Reactor Neutrino Measurement of 13

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Reactor Neutrino Measurement of ?13
Concept for a Novel Reactor Neutrino Oscillation
Experiment
What is novel? 2-3 detectors variable
baseline independent of absolute reactor
flux
Karsten M. Heeger for the LBNL ?13
Group Lawrence Berkeley National Laboratory
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?13 and CP Violation
Neutrino Mixing Matrix
Non-accelerator experiments have determined our
present knowledge of UMNS
solar ? present
0??? experiments future
atmospheric ? present
reactor and accelerator ? future
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Reactor Neutrino Measurement of ?13 - Basic Idea
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Reactor Neutrino Measurement of ?13
Searching for Subdominant Oscillations in ?e ?
??,?
?13 oscillation signature
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Baseline Optimization
Some numbers as guidelines Oscillation maximum
at 1.7 km From ?2 comparison of near and far
spectra Near 1 km (fixed) Far 2.6
km Constraints Reactor sites may force near
detector out of inner reactor area (R lt 0.5
m) Existing infrastructure or underground
sites Note Optimized detector baselines most
sensitive to ?matm2. May need to re-optimized
once we have precision measurements. Region of
interest for current ?matm2 region 1.5 - 3 km
Ref Huber et al. hep-ph/0303232
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MC Studies
far-far L16 km L27.8 km
near-far L1 1 km L2 2.5 km
Optimize baseline for a measurement of an
oscillation signal Goal to observe oscillatory
signal
Normalization 10k events at 10 km
Oscillation Parameters sin22?13 0.14 ?m2 2.5
x 10-3 eV2
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A ?13 Reactor Experiment in the US ?

• Site Requirements
• 1. A reactor, or multiple-reactor complex
• 2. Sites for 2-3 detectors at distances of 1-3 km
  from reactor
• 3. Detector overburden for reduction of cosmic
  ray background
• Man-made overburden or (too shallow)
• Underground site in a mine
• Underground site in tunnels
• 4. Movable detector for systematic control
• and demonstration of oscillation effect

Movable detectors?
Does a site like this exist?
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Criteria for Site Selection
? Site selection critical to experimental design
and success of ?13 experiment. ? Detailed
optimization once feasible site has been
selected. Some important aspects -
overburden (gt 300 mwe) - optimized detector
placement - variable baseline for optimization
to ?m2atm and to demonstrate subdominant
oscillation effect (if ?13 gt 0 measured) -
access to site - cost for infrastructure and
detector halls
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Diablo Canyon - An Ideal Site?
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Location and Access
50 min flight from SFO 3.5 hrs by car
1/2 hr
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Diablo Canyon Site
1500 ft
600 ft
Powerful Two reactors (3.13.1 GW Eth) on the
California coast Overburden Horizontal tunnel
could give 800 mwe shielding. Infrastructure
Roads built for heavy machinery. Controlled
access. Scientific Collaborations existing
collaborations between PGE and marine
scientists, biologists, and geologists with site
access.
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Reactor Operations

• - Refueling cycle every 18-21 months
• Average livetime 75-80
• - Combined power of DC III 6 GWth

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South Gate Access
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Access Road
4 ft-thick concrete road
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Diablo Canyon
From South East
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Diablo Canyon
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Facilities at Diablo Canyon
100 m
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Facilities at Diablo Canyon
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Restricted Areas at Diablo Canyon
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Possible Locations for Near Detector
Space constrained by hills and infrastructure
Best overburden to the North East of the
powerplant
Distances of near detector gt 0.4 km
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Far Detector
Possible location Crowbar Canyon Parallel to
Diablo Canyon Existing road access Possibility
for good overburden Tunnels in radial direction
from reactor
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An Ideal Oscillation Experiment with Variable
Baseline? Possible layout of 2 or 3 detectors
at Diablo Canyon
FAR II distance 2-2.5 km
FAR I distance 1.5-2 km
tunnels
NEAR distance 0.5 km
600-800 mwe
Reactor separation 100 m
400 mwe
Tunnel excavation required ? further studies
necessary
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Overburden of Far Detectors
tunnel length 50 m for 600 mwe overburden
tunnel length 100 m for 800 mwe overburden
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Alternative Detector/Tunnel Locations
Overburden profile of peaks south of powerplant
(Mt Diablo, Green Peak) not ideal May
interfere with restricted areas and dry storage
waste site
tunnel length 200 m for 300 mwe overburden
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Overburden and Muon Flux
From Chooz Background rate 0.2 events/t/day at
300 mwe
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Geology
cross-section
Bedrock around and south to the
powerplant Detailed geologic information on DC
available
Diablo Canyon
sedimentary bedrock
cross-section
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Excavation of Horizontal Tunnels
The Alpine Tunnel Miner
purchase cost 0.5M ATM is reusable, can be
rented tunnel excavation cost 5-10k/m
Excavation speed 5-10 m/day
5-10M for 1 km long tunnel
Note Restoration of old gold-mine tunnels as
costly, and they are public land.
ATM at Yucca Mountain
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Seismicity
Hosgri fault zone in Pacific near Diablo
Canyon Length 140 km
- Experience with magnitude 3-3.5 rockbursts at
SNO - Instantaneous event bursts (flashing PMTs)
but no long-term damage
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Schematic of Movable Detector
Modular, movable liquid scintillator detector
to control systematics active muon veto
Vfiducial 60-100 t
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Calibration I
SNO-like, low-background pulley system
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Calibration II
Optimize detector design for multiple access
ports Integrated calibration system for control
of fiducial volume and energy scale systematics
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Detector and Shielding Concept
I. Movable, inner liquid scintillator
detector II. Possibly fixed passive shielding and
active muon veto ? may need halls at different
distances beyond tunnel to accommodate
shielding

muon veto
water shielding
muon veto
iron
Gd paint
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Event Statistics
Number of Events in Detector assuming CHOOZ
efficiency
Statistical Error
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Costs
I. Cost of infrastructure Purification, control
room etc II. Cost of excavation 1 km tunnel 6 m
wide 7-12M III. Cost of detectors 5-100 t
(near and far) detectors 3-15M/detector III.
Cost of shielding muon veto passive shielding

Including excavation of tunnel, cost of
experiment lt 50M Phased approach possible as
horizontal tunnels can be used to accommodate
additional detectors.
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And most importantly ...
A Southern rock band .
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Reactor Measurement of ?13 at Diablo Canyon?
Site selection critical to experimental design
and success of ?13 experiment. Detailed
optimization of detectors once suitable site has
been found. Diablo Canyon is a versatile site
with several possible configurations -
overburden (gt 300 mwe) - variable baseline for
optimization to ?m2atm and to demonstrate
subdominant oscillation effect (if ?13 gt 0
measured) - near and far detectors of identical
design for systematic control Established
dialogue with PGE to explore possibility of
partnership for scientific work at Diablo Canyon.
Interest from a number of UC institutions and
LLNL. Receiving LBNL support and funding for
site evaluation and exploratory studies.
http//kmheeger.lbl.gov/theta13/
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Next Workshop
May know more about the possibility of using this
experimental site in a few weeks or
months Topics Detector RD, detector
concepts Design and optimization of
experiment Date in about 3 months
(beginning of August) possibly before or after
TAUP2003 in Seattle? Offer to host next
workshop in Berkeley. Will discuss with
organizers.
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Sensitivity and Complementarity of ?13 Experiments
Reactor ?13 experiment No matter
effect Correlations are small, no
degeneracies Independent of solar osc. parameters
?12,?m212
Sensitivity to sin22?13
Ref Huber et al., hep-ph/0303232
10-3
10-1
10-2
?13 sensitivity of reactor experiments comparable
to JHF-SK