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Distance Determination between the MINOS Detectors for TOF Measurements

Dr. Virgil Bocean

Alignment & Metrology Department Fermilab

2 September 12, 2012 Virgil Bocean – IWAA2012

• Part of the neutrino research program at Fermilab is the search for non-zero neutrino mass • Looks for neutrino oscillations (νµ → ντ) or (νµ → νe) • NuMI (Neutrinos at the Main Injector) has built a new particle beamline capable of directing a pure

beam of muon neutrinos • MINOS (Main Injector Neutrino Oscillation Search) experiment uses NuMI beam to search with

significantly greater sensitivity for neutrino oscillations utilizing two detectors: • Near Detector - located close to the neutrino source (1 km away from the target) • Far Detector - 735 km away, in a deep underground mine in northern Minnesota, 710 m below

the surface

• Recent results on neutrino velocity measured with the Opera detector and CNGS beam raised questions about the neutrinos possibly traveling faster than light.

• As a result, this generated increased interest in determining the precise distance for verification of the neutrino time-of-flight (TOF)

• The distance for NuMI TOF measurements was computed between the front (most upstream) planes of the Near and Far detectors (the events timestamp was reduced to those planes)

• A rigorous solution for computing the Euclidian distance between the two detectors along the beam path requires precise knowledge of the absolute positions of those detectors in space

Introduction

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NuMI Beamline From Fermilab to Soudan, MN

September 12, 2012 Virgil Bocean – IWAA2012

735 km

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NuMI Tunnels and Halls

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IWAA2010 September 13-17, 2010

DESY, Germany

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• Primary proton beam centered ± 12 m at the far detector (± 0.016 mrad = 3.4 arc sec) • Neutrino beam centered ± 75 m at the far detector ± 0.102 mrad = 21 arc sec) • NuMI is mainly sensitive to final primary beam trajectory : primary beamline components, Target and Horn

alignment => relative positions ±0.35 mm

Beam position at target ± 0.45 mm

Beam angle at target ± 0.7 mrad

Target position - each end ± 0.5 mm

Horn 1 position - each end ± 0.5 mm

Horn 2 position - each end ± 0.5 mm

Decay pipe position ± 20 mm

Downstream Hadron monior ± 25 mm

Muon Monitors ± 25 mm

Near Detector ± 25 mm

Far Detector ± 12 m

Alignment Tolerances (1σ)

September 12, 2012 Virgil Bocean – IWAA2012

• The correct aiming of the beam is of great importance for the experiment

• Requires a rather exact knowledge of the geodetic orientation parameters of the beam => absolute & relative positions of the target (Fermilab) and the far detector (Soudan) at the global level

• Two steps procedure:

1. FNAL/Soudan long GPS baseline measurements tie the surface control to the National Geodetic Survey’s Continuously Operating Reference Station (CORS) precision GPS geodetic network vector known to better than 1 cm horizontally and vertically solution in International Terrestrial Reference Frame of 2000

(ITRF00) reference system => then transformed in the national North American Datum of 1983 (NAD 83) system

NGS will provide an independent solution (excellent agreement within 1 cm)

2. Inertial system survey through 713 m shaft tied the the 27th level of the mine to surface geodetic control

University of Calgary Department of Geomatics Engineering contracted to perform the survey with an rms be below 1 meter

A posteriori coordinates transfer accuracies : latitude 0.48 m, longitude 0.20 m and height 0.23 m

Geodetic determination of global positions

6 September 12, 2012 Virgil Bocean – IWAA2012

Ellipses of Error @ 95% confidence level (bar scale tick = 1 mm)

Ellipses of Error in x, y plane Errors in Height

Rms of residuals @ 95% confidence level Long/Lat = 2 mm Height = 6 mm

Geodetic determination of global positions Results

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• NuMI global position accuracy is shown

September 12, 2012 Virgil Bocean – IWAA2012

Comparison between coordinates and geodetic parameters

8 September 12, 2012 Virgil Bocean – IWAA2012

FROM TO Normal Sect Az ∆ Az Vertical Angle ∆ VA Distance ∆ D(d-m-s) ( sec) (d-m-s) ( sec) (m) ( m)

66589_94 SHAFT_94 336-05-52.35714 0.01079 3-17-17.88121 0.00122 735272.273 0.78566589_94 SHAFT_98 336-05-52.33031 0.03762 3-17-17.89081 -0.00838 735272.862 0.19666589_CORS Fermi SHAFT_CORS Fermi 336-05-52.36793 -0.00335 3-17-17.88412 -0.00169 735273.061 -0.00366589_CORS NGS SHAFT_CORS NGS 336-05-52.36458 0 3-17-17.88243 0 735273.058 0.000

FROM TO n e up ∆ n ∆ e ∆ up Comment(m) (m) (m) ( m) ( m) ( m)

66589_93 SHAFT_93 671107.806 -297423.720 -42175.340 0.725 -0.296 -0.050 NGS NAD83 tie66589_93 SHAFT_98 671108.303 -297424.045 -42175.408 0.229 0.029 0.018 GPS differential66589_CORS Fermi SHAFT_CORS Fermi 671108.540 -297424.003 -42175.396 -0.008 -0.013 0.006 CORS calc Fermi66589_CORS NGS SHAFT_CORS NGS 671108.532 -297424.016 -42175.390 0.000 0.000 0.000 CORS calc NGS

Coordinates in Local Geodetic System at 66589

Geodetic parameters for beam orientation

Underground coordinate transfer at Soudan The weakest link!

9 September 12, 2012 Virgil Bocean – IWAA2012

Setup of the IMU in the cage and the coordinate transfer performed by a total station at the surface

• HG Honeywell 2001 Inertial Navigation System (INS) unit: o composed of 3 accelerometers and 3 gyroscopes o output specific forces and respective angular velocities

from the orthogonal sensor triads o outputs used in a dead-reckoning method which after

initialization provides three dimensional geodetic coordinates at a high data rate

• The accuracy of the results depends of: o the quality of the hardware, on the o the method used to estimate systematic errors

inherently present in the sensors

• Multiple determinations running the unit rigidly attached in the center of the elevator car

• Mapped the 710 m deep access shaft by setting the inertial system at 1 second data collecting rate

• A posteriori coordinates transfer accuracies : latitude 0.48 m, longitude 0.20 m and height 0.23 m

Performance Parameter Class II 1.0 nmi./h gyro bias uncertainty (deg/h) 0.003 gyro random noise (deg/ √h) 0.001 gyro scale-factor uncertainty (ppm) 1 gyro alignment uncertainty ( arc sec) ? accelerometer bias uncertainty (mGal) 10-25 accel. scale-factor uncertainty (ppm) 50 accelerometer alignment uncertainty (sec) 5 accelerometer bias trending (mGal/sec) ? σpos 0.5 m at ZUPTs every 3 min σacceleration net bias < 50 mGal

short term bias < 3 mGal

• Needed knowledge of the gravity vector at the origin (Fermilab) • Previous study comparing a Local Geoid Model and NGS Geoid93 model • Differences up to 5 mm (consistent with expected values) • LBNE beam within 1.5 mm range of differences • Geoid93 model (presently used) - sufficient to cover tolerance

requirements

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41 48 5141 49 0041 49 0941 49 1841 49 2741 49 3641 49 4641 49 5541 50 0441 50 1341 50 2241 50 3141 50 4041 50 4941 50 5841 51 0741 51 1641 51 2541 51 3441 51 4341 51 53Main Injector

LBNE

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Main Injector

LBNE

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Geodetic determination of global positions Geoid consideration

September 12, 2012 Virgil Bocean – IWAA2012

N

• Provides the basis for construction surveys and for the precision underground control networks • existing Fermilab control network (accuracy < 2 mm @ 95% confidence level)

• horizontal geodetic datum = North American Datum of 1983 (NAD 83) based on the reference ellipsoid Geodetic Reference System 1980 (GRS-80)

• vertical datum = North American Vertical Datum of 1988 (NAVD 88)

• geoid model = NGS model Geoid93

• includes 3 monuments tied through CORS to Soudan

• add 6 new geodetic monuments (densification around access shafts) • ~400 GPS, terrestrial and astronomic observations • error ellipses in millimeter range (@ 95% confidence level)

NuMI

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Primary geodetic network at Fermilab

September 12, 2012 Virgil Bocean – IWAA2012

Ellipses of Error @ 95% confidence level (bar scale tick = 1 mm)

Ellipses of Error in x, y plane Errors in Height

Primary surface geodetic network at Fermilab Results

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Histogram of standardized residuals (bar scale tick = 1 σ)

September 12, 2012 Virgil Bocean – IWAA2012

• NuMI surface geodetic network accuracy is shown

• Provided vertical sight risers for transferring coordinates from the surface to the underground (better and more efficient for controlling error propagation in a weak geometry tunnel network)

• Network simulations => 7 locations for transferring coordinates from the surface (3 vertical sight risers, 2 tunnel Access Shafts and 2 Exhaust Air Vent pipes)

• Due to the increased depth of the tunnel, designed adequate procedure for precision transfer of surface coordinates underground

Precision underground control networks

13 September 12, 2012 Virgil Bocean – IWAA2012

• Built to support the alignment of Primary Beam components, the Target and focusing Horns and the installation of the two Near and Far detectors

• Components alignment scope: - Primary beam magnets and instrumentation aligned to ±0.25 mm - Target station components aligned to ±0.5 mm - Detectors :

determine the relative position of the scintillator modules with respect to each other and the detector structure within ±5 mm

additionally: provided feedback on plane-to-plane movements (lateral drifts, pitch, and warping of the planes)

• Error budget networks requirements ±0.50 mm at 95% confidence level

• Primary Beam network => continuous from MI-60 to the downstream end of the Target Hall + two separate Near and Far detector networks

• Constraints at underground transfer points: sight risers, access shafts and aer exhaust vents • Network type: Laser Tracker processed as trilateration • Additional measurements to study and control network behaviour

• Final primary beam trajectory azimuth confirmed by first order Astronomical Azimuth at 0.004 mrad (0.74 arc sec) with s=±0.001 mrad (0.21 arc sec)

• Detectors azimuth confirmed through precision Gyro azimuth to < 0.010 mrad (2 src sec)

Precision underground control networks

14 September 12, 2012 Virgil Bocean – IWAA2012

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-0.330 -0.220 -0.110 0.000 0.110 0.220 0.3300

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5000Data: NuMI Tunnel Network (Stub+Pre Target+Target Hall)Model: GaussEquation: y=y0 + (A/(w*sqrt(PI/2)))*exp(-2*((x-xc)/w)̂ 2)Weighting: y No weighting Chî 2/DoF = 6.08502R^2 = 0.99442

count 22976σ 0.110 mm

y0 72.79747 ±24.34984 mmxc 0.02451 ±0.142 mmw 0.15296 ±0.003 mmA 1035.41393 ±19.33207 mm

Freq

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Residuals (mm)

Residuals Gaussian Fit

(bar scale tick = 1 σ)

NuMI primary beam underground control network Results

• Errors Ellipses ±0.45 mm and histogram of residuals σ=±0.110 mm at 95% confidence level XY Error Ellipses 95% Confidence Level (2.45σ)

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• NuMI underground network accuracy is shown

September 12, 2012 Virgil Bocean – IWAA2012

MINOS detectors underground control networks Results

16 September 12, 2012 Virgil Bocean – IWAA2012

-0.36 -0.24 -0.12 0.00 0.12 0.24 0.360

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Count = 13187 σ = 0.120 mmCenter = 0.022 mm

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Count = 1688 σ = 0.077 mmCenter = 0.010 mm

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Residuals (mm) Gaussian Fit

• measured with the Laser Tracker and processed as trilateration • additional measurements to study/control network behaviour and for confirmation: Mekometer distances, angles, gyro-azimuths and precision levelling • network results: relative errors below ±0.35 mm at 95% confidence level

MINOS Far Detector Hall Network Histogram of standardized residuals

(bar scale tick = 1 σ)

MINOS Near Detector Hall Network Histogram of standardized residuals

(bar scale tick = 1 σ)

• MINOS underground network accuracy is shown

MINOS detectors installation

17 September 12, 2012 Virgil Bocean – IWAA2012

MINOS far detector: at Soudan mine 5.4 kton tracking calorimeter 486 planes (steel and scintillator) 8 m wide, octagonal shape two super modules surveyed with the indoor GPS system: a

posteriori accuracy sX =±2 mm, sY =±3.5 mm, σZ (along the detector) =±6.8 mm

MINOS near detector: at Fermilab 980 tons (smaller version) 282 planes (steel and scintillator) 3.8x4.8 m, “squashed octagon” reference for the far detector surveyed with the Laser Tracker: a posteriori

accuracy σX, Y, Z (along the detector) =±1 mm

Surveying MINOS Far Detector with Indoor GPS (conceptual setup)

18 September 12, 2012 Virgil Bocean – IWAA2012

MINOS TOF distance summary

19 September 12, 2012 Virgil Bocean – IWAA2012

• The MINOS TOF distance from the front plane of the Near Detector to the front plane of the Far Detector:

D = 734286.898 m±0.5 m

• In the error budget analysis, the accuracy of determining this distance is preponderantly being driven by the uncertainty of the Inertial Measurement System instrument used to tie the precise geodetic network on the surface and the underground control used to support the installation of the Far Detector.

• As reported by the contractor who performed the survey (The Department of Geomatics Engineering from the University of Calgary), the computed accuracies were 0.48 m, 0.20 m and 0.23 m in latitude, longitude and height, respectively, where the 0.48 m on latitude is dominant since the beam points almost North.

Backup slides

20 September 12, 2012 Virgil Bocean – IWAA2012

Slide Number 1Slide Number 2Slide Number 3Slide Number 4Alignment Tolerances (1s)Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 10Slide Number 11Slide Number 12Slide Number 13Slide Number 14Slide Number 15Slide Number 16Slide Number 17Slide Number 18Slide Number 19Slide Number 20