Oscillation Project with Emulsion tRacking Apparatus F. Juget
Institut de Physique Universit de Neuchtel Neutrino-CH meeting,
Neuchtel June 21-22 2004 Slide 2 Physics motivation The OPERA
detector Physics performance Conclusion Slide 3 Motivation
Appareance search of oscillations in the parameter region indicated
by S-K for the atmospheric neutrino deficit. P( ) = cos 4 ( ) sin 4
( 23 ) sin 2 (2 23 ) sin 2 (1.27 m 2 L/E) P( e ) = sin 2 ( ) sin 2
( 13 ) sin 2 (1.27 m 2 L/E) m 2 = m 2 23 m 2 13 Search for e : put
new constraints on Actual result: (CHOOZ): sin 2 13 < 0.1 =>
Search for appearance in the CNGS beam Recent results
Super-Kamiokande (NOON 2004) best fit: m 2 = 2.4 10 -3 eV 2 sin 23
= 1.00 1.9 10 -3 eV 2 < m 2 < 3.0 10 -3 eV 2 sin 23 > 0.9
} at 90% CL P( ) = cos 4 ( ) sin 4 ( 23 ) sin 2 (2 23 ) sin 2 (1.27
m 2 L/E) Slide 4 OPERA/CNGS: long base-line project Seach for
appearance at the Gran Sasso laboratory 732 km from CERN Beam
optimized for appearance For m 2 = 2.4 10 -3 and maximal mixing
(sin 2 2 expect 23 CC/kton/year at Gran sasso 6.7 10 19 pot/year at
CERN (shared mode) Slide 5 Principle: direct observation of decay
topologies in cc events The basic unit: The BRICK sandwich of 56 Pb
sheets 1mm + 57 emulsion layers 206 336 bricks are needed target
mass: 1.8 ktons requires high resolution detector ( m): use
photographic emulsions Needs large target mass: alternate emulsion
films with lead layer Slide 6 8 m Target Trackers Pb/Em. target
Electronic detectors select interaction brick Emulsion scanning
vertex search Extract selected brick Pb/Em. brick 8 cm Pb 1 mm
Basic cell Emulsion decay search spectrometer e/ ID, kinematics ID,
charge and p (DONUT) OPERA an hybrid detector What the brick cannot
do: trigger for a neutrino interaction muon identification, charge
measurement => need for an hybrid detector Slide 7 Slide 8 Slide
9 Spectrometer 1 May 17 Slide 10 Last slab placing 19/5 (2.5 weeks
in advance) Slide 11 May 25: Main structure start (drilling the
floor for fixing) Slide 12 Detector installation schedule Brick
walls and Target Tracker walls for SM1 Aug. 04 Jun 05 Brick walls
and Target Tracker walls for SM2 Jul. 05 Mar 06 Installation of
Brick Manipulator System (BMS) Beginning 2005 Start filling walls
with bricks July 2005 Ready to take data for 2006 Slide 13 CC
interaction identified looking at the decay => search for a kink
in consecutive emulsions decay channels: (17%) e e (18%) h +
neutrals + (49%) 3h + neutrals + (15%) Slide 14 Basic Ideas of
Volume Scanning 3D reconstruction of microtracks Track linking
through emulsion base Track linking through different emulsion
sheets Vertex/Decay Reconstruction Track processing takes further
steps to reach physics goals Slide 15 Automatic Scanning:Nagoya and
Europe R&D efforts Bari, Bern, Bologna, Lyon, Mnster, Napoli,
Neuchtel, Roma, Salerno Routine 10cm 2 /hr Near future 20cm 2 /hr
S-UTS prototype at Nagoya Dedicated hardware Hard coded algorithms
Europe prototype (Neuchtel exemple) Commercial products Software
algorithms ~ 2mrad x ~ 0.5 m Slide 16 Track M Track D 1 Manual
Check Track M was not found in sheet 29; Track D 1 was not found in
sheet 30; Track D 2, pointing to interaction vertex, was found only
in upstream layer of sheet 29 (electron?); Sheet 30 Sheet 29 Track
M Track D 1 Track D 2 980 m Reconstruction Track M having beam
slopes (0.056;- 0.004) and track D 1 having slopes intersect in a
kink topology; Brick exposed to beam at 7 GeV/c Detected
interaction vertex Slide 17 Movie from E. Barbuto Salerno
University Slide 18 Event reconstruction with emulsions Topological
and kinematical analysis event by event High precision tracking ( x
< 1 m ; < 1mrad) Kink decay topology Electron and / 0
identification Energy measurement By Multiple Coulomb Scattering
P/P < 0.2 after 5X 0 up to 4 GeV Slide 19 Long decays ( ) kink
angle kink > 20 mrad kink kink Long decays Pb (1 mm) Short
decays ( ) impact parameter I.P. > 5 to 20 m plastic base I.P.
Short decays emulsion layers Pb (1 mm) Exploited decay topologies
Slide 20 Expected number of background events (5 years run with
kton average target mass) 1.50.42.33.31 Total per
channel.313.174.139 Hadronic background.174 Large angle
scattering.573.243.017.31 Charm background total hhee 1. Charm
background : Being revaluated using new CHORUS data: cross section
increased by 40% id by dE/dx would reduce this background by 40%
tested at PSI (pure beam of or stop) x 18 ! in the channel without
a spectrometer 2.Large angle scattering : Upper limit from test @
CERN Calculations including nuclear form factors give a factor 5
less will be measured this autumn in X5 beam with Si detectors
3.Hadronic background : Estimates based on Fluka standalone : 50%
uncertainty Extensive comparison of FLUKA with CHORUS data and
GEANT4 would reduce this uncertainty to ~15% 3h3h.44 Slide 21
Expected number of events Channel Signal ( m 2 (eV 2 ) ) BR BR
Background 1.9 10 -3 2.4 10 -3 3.0 10 -3 e 3.7 6.1 9.2 19.4% 0.175
3.4% 0.31 3.1 4.8 7.6 16% 0.175 2.8% 0.33 h 3.2 5.1 7.8 5.8% 0.50
2.9% 0.42 3h 1.4 2.2 3.5 8.3% 0.15 1.25% 0.44 Total 11.4 18.2 28.1
49.5% ~1 10.35% 1.5 full mixing, 5 years run @ 6.7 x10 19 pot /
year Slide 22 Probability of claiming a 4 discovery in 5 years SK
90% CL Opera, no beam upgrade but half background Opera with beam*2
Opera with beam*3 Opera with beam*4 Opera no beam upgrade Opera
with foreseen beam upgrade (1.5) 1.9 10 -3 3 10 -3 Slide 23
Electron identification and Energy measurement Identification :
Method based on shower identification and on Multiple Coulomb
Scattering of the track before showering e/ ratio is measured with
Cerenkov and ECC (test beam) ECC 1.420.17 Cerenkov 1.460.11 at 2GeV
ECC 0.410.05 Cerenkov 0.320.03 at 4GeV 5X 0 ( ~ brick) 1 mm 5 cm
Energy : Measured by counting the number of track segments into a
cone along the electron track Multiple Coulomb Scattering before
showering @ a few GeV Slide 24 Electron identification efficiency
e.m. and hadronic shower simulated in OPERA brick. No background
simulation. Analysis based on neural network. Note that in the
range 2 15 GeV and for particle crossing at least 2.5 X 0, eID and
pID is ~ 99%. OK for both e and e searches efficiencies for showers
followed for 36 ECC (6.4 ~X 0 ) To be tested in July @ DESY with a
pure electron beam at 1-6 GeV Slide 25 Expected signal and
background for the e search 185.21.04.71.233 0.0827.0 10 -4 0.34 10
-4 0.0320.31 e CC beam NC CC ee signal 13 185.21.04.65.877
185.21.04.59.399 Statistique sur le bdf Slide 26 OPERA sensitivity
to 13 Only 15% increase scanning because the event location is
already performed for search. Preliminary 2.5x10 -3 eV 2 0.06 7 sin
2 2 13 m 2 23 (eV 2 ) 4.50 10 19 pot/yr 6.76 10 19 pot/yr syst. on
the e contamination up to 10% By fitting simultaneously the E e,
missing p T and E vis distributions we got the sensitivity at 90%
NC e e beam Events Missing p T (GeV) Slide 27 Activities of the
swiss groups Bern and Neuchtel are involved in OPERA Electronics
Frontend Chip for the target tracker (Bern) Test and calibration of
PMT for the Target Tracker (Bern) Scanning 1 microsope in each lab
is already working A third one will be installed this year in Bern
Development of an automatic emulsion changer (Bern) Simulation
Geant4 simulation (Neuchtel) Slide 28 Conclusions Important Physics
Program First evidence of - appearance in few years data taking In
a five years run: 18 signal (SK best fit) and 1.5 background events
Studies to improve efficiency and to reduce the background
Significant measurement of 13 Detector construction and
installation Installation of detector in progress Detector (and
CNGS beam !) will be ready in 2006 Scanning strategy still to be
optimised Very low background is the key issue
