17.12.2008 Jeff deJong, IIT 1MINOS,
Newest Results From MINOSNewest Results From MINOSJeff de JongJeff de Jong
(on behalf of the MINOS Collaboration)(on behalf of the MINOS Collaboration)
Illinois Institute of TechnologyIllinois Institute of TechnologyMiami 2008, Dec 16-20Miami 2008, Dec 16-20
17.12.2008 Jeff deJong, IIT 2MINOS,
Talk Outline Introduction to MINOS/NuMI Recent Results from MINOS
Charge Current:
dissappearance results
Neutral Current: s Sterile search results
Charge Current: e appearance sensitivity studies
Other ongoing MINOS studies(not discussed here)●
vs
ie CPT
● atmospheric neutrinos● Cosmic rays● neutrino flux/crosssection measurements using ND
17.12.2008 Jeff deJong, IIT 3MINOS,
MINOS Collaboration
Argonne – Athens – Benedictine – Brookhaven – Caltech – Cambridge-Campinas Diderot – Fermilab – Harvard -IIT – Indiana – ITEP - Lebedev – LLNL Minnesota – Twin Cities –
Minnesota/Duluth – Oxford - Pittsburgh Rutherford Sao Paulo – South Carolina – Stanford Sussex - Texas A&M – Texas/Austin Tufts – UCL -Warsaw- Western Washington – William & Mary
172 Physicists from 31 Institutions
17.12.2008 Jeff deJong, IIT 4MINOS,
MINOS Overview• Main Injector Neutrino
Oscillation Search• Neutrinos at the Main Injector
(NuMI) beam at Fermilab Two detectors Near detector at Fermilab
measure beam composition
energy spectrum Far detector in Minnesota
search for evidence of oscillations
17.12.2008 Jeff deJong, IIT 5MINOS,
NuMI / Neutrino Production
● Low Energy Beam composition(%)92.9
5.8
,1.3 ee
●Neutrino beam energy is tunable by modifying the target position wrt the horn.● Run in LE configuration as peak is closer to expected oscillation minimum.
● two magnetic focusing horns guide positive mesons down the decay pipe
Beam Stats.~ 275 kW,1018 POT/day,3x1013POT/10 s spill
17.12.2008 Jeff deJong, IIT 6MINOS,
Integrated Protons on Target
Shut
down
1st Results Dataset (1.27x1020 POTs LE10)
Additional 1.98x1020 POTs LE10
High Energy Runs
Run I Run II
Shut
down
Run III
Ongoing LE10 Running (>1.5×1020 POTs)
1st Results Dataset (1.27x1020 POTs LE10)
Additional 1.98x1020 POTs LE10
High Energy Runs
Ongoing LE10 Running (>2.5×1020 POTs)
●Jan 21,2005 First interaction in ND. CC
NC
17.12.2008 Jeff deJong, IIT 7MINOS,
MINOS Detectors
Near DetectorNear Detector
Far DetectorFar Detector
Detector Near FarDepth ~100m ~700mFrom Target ~ 1 km ~735 km
0.98 5.4Mass (kTon)
Two functionally identical detectors ● iron/scintillator tracking calorimeter● magnetized 1” steel planes <B>~1.3T● Scintillating strips 1.0cm x 4.1 cm● multianode PMT readout● GPS time stamping to synchronize FD to ND
●two detectors minimizes systematics due to flux/coss section uncertainties
17.12.2008 Jeff deJong, IIT 8MINOS,
Neutrino Interactions
ν ν
γγ
Z
π0
N(+X)
νµ µ
W
N X
νe e
W
N X
νµ CC Event NC Event ν e CC Event
17.12.2008 Jeff deJong, IIT 9MINOS,
Neutrino Interactions
long µ track+ hadronic activity at vertex
νµ CC EventUZ
VZ
3.5m
short event, often diffuse
NC Event
1.8m
short, with typical EM shower profile
ν e CC Event
2.3m
17.12.2008 Jeff deJong, IIT 10MINOS,
Charged Current Analysis of 3.36×1020 POT of MINOS Data
Precision measurement of |∆m322| and sin22θ
23
Phys Rev Lett 101 131802 (2008)
CC Analysis
17.12.2008 Jeff deJong, IIT 11MINOS,
Particle ID
CC/NC separation using a nearest neighbour algorithm (kNN) with 4 inputs
Track Length(# of planes)●For Hits on Track
Mean Pulse Height Fluxuation in Pulse Height Transverse Track Profile
●Neutral Current contamination increases at low energy/short tracks
17.12.2008 Jeff deJong, IIT 12MINOS,
Near Far ExtrapolationDue to different solid angles Far Detector Spectrum != Near Detector SpectrumUse MonteCarlo to provide corrections to the observed ND spectrum
FD
Decay Pipe
π+Target
NDp
Encode the pion decay kinematics and angular acceptance into a beam transfer matrix
● convert ND spectrum to FD
17.12.2008 Jeff deJong, IIT 13MINOS,
Systematic Uncertainties
● Relative (ND to FD) normalisation (4%)● Absolute hadronic energy scale (10%)● NC background (50%)
Effects of uncertainties estimated by fitting systematically shifted MC in place of data.
Note: analysis is still statistically limited!
Three largest uncertainties included as penalty terms in fit to data :
€
χ2= (2(ei−oi)+2nbins
∑ oiln(oi/ei))+∆sj
2
σsj
2nsys
∑
17.12.2008 Jeff deJong, IIT 14MINOS,
Far Detector CC spectrum
● Significant energydependent suppression of
CC events observed
Best Fit (constrained) parameters :
2flavor oscillations
|∆m2| = (2.43±0.13) x 103 eV2 (68% C.L.)sin2(2θ) > 0.90 (90% C.L.)2/ndof=90/97
Best Fit (unconstrained) parameters
|∆m2| = (2.33) x 103 eV2
sin2(2θ) =1.07 2/ndof=0.6
Observed 848/ Expect 1065±60 (syst).
P=sin2 2sin2
1.27m2LE
17.12.2008 Jeff deJong, IIT 15MINOS,
Other Interpretations
Decay
Decoherence
V. Barger et al., PRL82:2640(1999)
2/ndof=104/97 2=14Disfavored at 3.7
2/ndof=123/97 2=33Disfacvored at 5.7
G.L. Fogli et al, PRD 67:093006(2003)
P=sin2cos2 e−L2E 2
P=1−sin22
21−e
−2L2E
17.12.2008 Jeff deJong, IIT 16MINOS,
NC Analysis
Neutral Current Analysis of 2.46×1020 POT of MINOS Data
Looking for sterile neutrino mixing Phys Rev Lett 101 221804 (2008)
17.12.2008 Jeff deJong, IIT 17MINOS,
NC Motivation● Given the standard 3flavor oscilllation model, the extrapolated near detector neutral current rate at the FD should match the total observed Neutral Current (NC) rate.
● An observed deficit of NC events at the Far Detector could indicate oscillation to sterile neutrinos.(which don't interact at all)
●Compare the NC energy spectrum with the expectation of standard 3flavor oscillations●Fix the oscillation parameters at :
Reminder: For NC events we expect showers and no tracks, or very short tracks.(e events will fall into NC sample)
sin2(223)=1.0 and m232=2.43x103eV2 ⟵ MINOS 2008 CC Result
=0.61 and m221=7.59x105eV2 ⟵ KAMLAND+SNO
=0 or 0.21 and NMH) ⟵ From Chooz Limit
17.12.2008 Jeff deJong, IIT 18MINOS,
NC Event Selection
Main background: inelastic (highy)νμ CC events
Excluded
Excluded
Excluded
Cleaned Near Detector Data Set
FD Same cuts as ND: < 60 planes; no track or no track
beyond 5 planes from shower
17.12.2008 Jeff deJong, IIT 19MINOS,
NC ResultsNC Far Detector SpectrumNC Far Detector SpectrumShown for Shown for 1313=0 and the Chooz Limit=0 and the Chooz Limit
● Assume 1 sterile neutrino and that mixing occurs at one value of m2
● Far detector background predictions depends on oscillation parameters.●Survival and oscillation probabilities
●Fraction of all dissappearing events going to a sterile neutrino
)/27.1(sin)(
)/27.1(sin1)(22
22
ELmP
ELmP
ss ∆α=ν−ν
∆α−=ν−ν
µ
µµµ
f s=P s
1−P
w/o e appearance with e appearancef s=0.28−0.28
0.25statsyst f s0.68 90%C.L.
f s=0.43−0.270.23statsyst
f s0.80 90%C.L. Results Consistent with no deficit in NC rate !!
17.12.2008 Jeff deJong, IIT 20MINOS,
e CC appearance Analysis
e CC appearance SensititiesResults expected in a few months
17.12.2008 Jeff deJong, IIT 21MINOS,
e CC appearanceWorking toward a measurement of sin2(213)
selection is a neural network based on characteristics of EM showers.
e spectrum is background dominatedDominant backgrounds are short CC/NC
events
Data driven systematic uncertainty currently at ~ 10% :
Pe=sin2213sin
2223sin21.27m13
2 L /E
hope is to reduce this to 5% in near future
With 3.25x1020 protons (ie current exposure) at the Chooz limit we expect 12 signal and 42 background events.
MINOS can improve CHOOZ limit by a factor of 2
17.12.2008 Jeff deJong, IIT 22MINOS,
Summary Slide
● Updated results for CC dissappearance have been presented
|∆m2| = (2.43±0.13) x 103 eV2 (68% C.L.)sin2(2θ) > 0.90 (90% C.L.)
● First results for NC dissappearance/sterile searches: (w/o ne appearance)f s=0.28−0.28
0.25statsyst f s0.68 90%C.L.
● MINOS is on the verge of having its first e appearance measurement