Long Baseline Neutrino Oscillation Experiments

1
Long Baseline Neutrino Oscillation Experiments

• Alfons WeberUniversity of Oxfordfor theMINOS
  OPERA CollaborationsHEP 2001, BudapestJuly 18,
  2001

2

• Beam travels 730 km toSoudan Minnesota
• Sagitta10 km
• 1km wide at destination

3
NuMI Beam Energy

• Fermilab MI
• E 120 GeV
• N 4x1013 p / pulse
• Every 2 seconds
• 10 msec spill

• Tuneable neutrino energy
• Select energy to matchmass difference
• high 7 - 30 ? 10-3 eV2
• medium 3 - 10 ? 10-3 eV2
• low 1 - 5 ? 10-3 eV2

4
MINOS Collaboration
Around 180 Physicists and Engineers
IHEP-Beijing ?Athens ? Dubna ? ITEP-Moscow ?
Lebedev ? Protvino ? Cambridge ? Oxford
Rutherford ? Sussex ? University College London
? Argonne ? Brookhaven ? Caltech ? Chicago ?
Elmhurst ? Fermilab ? James Madison ? Harvard ?
Illinois ? Indiana ? Livermore ? Macalester ?
Minnesota ? Northwestern ? Pittsburgh ? South
Carolina ? Stanford ? Texas-Austin ? Texas AM ?
Tufts ? Western Washington ? Wisconsin
5
MINOS Far Detector

• 2 Super-modules 2.7 kiloton each
• 486 planes of steel and scintillator
• 96 scintillator strips/plane
• read out at both sides with multi-anode PMTs
• Toroidal magnetic field(1.5 T at 2 m radius)

6
MINOS Scintillator Module

• Extruded scintillator, 4.1 cm wide
• Two-ended WLS fiber
• readout.
• Strips assembled into
• 20 or 28-wide modules.
• WLS fibers routed to
• optical connectors.
• Light routed from modules
• to PMTs via clear fibers.
• 8 Fibers/PMT pixel in far
• detector. (Fibers separated
• by 1m in a single plane.)
• 1 Fiber/PMT pixel in near
• detector (avoids overlaps).
• Multi-pixel PMTs Hamamatsu M16 (far), M64
  (near)

Clear Fiber Ribbon Cable (2-6 m)
7
MINOS Plane
2-m wide, 0.5-inch thick, steel plates
Bottom steel plane layer
Scintillator plane Orientations alternate ?90o in
successive planes
Top steel plane layer
8
MINOS Oscillation Physics

• Several channels to analyse neutrino oscillations
• T-Test
• ne appearance
• Combination of all analysis will reveal mixing
  parameters
• Dm2
• sin22q
• flavour

µ
? µ
nm disappearance
hadrons
5 m
nt appearance
hadrons
? µ
? µ
1.5 m
9
T-Test

• Oscillations or not?
• Compare number of short and long events in near
  and far detector
• long events CC nm
• short eventsNC nm, ne, nt CC ne, nt

10
?µ CC Energy Analysis

• Select ?µ charge current events and reconstruct
  neutrino energy
• Resolution functions
• Compare energy spectrum in near and far detector
• Measure ?m2 and sin22?

range, B field
calorimetry
?m2
sin22?
11
?µ Disappearance Results
12
CNGS Beam

• Baseline 730km
• ltE?gt 17 GeV
• optimised for t appearance

• CERN SPS
• Ep 400 GeV
• 4.81013 ppp
• cycle 6 - 27.6 sec
• 7.61019 pot/year

13
OPERA Collaboration
METU, Ankara, Turkey ? LAPP and Université de
Savoie, Annecy, France ? INFN and Bari
University, Bari, Italy ? IHEP, Beijing, China PR
? Humboldt University,Berlin, Germany ? Bern
University, Bern, Switzerland ? INFN and Bologna
University, Bologna, Italy ? IIHE (ULB-VUB),
Brussels, Belgium ? Joint Institute for Nuclear
Research (JINR), Dubna, Russia ? Laboratori
Nazionali di Frascati, INFN Frascati, Italy ?
Toho University, Funabashi, Japan ? CERN, Geneva,
Switzerland ? Märkische Fachhochschule FB
Elektrotechnik, Hagen, Germany ? Technion, Haifa,
Israel ? Hamburg University, Hamburg, Germany ?
High Energy Physics Group Shandong University,
Jinan, Shandong, China PR ? Aichi Educational
University, Kariya, Japan ? Kobe University,
Kobe, Japan ? IPNL and Université C.Bernard,
Lyon, France ? INR, ITEP and MEPHI, Moscow,
Russia ? Münster University, Münster, Germany ?
Nagoya University, Nagoya, Japan ? INFN and
"Federico II" University, Naples, Italy ? LAL and
Université Paris-Sud, Orsay, France ? INFN and
Padova University, Padova, Italy ? INFN and "La
Sapienza" University, Rome, Italy ? Rostock
University, Rostock, Germany ? INFN and Salerno
University, Salerno, Italy ? IRES, Strasbourg,
France ? Utsunomiya University, Utsunomiya, Japan
? Rudjer Boskovic Institute (IRB), Zagreb,
Croatia
14
The OPERA Experiment
super module
15
Muon Identification

• Reject charm background
• Tag and analyse t?µ
• measure E? spectrum with
• target
• spectrometer (calorimeter)
• Fe walls 7.1 ?int instrumented
• identify muons
• shower energy measurement
• Spectrometer
• 3 external high resolution drift tubes

16
Target section

• Emulsion-Scintillator strip Hybrid Target
• Tracker task
• select bricks efficiently
• High scanning power low background allow
  coarse tracking

Selected bricks extracted daily using dedicated
robot
17
Scintillator Strip Target Trackers

WLS fibres
PMT
64 strips
unit
planes
6.7 m

• Scintillator strips (2.6cm wide, 1cm thick)
• Light read out at both WLS fibre ends
• Multi anode 64 ch. PMT (baseline)
• Minimum 6 p.e.
• Probability for 0 p.e. 0.2

18
Emulsion Brick
Origami packed ECC brick for OPERA

• Vacuum packing
• Protection against light and humidity
  variations.
• Keep the position between films and lead plates.
• Vacuum preserved over 10 years

n
10X0 ( 56 emulsion films )
12.5cm
235k bricks for 3 super modules
19
nt Candidate Classes
Long decays? reconstruct kink topology
Short decays ? detect large impact
parameter track
Loose cut to reject low momentum tracks
20
Selection Efficiencies (in and including BR)

• Muon ID
• track in brick
• MIP in scintillator tracker
• momentum measurement in dipolar magnet

• Electron/Hadron ID
• track in brick
• shower in brick E
• multiple scattering
• number of tracks
• distinguish by fit to shower profile

weighted sum of DIS and QE events
21
Sensitivity
(average 90 CL upper limit for a large number
of experiment in the absence of a signal)
5 years data taking
?m2 1.2x10-3 eV2 at
full mixing sin2 (2?) 6.0x10-3
at large ?m2
22
Determination of ?m2
(mixing constrained by SuperK)
assuming the observation of a number of events
corresponding to those expected for the given ?m2
Probability to observe SuperK signal
23
Schedule

• MINOS
• approved (1999)
• FD installation (now)
• cosmics (2001)
• ND installation (2003)
• neutrino beam (2004/5)
• physics results 2 years

• OPERA
• approved (2001)
• installation (2002)
• cosmics (2004/5)
• Filling emulsion (2004)
• neutrino beam (2005)
• physics results 3-5 years

Exciting time! The 2 complementary experiments
will reveal the exact nature of the atmospheric
neutrino anomaly and measure the oscillation
parameters.
24
Particle ID
(1) Different energy loss by multiple scattering
E(x)E0e (-x/X0) for electrons
c2e E(x)E0(1-(dE/dx)x) for hadrons c2h (2)
Detection of electromagnetic shower Requires
low background track density ? controlled fading
Sensitive to electrons close to the Pb critical
energy
25
Expected background
(5 years data taking)