Emulsion detector at a Neutrino Factory

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Emulsion detector at a Neutrino Factory
Giovanni De Lellis University of NaplesFederico
II on behalf of the ECC WG
Detector Working Group, Nov. 17th, Imperial
College, London
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Outline of the talk

• Starting point ideas shown in September at the
  ISS meeting at CERN
• Synergy of the golden and silver channel with an
  OPERA-like detector (G. D. L.)
• Nuclear emulsions in magnetic field (Nakamura)
• Revise the potentiality of the technique
• New ideas
• A document written by the next ISS meeting in
  Japan

Set up of a Working Group mailing list and a web
page http//people.na.infn.it/pmiglioz/ISS-ECC-W
G/ISSMainPage.html
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A physics case synergy of golden and silver
channels

• Study the CP violation in the leptonic sector ?e
  ? ?µ the most sensitive (golden) channel
• In the (?13,?) measurement, ambiguities arise
• Intrinsic degeneracy Nucl. Phys. B608 (2001)
  301
• ?m2 sign degeneracy JHEP 0110 (2001) 1
• ?23, ?/2 -?23 symmetry Phys. Rev. D65 073023
  (2002)
• The silver channel (?e ? ?? and ? ? µ) is one
  way of solving the intrinsic degeneracy at the
  neutrino factory
• A. Donini et al., Nucl. Phys. B646 (2002) 321.
• An hybrid emulsion detector is considered
• D. Autiero et al., Euro. Phys. J. C33 (2004) 243

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Golden and silver channels
ambiguities
Solving the ambiguities
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A hybrid emulsion detector

• Target based on the Emulsion Cloud Chamber (ECC)
  concept
• Emulsion films (trackers) interleaved by lead
  plates (passive)
• At the same time capable of large mass (kton)
  and high spatial resolution (lt1mm) in a modular
  structure

The basic unit the  brick 

• ECC topological and kinematical measurements
• Neutrino interaction vertex and decay topology
• reconstruction
• Measurement of hadron momenta by Multiple
  scattering
• dE/dx for ?/µ separation at the end of their
  range
• Electron identification and energy measurement
• Visual inspection at microscope replaced
• by kinematical measurements in emulsion

10.2 x 12.7 x 7.5 cm3
ECC technique successfully used in cosmic rays
(X-particle discovery in 1971) and by DONUT for
the ?? direct observation
8 GeV
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Electronic detector task

• trigger and locate the neutrino interactions
• muon identification and momentum/charge
  measurement

ECC emulsion analysis Vertex, decay kink e/g
ID, multiple scattering, kinematics
Electronic detectors
Target Trackers Pb/Em. target
Spectrometer
supermodule
Link to muon ID, Candidate event
Pb/Em. brick
Basic cell
Pb
1 mm
Emulsion
Extract selected brick  
Brick finding, muon ID, charge and p
?p/p lt 20
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Topology and kinematics of signal and background
Background
Charge misidentification 1-3 x 10-3
Signal and background versus E?
charm
decay in flight and punch-through
732 km
t
signal
3000 km
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Emulsion scanning

• Real time analysis several tens of bricks
  extracted/day
• High speed (20 cm2/h) fully automatic scanning
  systems (one order of magnitude faster than
  previous generation)
• independent RD in Europe and Japan based on
  different approaches
• First prototype developed and tuned in Europe
• Successfully running since Summer 2004 with high
  efficiency (gt90), high purity (2 tracks/ cm2
  /angle) and design speed
• 2 mrad accuracy at
• small incident angles

? Fast CCD camera (3 k frames/sec) ? Continuous
movement of the X-Y stage
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Emulsion Scanning load

• Boundary conditions
• 1 Kton detector located 732 km from the beam
  source
• 5 years data taking
• Scan all events with a negative (wrong sign) µ
• silver 30 events and golden 310
• Anti-?µ with misidentified charge 2200
• Charm background 80 events
• ? NC with punch-through or decaying h 4800
• 8 x 103 events in 5 years
• 10 kton ECC detector feasible

European scanning system
CHORUS
DONUT
OPERA
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Combining ECC _at_ 732km and iron _at_ 3000km
Allowed regions from the analysis of simulated
data for ?13 1, ? 90. The best fit is ?13
0.9, ? 80.
5 kton ECC 40 kton Iron
No clone regions for ?13gt1, for ?131 they
show-up in less than 10 of the experiments
Both at 3000 km

• Large reduction of all backgrounds (? 1/L2)
  except the muonic decay of ? events from
  anti-?µ? anti- ??
• scanning load reduced by about a factor of 20

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Precision measurements
Position measurement of particle trajectories
0.05 µm
0.06 µm
Nucl. Instr. Meth. A in press
RMS distribution of fitted angular trajectories
Median 0.4 mrad
Median 0.64 mrad
Inclined (200 mrad) particles
Perpendicular particles
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dE/dx measurement NIM A516 (2004) 436
P1.2GeV/c Hadron _at_KEK/PS
Film
Pb
dE/dx b measurement
p
P
dE/dX
number of grains
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Electron energy measurement
Test exp. _at_ CERN
MC
Data
Energy determination by calorimetric
method (under study)
_at_ a few GeV
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Momentum measurement by Multiple Scattering
Routine scanning performed
2 GeV pions
3 GeV pions
22 resolution with 5 X0
30 resolution with 3 X0
Nucl. Instr. Meth. A512 (2003) 539
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? /µ separation using neural network (multiple
scattering and energy deposit)
Exposure at PSI (Zurich) with pure ? and µ
beams ?? (P?202MeV) and ?? (P?120MeV)
follow tracks till they stop and characterize
them according to the energy deposition per unit
length and the scattering angle
Data
µ
PRELIMINARY
?
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?/e separation study??2 ?2e -?2? separator
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Emulsion detector in a magnetic field

• Measure the charge (and momentum)
• The charge determination allows the extension of
  the silver channel to the non-muonic decays (BR
  gain)
• Study the feasibility of the platinum channel
  (?µ??e) by means of the charge determination and
  electron identification capabilities

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A possible detector structure
DONUT/OPERA-like target Emulsion spectrometer
mu
B
Air Gap
Stainless steel or Lead
Film
3Xo 10Xo
Low density and long X0 material as
target Conservative assumption of 10 µm accuracy
in the film by film alignment (0.5mrad angular
resolution with 20mm gap structure)
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Charge determination (0.5T)
gt30mm Gap
20mm Gap
10mm Gap
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Momentum resolution (0.5T)
10mm Gap
20mm Gap
30mm Gap
40mm Gap
50mm Gap
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Emulsions in magnetic field (conclusions)

• Emulsion Spectrometer ( B 0.5T, Gap gt 20mm,
  Total Length10cm) allows the charge momentum
  determination efficiently
• Technological RD needed such as the unique track
  connection planning test experiments
• Consider other possible structures

Analyzer
Target
Emulsion spectrometer
B
Low ? and large X0 ( 1 X0)
Film
Air Gap
Lead
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Conclusions

• A hybrid detector for the study of CP violation
  in the leptonic sector by means of the silver
  channel is feasible
• The OPERA experiment with the same technology
  will be running from 2006 and demonstrate it
• The scanning load is feasible already now
• Very preliminary estimation of the performances
  of emulsion detectors in magnetic fields look
  very promising both for the extension of the
  silver channel and perhaps for the platinum
  channel study
• Detailed studies will be done and test
  measurements are planned
• A document available by next ISS meeting