Status of MINOS

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Status of MINOS

• Alec Habig for the MINOS Collaboration
• Neutrino Workshop, IIT-Mumbai, India
• Tuesday, August 2, 2005

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 AM Texas-Austin
Tufts UCL Western Washington William Mary
Wisconsin
32 institutions 175 physicists
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MINOSMain Injector Neutrino Oscillation Search

• Investigate atmospheric nm 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

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Physics Goals

• Confirm nm?nt flavor oscillations
• Provide high statistics discrimination against
  alternatives such as decoherence, n decay, etc
• Precise (10) measurement of Dm223
• Search for subdominant nm?ne oscillations
• a shot at measuring q13
• Directly compare atmospheric n vs n oscillations
  (a test of CPT)
• MINOS is first large underground detector with a
  magnetic field for m/m- tagging

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nm Disappearance Sensitivity

• Measure nm flux at Near Det, see whats left at
  Far Det
• Simulated results plotted as ratio
• Position of dip gives Dm2
• Depth of dip gives sin22q
• Spectral ratio shapes differ in alternative
  models

Data simulated at ?m2 0.0025eV2,
sin22? 1.0 Top after 3 years at nominal
intensity Bottom after possible intensity
upgrades
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ne Appearance Sensitivity

• Detection of ne at Dm2atm is evidence for
  non-zero q13
• If q13 close to CHOOZ limit
• MINOS will see a 3s signal in 3 years of running
• Otherwise, will improve limit by factor of several

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Far Detector

• 486 planes, 5400 tons total
• Each 1 steel 1 cm plastic scintillator thick
• 8 m diameter, 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

A module of 20 strips
8 fibers on a pixel
on a plane
M16 PMT
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Soudan Mine Underground Lab

• Soudan Iron Mine has been a state historical park
  since the 1960s
• A new cavern has been excavated at the bottom of
  the mine
• 700 m (2070 mwe) deep
• Adjacent to site of former Soudan-2 experiment
• Cryogenic Dark Matter Search (CDMS 2) in Soudan-2
  hall

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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

4.8 m
3.8 m
n
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Caldet

• 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
• 2 relative, 5 absolute energy scale are the
  goals of the total MINOS calibration

EM
Hadronic
Hadronic
EM
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Scintillator

• Polystyrene strips co-extruded with TiO2
  reflective coating
• 1 PPO, 0.030 POPOP
• Wavelength shifting fiber glued into groove to
  remove light without self re-absorption

A blue LED lights up the Scintillator
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Main Injector

• The Main Injector accelerator
• rapid cycling (up to 204 GeV/c/s)
• 120 GeV protons
• Current NuMI intensity 1.9-2.2 x1013 protons per
  pulse every 2-4 sec
• 5 (6) proton batches are
• injected from Booster into MI
• Accelerated
• single-turn extracted to the NuMI target in 8
  (10) ms
• NuMI gets that 6th batch when pbar do not need to
  be made
• Intensity goals
• This year 2.5x1013 ppp every 2 s
• NuMI design goal 4x1013 protons every 1.9 s (0.4
  MW)
• 2008-9 expected rate 3.4x1020 protons/year

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NuMI Beamline
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NuMI Beam

• H2O cooled graphite target
• 2 interaction lengths absorb 90 of primary
  protons
• Flexible configuration of 2 parabolic horns
• H2O cooled, pulsed with a 2.6 ms half-sine wave
  pulse of 200 kA
• Target, horns movable in beam direction
• Allows tuning of focused pion energy
• 675 m long decay pipe
• radius of 1 m, evacuated to 1 Torr
• 1 hadron monitor and 3 muon monitor stations

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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
• At L of 735 km and Dm2 indicated by Super-K, the
  Low energy beam is closest to the first
  oscillation minima
• And unfortunately also the least intense

Fardet ?µ CC Events/year (_at_2.5x1020 pot) (with no
oscillations) Low Medium High 1,600
4300 9250
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First Beam nm

• In the Near Detector
• During beam engineering runs January 21, 2005
• In the Far Detector
• Soon after nominal intensity first reached, March
  20, 2005

See http//www.sudan.umn.edu/ for live MINOS
events!
U view V view
First beam n seen in the Far Detector, an
entering rock m
Note the curvature this is a m-
Face-on
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Lots of n in the Near Detector

• Many n interactions per spill (in 8 ms)
• Near Detector Electronics gates for 19 ms during
  the entire spill
• Digitizes continuously every 19 ns, no dead time

U view V view
A typical pHE spill
Events per spill at different beam energies
from real data!
Face-on
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Event Slicing
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Sanity Checks
Using Near Det n events
Events have correct time structure wrt the beam
spill 5 batches over 8 ms
Coil hole Fiducial volume
Events coming from expected direction 3o above
horizon, 156o in azimuth
Event vertices where they should be (beam
direction out of page)
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n in Far Detector
Using Far Det n events from pHE beam to validate
30 n candidates
Far Det. Beam contained vertex neutrino candidate
Beam n Cosmics
They camefrom Fermilab
Rather than many per spill _at_NearDet, only
one interaction per thousands of spills _at_FarDet!
Track angle w.r.t. beam direction
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Beam Status

• Steady running, around 1.9-2.2x1013 protons every
  2 seconds
• In April, coolant leak in target stopped things
• gt10,000 events/day in Near Detector!
• Goal by Fermilabs annual shutdown this fall
• 1x1020 pot
• gt100 Far Detector nm CC events (if no osc.)

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End of Year Sensitivity

• Comparable to K2K statistics by end of 2005!

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Atmospheric n

• n oscillations depend upon baseline and energy
• B-field, m range determine pm (correlated to En),
  arrival direction determines L (from geometry of
  Earth)

Plot data by momentum and cos(qzen) for best
oscillation sensitivity
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Atmospheric nClasses
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Contained Vertex Atmospheric n

• Data from commissioning of Far Detector July 2003
  through March of this year
• After data quality cuts, 418 live-days or 6.18
  kton-yr
• Monte Carlo data for signal and background
• GMINOS GEANT3 Detector simulation, Barr'04
  neutrino flux at solar maximum, NEUGEN 3
  cross-section models, GCALOR used as default
  hadronic package.
• Cosmic muons reweighted for azimuth/zenith
• 19M Cosmic MC (280 days), full spectrum.
• 2M Cosmic MC, Eµlt2GeV 4.1 years
• 1300 years of atmospheric n signal MC.

Preliminary!
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Contained Vertex Atmospheric n Data

• 28 upward vs 49 downward
• up/down Rdata 0.5710.135
• Selection not up-down symmetric
• expect RMC 0.92 0.03 (no osc.)
• Rdata/RMC 0.620.140.02 (2.6 sigma from 1)
• (Currently no sys error for up-down flux
  uncertainties, likely around 5)

Preliminary!
Contained n Vertex Data Expect (no osc) Expect (Dm20.0025 eV2)
Low res timing 30 374 283
Ambiguous nm/nm 25 263 202
nm 34 424 313
nm 18 232 172
Good timing subtotal 77 929 697
Total 107 12913 979
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Contained Vertex Atmospheric n Data
Preliminary!
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Upward-going m

• High energy atmospheric nm interacting in the
  rock surrounding the detector produce an entering
  m
• Cosmic ray induced m come downward through
  smaller rock overburdens
• Any m going up is from a nm
• Long m range in rock at high energies allows a
  much larger target volume of rock than the
  detector itself

µ
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m Direction

• Cosmic Ray m give 1/b Gaussian distributed about
  1
• Arrive at a rate of one every couple seconds
• m going in the reverse direction (up!) are
  Gaussian distributed about -1
• Arrive at a rate of about once per week
• The two types of events are clearly separated
• Good timing resolution prevents tails of CR
  events from contaminating n events

Upward-going n-induced m mean b-1.0, sb0.051
Downward-going CR-induced m Mean b1.0, sb0.049
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Up-m Data

• Data collected from July 2003 till April 2005
• 464 live-days
• 304 with normal B-field
• 160 with reversed B-field for cross-checks
• Cuts applied
• lt2.0 m track length, lt20 planes crossed
• Vertex, endpoint of track within 50 cm of
  detector surface
• Tracking, timing quality criteria
• 72 efficient
• 91 n-induced up-m found
• 1 per 5.1 days

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An up-m Event
U vs Z view
To FNAL
V vs Z view
Time vs Y (note upward slope!)
Face-on (X-Y) view. N enters lower right, exits
upper left
n-induced upward m pm 8.4 GeV/c
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Up-m Monte Carlo

• Expectations calculated using 2500 years exposure
  equivalent Monte Carlo data
• NUANCE event generator using Bartol96 flux, GRV94
  pdf, GEANT 3 detector simulation
• Same reconstruction and cuts as data
• MC validated with CR m data (eg. figs below)

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Zenith Angles
All data
Low pm
Medium pm
High pm
Up (long L)
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n vs n

• First deep underground detector with a magnetic
  field
• Can get m charge ID on an event by event basis
• Thus able to check that n oscillate the same as
  n, a probe of CPT violation
• Can also measure cosmic ray m/m- ratio n-induced
  up-m charge results
• 25 m-,16 m rest too stiff to get a reliable
  charge ID

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Summary

• MINOS is alive, the NuMI beam is beaming
• Gobs of Near Detector data already
• Far Detector interactions ticking along, will be
  able to compare to K2K this year
• Atmospheric n data continues to be acquired
  during beam running
• Charge and momentum determination hold promise as
  more data is acquired for Oscillation, CPT
  analyses
• Atmospheric data consistent with Oscillations,
  proper oscillation fits in progress

This work was supported by the U.S. Department of
Energy, the U..K. Particle Physics and Astronomy
Research 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 presentation
was directly supported by NSF RUI grant 0354848.
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Extra Slides
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Timing Calibrations

• Timing can tell the direction
• Use downgoing CR m to calibrate timing
• Adjust timing constants (electronics offsets,
  cable lengths, timewalk, etc.) to properly
  reconstruct them with b v/c 1
• Crosscheck time light seen at opposite ends of
  same strip with position from track, get
  difference D
• sD0.17 m ? st2.4 ns resolution
• Composed of 1.56 ns clock granularity, 2.0 ns
  inherent signal resolution

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Target Leak

• Target filled with water in March due to coolant
  leak
• Currently back-pressurized with He
• Have spare target, but no spare target carrier
• Building new spare carrier will be ready in
  August

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Moon Shadow

• Far Det has been taking Cosmic Ray data since
  July 2003
• gt10 million cosmic m
• Observing the shadow of the moon validates muon
  tracking, surveying, ability to project tracks
  onto the sky
• Demonstrates angular resolution lt1o
• High-momentum m give better resolution