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# Measuring q 13 with Reactors Stuart Freedman University of California at Berkeley - PowerPoint PPT Presentation

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.

-

=

UMNSP Matrix

12 ~ 30°

tan2 13 < 0.03 at 90% CL

23 ~ 45°

Mass Hierarchy

Slide Courtesy of B. Kayser

B. Kayser

S. Bilenky

S. Glashow

A Smirnov

Testimonials

decay pipe

detector

p

target

horn

+

+

+

e

e

e

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

Minakata and Nunokawa, hep-ph/0108085

d2

d1

Detector 2

Detector 1

Reactor

Experimental Design

Scintillator

ne

e+

n

2.2MeV

n

m

Reines and Cowan 1956

235U fission

Neutrino Spectra from Principal Reactor Isotopes

KamLAND

4 m

Chooz

1m

Long Baseline Reactor Neutrino Experiments

Poltergeist

from 12C(n, g )

tcap = 188 +/- 23 msec

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,,

~ 1.5-2.5km

e

< 1 km

• • 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

~250,000

~60,000

~10,000

Statistical error: stat ~ 0.5%for L = 300t-yr

Statistical Precision Dominated by the Far Detector

Variable Baseline

2 or 3 detectors in 1-1.5 km tunnel

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

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

1-2 km

~12 m

• Modular, movable detectors

• Volume scalable

• Vfiducial ~ 50-100 t/detector

Kashiwazaki:13 Experiment in Japan

- 7 nuclear reactors, World’s largest power station

far

near

near

Kashiwazaki-Kariwa

Nuclear Power Station

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

~1.5 x 106 ev/year

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

%

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%

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%

LBNL

‘near-far’ L1 = 1 km

L2 = 3 km

‘far-far’ L1=6 km

L2=7.8 km

MC Studies

Normalization:

10k events at 10km

Oscillation Parameters:

sin2213 = 0.14

m2= 2.5 x 10-3 eV2

Sensitivity to sin2213at 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

statistics

Statistics

Systematics

Correlations

Degeneracies

Upper limits correspond to 90% C.L.