Measuring q 13 with Reactors Stuart Freedman University of California at Berkeley SLAC Seminar September 29, 2003. q 13. How to Weigh Dumbo’s Magic Feather. I am going to argue that 
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Measuring q13 with Reactors
Stuart Freedman
University of California at Berkeley
SLAC Seminar September 29, 2003
q13
How to Weigh Dumbo’s Magic Feather
I am going to argue that 
the fastest and cheapest way to determine the value of Sin22q13 is to measure two big things and subtract the results.

=
What do we know and how do we know it
Slide Courtesy of B. Kayser
decay pipe
detector
p
target
horn
+
+
+
e
e
e
Measuring13Accelerator Experiments
• appearance experiment
• measurement of e and e yields 13,CP
• baseline O(100 1000 km), matter effects present
Reactor Neutrino Oscillation Experiment
• disappearance experiment
• but: observation of oscillation signature with 2 or multiple detectors
• look for deviations from 1/r2
• baseline O(1 km), no matter effects
Minakata and Nunokawa, hepph/0108085
235U fission
Neutrino Spectra from Principal Reactor Isotopes
q13 at a US nuclear power plant?
Site Requirements
• powerful reactors
• overburden
• controlled access
scintillator e detectors
e + p e+ + n
coincidence signal
prompt e+ annihilation
delayed n capture (in s)
e,,
~ 1.52.5km
e
< 1 km
• disappearance experiment
• look for rate deviations from 1/r2 and spectral distortions
• observation of oscillation signature with 2 or multiple detectors
• baseline O(1 km), no matter effects
~250,000
~60,000
~10,000
Statistical error: stat ~ 0.5%for L = 300tyr
Statistical Precision Dominated by the Far Detector
IIIa
Ge
Geology
II
I
muon veto
acrylic vessel
5 m
liquid scintillator
buffer oil
1.6 m
passive shield
Variable baseline to control systematics and demonstrate oscillations (if 13 > 0)
10
5 m
Movable Detectors
12 km
~12 m
• Modular, movable detectors
• Volume scalable
• Vfiducial ~ 50100 t/detector
 7 nuclear reactors, World’s largest power station
far
near
near
KashiwazakiKariwa
Nuclear Power Station
far
near
near
70 m
70 m
200300 m
6 m shaft hole, 200300 m depth
~1.5 x 106 ev/year
Kr2Det: Reactor 13 Experiment at KrasnoyarskFeatures
 underground reactor
 existing infrastructure
Detector locations constrained by existing infrastructure
Reactor
Ref: Marteyamov et al, hepex/0211070
%
Total LS mass 2.1
Fiducial mass ratio 4.1
Energy threshold 2.1
Tagging efficiency 2.1
Live time 0.07
Reactor power 2.0
Fuel composition 1.0
Time lag 0.28
e spectra 2.5
Cross section 0.2
Total uncertainty 6.4 %
E > 2.6 MeV
flux < 0.2%
rel eff ≤ 1%
target ~ 0.3%
acc < 0.5%
nbkgd< 1%
SystematicsBest experiment to date: CHOOZ
Ref: Apollonio et al., hepex/0301017
Reactor Flux • near/far ratio, choice of detector location
Detector Efficiency • built near and far detector of same design • calibrate relative detector efficiency variable baseline may be necessary
Target Volume & • well defined fiducial volume
Backgrounds • external active and passive shielding for correlated backgrounds
Total syst ~ 11.5%
LBNL
‘nearfar’ L1 = 1 km
L2 = 3 km
‘farfar’ L1=6 km
L2=7.8 km
MC StudiesNormalization:
10k events at 10km
Oscillation Parameters:
sin2213 = 0.14
m2= 2.5 x 103 eV2
Sensitivity to sin2213at 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., hepph/0303232
ReactorI: limit depends on norm (flux normalization)
ReactorII: limit essentially independent of norm
statistical error only
Upper limits correspond to 90% C.L.