Measuring the Measuring the

total neutrino cross section total neutrino cross section

using the IceCube detectorusing the IceCube detector

Sandy MiareckiSandy Miarecki

University of California-BerkeleyUniversity of California-BerkeleyLawrence Berkeley National LabLawrence Berkeley National Lab

Neutrino Summer School, July Neutrino Summer School, July 20112011

IceCube at the South IceCube at the South PolePole

IC09 (2006)

IC22 (2007)IC40 (2008)

IC59 (2009)IC79 (2010)

IceTop81 stations x 2 tanks

IceCube80 strings ~125 m spacing60 DOMs per string ~17 m spacing

2.5 km

DeepCore array of 6 strings60 DOMs per string ~7 m spacing

IceCube Lab (ICL)central computing facility

IC86 (2011)

33

IceCube SensorsIceCube Sensors Digital Optical Modules (DOMs)Digital Optical Modules (DOMs)

Hamamatsu 25 cm PMTs with Hamamatsu 25 cm PMTs with digitized waveformsdigitized waveforms

Quantum efficiency is higher for Quantum efficiency is higher for DeepCore than IceCube DOMsDeepCore than IceCube DOMs

IceCube detects the Cherenkov IceCube detects the Cherenkov photons from charged particlesphotons from charged particles

~70,000 upgoing muons/year~70,000 upgoing muons/year Energies 10 GeV-1 EeVEnergies 10 GeV-1 EeV Supernovae, neutrino point Supernovae, neutrino point

sources, dark matter, neutrino sources, dark matter, neutrino oscillations, magnetic oscillations, magnetic monopoles, and much much monopoles, and much much more ! more !

44

Energy Differences Energy Differences (simulated events)(simulated events)

Eµ= 10 TeV, 90 hits Eµ= 6 PeV, 1000 hits

Color of DOM indictates time of arrival (red to Color of DOM indictates time of arrival (red to purple)purple)

Size of DOM indicates number of photoeletrons Size of DOM indicates number of photoeletrons (PE)(PE)

Neutrino cross sectionNeutrino cross section

Neutrinos are "detected" when they interact in Neutrinos are "detected" when they interact in the Earth and create muonsthe Earth and create muons

Idea: examine neutrino absorption in the Earth Idea: examine neutrino absorption in the Earth to find total neutrino-nucleon cross sectionto find total neutrino-nucleon cross section

Use atmospheric neutrinos as luminosity sourceUse atmospheric neutrinos as luminosity source Use current Earth model for density profileUse current Earth model for density profile Approximately 20,000 "upgoing" muon events Approximately 20,000 "upgoing" muon events

seen in IceCube per year > ~1 TeV (IC79 config)seen in IceCube per year > ~1 TeV (IC79 config) Compare event rate per zenith angle per energy Compare event rate per zenith angle per energy

to expected values to calculate total to expected values to calculate total cross cross sectionsection

55

Atmospheric neutrinosAtmospheric neutrinos

Cosmic rays (mainly protons and He ions) interact with Cosmic rays (mainly protons and He ions) interact with atmosphere, form kaons and pions, decaying into neutrinosatmosphere, form kaons and pions, decaying into neutrinos

Earth diameter ~interaction length ~40 TeVEarth diameter ~interaction length ~40 TeV Higher zenith angles = higher absorptionHigher zenith angles = higher absorption Higher neutrino energies = higher absorptionHigher neutrino energies = higher absorption

66

IceCube: arXiv:1010.3980v2

Neutrino EnergyNeu

trin

o

Effective Earthdiameter

interaction length vs. energy

R. Gandhi: arXiv:hep-ph/9512364v1

Atmospheric muonneutrino flux

area ofthesis interest

Preliminary Reference Preliminary Reference Earth Model (PREM)Earth Model (PREM)

77

Zenith = 180 degAve = 8.0 g/cm3

Dist = 12,742 kmZenith = 150 degAve = 4.0 g/cm3

Dist = 11,035 km

Zenith = 120 degAve = 3.2 g/cm3

Dist = 6,371 km

2,200 km

Zenith=100 deg will provide a near zero-absorption baseline

Muon energy measurement is very important to the resultsMuon energy measurement is very important to the results

Zenith = 100 degAve = 2.6 g/cm3

Dist = 2,213 km

Energy Calculation MethodEnergy Calculation Method(Truncated Mean)(Truncated Mean)

88

Similar method to wire chamber and Similar method to wire chamber and calorimeter studies by omitting highest wire calorimeter studies by omitting highest wire measurementsmeasurements

Energy resolution improved by ~40%Energy resolution improved by ~40% Significant decrease in scatter with cutsSignificant decrease in scatter with cuts

PreliminaryPreliminary

99

USA: Pennsylvania State University Lawrence Berkeley National Lab University of California-Berkeley University of California-Irvine Clark-Atlanta University Georgia Institute of Technology University of Maryland Ohio State University University of Wisconsin-Madison University of Wisconsin-River Falls University of Kansas University of Delaware-Newark University of Alabama-Tuscaloosa Southern University and A&M

College, Baton Rouge University of Alaska, Anchorage

Sweden: Uppsala Universitet Stockholm Universitet

UK: Oxford University

Belgium: Université Libre de Bruxelles Vrije Universiteit Brussel Universiteit Gent Université de Mons-Hainaut

Germany: Universität Mainz DESY-Zeuthen Ruhr-Universität Bochum Universität Dortmund Universität Wuppertal Humboldt Universität Universität Bonn MPI Heidelberg RWTH Aachen Japan:

Chiba University

New Zealand: University of Canterbury

36 institutions, ~250 members http://icecube.wisc.edu

Barbados: University of the

West Indies

Switzerland: EPFL

The CollaborationThe Collaboration

Canada:University of Alberta

Questions?Questions?

1010

dE/dx ReferencesdE/dx References

Auchincloss, P.S., “A study of the energy dependence of the Auchincloss, P.S., “A study of the energy dependence of the mean, truncated mean, and most probable energy mean, truncated mean, and most probable energy deposition of high-energy muons in sampling calorimeters”, deposition of high-energy muons in sampling calorimeters”, Nucl. Instr. and Meth. in Phys. Res. A, 343 (1994) 463-469.Nucl. Instr. and Meth. in Phys. Res. A, 343 (1994) 463-469.

Cowen, Glen, “Ideas on Particle Identification Using Cowen, Glen, “Ideas on Particle Identification Using Ionization Energy Loss”, ALEPH 95-101, TPCGEN 95-001, Ionization Energy Loss”, ALEPH 95-101, TPCGEN 95-001, August 15, 1995 (Univ of Siegen).August 15, 1995 (Univ of Siegen).

Bichsel, Hans, “Particle Identification at Star-TPC with Bichsel, Hans, “Particle Identification at Star-TPC with Ionization Measurements”, Astroparticle, Particle and Space Ionization Measurements”, Astroparticle, Particle and Space Physics, Detectors And Medical Physics Applications, Sep Physics, Detectors And Medical Physics Applications, Sep 2003.2003.

Bichsel, Hans, “A Method to Improve Tracking and Particle Bichsel, Hans, “A Method to Improve Tracking and Particle Identification in TPCs and Silicon Detectors”, Nuclear Identification in TPCs and Silicon Detectors”, Nuclear Instruments and Methods in Physics Research A, 562 (2006) Instruments and Methods in Physics Research A, 562 (2006) 154–197.154–197.

1111

Neutrino ReferencesNeutrino References

Gaisser, T. et al, “Particle Astrophysics with High Energy Gaisser, T. et al, “Particle Astrophysics with High Energy Neutrinos”, Phys. Reports 258 (1995) 173-236.Neutrinos”, Phys. Reports 258 (1995) 173-236.

Gandhi, R. et al, “Ultrahigh-Energy Neutrino Gandhi, R. et al, “Ultrahigh-Energy Neutrino Interactions”, Astropartricle Physics 5 (1996) 81-110.Interactions”, Astropartricle Physics 5 (1996) 81-110.

Lipari, P., and Stanev, T., “Propagation of Multi-TeV Lipari, P., and Stanev, T., “Propagation of Multi-TeV Muons”, Phys. Rev. D v.44, n.11, 1 Dec 1991.Muons”, Phys. Rev. D v.44, n.11, 1 Dec 1991.

Gaisser, T., “Atmospheric Neutrino Fluxes”, arXiv:astro-Gaisser, T., “Atmospheric Neutrino Fluxes”, arXiv:astro-ph/05023801 v1, 18 Feb 2005.ph/05023801 v1, 18 Feb 2005.

Particle Data Group, "Plots of Cross Sections and Related Particle Data Group, "Plots of Cross Sections and Related Quantities", pdg.lbl.gov/2011/reviews/rpp2011-rev-cross-Quantities", pdg.lbl.gov/2011/reviews/rpp2011-rev-cross-section-plots.pdfsection-plots.pdf

Dziewonski, A., and Anderson, D., "Preliminary Reference Dziewonski, A., and Anderson, D., "Preliminary Reference Earth Model", Phys. Earth Planet. Inter. 25:297-356.Earth Model", Phys. Earth Planet. Inter. 25:297-356.

1212

The EndThe End

1313

Digital Optical ModulesDigital Optical Modules

25 cm PMT25 cm PMT 12 LED flashers for 12 LED flashers for

calibration calibration full digitized waveforms:full digitized waveforms:

Analogue Transient Analogue Transient Waveform Digitizer Waveform Digitizer (ATWD) (ATWD) 400 ns / 320 MHz 400 ns / 320 MHz samplingsamplingx 3 different gainsx 3 different gains

Fast ADCFast ADC6.4 6.4 μμs / 40 MHz s / 40 MHz samplingsampling

Neutrino x-section Neutrino x-section (PDG)(PDG)

(E < 350 GeV)(E < 350 GeV)

1515

Toy Model slideToy Model slide

1616

Gandhi 1996

Gaisser Halzen Stanev 1995

Gaisser Halzen Stanev 1995

X() = density * distance tot(E) ~ 0.96x10-35 * E0.80

dE/dx Energy MethoddE/dx Energy Method

Calculate the expected PE for each eventCalculate the expected PE for each event Compare to the actual PE for each eventCompare to the actual PE for each event

Use energy equation: dE/dx = A + B*E to get EUse energy equation: dE/dx = A + B*E to get E Roughly linear > 850 GeVRoughly linear > 850 GeV A = 0.931 x 0.25958 GeV/m (ionization)A = 0.931 x 0.25958 GeV/m (ionization) B = 0.931 x 3.5709e-4 /m (brem, pair, B = 0.931 x 3.5709e-4 /m (brem, pair,

nuclear)nuclear) Affected by large errors due to random PE Affected by large errors due to random PE

spikesspikes 1717

Total PE (actual)Total PE (actual)Total PE (expected)Total PE (expected)

= dE/dx (GeV/m)= dE/dx (GeV/m)

IceCube Energy MethodIceCube Energy Method

Muon energy reconstruction has sizeable Muon energy reconstruction has sizeable uncertainties due to large stochastic lossesuncertainties due to large stochastic losses

Distribution of energy losses (dE/dx) for Distribution of energy losses (dE/dx) for events has a long high-energy tailevents has a long high-energy tail

1818

N

um

ber

of

Even

ts

Calculated dE/dx (GeV/m)

The mean should be in here…

…but these events skew the mean

Typical 10 TeV Muon Typical 10 TeV Muon (simulation)(simulation)

Detector viewDetector view Plot of Plot of

photoelectrons (PE) photoelectrons (PE) per binper bin

High PE seen in bin High PE seen in bin 1 and bin 51 and bin 5

High PE bins skew High PE bins skew the average dE/dx the average dE/dx calculation, which is calculation, which is used for energy used for energy reconstructionreconstruction

1919

Truncated Mean MethodTruncated Mean Method Wire chamber and calorimeter studies of Wire chamber and calorimeter studies of

charged particles had a similar energy charged particles had a similar energy resolution problemresolution problem

Wires detected ionization energy at intervalsWires detected ionization energy at intervals The resolution improved by ~40% by omitting The resolution improved by ~40% by omitting

highest 30-50% of wire measurementshighest 30-50% of wire measurements Truncated MeanTruncated Mean

2020

Particle

Wires

X X X X

Truncated BinsTruncated Bins

Binning DOMs within cylinder 20-80m from trackBinning DOMs within cylinder 20-80m from track Minimum of 3 bins for event to qualifyMinimum of 3 bins for event to qualify Cut highest 10%, 20%, etc. of binsCut highest 10%, 20%, etc. of bins

Most precise cut at 40%Most precise cut at 40% Get new dE/dx values for simulated eventsGet new dE/dx values for simulated events Plot LOGPlot LOG1010 dE/dx vs. actual sim energy (center) dE/dx vs. actual sim energy (center) Determine new constants for energy equationDetermine new constants for energy equation Calculate the new energy for each eventCalculate the new energy for each event Works for all zenith angles (full detector)Works for all zenith angles (full detector)

2121

Progression of TruncationsProgression of Truncations10 TeV – 100 PeV10 TeV – 100 PeV

2222

LOGLOG1010 plots of dE/dx plots of dE/dx vs. MMC energyvs. MMC energy

Significant decrease Significant decrease in scatter with cuts in scatter with cuts

Lower energies also Lower energies also improvedimproved

20% bins cut0% bins cut

40% bins cut

Preliminary Preliminary

Preliminary