Geoneutrino overview
Download
1 / 30

Geoneutrino Overview - PowerPoint PPT Presentation


  • 192 Views
  • Uploaded on

Geoneutrino Overview. 1 . Review of Geoneutrino Physics (with KamLAND) 2 . KamLAND Result and Prospects 3 . Physics with Proposed Detectors. Sanshiro Enomoto KamLAND Collaboration RCNS, Tohoku University.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Geoneutrino Overview' - gabe


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Geoneutrino overview l.jpg
Geoneutrino Overview

1.Review of Geoneutrino Physics (with KamLAND)

2.KamLAND Result and Prospects

3.Physics with Proposed Detectors

Sanshiro Enomoto

KamLAND Collaboration

RCNS, Tohoku University

Neutrino Science 2007 – Deep Ocean Anti-Neutrino Observatory Workshop, Univ. of Hawaii at Manoa, March 23-25 2007


Geoneutrinos l.jpg
Geoneutrinos

  • Geoneutrinos are produced by

    • Direct measurement of HPE

    • U:~8TW, Th: ~8TW, K: ~3TW

  • Geoneutrinos are detected by

    • Two consecutive signals

    • Threshold 1.8 MeV

    • Not sensitive to 40K;other targets discussed [M.C.Chen (2005)]

Threshold: 1.8 MeV


Kamland the first detector sensitive to geoneutrinos l.jpg
KamLAND: The First Detector Sensitive to Geoneutrinos

Detector Center

Liquid Scintillator 1000 tonContained in plastic balloon

Surrounded by

17-inch PMT1325

20-inch 554

(PMT : Photo Multiplier Tube, a photo sensor)

Liquid Scintillator

20m

  • Yields light on ionization (8000 photons / MeV)

  • Mainly consists of only C and H


Kamland location l.jpg
KamLAND Location

Geological Setting

  • Boundary of Continent and Ocean

  • Island Arc (Orogenic)

  • ‘Hida’ Metamorphic Zone

  • Zn, Pb, limestone mine (skarn)

  • Surrounded by Gneiss Rocks

KamLAND

You are here

Sea of Japan

KamLAND

JapanTrench

KamLAND is surrounded bya number of nuclear reactors


First result from kamland l.jpg
First Result from KamLAND

[T. Araki et al. (2005)]

  • Fiducial Volume: 408 ton

  • Live-time: 749 days

  • Efficiency: 68.7%

  • Expected Geoneutrinos

  • U-Series: 14.9

  • Th-Series:4.0Backgrounds

  • Reactor: 82.3±7.2

  • (α,n) : 42.4±11.1

  • Accidental:2.38±0.01BG total: 127.4±13.3

  • Observed: 152

Number of Geoneutrinos:

25

+19

-18


A reference earth model to predict flux l.jpg
A Reference Earth Model to Predict Flux

  • BSE composition by [McDonough1999]

  • Crustal composition by [Rudnick et al. 1995]

  • Crustal thickness by CRUST 2.0

  • Uniform Mantle Model

  • No U/Th in the Core

  • Expected Geoneutrino Flux

  • U-Series

  • 2.3x106 [1/cm2/sec]

  • Th-Series

  • 2.0x106 [1/cm2/sec]

Geoneutrino Origination PointsDetectable at KamLAND (MC)

50% within 500km25% from Mantle

KamLAND

  • With 1032 target protons,

  • U-Series

  • 32 events / year

  • Th-Series

  • 8 events / year

Australia

Greenland

Total 19 is predictedfor KamLAND 749 days

Antarctic

South America


Uncertainties of the model l.jpg
Uncertainties of the Model

  • Geochemical / Geophysical datararely come with error estimation

  • Fiorentini et al. (2005)

    • Error is given as “spread in published estimates”

  • Fogli et al. (2006): GeoNeutrino Source Model (GNSM)

    • Correlations (reservoirs, elements) added

  • Enomoto et al. (2005)

    • Inversion framework discussed


Local geological effects l.jpg
Local Geological Effects

  • ~50% of flux comes within ~500km radius

  • ~25% within ~50km

  • Characteristic U/Th depletion in Japan Arc[Togashi et al. (2000)]

    • U: -17%, Th: 22% ⇒ affects total flux at 6.4% (U) and 8.4% (Th)

  • Surface heterogeneity[Enomoto et al. (2005)]

    • 20% flux variation possible ⇒ 3.2% uncertainty in total flux

  • Vertical heterogeneity ???

~500km


Other source of uncertainties l.jpg
Other Source of Uncertainties

  • Crustal Thickness Map Resolution (2×2 deg)

    • 3~4% Total Flux Uncertainty

  • Neutrino Oscillation Parameter (sin22θ=0.82±0.07)

    • 6% Flux Uncertainty

Comparison of CRUST 2.0 and Zhao et al.

CRUST2.0

Propagation of crustal thickness error

Zhao et al. (1992)


Summary of total flux uncertainties l.jpg
Summary of Total Flux Uncertainties

  • Global Modeling (not uncertainty; our interest)

    • BSE comopsition: ~20%

    • Mantle models (uniform / layered): <3%

  • Local Geological Effects

    • Island Arc Characteristics: 6-8%

    • Surface Geology Heterogeneity: 3.2%

    • Vertical Heterogeneity: ???

  • Other Uncertainties

    • Crustal Thickness Map Resolution: 3~4%

    • Neutrino Oscillation Parameter: 6%


Flux prediction from earth models l.jpg
Flux Prediction from Earth Models

Scale Bulk Composition

Geoneutrino Flux [1/cm2/sec]

Fix Crustal Composition,

Parameterize Mantle

U+Th Mass[kg]


Kamland result l.jpg
KamLAND Result

[T. Araki et al. (2005)]

  • Fiducial Volume: 408 ton

  • Live-time: 749 days

  • Efficiency: 68.7%

  • Expected Geoneutrinos

  • U-Series: 14.9

  • Th-Series:4.0Backgrounds

  • Reactor: 82.3±7.2

  • (α,n) : 42.4±11.1

  • Accidental:2.38±0.01BG total: 127.4±13.3

  • Observed: 152

Number of Geoneutrinos:

25

+19

-18


Kamland spectrum analysis l.jpg
KamLAND Spectrum Analysis

Parameters NU, NTh: Number of Geoneutrinos sin22θ, Δm2 : Neutrino Oscillation α1, α2: Backgrounds Uncertainties

Total Number of U and Th

  • KamLAND is insensitive to U/Th ratio→ adopt U/Th ~ 3.9from Earth science

  • Number of Geoneutrinos:28.0

  • 99% C.L. upper limit:70.7 events

  • Significance 95.3% (1.99-sigmas)

+15.6

-14.6

Discrimination of U and Th


Comparison with earth model predictions l.jpg
Comparison with Earth Model Predictions

KamLAND 99% Limit

Geoneutrino Flux [1/cm2/sec]

KamLAND 1-σ Range

Earth Model Prediction

U+Th Mass[kg]

  • Consistent with BSE model predictions

  • 99%C.L. upper limit too large to be converted to heat production (No Earth models applicable)


Kamland problem l.jpg
KamLAND Problem

(α,n) BG

Reactor

Neutrino

BG

210Pb

222Rn

22.3 y

3.8 d

n + p → n + p

13C (α,n) 16O

210Bi

210Po

206Pb

Cross-section error: 20%

5.013 d

138.4 d

stable

Quenting factor error: 10%

210Po decay rate error 14%


Kamland prospects 1 l.jpg

New (α,n) Cross section data available

Vertex reconstruction algorithm improved

Proton quenching factor measurement

210Po-C source calibration performed⇒ (α,n) error reduced from ~26% to ~5%

KamLAND Prospects (1)

(α,n) Background error had been reduced

P quenching measurement

Po-C Calibration (MC/Data)


Kamland prospects 2 l.jpg
KamLAND Prospects (2)

LS Distillation in Progress⇒ removes radioactivity by 10-5

we remove these

BEFORE

AFTER

Another 749 days operation after purification,

  • Error is reduced:from 54% to 28% (error is dominated by reactor neutrinos)

  • Significance: 99.96%


Kamland prospects l.jpg
KamLAND Prospects

Upper limit (~40TW)comparable withheat flow(~40TW)

28% uncertainty



The world map of geoneutrino flux l.jpg
The World Map of Geoneutrino Flux

Typical Rate

from Crust

30~70 /1032P/year

from Mantle

~10 /1032P/year


Reactor neutrino backgrounds l.jpg
Reactor Neutrino Backgrounds

KamLAND-II 750 days

(expected)

without reactor BG



Geoneutrino flux @ future detector sites l.jpg
Geoneutrino Flux @ Future Detector Sites

KamLAND

SNO+

Hanohano

Borexino

LENA


Required exposure for 20 precision determination l.jpg
Required Exposure for 20% precision determination

Typical Time

on CC, estimate BSE

0.5~1 [1032P・year]

on CC, estimate M

~30[1032P・year]

on OC, estimate M

4.5 [1032P・year]

Sensitive to

Crustal Composition

Sensitive to

Mantle Composition

Worst Place


Sensitivity to regional structure l.jpg
Sensitivity to “Regional” Structure

Gran Sasso / Mesozoic Crust

Kamioka / Island Arc

Hawaii / Oceanic Island

Sudbury / Archean Crust

  • We have to discriminate the global and regional signature

  • Correlation matrix used by GNSM (Fogli et al (2006)) could be extended ??

  • if correlation coefficients among different crustal types are given.


Plumes ocean ridges l.jpg
Plumes, Ocean Ridges,

Neutrino Detector on Plume

At Tahiti, 13% comes from “hot” mantle⇒ sensitive to a factor enrichment

Neutrino Detector on

Mid-Ocean Ridge

If the mantle beneath mid-ocean ridge

Is depleted by a factor, it should be visible

Portable detector (like Hanohano)will open new application


Summary l.jpg
Summary

  • Geoneutrino provides a direct measurement of heat producing elements (HPE)

  • KamLAND measurement will be improved

    • Reduced systematic error for existing data

    • Radioactive BG reduction by LS distillation

  • Multiple site measurement is important

    • Reduction of local geological effects

    • Separation of mantle and core

    • Sensitivity to regional characteristics

    • No nuclear reactor BG

  • Wish List

    • Error estimations for U/Th content in each reservoir

    • Better resolution crustal map


Backup slides l.jpg

Backup Slides

Appendix