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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 q 13 with reactors stuart freedman university of california at berkeley

Measuring q13 with Reactors

Stuart Freedman

University of California at Berkeley

SLAC Seminar September 29, 2003


Measuring q 13 with reactors stuart freedman university of california at berkeley

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.

-

=


Measuring q 13 with reactors stuart freedman university of california at berkeley

Neutrino LANDscape


Measuring q 13 with reactors stuart freedman university of california at berkeley

Constraints from most recent Experiments


Measuring q 13 with reactors stuart freedman university of california at berkeley

UMNSP Matrix

12 ~ 30°

tan2 13 < 0.03 at 90% CL

23 ~ 45°

Mass Hierarchy


Measuring q 13 with reactors stuart freedman university of california at berkeley

What do we know and how do we know it

Slide Courtesy of B. Kayser


Measuring q 13 with reactors stuart freedman university of california at berkeley

Is it important to measure q13?


Measuring q 13 with reactors stuart freedman university of california at berkeley

L. Wofenstein

B. Kayser

S. Bilenky

S. Glashow

A Smirnov

Testimonials


Measuring 13

absorber

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


Measuring q 13 with reactors stuart freedman university of california at berkeley

Figuring out CP for leptons

Minakata and Nunokawa, hep-ph/0108085


Measuring q 13 with reactors stuart freedman university of california at berkeley

Basic Idea for a Disappearance Experiment

?


Measuring q 13 with reactors stuart freedman university of california at berkeley

d2

d1

Detector 2

Detector 1

Reactor

Experimental Design


Measuring q 13 with reactors stuart freedman university of california at berkeley

First Direct Detection of the Neutrino

Scintillator

ne

e+

n

2.2MeV

n

m

Reines and Cowan 1956


Measuring q 13 with reactors stuart freedman university of california at berkeley

Inverse Beta Decay Cross Section and Spectrum


Measuring q 13 with reactors stuart freedman university of california at berkeley

235U fission

Neutrino Spectra from Principal Reactor Isotopes


Measuring q 13 with reactors stuart freedman university of california at berkeley

20 m

KamLAND

4 m

Chooz

1m

Long Baseline Reactor Neutrino Experiments

Poltergeist


Measuring q 13 with reactors stuart freedman university of california at berkeley

CHOOZ


Measuring q 13 with reactors stuart freedman university of california at berkeley

CHOOZ


Measuring q 13 with reactors stuart freedman university of california at berkeley

KamLAND


Measuring q 13 with reactors stuart freedman university of california at berkeley

KamLAND


Measuring q 13 with reactors stuart freedman university of california at berkeley

Inverse Beta Decay Signal from KamLAND

from 12C(n, g )

tcap = 188 +/- 23 msec


Measuring q 13 with reactors stuart freedman university of california at berkeley

q13 at a US nuclear power plant?

Site Requirements

• powerful reactors

• overburden

• controlled access


Measuring q 13 with reactors stuart freedman university of california at berkeley

Diablo Canyon Power Station


Measuring q 13 with reactors stuart freedman university of california at berkeley

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


Measuring q 13 with reactors stuart freedman university of california at berkeley

Overburden Essential for Reducing Cosmic Ray Backgrounds


Measuring q 13 with reactors stuart freedman university of california at berkeley

Detector Event Rate/Year

~250,000

~60,000

~10,000

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

Statistical Precision Dominated by the Far Detector


Measuring q 13 with reactors stuart freedman university of california at berkeley

Diablo Canyon

Variable Baseline

2 or 3 detectors in 1-1.5 km tunnel


Measuring q 13 with reactors stuart freedman university of california at berkeley

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


Detector concept

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| > 0)


Measuring q 13 with reactors stuart freedman university of california at berkeley

6

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

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

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


Kr2det reactor 13 experiment at krasnoyarsk

~20000 ev/year

~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


Measuring q 13 with reactors stuart freedman university of california at berkeley

Systematic Uncertainties

%

Total LS mass2.1

Fiducial mass ratio4.1

Energy threshold2.1

Tagging efficiency2.1

Live time0.07

Reactor power2.0

Fuel composition1.0

Time lag0.28

e spectra2.5

Cross section0.2

Total uncertainty6.4 %

E > 2.6 MeV


Systematics

.

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%


Mc studies

Optimization at

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


Measuring q 13 with reactors stuart freedman university of california at berkeley

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

Chooz5 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


Measuring q 13 with reactors stuart freedman university of california at berkeley

Ref: Huber et al., hep-ph/0303232

statistics

Statistics

Systematics

Correlations

Degeneracies


Expected constraints on 13

Expected Constraints on13

Upper limits correspond to 90% C.L.


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