# Presentation: 465690

## The MINOS Long Baseline Neutrino Oscillation Experiment

- The MINOS Long Baseline Neutrino Oscillation Experiment

- Jeff Nelson
- William & Mary
- Fermilab Users’ Meeting
- June 6, 2007

## MINOS

- Overview
- Detector & beam
- Oscillation analysis
- Neutrino time of flight
- What’s New?
- 2nd year of running
- Advances
- Prospects

- Argonne • Athens • Benedictine • Brookhaven • Caltech • Cambridge Campinas • Fermilab • College de France • Harvard • IIT • Indiana Minnesota-Twin Cities • Minnesota-Duluth • Oxford • Pittsburgh Rutherford • Sao Paulo • South Carolina • Stanford • Sussex • Texas A&M • Texas-Austin • Tufts • UCL • William & Mary • Wisconsin

## MINOS Physics Goals

- Test the *ν*μ → *ν*τ oscillation hypothesis
- Measure precisely |Δm232| & sin22θ23
- PRL 97, 191801 (2006)
- Search for / constrain exotic phenomena
- Search for *ν*μ → *ν*e oscillations
- Compare *ν*, *ν* oscillations
- CPT test
- Neutrino interaction physics
- Atmospheric neutrinos
- PRD 75, 092003 (2007)
- PRD 73, 072002 (2006)
- Cosmic rays
- hep-ex/0705.3815
- 10 papers to ICRC 2007
**	****See poster by Jeff de Jong**** **

- Useful Approximations
*ν*μ disappearance (2 flavors):
-  	P(νμ→νx) = 1 - sin22θ23 sin2(1.27Δm232 **L**/**E**)
*ν*e appearance:
-  	P(νμ→νe) ≈ sin2θ23sin22θ13sin2(1.27Δm231 **L**/**E**)
- where **L**, **E** are experimental parameters & θ23, θ13, Δm232 are to be determined

- Δm232 = m32 – m22

*ν*1

*ν*2

*ν*3

*ν*1

*ν*2

*ν*3

## Example of a disappearance measurement

- Look for a deficit of *ν**μ* events at a distance...

- Unoscillated

- Oscillated

- Monte Carlo

- Spectral ratio

- NC subtracted

- 0.0033 eV2

- Unoscillated

- Oscillated

## Example of a disappearance measurement

- Look for a deficit of *ν**μ* events at a distance...

- Unoscillated

- Oscillated

- Monte Carlo

- Spectral ratio

- NC subtracted

- 0.0033 eV2

- Unoscillated

- Oscillated

## Example of a disappearance measurement

- Look for a deficit of *ν**μ* events at a distance...

- Unoscillated

- Oscillated

- Monte Carlo

- Spectral ratio

- NC subtracted

- 0.0033 eV2

- Unoscillated

- Oscillated

## Producing the neutrino beam (NuMI)

- 120 GeV protons strike target
- 10 s pulse every ~2.4s
- Typically running at 2.5e13 protons per pulse
- 2 magnetic horns focus secondary π/K
- π/K decays produce neutrinos
- Moveable target & horn provides variable beam energy

## MINOS Detectors

- Iron and Scintillator tracking calorimeters
- magnetized steel planes <B> = 1.2T
- 1×4.1 cm2 scintillator strips
- Multi-anode PMT readout
- GPS time-stamping to synchronize FD data to ND/Beam
- Main Injector spill times sent to the FD for a beam trigger

- Far Detector
- 5.4 kton
- 8  8  30 m3
- 484 planes

- Near Detector
- 1 kton
- 3.8  4.8  15 m3
- 282 steel planes
- 153 scintillator planes

**Notes:**
Actual FD strips (w/o shield) is 92,928

## A 2 GeV νμ event in the far detector

**1pe PMT cross-talk**

- A 2 GeV *ν**μ* event in the far detector

- Track Energy 	2.04 GeV
- Shower energy 	0.20 GeV
- q/p = -0.52 ± 0.03

## Energy spectra in ND

## Energy spectra in ND

- Data & Nominal MC discrepancy changes energy with beam tune
- Suggests production of hadrons off the target is to blame

## Energy spectra in ND

- Took data in 6 different beam tunes (only 3 shown)
- Varied the dependence on pT and *x*

## MINOS best-fit spectrum for 1.27×1020 POT

- Measurement errors are 1 sigma, 1 DOF
**See poster by Niki Saoulidou**

- PRL 97, 191801 (2006)

| Systematics | Δm2 (10-3 eV2) | sin22θ |
| --- | --- | --- |
| Near/Far normalization | 0.05 | 0.01 |
| Absolute hadronic scale | 0.06 | 0.05 |
| NC contamination | 0.09 | 0.05 |
| All other systematics | 0.04 | 0.01 |
| Total systematic error | 0.13 | 0.07   |

## MINOS allowed region for 1.27×1020 POT

- Measurement errors are 1 sigma, 1 DOF
**See poster by Niki Saoulidou**

- PRL 97, 191801 (2006)

## Projected MINOS sensitivity

- Statistical errors
- 90% C.L.

## Prospects

- Neutrino time of flight
- New data
- 2nd year running experience
- Post-shutdown intensity
- Prospects for future
- Advancing the oscillation analysis
- Electron neutrino appearance
- Neutral current
- Antineutrinos
- Non oscillation physics

## Neutrino Time of Flight(TOF)

- PDG limit is
- |v−c|/c < 4 × 10-5 (95% C.L.)
- Exotic models predict values all the way up to this limit
- Separation between the detectors
- L = 734,298.6 ± 0.7 m
- The TOF for a massless particle
*τ* = 0.002449356 s
- 	δ = -126 ± 32 (stat) ± 64 (syst.) ns
- 	(v−c)/c = [5.1 ± 2.9 (syst. + stat.)] × 10-5 	(68% CL)

- hepex/0706.0437

- δ (μs)

## Neutrino Time of Flight (TOF)

- PDG limit is
- |v−c|/c < 4 × 10-5 (95% C.L.)
- Exotic models predict values all the way up to this limit
- Separation between the detectors
- L = 734,298.6 ± 0.7 m
- The TOF for a massless particle
*τ* = 0.002449356 s
- 	δ = -126 ± 32 (stat) ± 64 (syst.) ns
- 	(v−c)/c = [5.1 ± 2.9 (syst. + stat.)] × 10-5 	(68% CL)

- δ (μs)

- hepex/0706.0437

## Relativistic mass measurement

- Use time and energy to compute a relativistic mass limit
- If the neutrino have mass *m**v** *its time of flight would be
- 		where *τ* is the TOF for a massless particle
- We find
- The limit is driven by the few points near edge
- With full data MINOS dataset ~10 MeV at 99% C.L.

- Line = 68% C.L.
- Shaded = 99% C.L.

- hepex/0706.0437

## The 2nd year of MINOS running

- 1st year of running (published dataset)

- Double dataset
- Collected with 99.4% live time

- More !

## MI intensity improvements: slip stacking

- MI currently running in “2+5” slip stacking
- 2 MI bunches for pbar
- 5 MI bunches for NuMI
- AD demonstrated “2+9” slip stacking
- 2 MI bunches for pbar
- 9 MI bunches for NuMI
- New record for beam in the MI set in April
**4.608****×****10****20**** POT** with good transport efficiency
- Beam delivery limited to 4.0x1020 POT until we have a spare target in-hand (this summer)
- AD plans “2+9” as default after the shutdown

**Notes:**
blue = cumulative beam injected into the MI
green = beam circulating in the MI (on the left hand scale)
red = beam ejected from the machine by the injection kicker (some beam isn't captured in the slip-stack buckets and ends up in the wrong place around the circumference, and is then lost when we inject another batch on top of it) 
magenta = all other beam loss (the big step at 0.8s is the start of acceleration, where we lose any remaining beam that isn't captured in RF buckets). 

## How to we plan to exploit this new data?

- Modeling & reconstruction
- Additional data at higher energies
- Updated flux model
- New hadronization & intranuclear scattering models
- Improved reconstruction & PID algorithms
- Reduce NC systematic errors
- Ongoing improvements in calibration
- Working to extend the oscillation analysis to antineutrinos & higher energies

- MC

## Since initial analysis, implemented beam fitting to antineutrinos

- Since initial analysis, implemented beam fitting to antineutrinos

- Antineutrinos come from π* ***-** off the target
- Rates shown are for normal running conditions
- Simultaneous neutrino and antineutrino fit
- Compared to new p+C data from CERN NA49

**

- Eur.Phys.J.C49:897-917,2007

## High energy neutrinos and kaon production

- Kaons decays tend to produce higher energy neutrinos
- MIPP took p+C thin target data at 120-GeV/*c*
- MIPP took thick-target data with our NuMI target
- Forthcoming

- K ratio

*p*T<0.2 GeV/*c*

- 0.2<*p*T<0.4 GeV/*c*

**Andre Lebedev, Harvard  Ph.D., MIPP-doc-218**

##  → e oscillation search

-  → e oscillation search

**See poster by Tingjun Yang**

**4×10****20**** POT**

**16×10****20**** POT**

- P(νμ→νe) ≈ sin2θ23 **sin****2****2****θ****13** sin2(1.27Δm231L/E)

## Neutral current (NC) events

- NC unaffected by νμ  ντ oscillations
- Can test for sterile neutrino contributions
- Near detector NC energy spectrum
- Far Detector data for this analysis is still blinded
- Currently working on
- Near/Far extrapolation
- FD systematic error evaluation

## Neutrino scattering in the near detector

- Intense NuMI beam
- Recorded 3 ×1020 POT
- 5 × 106 events in the fiducial volume
- Can explore new kinematic regions
- Connect to precision higher energy experiments
- Some non-oscillation analyses underway
- Total CC differential cross-section
- Flux extraction
- DIS differential cross-section
- Structure functions
- Quasi elastic scattering
- Coherent production cross-section ...

- MC

**See poster by Minsuk Kim**

- MC

## Conclusions 

- Results from the first year of accelerator neutrino exposure
- It is consistent with νμ disappearance with the following parameters
- Data also used to measure the TOF and relativistic mass of neutrinos
- 		(v−c)/c = (5.1 ± 2.9) × 10-5 (68% CL, syst. + stat.)
- More than doubled the dataset since shutdown
- Slip stacking offers the prospect of significant intensity improvements after the shutdown
- New analyses are underway on a number of samples

## Slide 29

## MI intensity improvements with slip stacking

- MI currently running in “2+5” slip stacking mode
- 2 MI bunches for pbar
- 5 MI bunches for NuMI
- AD demonstrated “2+9” slip stacking mode
- 2 MI bunches for pbar
- 9 MI bunches for NuMI
- New record for beam in the MI set in April
**4.608E13 POT** with good transport efficiency
- Beam delivery limited to 4.0E13 POT until we have a spare target in-hand (this summer)
- AD plans “2+9” as default after the shutdown
- The intensity to be gradually increased from 2.4E13 POT
- AD continuing preparations for the MI collimator installation during the shutdown

## Look for e appearance
P(νμ→νe) ≈ sin2θ23 sin22θ13 sin2(1.27Δm231L/E)
(plus CP violation and matter effects)
Look for events with compact shower and typical EM profile
Primary background from NC events
Matter effects alter e yield by 20% 
Reach depends strongly on POT
Far Detector data for this analysis is still blinded 
4×1020 POT - can challenge the world’s best limit  (CHOOZ)
16×1020 POT - can significantly improve limit and increase chance of discovery

- Look for e appearance
- P(νμ→νe) ≈ sin2θ23 sin22θ13 sin2(1.27Δm231L/E)
- (plus CP violation and matter effects)
- Look for events with compact shower and typical EM profile
- Primary background from NC events
- Matter effects alter e yield by 20%
- Reach depends strongly on POT
- Far Detector data for this analysis is still blinded
- 4×1020 POT - can challenge the world’s best limit  (CHOOZ)
- 16×1020 POT - can significantly improve limit and increase chance of discovery

-  → e oscillation search

**See poster by Tingjun Yang**

## Neutral current (NC) events

- NC interactions
- Unaffected by νμ  ντ oscillations
- Can test for sterile neutrino contributions
- Large cross-section uncertainty for E ~1 GeV
- Near detector NC energy spectrum
- Far Detector data for this analysis is still blinded
- Currently working on
- Near/Far extrapolation
- FD systematic error evaluation

## Neutrino scattering in the near detector

- Intense NuMI beam offers opportunities for exploring cross-sections
- Recorded 3×1020 POT
- We have 5.5×106 CC interactions in the fiducial volume
- Some non-oscillation analyses underway
- Total CC differential cross-section
- Flux extraction
- DIS differential cross-section
- Structure functions
- Quasi elastic scattering
- Coherent production cross-section
- A few examples of work in progress...

- MC

**See poster by Minsuk Kim for more**

## Deep Inelastic Scattering

- Largest component of the MINOS event sample
- The measurement will be systematics limited
- Can explore new kinematic regions
- Connects to precision higher energy experiments

- MC

## Quasi elastic scattering(vn → μp)

- The QE-enhanced sample can be used to extract the flux for MA measurement
- 3×1020 POT
- 		~ 800,000 events
- Look for
- Well-defined muon track
- Low shower energy
- Low W
- Main background
- Single charged pions