Measuring q 13 with Reactors

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Measuring q 13 with Reactors Stuart
Freedman HEPAP July 24, 2003 Bethesda
d2
d1
Detector 1
Detector 2
Reactor
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MNSP Matrix
?12 30
?23 45
tan2 ?13 lt 0.03 at 90 CL
Mass Hierarchy
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Figuring out CP for leptons
Minakata and Nunokawa, hep-ph/0108085
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The Basic Idea
Pee, (4 MeV)
?e flux
?
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First Direct Detection of the Neutrino
n
m
Reines and Cowan 1956
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Neutrino Spectra from Principal Reactor Isotopes
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Inverse Beta Decay Cross Section and Spectrum
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Inverse Beta Decay Signal from KamLAND
from 12C(n, g )
tcap 188 /- 23 msec
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20 m
KamLAND
4 m
Chooz
1m
Long Baseline Reactor Neutrino Experiments
Poltergeist
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CHOOZ
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CHOOZ
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KamLAND
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Two Detector Reactor Experiment
Spectral Ratio
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Sensitivity to sin22?13 at 90 CL
?cal relative near/far energy calibration
?norm relative near/far flux normalization
Reactor I 12 t, 7 GWth, 5 yrs
Reactor II 250 t, 7 GWth, 5 yrs
Chooz 5 t, 8.4 GWth, 1.5 yrs
fit to spectral shape
Ref Huber et al., hep-ph/0303232
Reactor-I limit depends on ?norm (flux
normalization) Reactor-II limit essentially
independent of ?norm
statistical error only
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We need accelerators and reactors--Reactors first!
Reactor Neutrino Measurement of ?13 No matter
effect Correlations are small, no
degeneracies Independent of solar parameters
?12, ?m212
Sensitivity to sin22?13
Ref Huber et al., hep-ph/0303232
sin22?13 lt 0.01-0.02 _at_ 90 CL within reach of
reactor ?13 experiments Knowing ?13 is useful
for the intelligent design of a CP
experiments.
10-3
10-2
10-1
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Huber et al hep-ph/03030232
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Kr2Det Reactor ?13 Experiment at Krasnoyarsk
Features - underground reactor - existing
infrastructure
Detector locations constrained by existing
infrastructure
Reactor
Ref Marteyamov et al, hep-ex/0211070
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Kr2Det Reactor ?13 Experiment at Krasnoyarsk
Energy (MeV)
Ref Marteyamov et al., hep-ex/0211070.
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Proposal for Reactor ?13 Experiment in Japan
Kashiwazaki -7 nuclear power stations, Worlds
most powerful reactors - requires
construction of underground shaft for detectors
far
near
near
Kashiwazaki-Kariwa Nuclear Power Station
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Kashiwazaki Proposal for Reactor ?13 Experiment
in Japan
far
near
near
70 m
70 m
200-300 m
6 m shaft, 200-300 m depth
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q13 at a US nuclear power plant?
Site Requirements powerful reactors
overburden controlled access
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Berkeley 230 miles
Pasadena 200 miles
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Diablo Canyon Nuclear Power Plant
1500 ft
Powerful Two reactors (3.1 3.1 GW Eth)
Overburden Horizontal tunnel could give 800 mwe
shielding Infrastructure Construction roads.
Controlled access. Close to wineries.
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Detector Concept
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Requirements Overburden and Large Detectors
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Neutrino Detectors at Diablo Canyon
2 neutrino detectors, railroad-car size in
tunnels at (variable) distance of NEAR/FAR I
0.5-1 km FAR II 1.5-3 km
Possible location Crowbar Canyon Parallel to
Diablo Canyon Existing road access Possibility
for good overburden Tunnels in radial direction
from reactor
Crowbar Canyon parallel to Diablo Canyon
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MC Studies
Optimization
far-far L16 km L27.8 km
near-far L1 1 km L2 3 km
Oscillation Parameters sin22?13 0.14 ?m2 2.5
x 10-3 eV2
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Timescale and Size of a ?13 Reactor Project
Moderate Scale ( lt 50M ) Medium-size,
low-energy experiment Little RD necessary
(KamLAND, SNO, CHOOZ) Construction time
2-3 yrs Start in 2007/2008?
The Particle Physics Roadmap (in the US)
2000
2005
2010
?m223, ?23
?CP
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Conclusions

• Top priorities in neutrino physics include
  pinning down
• MNS matrix elements and discovering CP
  violation.

We will need a number of experiments to resolve
ambiguities from matter effects and
correlations.
Reactor experiments and accelerator experiments
are complementary.
Reactor experiments have the potential of being
faster, cheaper and better for establishing the
value of q13.
Executing a reactor experiment at an
appropriate site should be put on a fast track.
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