Recent Results from KamLAND

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Recent Results from KamLAND

• R. D. McKeown
• Caltech

BNL January 17, 2006
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Outline

• Historical Introduction
• Neutrino physics
• Neutrino mixing and oscillations
• KamLAND reactor neutrino results
• Geoneutrinos
• Future prospects

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Discovery of the Neutrino 1956
F. Reines, Nobel Lecture, 1995
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Subsequent History

• 60s and 70s n became the darling of
  accelerator-based particle physics
• ne ? nm
• 1968 1st solar n anomaly evidence
• 1980s new interest in neutrino oscillations
  (F. Reines, ..)
• 1980-present the quest for neutrino oscillations
• 1998 evidence from Super-K

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Super-Kamiokande Results
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Two Generation Model
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Missing solar neutrinos
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Matter Enhanced Oscillation (MSW)
Mikheyev, Smirnov, Wolfenstein
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Maki Nakagawa Sakata Matrix
CP violation
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Pre KamLAND summary

• Persistent observations of deficit of solar
  neutrinos
• 1998 observation of oscillations of atmospheric
  neutrinos by Super-K
• 2002 SNO results imply matter-dependent
  oscillations of solar neutrinos

Time to get our feet on the ground!!
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W.A. Fowler Nobel Lecture, 1983
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Enter

• Long Baseline (180 km)
• Calibrated source(s)
• Large detector (1 kton)
• Deep underground (2700 mwe)

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Neutrino Oscillation Studies with Nuclear
Reactors

• ne from n-rich fission products
• detection via inverse beta decay (nepgen)
• Measure flux and energy spectrum
• Improve detectors, reduce background
• Variety of distances L 10-1000 m

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Detection Signal

• Coincidence signal detect
• Prompt e annihilation g
  EnEpromptEn0.8 MeV
• Delayed n capture 180 ms capture time

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The Reactor Neutrino Flux and Spectrum

• 235U, 239Pu, 241Pu from b measurements
• 238U calculated
• Time dependence due to fuel cycle

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Precise Measurements
Flux and Energy Spectrum g 1-2
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Negative Oscillation Searches
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Distance (m)
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The BIG picture
(From PDG)
SK atm (nmgnt)
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KamLAND uses the entire Japanese nuclear
power industry as a longbaseline source
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Many reactors contribute to the antineutrino flux
at KamLAND
Site Site Dist (km) Cores () Ptherm (GW) Flux (cm-2 s-1) Rate noosc (yr-1 kt-1)
Japan Kashiwazaki 160 7 24.3 4.1105 254.0
Japan Ohi 179 4 13.7 1.9105 114.3
Japan Takahama 191 4 10.2 1.2105 74.3
Japan Tsuruga 138 2 4.5 1.0105 62.5
Japan Hamaoka 214 4 10.6 1.0105 62.0
Japan Mihama 146 3 4.9 1.0105 62.0
Japan Sika 88 1 1.6 9.0104 55.2
Japan Fukushima1 349 6 14.2 5.1104 31.1
Japan Fukushima2 345 4 13.2 4.8104 29.5
Japan Tokai2 295 1 3.3 1.6104 10.1
Japan Onagawa 431 3 6.5 1.5104 9.3
Japan Simane 401 2 3.8 1.0104 6.3
Japan Ikata 561 3 6.0 8.3103 5.1
Japan Genkai 755 4 10.1 7.8103 4.8
Japan Sendai 830 2 5.3 3.4103 2.1
Japan Tomari 783 2 3.3 2.3103 1.4
South Korea Ulchin 712 4 11.5 9.9103 6.1
South Korea Yonggwang 986 6 17.4 7.8103 4.8
South Korea Kori 735 4 9.2 7.5103 4.6
South Korea Wolsong 709 4 8.2 7.1103 4.3
Total Nominal Total Nominal - 70 181.7 1.3106 803.8
E?gt3.4MeV (Epromptgt2.6MeV)
Detailed power and fuel Composition calculation
used
From electrical power Japanese average fuel used
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A limited range of baselines contribute to the
flux of reactor antineutrinos at Kamioka
Korean reactors 3.40.3 Rest of the world JP
research reactors 1.10.5 Japanese spent
fuel 0.040.02
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Spectrum Distortion
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Front End Electronics
Waveforms are recorded using Analog Transient
Waveform Digitizers (ATWDs), allowing multi p.e.
resolution
Blue raw data red pedestal green pedestal
subtracted

• The ATWDs are self launching with a threshold
  1/3 p.e.
• Each PMT is connected to 2 ATWDs, reducing
  deadtime
• Each ATWD has 3 gains (20, 4, 0.5), allowing a
  dynamic range of 1mV to 1V

ADC counts (120 mV)
Samples (1.5ns)
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The KamLAND Collaboration
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KamLANDtimeline

• Summer 2000 PMT installation
• Jun-Sept 2001 Fill Liquid Scintillator
• Jan, 2002 Begin Data Taking
• Dec, 2002 Report 1st
  Physics Results
• Jun 2004 Report 2nd Reactor ? Results
• Sept 2005 Report geoneutrino evidence

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DE/E 6.2 /vE , Light Yield 300p.e./MeV
DEsyst 2.0 at 2.6 MeV
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Tagged cosmogenics can be used for calibration
t29.1ms Q13.4MeV
12B
12N
t15.9ms Q17.3MeV
µ
Fit to data shows that 12B12N 1001
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Energy calibration uses discrete ? and 12B/12N
n-p
n-12C
68Ge
60Co
65Zn
Carefully include Birks law, Cherenkov and light
absorption/optics to obtain constants for ? and
etype depositions
s/E 6.2 at 1MeV
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Vertexing is performed using timing from the 17
PMTs
-60 (2.6MeV)
Am/Be(8MeV)
-65 (1.1MeV)
-68 (1.0MeV)
z
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Fraction of volume inside the fiducial radius
verified using µ-produced 12B/12N and n (assumed
uniform)
12B/12N
neutrons
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Estimate of total volume and fiducial fraction
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Singles Background
SourceMeasuredPredicted
14C?
210Pb 102Hz--
High Energy (e.g. µ) 0.33Hz0.33Hz
85Kr 606 Hz--
40K1.9Hz2.1Hz
208Tl 3.2Hz1.4Hz
232Th, cosmogenic 0.19Hz
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Selecting antineutrinos, Epromptgt2.6MeV
5.5 m fiducial cut

• - Rprompt, delayed lt 5.5 m
• - ?Re-n lt 2 m
• - 0.5 µs lt ?Te-n lt 1 ms
• 1.8 MeV lt Edelayed lt 2.6 MeV
• 2.6 MeV lt Eprompt lt 8.5 MeV
• Tagging efficiency 89.8

(543.7 ton)
Balloon edge

• In addition
• 2s veto for showering/bad µ
• 2s veto in a R 3m tube along track
• Dead-time 9.7

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Observed Event Rates
2002-4 dataset 766.3 tonyr, Eprompt
gt 2.6 MeV Observed 258
events No-oscillation 365.2 23.7
events Background 17.6 7.2 events
accidental 2.69 0.02 9Li/8He (b, n) 4.8
0.9 fast neutron lt 0.89 13C(a,n) 10.0
7.1
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Evidence for Reactor ne Disappearance!!
99.998 C.L.
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Systematic
Scintillator volume 2.1
Fiducial fraction 4.2
Energy threshold 2.3
Cuts efficiency 1.6
Live time 0.06
Reactor Pthermal 2.1
Fuel composition 1.0
Time lag 0.01
Antineutrino spectrum 2.5
Antineutrino x-section 0.2
Total 6.5
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Ratio of Measured and Expected ne Flux from
Reactor Neutrino Experiments
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Oscillation Effect
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Correlation with reactor power variation
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KamLAND best fit Dm2 7.9 x 10-5 eV2 tan2q
0.45
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Combined fit with solar neutrino data
Dm27.90.6-0.5x10-5 eV2 tan2q0.400.10-0.07
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Solar Neutrino Results
Open circles combined best fit Closed circles
experimental data
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Geoneutrinos the early history
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More recent references
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Geoneutrinos

• U/Th/K in crust/mantle
• - amount of activity
• - distribution
• Energy budget heat generation
• - plate tectonics
• - magnetic field
• Structure of earths core
• - constrain models
• - georeactor?

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Inside the Earth
Region Thickness (km )
Continental crust 38 (20 70)
Oceanic crust 6-8
Upper Mantle 600
Lower Mantle 2300
Core 3500
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U/Th Distribution
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Geoneutrino spectrum
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The predicted sources of geoneutrinos
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KamLAND Data
13C(a,n)
Reactor n
Randoms
U
Th
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Confidence Intervals
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The press was interesting
Hindustan Times, August 8, 2005
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And finally
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KamLAND Future

• Precision Reactor Neutrino Measurements
• - 4p calibration system
• - refine analysis methods
• - more statistics
• Supernova detection
• Precision Solar Neutrino Measurements
• - radiopurity
• - low energy threshold
• More precise geoneutrino measurement

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Neutrino-proton elastic scattering
??, ?? ,??, ??
?e
?e
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