Learning from Atmospheric Neutrinos in the IceCube Deep Core Detector

Transcription

1 Learning from Atmospheric Neutrinos in the IceCube Deep Core Detector Irina Mocioiu Pennsylvania State University Miami 2010

2 IceCube Deep Core mobvabon: look for neutrinos from galacbc sources, dark mager annihilabon galacbc center is above horizon at South Pole need to reduce large cosmic muon background coverage look at down- going events, study galacbc sources, galacbc center 6+2 strings, 7m DOM spacing low energy threshold: opens the GeV neutrino energy range overlap with Super- Kamiokande at low energy and with IceCube at high energies

3 Atmospheric neutrinos Background to many searches lots of them 50,000 events per year!

4 Atmospheric neutrinos AMANDA II IC40

5 Three- flavor neutrino oscillabons Three- flavor mixing matrix (in terms of Euler angles) precision parameter measurement hierarchy (sign of ) CP violabng phase ConfirmaBon of standard 3 flavor oscillabon picture Large effort to build new long baseline accelerator experiments

6 Super- Kamiokande Atmospheric neutrinos expect: at low energies approximately isotropic use zenith angle distribubon to prove neutrino oscillabons IceCube Deep Core steep energy spectrum ( ) flux not measured at high energies

7 Neutrino oscillabons in the IceCube Deep Core tracks: - like fully contained events Angular distribubon: atmospheric flux normalizabon + main oscillabon signal ( ) + mager effects (, hierarchy, CP) Energy distribubon: neutrino oscillabons atmospheric neutrino flux Earth density profile ICDC physical mass: EffecBve mass in our analysis: (energy dependent) O. Mena, I. M., S. Razzaque (2008); G. Giordano, O. Mena, I. M. (2010) E. Fernandez- MarBnez, G. Giordano, O. Mena, I. M. (2010)

8 ICDC no fixed energy threshold can trigger 1 GeV muons most analysis use 35-50GeV threshold to avoid atmospheric neutrino background large effecbve volume above 10 GeV sbll working on track reconstrucbon Thanks to Jason Koskinen, Ty DeYoung

9 ICDC atmospheric neutrinos Observable energy: Measure main oscillabon parameters Present: : MINOS : Super- Kamiokande E. Fernandez- MarBnez, G. Giordano,O. Mena, I. M.(2010) IceCube Deep Core: very large stabsbcs contribubon from mulbple peaks

10 Presently allowed values: IceCube Deep Core: (MINOS) (Super- Kamiokande) Observable energies of 5 to 50 GeV 10 energy bins, 4 angular bins vs. 1st energy bin, 1 angular bin + 9 energy bins, 4 angular bins vs. Exclude first 2 energy bins: 8 energy bins, 4 angular bins vs vs completely free

11 2Ve m 32Θnis Ve m 32Θnis IceCube Deep Core Expected allowed regions depend on the true values of the parameters and control of systemabc uncertainbes

12 ElectromagneBc cascades Tau decay: CC interacbons: Hadronic cascades Tau decay: NC interacbons: How about cascades? CC interacbons: NC and CC interacbons Looking for oscillabons helped by:

13 OscillaBon probabilibes PropagaBon along Earth diameter

14 Tau cascade rates

15 cascades G. Giordano, O. Mena, I. M. (2010) or hadrons large present world sample of events: 5(9) DONUT + 1 (OPERA) Super- Kamiokande: consistent with appearance high stabsbcs interacbons direct evidence for appearance interacbon cross- secbon non- standard interacbons of experience with cascade detecbon

16 Normal versus inverted mass hierarchy fit to discriminate between normal and inverted hierarchy O. Mena, I. M., S. Razzaque (2008)

17 Non- Standard InteracBons (NSI) MaGer effects in neutrino oscillabons Very weak constraints in the sector

18 εeτ - εττ Preliminary

19 Outlook IceCube Deep Core detector already taking data! built to look for galacbc sources, dark mager annihilabon atmospheric neutrinos high stabsbcs, large energy range, many distances 50,000 events per year beger understanding the background for other sources neutrino oscillabons highly significant oscillabon signal good parameter sensibvity : oscillabons, interacbons, cascade detecbon mass hierarchy (if close to present bound)

20 Outlook IceCube Deep Core detector already taking data! someone s background can be someone else s signal experiments take a very long Bme to construct/operate use the data we already have and get the most of it! long baseline experiments: fixed baseline, limited energy range atmospheric neutrinos: many baselines, large energy range complementary informabon combined data: consistency checks expect SURPRISES!

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