Measuring q13 with Reactors

1
Measuring q13 with Reactors Stuart
Freedman University of California at
Berkeley SLAC Seminar September 29, 2003
2
How to Weigh Dumbos 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.
-

3
Neutrino LANDscape
4
Constraints from most recent Experiments
5
UMNSP Matrix
?12 30
?23 45
tan2 ?13 lt 0.03 at 90 CL
Mass Hierarchy
6
What do we know and how do we know it
Slide Courtesy of B. Kayser
7
Is it important to measure q13?
8
L. Wofenstein
B. Kayser
S. Bilenky
S. Glashow
A Smirnov
Testimonials
9
Measuring ?13
Accelerator 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
10
(No Transcript)
11
Figuring out CP for leptons
Minakata and Nunokawa, hep-ph/0108085
12
Basic Idea for a Disappearance Experiment
?
13
Experimental Design
14
First Direct Detection of the Neutrino
n
m
Reines and Cowan 1956
15
Inverse Beta Decay Cross Section and Spectrum
16
Neutrino Spectra from Principal Reactor Isotopes
17
20 m
KamLAND
4 m
Chooz
1m
Long Baseline Reactor Neutrino Experiments
Poltergeist
18
CHOOZ
19
CHOOZ
20
KamLAND
21
KamLAND
22
Inverse Beta Decay Signal from KamLAND
from 12C(n, g )
tcap 188 /- 23 msec
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
q13 at a US nuclear power plant?
Site Requirements powerful reactors
overburden controlled access
28
Diablo Canyon Power Station
29
No degeneracies No matter effects
Practically no correlations E? Ee
mn-mp Eprompt Ekin 2me
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
30
Overburden Essential for Reducing Cosmic Ray
Backgrounds
31
Statistical Precision Dominated by the Far
Detector
32
Diablo Canyon Variable Baseline
2 or 3 detectors in 1-1.5 km tunnel
33
IIIb
IIIa
Ge
Geology
II
I

• Issues
• folding may have damaged rock matrix
• - steep topography causes landslide risk
• tunnel orientation and key block failure
• seismic hazards and hydrology

34
Detector Concept
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 gt 0)
35
Movable Detectors
1-2 km
12 m
Modular, movable detectors Volume scalable
Vfiducial 50-100 t/detector
36
Kashiwazaki ?13 Experiment in Japan
- 7 nuclear reactors, Worlds largest power
station
far
near
near
Kashiwazaki-Kariwa Nuclear Power Station
37
Kashiwazaki Proposal for Reactor ?13 Experiment
in Japan
far
near
near
70 m
70 m
200-300 m
6 m shaft hole, 200-300 m depth
38
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
39
Systematic Uncertainties
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 gt 2.6 MeV
40
Systematics
Best experiment to date CHOOZ
Ref Apollonio et al., hep-ex/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 1-1.5
41
MC Studies
Optimization at LBNL
near-far L1 1 km L2 3 km
far-far L16 km L27.8 km
Normalization 10k events at 10km
Oscillation Parameters sin22?13 0.14 ?m2 2.5
x 10-3 eV2
42
(No Transcript)
43
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
44
Ref Huber et al., hep-ph/0303232
statistics
Statistics Systematics Correlations Degeneracies
45
Expected Constraints on ?13
Upper limits correspond to 90 C.L.
46
(No Transcript)