From movie Ice Age 4
continental drift
Group 2:
The Earth’s core Radius
Yao Li
Matthew Lawe
Amerndra Narayan
Yue Meng
Question 23:
Design an experiment that uses solar neutrinos to
determine the radius of the Earth’s core.
Approach to this question
1. Neutrino oscillation
2. Matter effect
3. Earth regeneration
Assumption:
1. Sun is large enough and neutrinos trajectory are parallel
2. Density of the core
3. Earth orbit is not changed
4. Earth density for each layer is uniform
2
Continental Crust: 2.7 to 3.0
Oceanic Crust:
3.0 to 3.3
Mantle (silicates): 3.3 to 5.7
Outer Core (liquid): 9.9 to 12.2
Inner Core (solid): 12.6 to 13.0
For this work we consider the
Earth’s inner and outer core
together and assume a constant
density of 12 gr/cm3
From http://k2.sci.u-toyama.ac.jp/yitp-g03/OHP/takamura.pdf
3
Matter oscillations of two neutrinos:
arXiv:hep-ph/0606054v2
E= 15.6MeV
This corresponds to the maximum probability of
oscillation into electron neutrino.
4
Solar neutrino energy spectrum
This energy range neutrino is what we
want to detect
5
One Day
Solar electron neutrino
day
night
One Year
Detector is sitting
in equatorial
location
e.g Indonesia
From Wikipedia
6
We count the neutrinos in our detector, and plot the
counter versus path distance or angle.
7
6 as factor for effective mass
Enhance the Oscillation
8
Cherenkov
Detector
Ref: http://www-sk.icrr.u-tokyo.ac.jp/sk/detector/howtodetect-e.html
•  20ton superK detector *10
•  Night time 12hours/day
•  Effective night time (neutrino pass through earth core): 4.4 hours/
day
•  SuperK 14 events/day
•  Estimate our detector event rate: 2.2 events/per/detector
•  We need 1 year to get 10000 events to calculate the earth core
radius
9
Thanks!~
10
Backup Slides
11
Cosmic ray background: shield+ veto
Real radius for the earth core roughly 3500km
12
Day/Night effect:
Ref: arXiv:hep-ex/0310064
13