the In order to be sure that the - - PowerPoint PPT Presentation

▶
the in order to be sure that the oscillation
SMART_READER_LITE
LIVE PREVIEW

the In order to be sure that the - - PowerPoint PPT Presentation

Sep 21, 2023 177 likes •410 views

INTRODUCTION We know that in Nature there are three kinds of neutrinos and in particular atmospheric neutrinos show a deficit of This effect, found first by the SuperKamiokande and confirmed by many other experiments

slide-1
SLIDE 1

MTM Bologna, 17/6/ 2005

We know that in Nature there are three kinds of neutrinos and in particular atmospheric neutrinos show a deficit of ν ν ν νµ

µ µ µ

This effect, found first by the SuperKamiokande and confirmed by many other experiments (for example by MACRO and K2K), has been deeply studied. So, the disappearance of muon neutrinos seems doubtless stated . Moreover, the experimental data agree very well with the hypothesis of ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ →

→ → → → → → → ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ oscillations.

  • scillations.

However, the experiments performed until now do not allow to observe the particle that should be produced in the oscillation: the ν

ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ

In order to be sure that the oscillation ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ →

→ → → → → → → ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ is

the right explanation of the data, we need the direct observation of the ν

ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ

INTRODUCTION

slide-2
SLIDE 2

The OPERA experiment The OPERA experiment

MTM Bologna, 17/6/ 2005

…….. to “see” the ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ

slide-3
SLIDE 3

Physics motivations Physics motivations

ν ν ν ντ

τ τ τ

τ τ τ τ

τ decay

~ 0.6 mm

ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ appearance signature:

appearance signature: detection of detection of ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ CC interactions

CC interactions and direct observation of and direct observation of τ τ τ τ τ τ τ τ decay topology decay topology Provide unambiguous evidence for Provide unambiguous evidence for ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ →

→ → → → → → → ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ oscillations

  • scillations

in the parameter region indicated by in the parameter region indicated by atmospheric neutrino data atmospheric neutrino data by searching for by searching for

ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ appearance

appearance

in the CNGS in the CNGS ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ beam

beam

MTM Bologna, 17/6/ 2005

slide-4
SLIDE 4

The CNGS Beam The CNGS Beam

negligible negligible

ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ prompt

prompt 17 17 GeV GeV <E <Eν

ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ>

>

Expected Expected ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ CC interactions/year:

CC interactions/year: ~25 25 ( (∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆m m2

2 = 2.4x10

= 2.4x10-

  • 3

3 eV

eV2

2, maximal mixing)

, maximal mixing)

Beam to LNGS in May 2006 Beam to LNGS in May 2006

L = 732 km MTM Bologna, 17/6/ 2005

slide-5
SLIDE 5

The The O Oscillation scillation P Project roject with with E Emulsion mulsion t tR Racking acking A Apparatus pparatus

In order to detect the decays In order to detect the decays

  • f the
  • f the τ

τ τ τ τ τ τ τ particles produced in particles produced in CC interactions CC interactions

  • f
  • f ν

ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ‘

‘s from s from ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ oscillations

  • scillations

a high a high-

  • resolution tracking detector is required

resolution tracking detector is required

Nuclear emulsions Nuclear emulsions

  • 3D particle reconstruction

3D particle reconstruction

  • Sub

Sub-

  • micron spatial resolution

micron spatial resolution

  • High granularity (~300

High granularity (~300hits hits/mm) /mm) Modular detector basic unit (BRICK): sequence of lead/emulsions

MTM Bologna, 17/6/ 2005

slide-6
SLIDE 6

Detector structure Detector structure

2 super 2 super-

  • modules

modules muon muon spectrometer + spectrometer + target walls target walls 52x64 bricks 52x64 bricks

20m 20m 10m 10m 10m 10m

hybrid set hybrid set-

  • up:

up: visual + electronic detection visual + electronic detection techniques techniques

MTM Bologna, 17/6/ 2005

TOTAL > 220000 bricks

slide-7
SLIDE 7

Automatic microscopes for emulsion scanning Automatic microscopes for emulsion scanning

European Scanning European Scanning System System

running in : running in : Bari, Bern, Bologna, Lyon, Napoli, Neuchâtel, Roma, Salerno

S S-

  • UTS

UTS (Nagoya) (Nagoya)

High speed CCD Camera (3 kHz) Piezo-controlled

  • bjective lens

Constant speed stage Synchronization of

  • bjective lens and stage

Scanning speed ~ 20 cm2/h/side

Single side track finding efficiency ~ 95% Sheet-to-sheet alignment (8 GeV/c) ~ 0.5 µ µ µ µm Angular resolution ~ 2 mrad MTM Bologna, 17/6/ 2005

slide-8
SLIDE 8

Automatic emulsion scanning Automatic emulsion scanning

16 16 tomographic tomographic images images 2D 2D Image Image processing processing

3D reconstruction of particle tracks 3D reconstruction of particle tracks

Field of view Field of view

Track segments found in 8 consecutive plates Connected tracks with >= 2 segments Passing-through tracks rejection Vertex reconstruction

MTM Bologna, 17/6/ 2005

slide-9
SLIDE 9

Conclusions Conclusions

  • A complex modular detector, using visual and electronic detecti

A complex modular detector, using visual and electronic detection

  • n

techniques, has been designed techniques, has been designed

  • The detector construction and installation at LNGS are

The detector construction and installation at LNGS are well underway well underway

  • Impressive progress in emulsion scanning automation has been ac

Impressive progress in emulsion scanning automation has been achieved hieved after after challenging R&D challenging R&D The OPERA experiment will start running in May 20 The OPERA experiment will start running in May 2006 06 to unambiguously confirm to unambiguously confirm ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ →

→ → → → → → → ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ oscillations

  • scillations

MTM Bologna, 17/6/ 2005

slide-10
SLIDE 10

fine fine

slide-11
SLIDE 11

ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ →

→ → → → → → → ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ oscillation search

  • scillation search

∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆m m2

2 = 3.0 x 10-3 eV2

∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆m m2

2 = 2.4 x 10-3 eV2

∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆m m2

2 = 1.9 x 10-3 eV2

19.9 1.0 12.8 8.0

τ τ τ τ decay channels Background Signal ALL

Main background sources: charm production and decays hadron re-interactions in lead large-angle muon scattering in lead MTM Bologna, 17/6/ 2005

slide-12
SLIDE 12

LNGS LNGS – – Gran Sasso Gran Sasso National Laboratory National Laboratory

OPERA (CNGS1) ICARUS

Hall C Hall B

BOREXINO

rock thickness 1400m (3800 m.w.e.) cosmic muon flux: ∼ ∼ ∼ ∼1/m2/h MTM Bologna, 17/6/ 2005

slide-13
SLIDE 13

ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ →

→ → → → → → → ν ν ν ν ν ν ν νe

e oscillation search

  • scillation search

∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆m m23

23 2 2 = 2.5 x 10-3 eV2

Θ Θ Θ Θ Θ Θ Θ Θ23

23 = 45

= 45° ° nominal CNGS beam 5 years

90% C.L. limits on sin2(2Θ Θ Θ Θ13) and Θ Θ Θ Θ13 : Combined fit of Combined fit of E Ee

e,

, E Evis

vis, (pt)

, (pt)miss

miss

sin sin2

2(2

(2Θ Θ Θ Θ Θ Θ Θ Θ13

13)<0.06

)<0.06 Θ Θ Θ Θ Θ Θ Θ Θ13

13 < 7.1

< 7.1º º

hep-ph/0210043

slide-14
SLIDE 14

Belgium IIHE (ULB-VUB) Brussels Bulgaria Sofia China IHEP Beijing, Shandong Croatia IRB Zagreb France LAPP Annecy, IPNL Lyon, LAL Orsay, IRES Strasbourg Germany Berlin Humboldt, Hagen, Hamburg, Münster, Rostock Israel Technion Haifa Italy Bari, Bologna, LNF Frascati, L’Aquila, LNGS, Naples, Padova, Rome La Sapienza, Salerno Japan Aichi, Kobe, Nagoya, Toho, Utsunomiya Russia INR Moscow, ITEP Moscow, JINR Dubna, Obninsk Switzerland Bern, Neuchâtel Turkey METU Ankara

The OPERA Collaboration The OPERA Collaboration

slide-15
SLIDE 15

WIN05, Delphi, June 6-11, 2005 1.0 (1.5) 19.9 (29.9) 12.8 (19.2) 8.0 (12.1) 0.7 (1.1) 16.4 (24.6) 10.5 (15.8) 6.6 (10.0) ∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆m m2

2 = 3.0 x 10-3 eV2

∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆m m2

2 = 2.4 x 10-3 eV2

∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆m m2

2 = 1.9 x 10-3 eV2

Signal Background Old analysis Old analysis New analysis New analysis full mixing, 5 years run @ 4.5x1019 pot / year

(…) CNGS beam intensity increase (x 1.5)

Comments on background Comments on background -

  • possible improvements

possible improvements: π π π π/µ µ µ µ separation at low energy by dE/dx in emulsion (charm background reduction) extensive comparison of FLUKA with GEANT4/CHORUS data (reduction of the uncertainty

  • n hadron re-interaction calculations, based on FLUKA, 50% systematic error assumed)

experimental measurement of large-angle muon scattering

slide-16
SLIDE 16

Experiment strategy Experiment strategy

ν ν ν ντ

τ τ τ

Target Spectrometer

On On-

  • line

line analysis analysis

  • f
  • f electronic

electronic data data Brick identification Brick identification and removal and removal

To the Scanning Stations - Laboratories

Emulsion Emulsion analysis analysis

ν ν ν ν interaction vertex

τ decay kink particle identification and kinematics

slide-17
SLIDE 17

WIN05, Delphi, June 6-11, 2005

Lead Lead – – Emulsion Target Emulsion Target

Emulsion films (Fuji) Emulsion films (Fuji)

mass production started in April ‘03 production rate ~8,000m2/month (206,336 brick ⇔ ⇔ ⇔ ⇔ ~150,000m2)

Lead plates Lead plates (

(Pb Pb + 2.5% + 2.5% Sb Sb) ) requirements: low radioactivity level, emulsion compatibility, constant and uniform thickness

6.7m

Wall prototype Wall prototype

2 emulsion layers (44 µ µ µ µm thick) glued onto a 200 µ µ µ µm plastic base

52 x 64 bricks 52 x 64 bricks

12.5cm 10.2cm

Pb 1 mm

τ τ τ τ ν ν ν ντ

τ τ τ

8.3kg 10 X0’s ν ν ν ν

BRICK: 57 emulsion foils + 56 interleaved Pb plates

Total target mass : 1766 t

slide-18
SLIDE 18

WIN05, Delphi, June 6-11, 2005

Detection of Detection of τ τ τ τ τ τ τ τ decays decays

New channel recently taken into account in the analysis: τ τ τ τ → → → → → → → → 3h Main background sources:

kink angle ϑ ϑ ϑ ϑkink > 20 mrad impact parameter I.P. > 5 ÷ 20 µ µ µ µm

short decays: τ τ τ τ → → → → → → → → µ τ τ τ τ → → → → → → → → e long decays: τ τ τ τ → → → → → → → → µ τ τ τ τ → → → → → → → → e τ τ τ τ → → → → → → → → h

kink

θ θ θ θkink

I.P. charm production and decays hadron re-interactions in lead large-angle muon scattering in lead

slide-19
SLIDE 19

WIN05, Delphi, June 6-11, 2005

τ τ τ τ τ τ τ τ detection efficiency detection efficiency

Recent improvements Recent improvements: τ τ τ τ → → → → → → → → 3h now included in the analysis + updated brick finding algorithm

* weighted sum on DIS and QE events

DIS long QE long DIS short Overall*

2.7 2.3 1.3 3.4 2.4 2.5 0.7 2.8 2.8 3.5

  • 2.9

Total

8.0 8.3 1.3 9.1 % τ τ τ τ → → → → µ µ µ µ τ τ τ τ → → → → e τ τ τ τ → → → → h

slide-20
SLIDE 20

WIN05, Delphi, June 6-11, 2005

  • Id µ

µ µ µ + ECC connection

  • Kink+ kinematics
  • Location
  • Others

Long dec. BR

Step-by-step efficiencies, τ τ τ τ → → → → µ

slide-21
SLIDE 21

WIN05, Delphi, June 6-11, 2005 OPERA OPERA + background reduction

  • 50%

probability to observe a number of events ≥ ≥ ≥ ≥ 4σ σ σ σ background fluctuation (5 years)

ν ν ν ν ν ν ν νµ

µ µ µ µ µ µ µ →

→ → → → → → → ν ν ν ν ν ν ν ντ

τ τ τ τ τ τ τ oscillations :

  • scillations :

OPERA sensitivity OPERA sensitivity

OPERA + background reduction (under study,

  • 30%)
slide-22
SLIDE 22

AHEP 2003, Oct. 14-18, Valencia - Spain

Particle separation by Particle separation by dE dE/ /dx dx

Grain density in emulsion is proportional to Grain density in emulsion is proportional to dE dE/ /dx dx By measuring grain density as a function of By measuring grain density as a function of the distance from the stopping point the distance from the stopping point, , particle identification can be performed particle identification can be performed. .

  • ne plate

average of 29 plates

pions protons Test exposure (KEK) : 1.2 GeV/c pions and protons, 29 plates

ph ≥ 25

pβ(π)=1188

ph < 25

pβ(p)=948

ph ≥ 25

pβ(π)=1188

ph < 25

pβ(p)=948

IONISATION IONISATION MCS MCS

expected value: pions expected value: protons

Calibration Calibration