unbelieveable particles

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Neutrinos

Unbelieveable particles

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Neutrinos are unbelievable particles !

Who foresaw their existence ?

Already in 1930 Wolfgang Pauli foresaw the existance of a new

particle, later getting the name neutrino (itl. for a little neutral one)The physicists had for a long time tried to find an explanation for

missing energy balance when beta particles (electrones) emanated by

some kinds of radioactivity.

There was something that would no agree, yes it was in conflict with

the princip of the law of the conservating of energy.

Pauli suggested that a neutrino particle cut off with some of the

energy, but he added: I have done something awful, I havepredicted a particle which not can detected.(2)

The neutrino is detected.

In 1955 a particle corresponding to what Pauli had foresawn was found, and it was closely connected

to the electrone. Later, one found out that there actually existed three variants of neutrino, where two

of them were some heavier muon- and tau-electrons. Those three has got their names as Ve (1955) Vm(1962) and Vt ( 1978) (1)

Common for this three types of electrones and their links to neutrines is that they will not be affected

by the so called strong force, which keep the atomic nucleous together. Such particles are calledleptons. Together with quarks, all attached to the atomic nucleus (protons and neutrons) , these two

groups form the whole foundation of the universe.(6)

There has been much disagreement whether a neutrino really has a mass. The exsistance of mass

would be of substantial interest to the comprehension of gravitation in the universe, and perhaps also

to the understanding of the assumed dark matter out in space.(1)

The sun stands for a conciderable part of all neutrinos coming to our earth. Cosmic radiation going

into our athmosphere liberate neutrons of the muon type, and some kind of radioactivity contribute for

a certain amount of neutrinos. The so called high energy neutrinos are assumed to come from super-

nova explotions. By such occations as much as 99 % of all energy is assumed..released as neutrinos.

In 1987 there was observed a supernova in The Great Magellan Cloud. When this happened, the

density of neutrinos hitting the earth corresponded to 100 millions of neutrinos per second on an area

corresponding to a tumbfinger-nail !

Such neutrinos has a speed close up to light, and will unhindered pass the enormous electromagnetic

forces around galaxies. They go only stright forward, and could do so in eternity. Even if they meet a

barrier of lead, 50 lightyears thick, they will unaffected pass. They also contain a unbelievable

quantity of energy. By collision with a proton, the energy liberated correspond to the kinetic energy

in a baseball coming with a 80 km / h speed. (2)

How to detect neutrinos ?

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This is possible because it happens (very, very seldom) that a neutrino particle collides with a proton.

When this happens, a muon type neutrino is formed. This muon particle should get a speed about 25

% higher than the speed of light, but here the nature takes over. For not exceeding the light speed

(300 000 km/s) the muon must get rid of of excessive energy, and gives away some light, the so called

Cherenkov Light, as a thin, bluish streak. (4,5)

A neutrino-detector is therefore quite different

from an astronomic observatory. It has an

enormous tank filled up with pure water, and

rows of sensors , named photomultiplicators.

When the surrounding medium is pure and clear

water, and it is complete darkness, the

photomultiplicators will be able to detect the

light streaks in a range of some tenth meters.

They will also be able to indicate the direction

with an accuracy of 3.5 degrees, and therefore

tell the accurate point on the sky where the neutrinoparticle came from.

All we know today about the universe has come to us by observations of light, included all types of

photons as visible light, infrared and ultraviolet, and besides specter of elektromagnetic radiation, like

radio waves and x-ray. All these kinds of radiation has on their way been influenced from

elektromagnetic and gravimetric fields , causing uncertaintly about their origin place.

This is not the case for the neutrinos. The have gone in a straight line from their origin, and this start

can be billions of light years away.

Different types of detectores

Detectors has been built on different placs around the earth. To avoid

influence from cosmic radiation and neutrinos from our own sun, many

detectors are placed in great, blasted rooms in deep rock-ground, but also

in very deep and clear water.

The first project for detecting neutrino-induced muons in natural water

was the russian installation in the deep Baikal.sea, with depths down to

1523 meters. (1)

Another type has been placed on the South Pole, on US Amundsen-ScottStation, called Amanda. It was primarely aiming to detect high energetic

neutrinos from black holes, gamma outburst and supernovas in far galaxis.

The next detector, called Amanda II. followed this. After drilling 1900 meters down in the ice, they

installed 680 detectors (photomultiplicators) in the size of basketballs, hanging down in 19 cables.

The detection system is surrounded by pure ice, and in complete darkness in a depth from 1500 to

1900 meters. Amanda did their first detection in summer 2001, and two years later the results was

published in Sidney. These has given astronomers very surprising and new visions about cosmos. (1)

Japanese experiments

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Japan has since 1985 got a lot more knowledge in neutrino reserach

after starting up their Super-Kamiokadedetector in the Japanese

Alps. The heart in their detector is an enormous tank filled with

50 000 tons of super clean water. For detecting of cherenkov-light

from collisions between neutrinos and protons , this tank issurrounded by 13 000 high sensitive photomultiplicators.

The detector made its great shots when the Great Magellan Cloud

showed up on 23.februar in 1987. It managed to detect 11 neutrino

hits from this unique event, and this was conciderd to be the

introduction of a new era in the exploration of the universe.

Many sources of error

It would be guite more simple if the detections only regstered light flashes from high energetic

neutrinos from outer space, but this is not the fact. Cosmic radiation gives collotion with protons in

our athmosphere, and create muons and the belonging muon-neutrinos. In addition, the surrounding

rock will have some radioactivity, which also can create cherenkov-light. Such false flashing comes

in higher numbers than those from pure neutrinos.

Unexpected problems

Super Kamiokade detected thousands of electron-neutrinos from the sun, but only halv of the numbers

they had expected. This problem strengthend when they studied muon-neutrinos from cosmicradiation. In a shower of cosmic particles one should expect a double number of muon- neutrinos as

electron-neutrinos, but in the Super-Kamiokade and other experiments the numbers was about equal.

Seen in a connexion , it looked like some of the muon-neutrinos from cosmic radiation disapperas, and

likewise the electron-neutrinos from the sun !

It was adjacent to think that something happened on the journey. The japanese did an experiment, and

sendt muon-neutrinos from their accelerator (KK in Tsjukuba) in the direction against the Super-

Kamiokade-detector , 250 km away. Although the detector totally registered a smaller number of

neutrinos, the amount of muon-neutrinos arrived as a minority.

The conclusion of this was that if each of these three unlike types of neutrinos can oscillate over to

another type, it is not unlikely that only a third of electron-neutrinos reach the earth. The answer to

this was still to wait for in new detections.

The Antares detector

In the Mediteranien, 37 km out from Cote d Azur, not far from Toulon, there is an area with a depth

going down to 2400 meters, and the water is extraordinary clear and pure. This means that there is

sufficiant water up to the surface to protect against all muons that cosmic radiation can give. Besides,

it is not so far from land, making installation and maintenance more simple.

The frenchmen did a thorough preliminary work, as to study the problems with possible microbe

fouling for the detection with photomultiplicators. After a whole year in the sea the light sensibility

was reduced with only 2 %.

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Another problem was all the small organisms which produced

some kind of light flashes. This light was bluish, like the

cherenkov-light, and could be rather strong. But because the

cherenkov light always is coherent, just as laser-light, it was

possible to filter out those amorous flashes from Mediteranian

creepy things, and only detect the astronomic light.

Another problem with the Antares was the cherenkov light from

the radioactive K40, which is present in sea water, but was

concidered to be only a cosmetic problem, and could be

substracted. Antares was expected to be operational in 2004, and

could probably exceed the american Amanda on the South Pole.

(1)

One thing has Antares and Amanda in common . They plan to

enlarge these detectors to about one cubic kilometer ! Some one

wrote the following about it : It will be possible to hear the

scream from far-off quasars and registrate schock waves from

the great gamma flashes.

Canadien experiments

In Canada they have developed a new technique, making it possible to distingquish what type of

neutrinos they detect. The installation has got the name Sudbury Neutrino Observatory (SNO). It has

a tank containing 1000 tons of water, surrounded by 10 000 light sensors (photomultiplicators).

A little trick has been used . For the most of time so called ultra clean water is used, but in a limited

time they use genuin heavy water (D2O) with a small addition of salt (NaCl) In the ultra pure water

they detect only electron.neutrinos, while in a smaller tank with D2O + NaCL all the three types willbe detected.

In this arrangement they are able to detect the total number of neutrinos. By subtracting the number of

electron- neutrinos from this, they can calculate the distribution between muon- and tau-neutrinos.

SNO will in a average only detect one neutrino per hour, and it took four years to gain meaningful

results. This has revealed the following relation :

Some of the electron-neutrinos from the sun changes to muon- or thau-neutrinos on their way to eart.

Det total number of neutrinos beeing detected , and include all the three variants, agree with the

number from the most advanced calculating models for the numbers from the sun. This has been

concidere as an important result within experimentel science (1), and was rewarded with the Nobel

Price in physics for 2003, given to Ray Davis (University of Pennsylvania) and Mashatoshi Koshiba

(Tokyo University) .

Neutrino generators

In 2004, intensions for producing a strem of muon-neutrinos from the Fermilab acelerator near

Chicago over to a detector in the Soudan- mine in Minnesota, a distance of 700 km. was established .

In the meantime, plans for sending a neutrino stream from the LHC (Large Hadron Accelerator, Cern)

to Gran Sasso Laboratory in Italy came up. At the top of this, plans for building a neutrino- generator ,

able to send a maelstrom of such particles to the other side of the earth, exist. (1)

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New problems.

The discoveries in Canada created new problems. The fact that a neutrino can oscillate and transform

to one of the other variants means in fact that they must have different mass. Neutrinos could not be

massless, as earlier proposed.

Another problem also showed up. When neutrinos shall be described as spinning particles, they arealways left-handed. And this penomena also pass for their antiparticles, this beeing quite unic. All

other particles in nuclear physics exist in both forms, and this gives some inbalance in the system.

This facts gives the theoretics a little glimps into a world far beyond our general comprehension of the

world, and our so called Standard Model for nuclear physics. In this other world, new dimensions

are brought in. Our nornal four dimensions (room and time) could then be locked up in a multi-

dimesional system, with perhaps as many as eleven dimensions. In such a system the left- and right

handed rotations could freely operate. Quantum theory should allow such behaviour for the three

types of neutrinos in short sequensies.(1)

The existance of so called super-heavy neutrinos gives new thoughts about the so called Dark

Matter in the universe. Neutrinos operate in incoprehensible numbers, and must have a fundamentalrole in the universe.

Appendix

The article given here was published in the norwegian periodical Astronomi in october 2004.

Skien, 8. mars 2010

Kjell W. Tveten

References :

(1) Reluctant hereos, article from New Scientist, 7.des. 2002 p. 35-43

(2) Cosmic ghost hunt, article from Astronomy Now, oct. 2003, 37-39

(3) Kamiokande, printing from Internet/Google, e pg.

(4) Imaging water Cherenkov detector, printing from Internet/Google, 3 pg.

(5) Measuring the velocity of light, printing from Internet/Google, 3 pg.

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What happened in neutrino

research after 2004 ?

The OPE RA project started in 2003, and has

been described like this :

The OPERA experiment has been designed to

perform the most straightforward test of the

phenomen of neutrino oscillations. This

experiment exploits the CNGS (Cern Neutrino

beam to Gran Sasso) high intensity and high

energy beam of muon neutrinos produced at the

CERN SPS SPS in Geneva pointing towards the

LNGS underground laboratory at Gran Sasso, 730 km away in central Italy. OPERA is located in the

Hall C of LNGS and is aiming at detecting for the first time the appearance of tau-neutrinos from the

transmutation (oscillation) of muon-neutrinos during their 3 millisecond travel from Geneva to Gran

Sasso. In OPERA , tau- leptonsresulting from the interaction of tau-neutrinos will be observed inbricksof photographic emulsion films interleaved with lead plates. The apparatus contains about

150 000 such bricks for a total mass of 1300 tons and is complemented by electronic detectors

(trackers ans spectrometers) and ancillary infrastructure. Its construction has been completed in spring

2008, and the experiment is currently in data taking.

http://opera.desy.de/project.html

In summer 2006, CERN gave the starting signal for the long-distance neutrino race to Italy. The

CNGS facility, embedded in the laboratorys accelerator complex, produced its first nautrino beam.

For the first time, billions of neutrinos were sent through the Earths crust to the Gran Sasso

laboratory, 732 km away in Italy, a journey at almost the speed of light which they completed in less

than 2.5 milli-seconds. The OPERA experiment at the Gran Sasso laboratory was then comissioned,

recording the first neutrino track.

The CNGS project is expected to unravel some of the mysteries surrounding neutinos. Neutrinos,

which are very light, neutral particles, interact very little with matter.They fill the Universe but are

virtually impossible to capture. 400 billions neutrinos pass through us every second, and yet only one

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or two will ever interact with our bodies througout our entire lives. The fact that they are extreemely

hard to intercept goes some way to explaining the mystery that surround them.

We know there are three types or flavours of neutrino : the electron neutrino, the muon neutrino and

the tau neutrino. But physicists want to find out whythe flux of neutrinos from the sun is much smaller

than theory predicts. This deficit may be due to the transformation (or oscillation) of neutrinos from

one flavour to another, a process which has been observed in recent experiments. This phenomenon ,

known as oscillation, is directly linked to another fundamental question that torments physicsists , that

of the neutrinos mass. Oscillations had shown that neutrinos have a mass, but ithas yet to be

determined. The mass of neutrinos is crucial. Even if theyare infinitisemally light, these particles could

contribute to the Universes mysterious dark matter., which is invisible to telescopes byt whose

gravitional effect can be observed.

The CNGS project is to provide evidence of neutrino oscillations which is thought to occur over log

distances. To achieve this, the OPERA, a first experiment nesting below 1440 meter of rock,

has been comissioned at the GranSasso laboratory. OPERAs huge detector , weighing 1800 tons,

shoulde identify particles transformed from muon neutrinos inti tau neutrinos during the journey, thus

demonstrating oscillation. OPERA is expected ti intercept and detect around 25 muon neutrinos out

over the one hundred billion that will reach it every day. Around fifteen tau neutrinos produced by bebuilt in the coming years.

The production of high-intensity neutrino beam ar CERN requires a complex faciliy. A proton beam

produced and acceleratedby the CERN accelerators is directed onto a graphite target to give birth to

other particles called pions and kaons. These particles are the fed into asystem comprising two

magnetic horns which focus them into a parallel beam that is directed towarde Gean Sasso. Next, in a

1000 metre long tunnel, the pions and kaons decay into muons and muon neutronos. At the end of this

decay tunnel, an 18 metre thick block of graphite and metal absorbs the protons, pions abd kaons that

did not decay. The muons ar5e stopped by the rock. Impervious to all such obstacles, the muon

neutrinos will leave the CERN tunnels and streak through the rock on their 732 km journey to Italy.

(September 2006). http://public.web.cern.ch/Public/en/Spotlight/SpotlightCNGS-en.html

The start-up for CERN accelerator was on the 10 september 2008. However, a very serious

incident happened on 19.september 2008, causing more than a year of delay to restart the

physics programs and a minium of delay two years to reach full energy.

From Geneva, 23 November 2009 was reported:

Today the LHC circulated two beams simultaneouslyfor the first time, allowing the operators to test the

synchronization of the beams and giving theexperiments their first chance to look for theproton-proton collisions. With just one bunch of

particles circulating in each direction, the beams canbe made to cross in up to two places in the ring.

From early in the aftenoon, the beams were made tocross at points 1 and 5, home to the ATLAS and CMS detectors, both of which were on the lookout forcollisions. Later, beams crossed at points 2 and 8,

ALICE and LHCb .

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How far away experiments for the OPERA project lays now is hard to guess. Probably it will be a

question of priorities, and time will show.

Skien, 8. mars 2010

Kjell W. Tveten

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