NuMI

MINOS

Neutrinos Change FlavorUnder Wisconsin

Current NuMI/MINOS Oscillation ResultsAlec Habig, for the MINOS Collaboration

XLIII Rencontres de Moriond EW 2008

27 institutions147 physicists

Argonne • Arkansas Tech • Athens Benedictine • Brookhaven • Caltech Cambridge • Campinas • Fermilab

Harvard • IIT • Indiana Minnesota-Twin Cities • Minnesota-

Duluth Oxford • Pittsburgh • RutherfordSao Paulo • South Carolina • Stanford Sussex • Texas A&M • Texas-Austin

Tufts • UCL • Warsaw • William & Mary

NuMI

MINOS

Neutrinos Change FlavorUnder Wisconsin

Current NuMI/MINOS Oscillation ResultsAlec Habig, for the MINOS Collaboration

XLIII Rencontres de Moriond EW 2008

27 institutions147 physicists

Argonne • Arkansas Tech • Athens Benedictine • Brookhaven • Caltech Cambridge • Campinas • Fermilab

Harvard • IIT • Indiana Minnesota-Twin Cities • Minnesota-

Duluth Oxford • Pittsburgh • RutherfordSao Paulo • South Carolina • Stanford Sussex • Texas A&M • Texas-Austin

Tufts • UCL • Warsaw • William & Mary

NuMI

MINOS

MINOSMain Injector Neutrino Oscillation Search

• Investigate atmospheric sector oscillations using intense, well-understood NuMI beam

• Two similar magnetized iron-scintillator calorimeters– Near Detector

• 980 tons, 1 km from target, 90 m deep

– Far Detector• 5400 tons, 735 km away, 700 m deep

735 km

NuMI

MINOS

Physics Goals

• Precise (~10%) measurement of m223

• Confirm ↔ flavor oscillations– Provide high statistics discrimination against alternatives

such as sterile , decoherence, decay, etc

• Search for subdominant ↔e oscillations – a shot at measuring 13

• Directly compare vs oscillations (a test of CPT)– MINOS is first large underground detector with a magnetic

field for +/- tagging

• Study interactions and cross sections using the very high statistics Near Detector data set

• Cosmic Ray Physics

This talk Published Coming later this year

Atmospherics Beam

NuMI

MINOS

Disappearance Sensitivity

• Measure flux at Near Det, see what’s left at Far Det• Simulated results plotted as F/N ratio

– Position of dip gives m2

– Depth of dip gives sin22• Spectral ratio shapes would differ in alternative models

Unoscillated

Oscillated

spectrum

Monte Carlo Monte Carlo

ν ν

2

2 21 sn isi nL

PEm

θΔ

μ μ

Spectrum ratio

NuMI

MINOS

Far Detector

M16 PMT

16 mm

A module of 20 strips

…on a plane

8 fibers ona pixel

• 486 planes, 5400 tons total– Each 1” steel + 1 cm plastic

scintillator thick – 8 m diameter with torodial

~1.5 T B-field– 31 m long total, in two 15 m

sections– 192 scintillator strips across

• Alternating planes orthogonal for stereo readout

– Scint. CR veto shield on top/sides

• Light extracted from scint. strips by wavelength shifting optical fiber– Both strip ends read out with

Hamamatsu M16 PMTs– 8x multiplexed

NuMI

MINOS

3D Reconstruction

• Take all the “U” view lit-up strips– Cross with all the “V”

view lit-up strips– X marks the spot(s)

See live events athttp://www.soudan.umn.edu

NuMI

MINOS

3D Reconstruction

• This is a real interaction from the beam– appears inside

detector,– cruises along through

many planes,– curving in the

magnetic field,• Curvature tells us

momentum…

– stops.• …so does range

See live events athttp://www.soudan.umn.edu

NuMI

MINOS

Near Detector

• 282 planes, 980 tons total– Same 1” steel,1 cm plastic scintillator planar construction, B-field– 3.8x4.5 m, some planes partially instrumented, some fully, some steel only– 16.6 m long total

• Light extracted from scint. strips by wavelength shifting optical fiber– One strip ended read out with Hamamatsu M64 PMTs, fast QIE electronics– No multiplexing upstream, 4x multiplexed in spectrometer region

3.8 m

4.8 m

NuMI

MINOS

Hadronic: 56±2%/E

EM: 21±4%/ E

• 60-plane ‘micro-MINOS’– has taken data at T7 & T11 test beam lines

at CERN during 2001, 2002, 2003• Instrumented with both Near and

Far Detector electronics– To provide cross-calibrations– Energy uncertainties: 3% relative, and

1.9% (ND) & 3.5% (FD) absolute

Caldet

NuMI

MINOS

NuMI Spectrum

• Three standard beam configurations– Obtained by changing target and

horn 2 locations– Target easy to move, used to

approximate ME, HE with “pME”, “pHE” beams

– Horn 2 harder to move, has not yet been adjusted

– Can also adjust horn currents for more variations

• At L of 735 km and m2 indicated by Super-K, the “Low” energy beam is closest to the first oscillation minima– Unfortunately, also the least

intense (still 107 per 1020 pot at the Near Detector!)

BeamTarget z

position (cm)FD Events

per 1e20 pot

LE-10 -10 390

pME -100 970

pHE -250 134098.7% (5.8% )

1.3% e e

NuMI

MINOS

Beam Data Analyzed

• up to 3x1013 protons every 2.2 seconds (~250 kW) (104 events/day in ND!)

RUN I - 1.27x1020 POT(published in PRL)

Higher energy beam

RUN IIa1.23x1020 POT

(NEW)

RUN IIb~0.75x1020

POT(in can)

This talk: Run I + Run IIa - 2.497x1020 POT

RUN III>0.63x1020

POT(current)Far Det

>99% live!

NuMI

MINOS

Near Detector Data

• How do data look in the Near Detector, where we have ~unlimited statistics?

• If we understand things there, we can then look at the Far Detector data where the physics is happening, so:– Examine ND closely– Compare ND data/MC– “Blind” analysis done ?

? ?

NuMI

MINOS

Lots of in the Near Detector

• A mean of 3 interactions per spill (in 8 or 10 s), up to 10

• Near Detector Electronics gates for 19 s during the entire spill

– Digitizes continuously every 19 ns, no dead time

• Separate events using timing and topology• Below: ~35 x 106 events for 1.27 x 1020 POT

image the ND’s internal structure with !

A typical 6-event spill,colored by time

NuMI

MINOS

Z

N(+X)

W

N X

e e

W

N X

What sort of Interaction?

CC Event NC Event e CC Event

Long track + hadronic activity at vertex

3.5m

Short event, often diffuse

1.8m

Monte Carlo

E = Eshower+E

55%/E 5% range, 10% curvature(hadronic)

22%/E

(leptonic)

E = Eshower

Short, with typical EM shower profile

2.3m

7 variable log-likelihood PID formed, improves over PRL analysis

NuMI

MINOS

Reconstructed Beam Spectrum

LE-10 pME pHE

LE-10 events

Weights applied as a function of hadronic xF and pT.

MIPP data on MINOS target will be used to refine this in the future, NA49 and Harp results also used

Discrepancies between data and Fluka05 Beam MC vary with beam setting: so source is due to beam modeling uncertainties rather than cross-section uncertainties

MC tuned by fitting to hadronic xF and pT over 7 beam configurations (3 shown here)

NuMI

MINOS

What is Expected in Soudan?

• Measure Near Detector E spectrum• To first order the beam spectra at Soudan is the

same as at Fermilab, but: – Small but systematic differences between Near and Far– Use Monte Carlo to correct for energy smearing and

acceptance– Use our knowledge of pion decay kinematics and the

geometry of our beamline to predict the FD energy spectrum from the measured ND spectrum

f

to farDetector

Decay Pipe

(soft)

(stiff)

n

target

ND2

222 1

11

L

Flux221

43.0

EE

NuMI

MINOS

On to the Far Detector…

• “Blind” analysis– Only after understanding the

Near Detector, reconstruction, selected non-oscillation Far Detector parameters, and early pHE (ie, non-oscillating) beam data did we “open the box”

– Data “re-blinded” when developing analysis improvements and adding new data

NuMI

MINOS

Spectrum

expected

observed

i

i

e

o|m2

32| = 2.38 +0.20 (stat + syst) x 10-3 eV2

sin2223 = 1.00 -0.08 (stat + syst)

2/ndf=41.2/34 (18 bins x 2 spectra (Run I, Run IIa) – 2)

−0.16Measurement errors are 1σ, 1 DOF

2 2 2 2

1 1

( ,sin 2 , ,...) 2( ) 2 ln( / ) /j

nsystnbins

j i i i i i ji j

m e o o o e

NuMI

MINOS

Allowed Region

• Fit includes systematic penalty terms

• Fit is constrained to physical region: sin2(223)≤1

• Consistent with previous experiments

• Already best measurement of |m2

32|

NuMI

MINOS

MC MINOSMC

The Future

• disappearance– more data, looser cuts

as systematics are better understood

– add rock muons

• Anti-neutrino oscillations– in neutrino beam– anti-neutrino running?

• Search for/rule out exotics– Sterile neutrinos– Neutrino decay– Neutrino de-coherence

• e appearance– New sensitivities!

Simulated data based onm2=2.7x10-3 eV2 and sin22=1.0 (Old values! For Comparison Purposes Only,m2 really does = 2.38x10-3 eV2 these days, but this plot has not been remade)

NuMI

MINOS

Progress Towards the Future

• This year should see the first looks at:– A NC analysis to directly test for participation of s

in the disappearance

– A e analysis to search for 13 via e appearance

• As with the disappearance analysis, the Near Detector data and backgrounds must be well understood before the Far Detector data (and its potential new physics) is examined

• Here follow two important steps towards this goal:

NuMI

MINOS

Selecting Neutral Current Events

• Simple NC event selection:– < 60 planes;– no track or– no track beyond

5 planes from shower

NuMI

MINOS

NC Spectrum

• NC events can be used to search for sterile neutrino component in FD– via disappearance of NC events at FD– FD data coming soon

Real ND NC Data Projected s Limitswhen FD box is opened

NuMI

MINOS

e Appearance Sensitivity

• Working towards a 13 measurement by using Near Detector data-driven methods to estimate e appearance backgrounds– At Near Detector, all e events are background rather than due to e

appearance. – Apply the NN-based e selection to the ND data to get an all-

background sample.– Find what fraction of those background events are NC showers,

mis-ID’d CC events, or real e from the beam

• Use these new background estimates to correct Far Detector sensitivity projections for unknowns in hadronic shower modeling etc.

• Two independent methods agree• Estimated systematic errors based on these Near Detector

studies are 10%– Far Detector sideband studies are next

NuMI

MINOS

Muon Removal

• “MRCC” sample: – shower only events

obtained by removing the muon from CC selected events and reconstructing the shower remnant.

• Comes from a well understood spectra, with well known efficiency and purity.

• Apply the e selection to these non-e events– Results in a background

sample of electromagnetic dominated hadronic showers.

NuMI

MINOS

Muon Removal

• >20% Data/MC discrepancy in both the standard e and the muon removed CC samples

• Comparisons of standard Data and MC shower topological distributions disagree in the same way as does MRCC data with MRCC MC– So MC hadronic shower

production/modeling is a major contribution to the disagreement.

– Kinematic phase space of MRCC and selected NC events matches well, but MRCC and selected CC events do not.

• The MRCC sample is thus used to make and ad-hoc correction to the model to NC events per bin– Beam e from MC, CC events are

the remainder

NuMI

MINOS

Horn on/off Method

• After applying e selection cuts to Near Detector data, the composition of the selected events is quite different with the NuMI focusing horns on or off.

• Get horn on/off ratios from MC, then solve for NC and CCbackgrounds in bins of energy, get beam e from the beam MC (a well understood number)– Independent of hadronic modeling

Non = NNC + NCC + Ne (1)Noff = rNC*NNC + rCC*NCC + re*Ne (2)

from MC:rNC(CC,e) = NNC(CC,e)

off/NNC(CC,e)on

NuMI

MINOS

Horn on/off Method

rCC

rNC

Solve eqs.(1), (2)

• On/off ratios match well between data and MC (after fiducial volume cuts).

• Apply these fractions to the total data to deconvolute it into its components.

• The MC predicts 24% too much CC and 28% too much NC background!

• Also checked using 3rd beam spectrum, pHE

Agrees with Muon Removal method!

NuMI

MINOS

Projected 13 Limits

• Extrapolating these data-driven backgrounds to the Far Detector, e appearance limit projections are calculated using the horn on/off method

• Shown as a function of CP-violating phase , since over the MINOS allowed m2 range the limits vary little

• This plot is for our current exposure, with estimated 10% systematics

• Blind analysis in progress

NuMI

MINOS

Projected 13 Limits

• Projected limits shown for expected MINOS exposures

• Data-driven systematics are hoped to drop to 5% with more work plus more horn off data in future years

• Inverted hierarchy shown only for lowest exposure for simplicity, but mostly marches along behind the normal limits

NuMI

MINOS

• The first 2.51020 POT of NuMI beam data have been analyzed for disappearance oscillations and are consistent with standard neutrino oscillations with the following parameters:

• A Neutral Current data spectrum has been measured at the Near Detector. When extrapolated to the Far Detector and compared to data, direct limits on sterile neutrino participation will be set

• Studies of Near Detector data are used to establish data-drive backgrounds to e appearance at the Far Detector. The current MINOS exposure will be sensitive to 13 at the Chooz limit

Summary

This work was supported by the U.S. Department of Energy, the U..K. Science and Technology Facilities Council, and the State and University of Minnesota. We gratefully acknowledge the Minnesota Department of Natural Resources for allowing us to use the facilities of the Soudan Underground Mine State Park. This researcher was directly supported by NSF RUI grant #0653016.

2 0.20 3 232 0.16

223 0.08

2.38 10 eV

sin 2 1.00

m

NuMI

MINOS

Extra Slides

NuMI

MINOS

New Improved Analysis

• Several improvements over previous analysis– better reconstruction

– improved event separation

– improved shower modelling

– new intra-nuclear modelling

• CC event identification based on– track properties

– event length

– event kinematics

• Derive PID based on PDFs of the above

NuMI

MINOS

Improvements

• Larger fiducial volume (3%)• improved reconstruction (4%)• improved PID

– higher efficiency– higher purity

NuMI

MINOS

Unconstrained Fit

07.12sin

eV10 26.22

2-32

Δm

NuMI

MINOS

Parameter Spaces

04/19/23 Alec Habig, HE xyz Neutrino-induced muons observed with MINOS

NuMI

MINOS

What Changed?

04/19/23 Alec Habig, HE xyz Neutrino-induced muons observed with MINOS

NuMI

MINOS

What Changed?

Improvements:•reco & selection•shower modelling

04/19/23 Alec Habig, HE xyz Neutrino-induced muons observed with MINOS

NuMI

MINOS

What Changed?

Data sets:•Pre-shutdown•Post-shutdown

Improvements:•reco & selection•shower modelling

04/19/23 Alec Habig, HE xyz Neutrino-induced muons observed with MINOS

NuMI

MINOS

What Changed?

Data sets:•Pre-shutdown•Post-shutdown

Improvements:•reco & selection•shower modelling