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|TERM PAPER |
|MODERN PHYSICS AND ELECTRONICS |
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|COSMIC RAYS AND ITS EFFECTS |
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|SUMITTED BY : SOURAV |
|ROLL NO.:RC6903A16 |
|SUMITTED TO: Mr. BHARPUR SINGH |
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AKNOWLELDGEMENT

As usual large number of people deserves my thanks for the help they provided me for the preparation for this term paper.

First of all i would like to thanks my teacher Mr. Bharpur Singh for her support during the preparation of this topic. I am very thankful for her guidance.

I would also like to thanks my friends for the encouragement and information about the topic they provided to me during to me during my effort to prepare this topic.

Name: Sourav

Reg No. : 10901091

Section: C6903

THE TABLE OF CONTENTS

1-INTRODUCTION

2-HISTORY

3-WHERE DO THEY COME FROM?

4-COMPOSITION

5-EFFECTS

- ON HUMAN BODY

- ON OZONE LAYER

- ON ATMOSPHERE

- ON ELECTRONICS

6-REFRENCES

INTRODUCTION:-

1. Cosmic rays are energetic particles originating from outer space that impinge on Earth's atmosphere. Almost 90% of all the incoming cosmic ray particles are simple protons, with nearly 10% being helium nuclei (alpha particles), and slightly less than 1% is heavier elements, electrons (beta particles), or gamma ray photons.

2. The term ray is a misnomer, as cosmic particles arrive individually, not in the form of a ray or beam of particles. However, when they were first discovered, cosmic rays were thought to be rays. When their particle nature needs to be emphasized, "cosmic ray particle" is written. The variety of particle energies reflects the wide variety of sources.

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3. The origins of these particles range from energetic processes on the Sun all the way to as yet unknown events in the farthest reaches of the visible universe. Cosmic rays can have energies of over 1020 eV, far higher than the 1012 to 1013 eV that man-made particle accelerators can produce. (See Ultra-high-energy cosmic rays for a description of the detection of a single particle with an energy of about 50 J, the same as a well-hit tennis ball at 42 m/s [about 94 mph].) There has been interest in investigating cosmic rays of even greater energies.

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HISTORY:-

1. The term "cosmic rays" was coined by Robert Millikan who proved they were extraterrestrial in origin, and not produced by atmospheric electricity.

2. Millikan believed that cosmic rays were high-energy photons with some secondary electrons produced by Compton scattering of gamma rays. Compton himself held the (correct) belief that cosmic rays were primarily charged particles. During the decade from 1927 to 1937, a[pic] wide variety of experimental investigations demonstrated that the primary cosmic rays are mostly positively charged particles, and the secondary radiation observed at ground level is composed primarily of a "soft component" of electrons and photons and a "hard component" of penetrating particles, muons.

3. The muon was initially believed to be the unstable particle predicted by Hideki Yukawa in 1935 in his theory of the nuclear force. Experiments proved that the muon decays with a mean life of 2.2 microseconds into an electron and two neutrinos, but that it does not interact strongly with nuclei, so it could not be the Yukawa particle.

4. The mystery was solved by the discovery in 1947 of the pion, which is produced directly in high-energy nuclear interactions. It decays into a muon and one neutrino with a mean life of 0.0026 microseconds.

5. The pion→muon→electron decay sequence was observed directly in a microscopic examination of particle tracks in a special kind of photographic plate called a nuclear emulsion that had been exposed to cosmic rays at a high-altitude mountain station.[1]

Where do they come from?

1. Cosmic rays are probably accelerated in the blast waves of supernova remnants.[2]

2. The remnants of the explosions, expanding clouds of gas and magnetic field, can last for thousands of years, and this is where cosmic rays are accelerated.[2]

3. Bouncing back and forth in the magnetic field of the remnant randomly lets some of the particles gain energy, and become cosmic rays.[2]

4. Eventually they build up enough speed that the remnant can no longer contain them, and they escape into the Galaxy. [2]

|[pic] |[pic] |
|Supernova 1006 |Crab Nebula |

-Because the cosmic rays eventually escape the supernova remnant, they can only be accelerated up to a certain maximum energy, which depends upon the size of the acceleration region and the magnetic field strength. [2]

Composition:-

Cosmic rays may broadly be divided into two categories:-

1. Primary cosmic rays

2. Secondary cosmic rays

Primary cosmic rays:-The cosmic rays that arise in extra solar astrophysical sources are primary cosmic rays; these primary cosmic rays can interact with interstellar matter to create secondary cosmic rays. The sun also emits low energy cosmic rays associated with solar flares. The exact composition of primary cosmic rays, in general almost 90% of all the incoming cosmic rays are protons, about 9% are helium nuclei and nearly 1% are electrons. The ratio of hydrogen to helium nuclei (28% helium by mass) is about the same as the primordial elemental abundance ratio of these elements (24% by mass He) in the universe. [1]

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Secondary cosmic rays:- It consist of the other nuclei which are not abundant nuclear synthesis end products, or products of the Big Bang, primarily lithium, beryllium, and boron. These light nuclei appear in cosmic rays in much greater abundance (about 1:100 particles) than in solar atmospheres, where their abundance is about 10−7 that of helium. This abundance difference is a result of the way secondary cosmic rays are formed. [1] [pic]

Effect of cosmic ray on human body:-

Cosmic rays are energetic particles traveling rapidly through space. The effects are:-

1. It dozen slam into your body every second. These cosmic rays are too low-energy to cause any serious health effects, aside from a few genetic mutations, and cosmic rays are in fact one of the drivers of evolution. Your body receives about 2.4 mSv (milliSieverts) of radiation caused by the effects of cosmic rays every year. For comparison, it takes about 1 Sievert of radiation in a short time to cause nausea, and about 2-6 Sieverts to cause death.[3]

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2. The health effects of cosmic rays change at higher altitudes, where the cosmic ray flux increases exponentially up to an altitude of about 15 km (9 mi), then drops off rapidly. Because of this, people who spend a lot of time at high altitudes, like airline pilots, stewardesses, and Air Force test pilots, experience dozens of times the effects of cosmic rays that people on the ground do. This is still well below the career limit of 1-4 Sv recommended by the National Council on Radiation Protection and Measurements.[3]

3. Astronauts experience the effects of cosmic rays hundreds of times more numerous than those experienced by people on the ground. [3]

Effect of cosmic ray on ozone layer:-

1. Cosmic rays could be a major contributor to ozone destruction over Antarctica.

2. Cosmic rays may be enlarging the hole in the ozone layer, according to a study appearing in the 13 August print issue of PRL. Researchers analyzed data from several sources, and found a strong correlation between cosmic ray intensity and ozone depletion. [4]

3. They demonstrated a mechanism by which cosmic rays could cause a build-up of ozone-depleting chlorine inside polar clouds.[4]

4. Cosmic rays high-energy radiation from deep space is breaking down the CFCs buried in the polar clouds. Ozone depletion seemed to be greatest at altitudes and latitudes of high cosmic ray ionization intensity.[4]

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5. The effects of cosmic rays inside polar clouds. They bombarded the condensate with low-energy electrons like those created by cosmic rays ionizing atoms in the atmosphere. The electrons reacted with the CFCs and made active chlorine.[4]

6.The results suggest that electrons from cosmic rays are about a million times more likely to interact with CFCs inside polar clouds understand the ozone hole. A rise in global temperatures could cause an increase in polar cloud cover that would lead to more cosmic-ray-induced CFC reactions. That’s why in ozone layer create a hole.[4]

Effect of cosmic ray on atmosphere:-

1. Billions Of tonnes of water droplets vanish from the atmosphere in events that reveal in detail how the Sun and the stars control our everyday clouds. The consequences of eruptions on the Sun that screen the Earth from some of the cosmic rays - the energetic particles raining down on our planet from exploded stars.[5]

2.When solar explosions interfere with the cosmic rays there is a temporary shortage of small aerosols, chemical specks in the air that normally grow until water vapour can condense on them, so seeding the liquid water droplets of low-level clouds. Because of the shortage, clouds over the ocean can lose as much as 7 per cent of their liquid water within seven or eight days of the cosmic-ray minimum.[5]

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Effect of cosmic ray on electronics:-

1. Cosmic rays have sufficient energy to alter the states of elements in electronic integrated circuits, causing transient errors to occur, such as corrupted data in electronic memory devices, or incorrect performance of CPUs. [1]

2. This has been a problem in extremely high-altitude electronics, such as in satellites, but with transistors becoming smaller and smaller, this is becoming an increasing concern in ground-level electronics as well. Studies by IBM in the 1990s suggest that computers typically experience about one cosmic-ray-induced error per 256 megabytes of RAM per month. [1]

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3. The Intel Corporation has proposed a cosmic ray detector that could be integrated into future high-density microprocessors, allowing the processor to repeat the last command following a cosmic-ray event. [1]

4. Example- Cosmic rays were recently suspected as a possible cause of a Qantas Airlines in-flight incident where an Airbus A330 airliner twice plunged hundreds of feet after an unexplained malfunction in its flight control system. Many passengers and crew members were injured, some seriously. After this incident, the accident investigators determined that the airliner's flight control system had received a data spike that could not be explained, and that all systems were in perfect working order. This has prompted a software upgrade to all A330 & A340 airliners, worldwide, so that any data spikes in this system are filtered out electronically.[1]

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References:-

1. http://en.wikipedia.org/wiki/Cosmic_ray

2. http://imagine.gsfc.nasa.gov/docs/science/know_l1/cosmic_rays.html

3. http://www.wisegeek.com/what-are-the-health-effects-of-cosmic-rays-on-the-human-body.html

4. http://focus.aps.org/story/v8/st8

5. http://www.sciencedaily.com/releases/2009/08/090801095810.html