Doç. Dr. Erhan Pesen VIII. Uluslararası Katılımlı Parçacık Hızlandırıcıları ve...

The Particle Detectors (The Image Detectors)

Doç. Dr. Erhan Pesen

VIII. Uluslararası Katılımlı Parçacık Hızlandırıcıları ve Detektörleri Yaz Okulu

14-09-2012 Bodrum

History Early detectors are Image Detectors.

Principle: What you see what you get.

Could Chambers Bubble Chambers Nuclear Emulsions

Doç. Dr. Erhan Pesen 14-09-2012 Bodrum

The Cloud Chambers (1920-1950)


Also called Wilson chamber The cloud chamber contains a

supersaturated vapour of water or alcohol.

A charged particle interacting with the mixture, creates ions.

The ions act as condensation nuclei around which a mist (cloud of particles) will form

High energy alpha and beta particles leave a track due to the ions they produce along their path

If a magnetic field is applied positively and negatively charged particles will curve in opposite directions

http://www.youtube.com/watch?v=pewTySxfTQk

http://www.youtube.com/watch?v=Efgy1bV2aQo

The images at left are typical of those obtained by Wilson (C. T. R. Wilson, Proc.

Roy. Soc. (London), 87, 292 (1912)).



The Discovery of Positron


Positron discovery, Carl Anderson 1933 [Nobel price 1936]

Magnetic field 15000 Gauss, chamber diameter 15cm.

A 63 MeV positron passes through a 6mm lead leaving the plate with energy 23MeV.

The ionization of this particle, and its behavior in passing through the foil was the same as those of an electron but with positive charge

The Discovery of Muon


Muons were discovered by Carl D. Anderson and Seth Neddermeyer at Caltech in 1936 with a cloud chamber while studying cosmic radiation

http://apod.nasa.gov/apod/image/0608/crshower2_nasa_big.jpg

The Bubble Chambers (1952-1985)


A bubble chamber is a vessel filled with a superheated transparent liquid (Hydrogen at T=30K). A charge particle initiate boiling.

Urban history: Glaser was inspired by the bubbles in a glass of beer

The size of the chambers grew quickly: – 1954: 6.4cm – 1954: 10cm – 1956: 25cm – 1959: 183cm – 1963: 203cm – 1973: 370cm

Some disadvantages: – It cannot be triggered – Low rate capability – The photographic readout: for data

analysis one had to look through millions of photos

Invented in 1952 by Glaser (1960 Nobel Prize in Physics)

The Discovery of Omega


The Discovery of Neutral Currents


Gargamelle, a very large heavy-liquid (freon) chamber constructed at Ecole Polytechnique in Paris, came to CERN in 1970.

2 m in diameter, 4 m long and filled with Freon at 20 atm, in 2 T B field

Gargamelle in 1973 was the tool that permitted the discovery of neutral currents.


Nuclear Emulsions (1937 - ---)

Nuclear Emulsion particle detectors feature the highest position and angular resolution in the measurement of tracks of ionizing particles.

Nuclear Emulsion, used to record the tracks of charged particles, is a photographic plate.

A photographic emulsion consists of a large number of small crystals of silver halide, mostly bromide.

The sensitivity to light has allowed silver halides to become the basis of modern photographic materials.

A silver halide is one of the compounds formed between silver and one of the halogens — silver bromide (AgBr), chloride (AgCl), iodide (AgI), and three forms of silver fluorides

The method of recording tracks of charged particles in photographic plates is based upon two achievements of modern technology, the photographic emulsion and the optical microscopes

Nuclear Emulsions (1937 - ---)


A nuclear emulsion plate is a photographic plate with a thick emulsion layer and uniform grain size.

– It records the tracks of charged particles passing through

– It produce a cumulative record – The plates must be developed

before the tracks can be observed.

In 1937, Marietta Blau and Hertha Wambacher discovered nuclear disintegration stars due to spallation in nuclear emulsions exposed to cosmic radiation at a height of 2,300 meters above sea level

The Discovery of Pions


The pion was discovered in Nuclear emulsion techniques, Powell 1947; Nobel Prize 1950

Discovered in 1947 in nuclear emulsions exposed to cosmic rays, and they showed that it decay to a muon and an unseen partner.

The constant range of the decay muon from the pion decay indicate that this is a two body decay

The Discovery of Kaons


First evidence of the decay of the Kaon into 3 Pions was found in 1949 in Nuclear emulsion (by G. Rochester at Manchester)

Particle discoveries by 1959


Ω-

Discoveries Timeline


Today > 200 particles listed in PDG: 27 have cτ > 1 μm

• they can be seen as tracks in a detectors

• 13 have cτ < 500 μm

• displaced vertices

Nuclear Emulsion The only one that survives in Early

Image Detectors No time resolution No vertex location information Very good spatial resolution Very good track, two track resolution

(grain size ~1μm) Events are recorded and stays forever



Neutrino Oscillations


Active target

Calorimeter

Spectrometer

Air-core magnet

n

Emulsion target 4 stacks each made of 36 plates

Plastic base: 90 μmEmulsion on both side: 350 μm

Total mass : 770 kg

Recent Application : CHORUS (1992-2002)


Photographic developer is a chemical amplifier acting on the latent image.

A rather complex physics-chemical process is able to transform those grains with a suitable development centre into metallic silver.

After development, a silver halide emulsion is placed in a second bath, called as fixer which dissolves the unaffected grains of silver halide but leaves the small black granules of silver.

Finally, The plate is washed and dried.

Emulsion Films drying after development

The Emulsion Development


Automatic Scanning

track

90 mm plastic backing

350 mm (175 mm)emulsion sheet

CCDcamera

CCDcamera

microscope stroke

tomographic image

X50 magnification~3mm focal depth

150x150 mm view

Tracks reconstructed by a hardware video processor

frame to frame emulsion grains coincidence

350 mm (175 mm)emulsion sheete

muls

ion p

late


CERN/NIKHEF Scanning Systems (year 2000)


Scanning System In Nagoya ( year 2000)

Network data storage

UTS = a machine for general scanning: ~1 cm2/hour


Tracking and Reconstruction

Track segments from 8 plates overlapped

At least 2-segment

connected tracks

Eliminate passing-through

tracks

Reconstruct full vertex topology

‘Emulsion is the mass

storage’(Prof.K.Niwa)

~7000TB


Charm Dimuon Event

Zoom

D+

+

-

h


Detection of Ds


Today’s Application :The OPERA Experiment

Mainly designed for the direct search of ντ appearance in the pure νµ CNGS beam from CERN to Gran Sasso(732km).

Based on the use of Emulsion Cloud Chambers (ECCs) and of electronic detectors(Hybrid Detector).

In an ECC the nuclear emulsion films act as very high precision tracking detectors, and are interleaved with plates of lead.

The brick, is made of 57 emulsion films interleaved with 56 lead foils of 1 mm thickness. It has 128x102x79mm3, and weighs 8.3 kg.Emulsion Cloud Chamber


OPERA Setup The distinctive feature of ντ charged-current

interactions is the production of a short-lived τ lepton (cτ =87 µm).

This is achieved in OPERA using the Nuclear Emulsion technique that features an unrivaled spatial resolution (≤ 1 µm).

OPERA Detector is a hybrid (emulsion+electronics) with a modular structure. 2 SuperModules=2*(31walls+1spectrometer) Total Mass: 1766 Tons. # of Bricks=206336

ECC measures: Kink of Tau, Momentum(via MCS), Electromagnetic Shower, dE/dX, e/π separation, Event Kinematics,Vertex Location, τ ID,

Magnetic Spectrometer: μ ID, charge and momentum.Target tracker: Trigger and localiza ν interactions.


The required area of emulsion is of order of 100,000 m2 s

It is needed high-speed automatic scanning systems.

Scanning power is 10cm2/h at LHEP

Emulsions are scanned at Europe and Japanese scanning Labs.


Emulsion Scanning LAB. At University Of BERN


The Tau-Neutrino Candidate


Proton Radiography With Nuclear Emulsions

To obtain medical images of the patient’s body (proton radiography).

Proton radiography allows obtaining images directly proportional to the average density of the traversed material.

Emulsion detector is cheaper and easier to install and remove.


Emulsion Hybrid Telescope For Cosmic Gamma-ray Observation

Telescope observes

1. Brightness (Magnitute)2. Color (Wavelength)3. Direction of the light

Emulsion Measures

1. Event Rate (Flux)2. Energy (Momentum)3. Direction of gamma-ray

photon

Visible (Palomar)

2 mrad

Ultra Violet (UIT) Reconstructed

Tracks Gamma Shower


Cosmic-ray Muon Radiography Of Volcanos With ECC

muons

ECC

• Muon source with a well-known energy spectrum for different zenith angles.

•A well-understood muon detector.

•The information from counting muon events at different arriving angles can be used to infer on the matter profile.


Cosmic-ray Muon Radiography Of Volcanos With ECC


LEP Tunnel

Doç. Dr. Erhan Pesen VIII. Uluslararası Katılımlı Parçacık Hızlandırıcıları ve...

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