Upload
hollie
View
36
Download
0
Embed Size (px)
DESCRIPTION
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 -- - PowerPoint PPT Presentation
Citation preview
Measuring 13 with ReactorsStuart Freedman
University of California at Berkeley
SLAC Seminar September 29, 2003
I am going to argue that --
the fastest and cheapest way to determine the value of Sin2213 is to
measure two big things and subtract the results.
- =
How to Weigh Dumbo’s Magic Feather
1313
Neutrino LANDscape
Constraints from most recent Experiments
€
U =
Ue1 Ue2 Ue3
Uμ1 Uμ 2 U μ 3
Uτ1 Uτ 2 Uτ 3
⎛
⎝
⎜ ⎜ ⎜
⎞
⎠
⎟ ⎟ ⎟
=
cosθ12 sinθ12 0
−sinθ12 cosθ12 0
0 0 1
⎛
⎝
⎜ ⎜ ⎜
⎞
⎠
⎟ ⎟ ⎟×
cosθ13 0 e−iδ CP sinθ13
0 1 0
−e iδCP sinθ13 0 cosθ13
⎛
⎝
⎜ ⎜ ⎜
⎞
⎠
⎟ ⎟ ⎟×
1 0 0
0 cosθ23 sinθ23
0 −sinθ23 cosθ23
⎛
⎝
⎜ ⎜ ⎜
⎞
⎠
⎟ ⎟ ⎟×
1 0 0
0 e iα / 2 0
0 0 e iα / 2+iβ
⎛
⎝
⎜ ⎜ ⎜
⎞
⎠
⎟ ⎟ ⎟
12 ~ 30° 23 ~ 45°tan2 13 < 0.03 at 90% CL
UMNSP Matrix
Mass Hierarchy
Slide Courtesy of B. Kayser
What do we know and how do we know it
Is it important to measure 13?
Testimonials
L. Wofenstein
S. Glashow
B. Kayser S. Bilenky
A Smirnov
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
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
€
Pee ≈1− sin2 2θ13 sin2 Δm312L
4Eν+
Δm212L
4Eν
⎛
⎝ ⎜
⎞
⎠ ⎟cos4 θ13 sin2 2θ13
€
e →ν x
e
ee
€
→ e
€
Pμe ≈ sin2 2θ13 sin2 2θ23 sin2 Δm312L
4Eν+ ...
decay pipehorn absorbertargetp detector
+
+ +
Minakata and Nunokawa, hep-ph/0108085
Figuring out CP for leptons
€
P(ν μ →ν e ) − P(ν μ →ν e ) = −16s12c12s13c132 s23c23 sinδ sin
Δm122
4EL
⎛
⎝ ⎜
⎞
⎠ ⎟sin
Δm132
4EL
⎛
⎝ ⎜
⎞
⎠ ⎟sin
Δm232
4EL
⎛
⎝ ⎜
⎞
⎠ ⎟
Basic Idea for a Disappearance Experiment
?
ReactorDetector 1Detector 2
d2
d1
Experimental Design
First Direct Detection of the Neutrino
Reines and Cowan 1956
€
E prompt ≅ Eν − En − 0.8 MeV
)2.2( MeVdpn γ+→+
nepe +→+ +
sτ 210≈e ne+
2.2MeV~210 ms
Scintillator
Inverse Beta Decay Cross Section and Spectrum
Neutrino Spectra from Principal Reactor Isotopes
235U fission
1m
Poltergeist
Chooz4 m
KamLAND20 m
Long Baseline Reactor Neutrino Experiments
CHOOZ
CHOOZ
20
15
10
5
0
reactor neutrinos geo neutrinos background
25
20
15
10
5
086420
Prompt Energy (MeV)
2.6 MeVanalysis threshold
KamLAND data no oscillation best-fit oscillation
sin22 = 1.0 Δm2= 6.9 10x -5 eV2
KamLAND
KamLAND
from 12C(n, γ )
τcap = 188 +/- 23 sec
Inverse Beta Decay Signal from KamLAND
13 at a US nuclear power plant?
Site Requirements
• powerful reactors
• overburden
• controlled access
Diablo Canyon Power Station
scintillator e detectors
e + p e+ + n
coincidence signalprompt e+ annihilationdelayed n capture (in s)
€
Pee ≈1− sin2 2θ13 sin2 Δm312L
4Eν+
Δm212L
4Eν
⎛
⎝ ⎜
⎞
⎠ ⎟cos4 θ13 sin2 2θ12
• 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
e< 1 km
e,,τ~ 1.5-2.5km
Overburden Essential for Reducing Cosmic Ray Backgrounds
~60,000
~10,000
Statistical error: stat ~ 0.5% for L = 300t-yr
~250,000
Detector Event Rate/Year
Statistical Precision Dominated by the Far Detector
2 or 3 detectors in 1-1.5 km tunnel
Diablo Canyon
Variable Baseline
Ge
Issues
- folding may have damaged rock matrix- steep topography causes landslide risk- tunnel orientation and key block failure- seismic hazards and hydrology
Geology
I
II
IIIaIIIb
liquid scintillatorbuffer oil
muon veto
passive shield
Detector Concept
5 m
1.6 m
Variable baseline to control systematics and demonstrate oscillations (if |13| > 0)
acrylic vessel
Movable Detectors
5 m~12 m
• Modular, movable detectors• Volume scalable• Vfiducial ~ 50-100 t/detector
610
1-2 km
Kashiwazaki: 13 Experiment in Japan
- 7 nuclear reactors, World’s largest power station
near near
far
Kashiwazaki-KariwaNuclear Power Station
near near
far
70 m 70 m
200-300 m
6 m shaft hole, 200-300 m depth
Kashiwazaki: Proposal for Reactor 13 Experiment in Japan
Ref: Marteyamov et al, hep-ex/0211070
Reactor
Detector locations constrained by existing infrastructure
Features - underground reactor - existing infrastructure
~20000 ev/year~1.5 x 106 ev/year
Kr2Det: Reactor 13 Experiment at Krasnoyarsk
%Total LS mass 2.1Fiducial mass ratio 4.1Energy threshold 2.1Tagging efficiency 2.1Live time 0.07Reactor power 2.0Fuel composition 1.0Time lag 0.28e spectra 2.5
Cross section 0.2
Total uncertainty 6.4 %
Systematic Uncertainties
E > 2.6 MeV
Systematics
Reactor Flux • near/far ratio, choice of detector location
Best experiment to date: CHOOZ
Target Volume & • well defined fiducial volume
Backgrounds • external active and passive shielding for correlated backgrounds
Detector Efficiency • built near and far detector of same design • calibrate relative detector efficiency variable baseline may be necessary
Ref: Apollonio et al., hep-ex/0301017
Total syst ~ 1-1.5%
rel eff ≤ 1%
target ~ 0.3%
n bkgd < 1%
flux < 0.2%
acc < 0.5%
.
MC Studies
Normalization: 10k events at 10km
‘far-far’ L1=6 km L2=7.8 km
‘near-far’ L1 = 1 km L2 = 3 km
Oscillation Parameters:sin2213 = 0.14Δm2= 2.5 x 10-3 eV2
Optimization atLBNL
P νe → νe( )≈sin4θ13+cos4θ13 1−sin2(2θ12) ⋅sin2 Δm122 L
4Eν
⎛
⎝ ⎜
⎞
⎠ ⎟
⎧ ⎨ ⎩
⎫ ⎬ ⎭
Sensitivity to sin2213 at 90% CL
Reactor-I: limit depends on norm (flux normalization)
Reactor-II: limit essentially independent of norm
statistical error only
fit to spectral shape
cal relative near/far energy calibration
norm relative near/far flux normalization
Reactor I12 t, 7 GWth, 5 yrs
Reactor II250 t, 7 GWth, 5 yrsChooz 5 t, 8.4 GWth, 1.5 yrs
Ref
: H
uber
et a
l., h
ep-p
h/03
0323
2
statistics StatisticsSystematicsCorrelationsDegeneracies
Ref
: H
uber
et a
l., h
ep-p
h/03
0323
2
Expected Constraints on 13
Experiment sin2(213) 13 When?
CHOOZ < 0.11 < 10
NUMI Off- Axis (5 yr) < 0.006-0.015 < 2.2 2012
JPARC-nu (5 yr) < 0.006-0.0015 < 2.3 2012
MINOS < 0.06 < 7.1 2008
ICARUS (5 yr) < 0.04 < 5.8 2011
OPERA (5 yr) < 0.06 < 7.1 2011
KR2DET (Russia) < 0.016 < 3.6 ?
Kashiwazaki (Japan) < 0.026 < 4.6 [2008]
Penly/Cruas (France) < 0.025 < 4.5 [2010]
Diablo Canyon (US) < 0.01-0.02 < 2.9 [2009]
Upper limits correspond to 90% C.L.