NuMI Off-Axis Experiment

Alfons Weber

University of Oxford &Rutherford Appleton Laboratory

EPS2003, AachenJuly 19, 2003

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Content What is the physics? Why off-axis?

The beam The site

What experiment to build? Scintillator Resistive plate chambers (Liquid Argon)

Sensitivity

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What is the Physics? Precision Experiment to determine

m23

sin2223

Look for sub-dominant oscillation mode sin213

Needed: low background Low e beam contamination Few wrong energy neutrinos

e

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Why Off-Axis

e (|Ue32| = 0.01) e background

NC (visible energy), no rejection

spectrum

NuMI beam can produce 1-3 GeV intense beams with well defined energy in a cone around the nominal beam direction

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NuMI beam 120 GeV protons from

FNAL main injector 3-15 GeV neutrinos 3.8x1020 PoT / year 0.5 MW beam power

Baselines 700-950 km

Several sites with infrastructure

Road Electricity Network

Possible Sites

Canada

U.S.

L. Superior

Soudan

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Experimental Challenge Small signal

huge # NC Surface detector

No or light over-burden

cosmic induced n But:

Duty factor 10-5

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Detector Challenge NC versus Electron CC separation

Fine grain Low Z

Build affordable & massive detector 50+ kton fiducial mass >400k readout channels

Technologies: Solid scintillator (MegaMINOS, but not Mton) Liquid scintillator Glass RPCs (Liquid Argon TPC)

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Alternating horizontal and vertical scintillator planes

Passive material: woodOriented Strand Board (density .6 - .7 g/cm3)

Sampling: 1/3 rad. length

readout

read

out

read

out

15 m 15 m

15 m

Scintillatormodules4 ft

48 ft

8 ft 8 ft

8 in

9.4 tons

5300 = detector

6 = 1 plane

180 m

885 planes = detector

Fiducial fraction (1 m cut at all edges) 80%

Solid/Liquid Sintillator

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Scintillator Length 15 m Looped fibre readout

Scintillator Material Solid

MINOS like co-extruded (3.8x1 cm2)

Liquid Bicron 517 L (3.8x2.9 cm2)

WLS Fiber Kuraray (0.7 mm ø)

Photodetector APD PMT: M64

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 500 1000 1500 2000

LED 1.2mm PMT

LED 1.2mm APD

LED Ratio

Length in cm

Rel

ativ

e L

igh

t Y

ield

MINOS WLS Fiber

680,000 channels( 30 x MINOS)

( 2 x MINOS)

Scintillator and WLS Fibre

400,000 m2

( 16 x MINOS)

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Glass RPCs / LSTs

Used successfully Belle: 4 years operation Virginia Tech: 5 years testing

Wood/plastic absorber

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Signal & BG Events

typical signal event BG event

Fuzzy track = e- Clean track = muon2 tracks = π0

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Physics Reach (I) Phase I (2008-2014)

4x1020 PoT / year 50 kton detector

(fiducial) 1.5 years neutrinos 5 years anti-neutrinos

Phase II (2014-2020) A factor of 25 more:

PoT x detector mass 1.5 years neutrinos 5 years anti-neutrinos

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Physics Reach (II) Some Math:

need more than one experiment to determine oscillation parameters

A. Cervera et al., Nuclear Physics B 579 (2000) 17 – 55,

expansion to second order in 12 1213 12

23

, , , LA

P ( e) = P1 + P2 + P3 + P4

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Physics Reach (III) Measurement is oscillation probability Depends simultaneously on:

Mass hierarchy CP phase Mixing angles Typical Errors

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Summary The NuMI OA group is seriously trying to bring froward a

credible & affordable proposal Combination of

JPARC/SuperK and NuMI OA neutrino and anti-neutrino running

might reveal neutrino mixing parameters Masses & hierarchy Angles CP phase

For more information:

http://www-off-axis.fnal.gov

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Liquid Argon TPCExcellent pattern recognition capabilitiesHigh efficiency for electron identificationExcellent e/0 rejection