg(E

@can[GeV])

Muon energy at the can.


Cut in lambda.
! Comparison with RBR MC (runs 23 Nov 2010 - 20 Dec 2010

both in RBR and in MicroAndDST). All triggers except GC.

! Any cut lambda > -6.8 should be fine from the bottom plots

data MC MC


Cut in lambda
!

Number of hits per event with different lambda cut.
>-5.5 >-6

>-6.5

>-7

>-7.5


Statistics(lambda)
!

3N trigger was chosen since it's in ever y run (more uniformity of the data in time). Also it seems to be in better correspondence with MC for rates <150kHz (see analysis elog 548 by Colas). Probably cut for rate is also needed (<150kHz). Only "good"runs from the E.Gracheva). rate(N_active_PMTs) analysis (see presentation of

!


Problems & methods.
! Non uniform detector in space. It means that efficiency of

the detector depends on the azimuth. Efficiency function (theta,phi) is needed. Many experiments obtain it with averaging over time the data. MILAGRO divides all data on 30min data sample and fits them with the harmonics (For ward-Backward method). Can it be applied to ANATRES? Critical review of the ICRC07 paper 814 of Milagro is needed. Use RBR for efficiency function for ever y run!? soon.

! In addition ANTARES efficiency is not uniform in time.

! What can we do to cure both time/spacy nonuniformity? ! Group of Rome has shown interest: common discussion


Thank you for attention.