Yoshi Uchida Masterclass 2006 - Imperial College Londonyoshiu/Masterclass07/Yoshi.pdf · [email protected] UK Particle Physics Masterclass 29 March 2006 Title Neutrinos

[email protected] UK Particle Physics Masterclass 29 March 2006

Title

Neutrinos(and Electrons, Muons, and Pions)

Yoshi Uchida

UK Particle Physics Masterclass March 2007


up charm top

down strange bottom

electron muon tau

up charm top

down strange bottom

electron muon tau

u c td s be

u c td s be

electron muon tauneutrino neutrino neutrinoelectron muon tauneutrino neutrino neutrinoelectron muon tauneutrino neutrino neutrino

e

Matter Particles

Neutrinos:

Only feel the weak interaction⇒ the Earth is “transparent”

Massless by definition in the Standard Model

e creates electrons, creates muons, creates taus

through the Weak Interaction

The Standard Model


charm top

strange bottom

tau

tauneutrino

u c ts b

up

down

electron muon

electron muonneutrino neutrino

e

Matter Particles

ude

Particles inThis Talk

Dave Wark will talk aboutneutrinos too....


charm top

strange bottom

tau

tauneutrino

u c ts b

up

down

electron muon

electron muonneutrino neutrino

e

Matter Particles

ude

Particles inThis Talk

Pion


Particle Interactions


Electron Interactions in Matter

1m

electronwith 1 GeVof energy(about 2000 timesits mass)

Water

Electrons produces “showers” of positrons, electrons and photons, as they travel through matter


ComputerSimulations

Computer Simulations play a major role in particle physics.

The properties of particles and detectors are simulated using known properties of particle propagation in matter.


ComputerSimulations


More ParticleInteractions

1 Electron

10 Muons0.5 GeV 1.5 m H2O

0.5 Tesla Magnetic Field Can build detectors to take advantage of the different characteristics of particles


More ParticleInteractions

100000000000 Neutrinos


The PionSimilar in mass to the muon, but feels the Strong Interaction

Image is of tracks captured in photographic emulsion, showingNuclear Disintegration

First seen by D. H. Perkins in 1946, when he was a PhD studentat the Imperial College High Energy Physics group

...


Pion Decay and NeutrinosPion

Muon Electron

MuonAntineutrino

MuonNeutrino Electron

Antineutrino

– –

e–

Pions decay in fractions of a microsecond, eventuallyproducing 3 neutrinos


SuperKamiokande andAtmospheric Neutrinos


Atmospheric NeutrinosZenith Angle

180º − Zenith Angle

Isotropic flux ofcosmic rays

km`

10000

Cosmic rays hit upper atmosphere and create pions, which in turn decay into of a few GeV

Look at neutrinos from different zenith (up/down)angles.Distance travelled since neutrino creation depends on this angle


Neutrino Detection in WaterCharged particles (travelling faster than the speed of light in the medium) can emit light at specific angles to their direction of travel

chargedparticle

“Cerenkov” light

Detectors can identifythe “ring” formed bylight, to measure thedirection and speed ofthe particle

speed of light in water = 75%of speed in vacuum


Electron and Muon Neutrinos

electron neutrino

muon neutrino

creates a single electron, which then creates a shower of electrons

creates a single muon

“fuzzy”cerenkovring

clearcerenkovring

(with energies of about 1 GeV)


Problem

For a 1 metre thickness of water, only about

1 in every 1,000,000,000,000 neutrinos

actually interacts this way


Solution

Use a big detector


SuperKamiokande

40m by 40m tank1 km underground50,000 tonnes of waterLined with 11,000 photonsensors

8 atmospheric neutrinos / day!Kamioka Observatory,ICRR (Institute for Cosmic Ray Research),The University of Tokyo


SuperKamiokande (Winter 2005/06)

Rebuilding ofdetector after major accident in 2002 destroyed half of the photon sensors


SuperKamiokande (Winter 2005/06)


“fuzzy” electronlike ring

SuperK Neutrino Events

“clear” muonlike ring

Patterns of light detected in the 20inch photon sensors


Atmospheric NeutrinosZenith Angle

180º − Zenith Angle

Isotropic flux ofcosmic rays

km`

10000

Cosmic rays hit upper atmosphere and create pions, which in turn decay into of a few GeV

Look at neutrinos from different zenith (up/down)angles.Distance travelled since neutrino creation depends on this angle


Atmospheric Neutrinos at SuperK

HorizontalUp Down

muonlikeelectronlike

1 0 1 1 0 1cos(zenith angle)

150

100

0

50

Even

ts

DataExpected


Atmospheric Neutrinos at SuperK

HorizontalUp Down

muonlikeelectronlike

1 0 1 1 0 1cos(zenith angle)

150

100

0

50 DataExpected

Even

ts

Muon neutrinos “disappear” as they travel long distances

⇒ turning into tau neutrinos(invisible to SuperK)


Neutrino Oscillations

If neutrinos have different masses, Quantum Mechanicssays they can “turn into” each other as they travel

Oscillation probability

∝Interference of quantum matter waveswhich depends on mass differences


Neutrino Oscillations

0 500 1000 Distance[km]/E[GeV]

muonneutrino

tauneutrino

STARTwith a puremuonneutrinobeam

The probability that the neutrino has become a tau neutrino swings back and forth with distance


KamLAND and Neutrino Oscillations


The Kamioka Liquid Scintillator AntiNeutrino Detector


KamLAND

0 250 500 750 [km]

KamLAND ReactorBaseline Distribution

Reactor interactionsproduce antineutrinos:

1000 tonne detectorsees about 1 reactorantineutrino each day


KamLAND

(1879 PMTs)

(Water)


KamLAND


KamLAND Result October 2004

258 candidates (365.2 if inversesquare propagation)


“Distance / Energy” for KamLAND 2004

assuming 180km baseline (assuming

180km baseline)Distance / Energy [km / MeV]


Other Hypotheses for Neutrino Disappearance

assuming 180km baseline

(alternative theories for neutrino disappearance)

(assuming 180km baseline)Distance / Energy [km / MeV]


Evidence for Neutrino Oscillations

assuming 180km baseline (assuming

180km baseline)

To be improved in next results!

Distance / Energy [km / MeV]


Present Status of Neutrino OscillationsWe have seen two types of verified neutrino oscillations

● “SuperK” atmospheric & accelerator

● Solar (Dave’s talk) & “KamLAND” reactor (ask me)

Oscillations ⇒ neutrinos must have mass

The only indication of Physics Beyond the Standard Model


Present Status of Neutrino OscillationsOne mysterious oscillation result from the 1990s, currently being reexamined by the MiniBooNE experiment

⇒ the next big neutrino physics result, very soon?


The Ice Cube Experiment

The South Pole

half a mile

1.5

mile

s

Instrumented todetect neutrinos

Uses the icesheet at theSouth Poleto act as a NeutrinoTelescope for neutrinosfrom the NorthernHemisphere


How to Help Build a New Neutrino Experiment


The Concept

Oscillations seen in Atmospheric Neutrinos, can we make a better measurement?

Define Energy and Distance better

If our understanding is correct, a 3rd type of oscillation may exist, can we see this?

Use the most intense source of neutrinos possible


The K2K Experiment (1999—2004)Muon neutrinos sent 250 km across Japan from KEK

Saw 112 neutrinos, confirmed “atmospheric” oscillations


JPARCMajor new particle / nuclear physics facility being built in Japan

Construction started in 2001

Can be used to create avery powerful neutrino beam


The TokaitoKamioka (T2K) Experiment

Kamioka

JAPAN Tokai

T2K

SuperKamiokande

JPARC

JPARC

The most intense neutrino beamever

295 km baseline beam disappearance measuremente appearance discovery


A Neutrino Experiment at JPARC (formerly JHF)21 January 2003


The T2K CollaborationMore than 300 members from

CanadaFrance

GermanyItalyJapanKoreaPolandRussiaSpain

SwitzerlandUnited Kingdom

United States


Another Improvement

The most intense, optimised neutrino beam ever&

A 50,000 tonne neutrino detector

the need to understand the beam, and neutrino interactions, better than ever before

the performance of the experiment will depend on a much more sophisticated "Near Detector" than before

use a Magnetic Field, complex system of detectors


The JPARC Neutrino Beam

NCarbon Target

JPARC 50 GeV Proton Ring and Neutrino Beam Complex

Same principle as atmospheric neutrino production(except you stop the muons before they decay)

IntenseProton Beam

Showerof Pions

Neutrino Beam


The 280m Near Detector (ND280)

N

ND Hall

JPARC 50 GeV Proton Ring and Neutrino Beam Complex

280m

Distance is fixed from constraints due to surrounding structures(and untouchable forests)


The “UA1” Magnet

Use of magnet enhances particle identification / measurement dramatically

An old magnet from CERN (which helped discover the W & Z particles), was available

for the Near Detector


Conceptual Design Process 2004, 05

Design the “best” affordable Near Detector system which fits into the UA1 magnet



Use of computer simulations (and backoftheenvelope estimations) to investigate many different detector concepts



Vancouver Jul ’05

Rome Dec ’04




T2K ND280 Conceptual Design ReportPublished August 2005: “This Conceptual Design Report details the physics requirements, motivations, and design considerations [of the ND280 detectors].”


The T2KUK Proposal (January 2006)

UK Contributions on:● Neutrino Beam and Target Development● ND280 Electromagnetic Calorimeter Design and Construction● ND280 Electronics and Data Acquisition● ND280 Photosensor Development● T2K Software and Physics Analysis


The Imperial College T2K Group

From left: Johnathan Anderson, Morgan Wascko, Mark Raymond, Marie Endamne, Matt Noy, Dave Wark, Joe Walding, Daniel Orme, Francois Van Schalkwyk, Antonin Vacheret, Peter Dornan, Masaki Shibasaki, Ian Taylor, Yoshi Uchida


Imperial College T2K Group● Designing the detector

readout electronics for ND280

● Coordinates the photosensor study group in the UK

● Organises the Global T2K Offline Software group and UK Physics group

and


Present Status

Approved by UK GovernmentNeutrino Beam to turn on April 2009ND280 to start running Autumn 2009

Oscillation measurements / discoveries a few years later....


The Future

DailyTelegraph

Undergoing vigorous R&Din UK and internationally


Monitor our progress at

imperialhep.blogspot.com

Documents

Yoshi Uchida Masterclass 2006 - Imperial College Londonyoshiu/Masterclass07/Yoshi.pdf · [email protected] UK Particle Physics Masterclass 29 March 2006 Title Neutrinos