Review on Cosmic Ray (Gopal Datta Kalauni)

 Review on Cosmic Ray (Gopal Datta Kalauni)

                                                                                                                        Gopal Datta Kalauni                                                                                                                     Department of Science & Technology

                                                                                            

The existence of penetrating radiations coming from outer space was detected in 19th century by Wilson, Elaster and Geitel with the help of gold leaf electroscope. They observed changing and discharging of leaves due to ionization produced by these radiations in the surrounding gases inside the instrument. In 1912-1914 AD, Hess and Kolherster demonstrated increasing and decreasing of ionization currents in the chamber with height from surface which was due to radiations coming from outer space. They did not show differences in day and night in their intensity.

Miliken and his associates in America took observations on mountains altitudes and under snow-covered lakes at high altitudes. They observed that absorption of radiations were similar in air and water. Miliken gave new name as “cosmic rays” to these radiations. P.S. Gill, Bothe, clay Mcnon, Sreekonton and others studied the variations of cosmic ray intensity in different latitudes. They explained that cosmic ray particles were arriving at the earth surface with more intensity at magnetic poles and less intense at equator which due to bending of path towards equator.

Rossi, in 1993, demonstrated that cosmic rays possessed two groups which are soft component and hard component. Later, shows that soft particles were electrons and hard particles were µ-Mesons which decayed to softer particles of a lifetime of nearly equal to 2 x10-6 Sec. Mass of these particles was nearly 205 times mass of an electrons.

 Yukawa, a Japanese scientist, put forward a theory on nuclear forces. He predicted that photon was emitted or absorbed in electromagnetic field during excitation of nuclear quanta may be emitted or absorbed from nuclear field. Meson highly interacting with nuclei and decayed into µ-mesons as

π± → µ±   +   υ

It can be decayed into three particles as

µ± → e± + υ +          

These mesons are very little interacting with matter and can be found in sea level cosmic ray  and deep underground. They can be explained on the basis of air showers and ionization chambers.

The sun and other stars can produce particles which are accelerated and confined in their magnetic fields.

In solar flares, when the sun emits large quantity of ionized gases in violet explosion, it is shown that cosmic ray intensity towards lower energies – 1010 e V markedly increased at the times of flares. But the higher energies primaries are not affected much. This is so because filed around space is very weak -10-5 grams and cannot store or trap the high energy particles.

In recent theories, supernova explosion and pulsars is the major single objects which generate the highest energy flux and produce cosmic ray particles of largest energy nearly equal to 1020 eV.

The primary cosmic ray spectrum that we observe in neighborhood of solar system consisted of galactic as well as exta-galactic radiation and large varieties of acceleratory mechanisms. In pulsars, rotational energy converts into particle energy through hydromagnetic interaction.

They produce cosmic health effect which can damage DNA and biochemistry of cells and tissues which can alter gene transcription and tissue producing DNA mutations. They can affect  central nervous system also. Besides, they can be used to explore space and universe. They were helpful to discover antimatter and the muons, beyond proton , electron and neutron.

References:

White, Astr.dr. Vil. 143, 626

University physics ,FWseas Zimmley

Nuclear Physics , B.N. srivastava