Status and goals of the MINOS experimentAlberto Marchionni, FermilabNuFact ‘05, June 21-26, 2005

MINOS Near Detector surface building

32 institutions175 physicists

Argonne • Athens • Benedictine • Brookhaven • Caltech • Cambridge • Campinas • Fermilab College de France • Harvard • IIT • Indiana • ITEP-Moscow • Lebedev • Livermore

Minnesota-Twin Cities • Minnesota-Duluth • Oxford • Pittsburgh • Protvino • Rutherford Sao Paulo • South Carolina • Stanford • Sussex • Texas A&M

Texas-Austin • Tufts • UCL • Western Washington • William & Mary • Wisconsin

MINOS: a two detector neutrino oscillation experiment

Det. 1 735 km Det. 2

Near Detector: 980 tons

Far Detector: 5400 tons

shoot a neutrino beam from Fermilab to Soudan mine (Minnesota) over a baseline of 735 km

measure produced neutrino spectrum in a Near location, extrapolate it to the Far site and compare with spectrum measured at the Far site

A. Marchionni, NuFact05

A precision experiment at the atmospheric ∆m2

Verify dominant νµ→ντ oscillationsSee the characteristic oscillation energy dependenceStudy unconventional explanations: neutrino decay, extra dimensions, etc.Set a limit on sterile neutrino contributions

Precise measurement of the atmospheric ∆m232: ~10%

Search for sub-dominant νµ → νe oscillations: 3 σdiscovery about a factor of 2 below the CHOOZ limitMeasurement of atmospheric neutrino events with neutrino/antineutrino identification

1st large underground detector with a magnetic field

A. Marchionni, NuFact05

NuMI: ν’s at the Main Injector

Main Injector is a rapid cycling (up to 204 GeV/c/s) accelerator at 120 GeV

Current NuMI intensity 1.9×1013 pppevery 2-4 sec

5 (6) proton batches are successively injected from Booster into Main Injector, accelerated and single-turn extracted to the NuMI target in ~ 8 (10) µs

Goal for the end of the year ~2.5×1013

ppp every 2 s NuMI design is for 4×1013 protons

every 1.9 s (0.4 MW) (2008-9) expected rate ~3.4×1020

protons/year

A. Marchionni, NuFact05

NuMI beam-line

A. Marchionni, NuFact05

NuMI ν beam and monitoring instrumentation

water cooled graphite target, 2 interaction lengths, which provides absorption of ~ 90% of the primary protons

target readily movable in beam directionflexible configuration of 2 parabolic horns, water cooled, pulsed with a 2.6 ms

half-sine wave pulse of 200 kA675 m long decay pipe with a radius of 1 m, evacuated to 1 Torr1 hadron monitor and 3 muon monitor stations

207 m

A. Marchionni, NuFact05

Fully optimized spectra for each energy are obtained by moving the target and the 2nd horn

With a parabolic shaped horn inner conductor, the horn behaves like a lens (pt kick proportional to the distance from the axis), with a focal length proportional to the momentum

A flexible target and horn systemFar detector event spectra

3.8×1020 pot/year

Baffle and target carrier

Target/Baffle carrier

Allows for 2.5 m of target motion to vary the

beam energy

Target

Baffle, protection of horn components: 150 cm long graphite rod, with 11 mm ∅ hole

Target: 47 segments of graphite of 20 mm length and 6.4×15 mm2 cross section

Detector TechnologyDetector module with 20 solid scintillator strips

MUX boxes route 8 (1 in Near Detector) fibers to one MAPMT pixel in the Far Detector

The Near and Far neutrino detectors

Near Detector, 980 tons Far Detector, 5400 tons

Two “identical” detectors in all their important featurestracking calorimeters with interleaved planes of steel and solid scintillator2.54 cm thick steel planes1 cm thick and 4.1 cm wide scintillator strips alternate planes have orthogonal strip orientation~1.5 T toroidal magnetic field

Multi-anode Hamamatsu PMTs: M16 Far, M64 NearNear detector electronics allows measurement of charge in each 19 ns RF bucket

to separate multiple events in a same ~ 10 µs spill

Detector calibrationFrom calibration detector at CERN

Calibration Detector at CERNCalibration of detector responseComparison of Near and Far

electronics

Cosmics muonsscintillator strips inter-calibrationuse of stopping muons to relate the

energy scales of Near and Far detectors within 2%

Energy (GeV)

Energy (GeV)

Res

olut

ion

Cal

orim

eter

res

pons

e (M

EU

/GeV

)

E55%

E22%

MINOS start up and data taking

Target leak

Start data taking

Commissioning of the primary proton beam

Commissioning of the neutrino beam

In order to understand the systematic of neutrino production and detector response have run with different beam energies (LE, pME, pHE) just by moving target position, not the 2nd horn (fast, no downtime !)

Proton beam centering on the Hadron Monitor

Hadron Monitor Max flux ~ 109 part./cm2/spill

7×7 ion chamber array

4”×4” parallel plate ion chambers made from ceramic wafers with Ag-Pt electrodes

1 mm gap, He gas Beam points in the right direction within ~ 20 µrad

Monitoring ν beam with the Muon monitors

LE configuration

A. Marchionni, NuFact05

2 m × 2 m array of 9×9 ion chambers

3 Muon Stations in excavated alcovesMax. flux ~ 3×107 part./cm2/spill

µ monitors vertical profiles

preliminary

Stability of muon centroidsover ~ 1 month

Events in Near Detectorν events time distribution

1 full spillone of the events after slicing

Detector read out in 19 ns buckets, allowing event separation

µs

Time (s)

Distributions in Near Detector

Preliminary

E (GeV)

LEpME

pHE Near Detector, LE beam configurationexpect 1×106 ν interactions in a

cylindrical fiducial region of 1 m radius and 4 m length for 2.5×1020 pot

fiducial region

coil hole

m

m

reconstructed track angles with respect to vertical

Far Detector event

LE ν beam configurationexpect 1300 νµ CC events for

2.5×1020 pot/year in Far Detector (in absence of oscillations)

A. Marchionni, NuFact05

Far Detector pHE ν beam dataFrom ~150000 spills in pHE data

preliminary

Beam neutrino candidates are within a 10 µs time interval, as expected by the length of the primary proton beam

Time difference (in sec) between neutrino candidates and far spill signal in a ±50 µswindow

A. Marchionni, NuFact05

y

x

z

X angle (horz.)

Y a

ngle

(ver

t.)

Track angle with respect to beam direction

Neutrino Candidates

Cosmics

Short term conclusionsHave already accumulated ~ 0.8×1019 pot in LE configurationBy the end of the year we would be approaching ~ 1×1020 pot (> 100 νµ CC

events in 1-10 GeV energy range expected in Far Detector in case of no oscillations)

comparable data set to K2K

A. Marchionni, NuFact05

Longer term conclusions

In ~ 5 years 10% measurement of atmospheric ∆m2,

good sensitivity for unconventional explanations

3 σ sensitivity for non-zero θ13 if within a factor 2 of the CHOOZ limit

3 σ sensitivity plot

Backup slides

A. Marchionni, NuFact05

The primary proton lineTotal length ~ 350 m

MI tunnel

bringing the protons to the correct pitch of 58 mrad

bending down by 156 mrad

final focus

trim magnets

carrier tunnel~70 m

beam pipe 12” Ø

Main Injector

NuMI lineRecycler

Primary beam-line instrumentation

A. Marchionni, NuFact05

2 beam toroids24 beam position monitors54 loss monitors10 thin-foil profile monitors (SEM)

developed at U. Texas• 5 micron Titanium foils• Pitch 1 mm (8 units) or 0.5 mm (2 units)

last instrumentation post before target

H BPM V BPMprofile monitor

Profile monitor1 mm pitch

The target

47 segments of graphite of 20 mm length and 6.4×15 mm2 cross section0.3 mm spacing between segments, for a total target length of 95.4 cm

Horizontal target scan

A. Marchionni, NuFact05

Graphite protection ‘baffle’Graphite target

Water cooling line

21.4

mm

15.0

mm

11.0

mm

6.4mm