MINOS STATUS AND PHYSICS GOALS

1
MINOS STATUS AND PHYSICS GOALS
George Tzanakos University of Athens
Outline MINOS Experiment Physics
Goals Beam Detectors NUMI Project Status MINOS
Detectors Status Calibration Detector FAR
Detector Performance MINOS 5 Year
Plan Conclusions
2
THE MINOS EXPERIMENT
Precise study of atmospheric neutrino
oscillations, using the NUMI beam and two
detectors.
Far Detector 5400 tons
3
MINOS Physics Goals

• Demonstrate Oscillation Behavior
• Precise measurement of CC energy distribution
  between near and far detector (2-4 sys.
  uncertainty in En per 2 GeV bin).
• Standard or non-standard oscillations?
• Can we see clear oscillatory behavior from the
  first osc. max? Rise at low energy?
• Are there features in the energy spectrum not
  well described by a standard oscillation?
• Precise Measurement of Oscillation Parameters
• Precise Determination of Flavor Participation
• Number of CC nm events far/near 2 Probability
  for nm - nx oscillation.
• Number of CC ne events far/near Sensitive to nm
  - ne oscillation down to about 2.
  Discovery/first measurement of Ue3?
• Number of NC events far/near probability for nm
  - nsterile oscillation down to about 10.
• nms which disappear but dont appear as ne or
  disappear to nsterile must be nt!
• Direct Measurement of Atmospheric n vs n.

4
MINOS Experiment How is it done?
2 Detectors Experiment
Near Detector
Soudan mine
towards Soudan mine
Neutrino Source
Far Detector
5
THE MINOS COLLABORATION
Argonne Athens Brookhaven Caltech
Cambridge College de France Fermilab Harvard
IIT Indiana ITEP-Moscow Lebedev
Livermore University College London
Macalester Minnesota Minnesota-Duluth
Oxford Pittsburgh Protvino - Rutherford
South Carolina Stanford Sussex Texas AM
Texas-Austin Tufts UNICAMP/USP-Brazil
Western-Washington - Wisconson
6
Design Parameters for NuMI

• 120 GeV protons
• 1.9 second cycle time
• 4x1013 protons/pulse
• 0.4 MW!
• Single turn extraction (10ms)
• 4x1020 protons/year
• Initial intensity will be less
• 2.5x1020 protons/year?
• Possible to go beyond 4x1020/year with investment
  in the accelerator complex?

Near detector
7
NuMI Neutrino Beam
CC Events Rates in MINOS 5kt detector

• High 8,000 /2E20 POT
• Med 3,600 /2E20 POT
• Low 1,400 /2E20 POT

8
The NuMI Neutrino Energy Spectra
nm CC Events/kt/year
Low Medium High 470
1270 2740
nm CC Events/MINOS/2 year
Low Medium High 5080
13800 29600
4x1020 protons on target/year 4x1013 protons/1.9
seconds
By moving the horns and target, different energy
spectra are available using the NuMI beamline.
The energy can be tuned depending on the specific
oscillation parameters expected/observed.
9
NuMI Conventional Facilities at Fermilab

• Major complicated conventional construction
• Three major installations in three different
  areas
• Several hundred feet of accelerator
  enclosurehalf of which is between two operating
  machines
• Downstream end of carrier tunnel, Pre-Target
  and Target Areas--primary beam focus, 8KT
  neutrino beam
• MINOS areabeam monitoring, 1 KT hadron absorber
  and 1 KT neutrino detector

10
Installation Challenge NuMI in the Main
Injector Tunnel
MI ring on bottom, Recycler on top, NuMI in the
middle (fit between two accelerators)
NuMI Stub and Extension (needs cranes, utilities
etc.)
.
11
The NuMI Target Hall
12
Neutrino Beam Devices
Target from IHEP
Horn 2
Part of NuMI shielding
13
Fabrication and Testing of Horns
Horn 2 inner conductors.
Prototype horn 1 in test stand
14
NuMI Technical Components
Upstream and Downstream Decay Pipe Ends
Assembly of inner and outer conductors of
(production) Horn 2. (DOE L-1-6)
15
The NuMI Decay Tunnel
16
The Decay Pipe
Pipe is embedded in concrete to protect
groundwater.
17
MINOS Hall in May
18
Service Buildings
Target Service Building (MI-65)
MINOS Service Building
19
Status of NuMI Beamline Construction

• The excavation of the NuMI beamline halls and
  tunnels is complete.
• The decay pipe is installed along with the
  concrete shielding.
• The outfitting of the tunnels and halls is well
  advanced. Done by November.
• The surface buildings are being built.
• First protons on target expected in December
  2004.

20
Detector Technology

• Scintillator strips are extruded polystyrene
  (Itasca Plastic)
• PPO (1) and POPOP (0.03) fluors
• Co-extruded TiO2 reflective coating
• Fiber groove
• Kuraray 1.2mm WLS Fibers
• (Y-11 175ppm)
• PMTs
• Far Detector Hamamatsu R6000-M16 multi-anode
  PMTs (16 channels), 8 fibers/pixel.
• Near Detector M64, one fiber per pixel.
• Viking VA-based front-end electronics.

21
The MINOS Far Detector

• 8 m octagonal steel scintillator tracking
  calorimeter
• Sampling every 2.54 cm
• 4 cm wide strips of scintillator
• 2 sections, 15m each
• 5.4 kton total mass
• 55/?E for hadrons
• 23/?E for electrons
• Magnetized Iron (B1.5T)
• 484 planes of scintillator
• 26,000 m2

One Supermodule of the Far Detector
22
MINOS FAR DETECTOR

• 2 Supermodules
• 5.4 kT, 8.0 m x 8.0 m
• 484 scint. Planes
• 192 strips / plane
• x8 Optical MUX
• 2-end readout
• 1452 M16s
• 92,928 strips (4.1 x 1.0 cm)
• 722 km WLS fiber
• 794 km clear fiber

23
The Near Detector

• 3.8 x 4.8 m octagonal steel scintillator
  tracking calorimeter
• Same basic construction, sampling and response as
  the far detector.
• No multiplexing in the main part of the detector
  due to small size and high rates.
• Hamamatsu M64 PMT
• Faster Electronics (QIE)
• 282 planes of steel
• 153 planes of scintillator

24
MINOS NEAR DETECTOR
veto - target - shower - m spectrometer

• 1 kT, 3.8 m x 4.8 m squeezed octagon
• 282 steel planes
• 153 scint. Planes
• 1-end readout
• no MUX (x4 at m spec)
• 220 M64s
• QIE-based front-end
• 12,300 scint.strips
• 65 km WLS fiber
• 51 km clear fiber

Emulates the Far detector in absorber, active
planes, Bfield
25
SOUDAN MINE MINOS HALL
26
FAR DETECTOR ASSEMBLY
27
(No Transcript)
28
NEAR Detector Construction
29
CalDet Overview
MINOS is underground No calibration beam 5
absolute energy calibration needed 2 relative
Near/Far Calibration detector for Response vs
particle type p,m,e,p Event topology Response vs
energy MEU energy scale Different
electronics Near QIE, Far Viking
CalDet in T7 (CERN)
30
The MINOS Calibration Detector

• A mini-version of the MINOS near and far
  detectors
• 1m x 1m x 3.7 m
• 60 planes x 24 strips/plane
• Readout technologies of both the near and far
  detectors
• Being exposed to electron, pion, proton and muon
  beams from 0.5-10 GeV/c momentum at the CERN PS.
• First data in 2001 up to 3.5 GeV using far
  detector readout.
• Data in 2002 up to 10 GeV and to compare near
  and far electronics.
• Additional running in 2003 with full near
  readout system.
• Physics Goals
• EM and Hadron energy response
• EM and Hadron event topology
• Near/Far readout comparison

Last Dipole
T11
Beam Line
Electronics and PMTs
1m
24 strips
x 60 (3.7 m)
Scintillator
1m
Steel
5.9 cm
31
Calibration Detector
Measure detector response in electrons, muons
and hadrons

• L 3.7 m
• W 1.0 m
• H 1.0 m
• 8 tons
• 60 planes
• 24 strips/ plane
• total 1440 strips
• 2-ended readout
• WLS 3 m clear fiber ribbons
• FAR-Det / NEAR-Det readout
• No magnetic Field

• CERN test beam
• T11 0.5-3.5 GeV
• T7 1-10 GeV)

32
Example events 2 GeV
Electron
Pion
Muon
Proton
Strip
Plane
33
CalDet Response (Preliminary)
MC expectation
34
Cosmic Ray Muon in the Far Detector

• Downgoing Cosmic Ray Muon
• Current rate of CR muons 2 Hz
• Magnetic field not yet on (curvature measurable
  up to 70 GeV)

35
Cosmic Ray Muon in the Far Detector

• Downgoing Cosmic Ray Muon
• Current rate of CR muons 2 Hz
• Magnetic field not yet on (curvature measurable
  up to 70 GeV)

36
Calibrating With Cosmic Rays

• Cosmic ray muons are used to
• measure the light output of the
• scintillator system in all detectors.
• The cosmic-ray muons are used
• to intercalibrate the three detectors.
• Clean muons (no showers) are
• selected for light calibration and
• for each muon the light output is
• corrected for the pathlength to
• the equivalent light
• for 1 cm pathlength.
• PMT gains are corrected
• using light injection data.
• On average 8.5 pes/cm
• (corrected for path-length and
• for muon energy underground)

Single end readout, no corrections.
Average light output for all detector planes.
37
Light Output Uniformity

• Of the 90K scintillator strips currently online
• 0.17 scintillator strips with one-ended readout
• None (!) with zero-ended readout
• 8 pixels not reading out (out of 25k)
• No channels lost to bad cables no cabling
  errors
• Maintenance status as of last week (snapshot)
• 1 pmt readout hole
• 2 LEDs missing
• 1 light injection channel

11 variation (s) over 90 of production in plot
179,000 strip ends completed only 290 show any
damage lt0.2
38
Downward Muons

• 86.8 of the muons recorded come from single muon
  events
• MINOS single muon rates consistent with world
  averages
• Strong test of muon efficiency angular
  recon-struction

T.Gaisser, T.Stanev Particle Data Group
Preliminary MINOS Results (No field data)
39
Time Resolution in the Far Detector

• The time resolution of the MINOS scintillator
  system is determined primarily by the decay time
  of the Y11 fluor in the WLS fiber 8 ns.
• The time resolution for each scintillator strip
  is expected to be 2.5 ns based on the
  photoelectron statistics for muons.
• Current measurement of resolution using downgoing
  muons in the far detector is s2.6 ns/plane.
• The direction of muons can be determined with
  10 planes for contained vertex events.
• To distinguish upgoing from downgdoing
  through-going muons 20 planes are needed.

Distribution of measured time residuals for
muons Passing through all strips in the far
detector. The Time resolution of 2.6 ns is
calculated from this data.
40
Upward-Going Muons
_
_
_
m,m
MINOS
All eventsstopping through going
_
n,n
Earth
41
Direction Determination

• Use Y direction timing and direction cosines at
  vertex to identify upward-going muons
• Tight 1/b (c/v) distribution indicates good
  timing
• Negative 1/b values indicate upward-going muons
• Peak at 1/b -1 clearly seen

s 0.056
42
Example Eventm with p 5.4 GeV/c
Time vs z
Time vs y
y
x
y vs x
z
y vs z
Strip vs Plane
43
Preliminary Upward-Going Muon Flux

• Horizon cos q 0
• Nadir cos q -1
• cos q bins of 0.1
• There are 12 upward going events in the data
  sample

44
Charge and Momentum of Upgoing Muons
One Sign
The Other Sign

• All muons are assigned a charge, based on the
  most likely hypothesis.
• Above 100 GeV, the charges and the momenta are
  not very reliably
• determined at this time.
• Below 70 GeV, charge and momenta are generally
  well determined.

45
Contained Vertex Events

• We now have data from the completed and optimized
  SM1 veto shield
• Double layer everywhere but walls

46
A very low energy contained event
47
A medium energy contained vertex event
nm interaction
48
Atmospheric Neutrino Measurements

• MINOS is the first large underground detector
  which has a magnetic field.
• Measure charge/momentum of muons from 0.5-70
  GeV/c momentum.
• Events with the neutrino interaction in the
  detector and exiting muon still have complete En
  measurement L/E measurements.
• Event direction reconstructed using timing and
  topology.
• Able to distinguish CC nm and nm events from NC
  and CC ne events over a very broad energy range
  as long as pm gt 1 GeV/c.
• We can directly compare whether atmospheric nm
  and nm oscillate in the same way.

Probability of c2 for nominal neutrino
oscillation Parameters compared to different
values of dm2 For antineutrinos.
Number of events in 24 kT years
Neutrino Antineutrino Reconstructed contained
vertex with muon 620
400 Reconstructed upgoing muon
280 120
49
Atmospheric nu/nubar in MINOS
Contained Vertex Events
Reconstruction efficiency vs neutrino energy
Reconstruction efficiency vs muon momentum
Use all reconstructed contained vertex
events Direction and charge determined for
all reconstructed events Up/down ratios and L/E
can be used. Upgoing Muons Direction determined
by definition, charge up to 70 GeV
50
Neutrino L/E
L/E for all reconstructed contained-vertex
neutrino events in MINOS (5 years). Histogram is
no-oscillations while triangles are with nominal
oscillations.
Ratio of no-oscillation/oscillated L/E for all
reconstructed contained-vertex neutrino Events in
MINOS (5 years)
51
MINOS Running Plan

• Draft Fermilab Long-Range Plan
• NuMI beam commissioning starting in Dec. 2004.
• 4 years of physics running for MINOS starting in
  April 2005.
• Goal for protons on target in first year 2.5 x
  1020
• Plans are being developed for increased proton
  intensity.
• New MINOS Running Request (May 2003)
• MINOS has submitted a request to Fermilab for 5
  years of running with a total of 25 x 1020
  protons on target in that time.
• MINOS has provided updated physics sensitivity
  curves based on 7.4, 16 and 25 x1020 total
  protons on target. (Original MINOS physics
  sensitivity curves were based on 7.4 x 1020 pot.)
• There are several options for providing this
  number of protons.

52
Topology of Neutrino Events
nm CC
n
n

• Two views of a nm CC event with the neutrino
  interaction at the left side moving to the
  right. Each histogram bin is one scintillator
  strip. The height of each bin is the number of
  observed photo-electrons (energy deposition).
• Identified by a relatively long/simple track in
  an event. At very low energies, there can be some
  background from NC p-.
• The near detector is used to understand event
  identification.

53
Topology of Neutrino Events
ne CC
n
n
Quasi-elastic event with a 4 GeV electron

• Two views of a ne CC event with the neutrino
  interaction at the left side moving to the
  right. Each histogram bin is one scintillator
  strip. The height of each bin is the number of
  observed photo-electrons (energy deposition).
• Identified by lack of a long track and with a
  relatively concentrated EM shower in the core.
  Main background comes from NC p0 events.

54
Topology of Neutrino Events
nm NC
n
n

• Two views of a nm NC event with the neutrino
  interaction at the left side moving to the
  right. Each histogram bin is one scintillator
  strip. The height of each bin is the number of
  observed photo-electrons (energy deposition).
• Identified by lack of a long track and and lack
  of a strong EM shower in the core. Some high y CC
  events are background.

55
Measurement of Oscillations in MINOS
For Dm2 0.0025 eV2, sin2 2q 1.0
Oscillated/unoscillated ratio of number of nm CC
events in the far detector vs Eobserved
MINOS 90 and 99 CL allowed oscillation
parameter space.
56
Measurement of Oscillations in MINOS
For Dm2 0.0016 eV2, sin2 2q 1.0
Oscillated/unoscillated ratio of number of nm CC
events in the far detector vs Eobserved
MINOS 90 and 99 CL allowed oscillation
parameter space.
57
Appearance of Electrons
For Dm2 0.0025 eV2
For Dm2 0.0025 eV2, sin2 2q13 0.067
3 s discovery potential for three different
levels of protons on target and versus systematic
uncertainty on the background.
Observed number of events identified as coming
from ne CC interactions with and without
oscillations. 25x1020 protons on target.
58
Appearance of Electrons
(5 years, 3kt)
Dm2 0.0025 eV2
90 CL Exclusion Limits
MINOS 3s Discovery Limits

• MINOS sensitivities based on varying numbers of
  protons on target

59
Conclusions

• The MINOS Detectors together with the NuMI beam
  will permit a next step in precision measurements
  of atmospheric neutrino oscillations
• Precise energy distribution Showing the
  oscillation signature (?)
• Precise measurement of Dm2
• Precise determination of participation of
  different neutrino flavors
• Extend sensitivity for small nm - ne mixing
• Measurement of anti-neutrino mixing for
  atmospheric neutrinos
• Construction of the MINOS far detector is 99
  complete and cosmic ray data is being accumulated
  with installed planes.
• Data acquisition for cosmic rays and atmospheric
  neutrinos underway!
• Construction of the NuMI beamline is nearing
  completion. The tunnel excavation is complete.
  The outfitting and final civil construction is on
  schedule. The installation of beam components and
  near detector is ready to go.
• First protons on target scheduled for December
  2004.
• Running plans, including increased protons on
  target are being developed.