Peter Paul 03/10/05PHY313-CEI544 Spring-051 PHY313 - CEI544 The Mystery of Matter From Quarks to the...

Peter Paul 03/10/05 PHY313-CEI544 Spring-05 1

PHY313 - CEI544The Mystery of Matter

From Quarks to the CosmosSpring 2005

Peter Paul/Norbert Pietralla

Office Physics D-143

www.physics.sunysb.edu PHY313

mailto:[email protected]


Information about the Trip to BNL

• When and where: Thursday March 31, 2005 at 5:20 pm pickup by bus (free) in the Physics Parking lot. We will drive to BNL and arrive around 6pm (20 miles). We will visit The Relativistic Heavy Ion Collider (RHIC) and its two large experiments, Phenix and Star. Experts will be on hand to explain research and equipment. We will return by about 7:30 pm to arrive back at Stony Brook by 8pm.

• What are the formalities? You need to sign up either in class or to my e-mail address [email protected]. by this Friday night. You must bring along a valid picture ID. That’s all! The guard will go through the bus and check the picture ID’s.

• What about private cars: You will still have to sign up and must bring a picture ID (your drivers license) to the event. You will park your car at the lab gate, join the bus for the tour on-site and then be driven back to your car.

• There is NO radiation hazard on site. I hope many or even most will sign up for a unique opportunity.

mailto:[email protected]


What have we learned last time I• The elements up to the tightest bound

one, 56Fe, are formed during the burning process in the star as it uses its primordial fuel, 75% hydrogen (protons) and 25% Helium.

• In the first step the star burns four protons into 4He. Once sufficed 4He is produced, 3 4He will combine to yield 12C. This process produces more heat.

• In the next step the star uses 12C and the available hydrogen to go through the CNO cycle which produces the elements between 12C and 16O. This heats the star up further.

• One there is sufficient 16O around the star will produce still heavier elements by using available H and 4He to fuse with the 16O.

• This process continues until the elements that are produced reach the peak of the nuclear binding energy, at Fe/Ni.

• Then the star cools (Red Giant). Gravita-tion takes over compressing the star. The heaviest elements accumulate at the core in layers of density. Compression reheats the star & it explodes as a Supernova.

• Nuclear reactions occurring during this violent phase produce many neutrons. These are rapidly captured into the Fe/Ni core to produce the heavier nuclei (r-process). Beta decay changing n p inside the nuclei “moves” the neutron-rich nuclei toward the valley of stability.

• The final explosive phase spews these heavy elements into the interstellar medium. They are then incorporated into new stellar objects


What have we learned last time II

• The known “zoo” of strongly interacting particles (hadrons) was found naturally divided into very heavy particles (Baryons) and medium heavy particles (mesons).

• It became clear from the formation and decay of these particles that several hidden quantum numbers play a role, in addition to the conservation of electric charge.

• Strangeness S and Baryon number B are always conserved in reactions that involve the strong interaction.

• A concept of elemental building blocks, called up, down and strange quarks, could explain all aspects of the construction of the hadrons.

• The quarks have electric changes in units of 1/3 of the electron charge, Baryon number 1/3. and spin-1/2 .

• All known Baryons could be constructed combining 3 quarks; all mesons could be constructed with one quark and an anti-quark.

• The discovery of the particle, a com-bination of 3 s quarks, showed that there was reality behind the quark concept.

• Deep inelastic electron scattering from the proton showed that there were hard objects inside the proton. These are called partons, but are in fact quarks.

• Later, three heavier quarks, the charm, top and bottom quarks were discovered.

• The total of 6 quarks and 6 antiquarks group into three “families”.


The three quark families

http://hyperphysics.phy-astr.gsu.edu/hbase/particles/quark.html

Spin Charge First family Second family Third family

1/2 +3/2 up

(3 MeV)

charm

(1300 MeV)

top

(175,000 MeV)

1/2 -1/2 down

(6 MeV)

strange

(100 MeV)

bottom

(4,300 MeV)

• Today we know 3 families of quarks, and 3 antiquark families.

Note that the neutron and proton and the light mesons are all build up of the lightest quarks, the u and d.




The dynamics of quarks

• In addition to their regular quantum numbers quarks must have other property that differentiates them from each other. This property is called Color. (See e.g. the proton = uud

• There are 3 colors : Red, Green and Blue (these are just stand-in names). Thus the proton looks like this = uud or any other color combination)

• The colored Quarks interact with each other through the exchange of gluons. These gluons exchange color between the quarks (Color interaction).

• There are 9 color combinations but only 8 gluons.

green-

anti-green

green-

anti-red

green-

anti-blue

red-

anti-red

red-

anti-blue

red-

anti-green

blue-

anti-blue

blue-

anti-red

blue-

anti-green


Quark Confinement

• The color interaction between quarks binds the quarks such that no single quark can ever be free.

• This is different from two charged bodies bound by the Coulomb force, but similar to the binding of a magnetic north-pole and a south-pole

• Thus any quark that emerges forma proton will “dress itself with other quarks or anti-quarks and emerge as a jet.

• The binding force between quarks relatively weak when they are close together but grows stronger as they are pulled apart.

• At close distances they can almost be treated as free: Asymptotic freedom


Hidden color, hidden charm

• The J/ particle is made up of a c quark and an antiquark. This combination cancels out the “charmed” character of this particle. The charm is hidden inside.

• Trying to break up the bond between the c and cbar does not free them, but as the bond breaks the released energy produces non-charmed quarks. Thus the c and cbar quarks in the final products no longer cancel each other and the charm character is now apparent

•All quarks carry one of 3 colors so that the Pauli principle is satisfied. However, any real elementary particle, like p and n, cannot have any color, or lese we would have seen it in earlier experiments. The color is hidden inside. The total object must be “white” i.e. colorless.

•This requirement puts a restriction also on the gluons and is responsible for the fact that there are only 8 gluons, the 9th would be colorless and could not effect any color transformation.


Neutrinos: the last Frontier

• Neutrinos are today the least understood particles: They carry no electric charge and they only feel the weak interaction.

• The weak force is much weaker than the EM force

• EM

• Weak

• Thus the weak force is about weaker by a factor of 10,000

• Neutrinos have spin ½, similar to electrons and muons.

• Neutrinos are part of the Lepton (light particle) Family

• There are 3 neutrino species:

e, μ ,

62

2

106.0

137

1

c

g

c

e

Species Symbol Mass

electrons e+, e- 511 keV

muons μ+, μ- 105.7 MeV

tau +, - 1,500 MeV

neutrinos e, μ Very small


Types of weak decays

• n p+ + e- + vebar

+ 0 + e+ + + μ + e+ + • μ+ e+ + - - n + e + • K+ 0 + e+

• The rules of the game are clear:

1. Charge is conserved in the decay.

2. Baryon number is conserved.

3. Strangeness is conserved.

4. Lepton number is conserved for each lepton family.

• The latter means that on each side. of the decay we must have the same number of leptons. Anti-leptons cancel out leptons.

• The positron is the anti-particle to the electron. The μ+ is the antiparticle to the μ-.


History of the neutrino

• 1930 W. Pauli stipulates existence the neutrino

• 1956 F. Reines detects the first neutrinos from a nuclear reactor

• 1965 Schwartz discovers the muon neutrino

• 1966 It is proven by Goldhaber and Sunyar that muon and electron neutrinos are different

• 1967 Ray Davis starts to look for neutrinos from the sun

• 1970 Solar neutrinos show a large deficiency, only about 25 to 45% of expected neutrino flux is detected.

• 1976 The first direct observations of neutrinos from a supernova explosion

• 2000 The tau neutrino is detected

• 2000 It is shown that solar electron neutrinos change their “flavor” as they travel from sun to earth, thus explaining the flux

discrepancy

• 2004 The Kamiokande experiment shows muon neutrinos also change flavor.


How do we measure the barely measurable

• We need a huge mass of detection medium to give the neutrinos ample opportunity to interact.

• The detectors need to be deep underground to shield against cosmic muons. The neutrinos will go through all the rock, even through the earth from the other side

• The first experiment was a chemical experiment done by Ray Davis who was looking for solar neutrinos in tye Homestake mine in SD

• The second experiment was done with a huge Cerenkov water detector in the Kamiokande mine in Japan


The first detection of solar neutrinos by Ray Davis’s chlorineexperiment, and the subsequent confirmation by Kamiokande using real-time directional information and the first detectionof supernova neutrinos opened up a new exciting field ofneutrino astronomy. For these great achievements Ray Davisand Masatoshi Koshiba shared a Nobel Prize with RiccardoGiaconni who is the founding father of x-ray astronomy.

Ray Davis Masatoshi Koshiba Riccardo Giocconi

Nobel Prizes in 2000


Ray Davis experiment detectedthe first solar neutrinos usingChlorine Cl at Homestake

Kamiokande detected the firstneutrinos from a supernova usingwater (3,000 tons).

Big Underground Detectors


How do we detect neutrinos?

Ray Davis Homestake Experiment: 615 tons

Counts the number of 37Arusing a chemical methods

Kamiokande,Super-Kamiokande:3,000 tons , 50,000 tons

- Detect the recoil electron which is kicked by a solar neutrino out of a water molecule.

- Can measure the energy and direction of the recoil electron.

Detecting neutrinos


Physicists having fun in a boat in Super-Kamiokande


Physicist checking installed photomultipliers


Atmospheric Neutrinos

Water Cherenkov Detector: Kamiokande,IMB,Super-Kamiokande,SNO

Water is cheap and easy to handle!

When the speed of a chargedparticle exceeds that of lightIN WATER, electric shockwaves in form of light are generated similar to sonic boomsound by super-sonic jet plane .

These light waves form a coneand are detected as a ring bya plane equipped by photo-sensors.

How does a water Cherenkov detector work?


An event produced by an atmosphericmuon neutrino

Peter Paul 03/10/05 PHY313-CEI544 Spring-05 20electron-like ring

muon-like ring

+ n -> p +

e

+ n -> p +

e-

Major interactions:

Most of time invisible

Simulated events

Differentiating atmospheric muon and electron neutrinos


Neutrinos from a Supernova


A Supernova evolves into a black hole

Will we be able to see ’s from a black hole?


Neutrinos from this SN were observed by Kamiokande and IMB

SN 1987A, Feb.23, 1987 in Large Magellanic CloudAt about 170,000 light years away

Before After

12 events 8 events


Supernova

Background level

Birth of a supernova witnessed with neutrinos

How do we know detected neutrinos are from a supernova?

Kamiokande

Num

ber

of p

hoto

mul

tipl

iers

fir

edA few hours before optical observation

Taken by Hubble Space Telescope ( 1990)


How does the Sun shine?

Kamiokande

Can we see the neutrinos from the sun?

• The sun produces very energetic neutrinos (> 1 MeV) in the processes that go from 4He to 8B


Image of Sun by Super-Kamiokande

Seeing the sun 4000 ft underground


Solar Neutrinos

Summer: 4 Jul. 156 million km

Winter : 3 Jan. 146 million km

Distance Earth-Sun

Solar neutrino flux ~ (1/distance)2

Seeing the Earth’s Orbit Underground!

Note: Flux less than half of expected (deficit)!!!


Ray Davis

2002 Nobel Prize

The solar neutrino problem in 1994

Observation over many years shows that only about 25% of the expected number is observed!


Discovery of Muon Neutrinos• http://hyperphysics.pastr.gsu.edu/hbase/particles

/neutrino2.html

Beginning in 1965 Schwartz et al. at BNL bombarded a Be target with 15 GeV protons from the AGS. They produced copious which decayed into μ and neutrinos. The μ was different from the e

http://hyperphysics.phy-astr.gsu.edu/hbase/particles/neutrino2.html




Discovery of the -lepton in 1975

• The data were taken at the e+-e- colliding beam target. The reaction would be

e+ + e- + + -

• Note that this reaction satisfies all lepton conservation laws since e+ and + are both antiparticles.

• The search was for

events where only one

electron and one muon would

be detected

• The has a mass

3000 x that of the

electron!

Martin Perl receiving the Nobel Prize


Discovery of the -neutrino

• In 2000 the -neutrino was finally discovered at Fermilab. A proton beam produced a intense shower of neutrinos that should contain -neutrino.

• The dector is layers of iron separated by layers of plastic scintillator

• One in a million-million (10 -12) neutrinos would intercat in the iron plates and produce a -lepton which decayed leaving characteris-tic tracks. Four such tracks were isolated.

This completes the lepton family below 1 TeV


The weak interaction: W and Z bosons

eeNiCo 6028

6027

eepn

eeW

Wud

• The force carriers of the weak inter-action are the W+- (for “weak”) and the Z bosons.

• The carriers of the weak force are very heavy. That is the reason for the very short range of the force. The mass of the W is 80.4 GeV; the mass of the Z0 is 91.2 MeV.

• The W+ is the antiparticle to the W-; the Z0 is its own antiparticle

• Note on the right how the W is able to change the quarks from one flavor to another.

• Example: The beta decay of 60Co

• Inside the Co nucleus one of its 33 neutrons changes into a proton:

• Looking inside the neutron, at the quark level the reaction is the change of a d-quark into a u-quark:


Fundamental Force

An example of weak interaction

Free neutron decay: n -> p + e-e

-

Neutron beta decay at the quark level


How many neutrino families are there?

ffZee 0

(MZ=91.1882±0.0022 GeV)

At the e+-e- collider at SLAC the Z boson was produced in the reaction below where ffbar are any ½ spin particles. The mass energy was determined with high precision. The width relates to the number of neutrino families that are emitted in the decay. More families shorten the life time and increase the width. There is excellent agreement with 3 families.


What is matter made of?The Building Blocks of the Standard Model

• With the assurance that we have seen all 3 families of leptons, and having 3 families of quarks, a unified picture emerges:

1. There are the 6 basic weakly interacting particles (leptons). They all have spin 1/2 hbar.

2. There are 6 building blocks for strongly interacting particles (hadrons).

3. There are 4 basic force carriers (Bosons). They all have spin 1 hbar. There are 8 gluons, 2 W’s one Z and one

4. This scheme unifies the EM and the weak interaction: The Z and the have the same heritage but split into a heavy and a light twin.


Grand Unified Theories (GUTs)

Strong

Electric

Magnetic

Electromagnetic

Weak

Electroweak

Gravitational

GU

Ts

hard

19th c.

20th c.

21st c.?

GUTs predict:

Proton must decay

Neutrino must have mass

Unification of Forces


Seventh Homework Set, due March 17, 2005

1. Quarks have spin ½, like electrons, and thus must obey the Pauli principle. What property of quarks makes it possible to put two u quarks into a proton?

2. Gluons are the force carriers of the strong interaction. How many of them are there, how do they differ from each other, and what is their mass?

3. What are the names and properties of the three heavy quarks that have been detected experimentally.

4. How can we detect the elusive neutrinos: Give two characteristics of a successful detector.

5. What neutrinos can we expect to see from the sun? Why is the prediction of the neutrino flux that we expect so solid?

6. How many different neutrinos are there and what are the force carriers of the weak interaction?


Do neutrinos have mass?


Long baseline neutrino oscillation


The SNO experiment


Particle Physics

Neutrino Oscillation

There are three kinds of neutrinos: e

If neutrinos have mass, they can change their identities (flavours)

e

What is neutrino oscillation?

(flavours)

oscil

lation oscillation

oscillation



Super-Kamiokande: The successor of highly successful Kamiokande

50,000 tons of pure water equipped with 12,000 50 cm photomultipliersand 2,800 20 cm photomultipliers (PMTs).

40 m diameter

40 m

he

ight

1,000 m deep



Source of atmospheric neutrinos

Earth’s atmosphere is constantlybombarded by cosmic rays.

Energetic cosmic rays (mostlyprotons) interact with atoms inthe air.

These interactions produce manyparticles-air showers.

Neutrinos are produced in decaysof pions and muons.


Atmospheric NeutrinosEvidence of neutrino oscillation/mass

low energye

high energye

low energy

high energy

with oscillation

without oscillation

First crack in the Standard Model!!!

No tim

e to

oscil

late

Enou

gh ti

me

to o

scill

ate


Solar Neutrinos How do we see neutrino oscillation with solar neutrinos?

Homestake : 0.27

Kamiokande : 0.44Super-Kamiokande : 0.47

Flux: measured/expected

Neutrino deficit!!!Not enough neutrinos

is not visible to allexperiments above

Should be 1

Neutrino oscillations


Solar Neutrinos How can we prove it’s neutrino oscillation?

Neutral current

SNO experiment uses heavy water D2O instead of normal water H2O


Solar Neutrinos How does the neutral current confirm neutrino oscillation?

Elastic scattering Neutral current interaction

-This reaction is available only for e . -This reaction is flavour blind and is available for all kinds of neutrinos.

-Available for both water and heavy water. - Available only for heavy water.


Solar Neutrinos Confirmation of solar neutrino oscillation by SNO

is visible only to SNOBut NOT to Homestake, Kamiokande or Super-Kamiokande.

Even if solar neutrinoe

changes its flavour to

or total flux of solarneutrino can be measuredby SNO

Solar flux measured: 6.4+-1.6 x 106 cm-2 s-1

Solar flux predicted : 5.1+-1.0 x 106 cm-2 s-1

Solar neutrinos oscillate!!!!

Good agreement!


Supernova Why is detection of supernova neutrinos important?

- Properties of neutrinos: its mass (or limit of it), magnetic moment,electric charge, etc.

- Details of supernova explosion: how a star dies

We learn:

- How a neutron star or a black hole is formed if it happens

Peter Paul 03/10/05PHY313-CEI544 Spring-051 PHY313 - CEI544 The Mystery of Matter From Quarks to the...

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