Tag Archives: Radiation

Google Honors Madame Marie Curie With A Doodle On Her Birthday

She is the epitome of true grit, all packaged in a gentle feminine form. A scientist par excellence, a double Nobel Prize winner, a pioneer on many fronts and an exemplary human being, Madame Marie Curie showed how much a human can endure and still succeed! Today is her birthday and Google duly honours her with a doodle.

Madame Curie

The doodle is a simple image of Curie holding up a flask with a fixed chemical apparatus on the table in front of her. Her work, involving the extraction of minute quantities of radium and polonium from uranium ores, must have involved more complicated apparatus setups. Click on the doodle and you’ll be redirected to a page returning the search results to her name. The doodle is a simple one, a humble offering of respect, just like Marie Curie might have wanted to be.

Her Life

Born in Poland on this day in 1867, she was the fifth and youngest child. Tragedies in her life started early, when she lost her mother at an early age, followed by her elder sister. Jolted twice, she renounced her faith (Catholicism) and became agnostic. Her academic pursuits would take her to Sorbonne; there she would obtain a degree in math. She would also start working with magnetism, which would eventually prove a great source of attraction between her (then Marie Sklodowska) and her future husband Pierre Curie.

The Physics and Chemistry that she did

The physics world was rocked by the discovery of unknown rays given off by certain substances in the late 1890’s. It was Becquerel’s seminal discovery of radioactivity that set Marie and Pierre on a hunt for a new element radium! Nothing was known about radioactivity not even the harm that it does.

Madame Marie Curie and Pierre Curie together in the lab

From a ton of pitch blende (Uranium dioxide – ore from which Uranium is extracted), less than one-tenth of a gram of radium chloride was extracted. This was 1898. Polonium, discovered by the Curies in the previous year, was easier to extract. Both were much more radioactive than Uranium. Madame Curie wrote a characteristically tepid sentence, which was immensely insightful:

The fact is very remarkable, and leads to the belief that these minerals may contain an element which is much more active than uranium.

Becquerel was her doctoral advisor; she obtained her DSc from the University of Paris in 1903. In the same year, she received her first Nobel Prize – in Physics and with Pierre Curie and Henri Becquerel.

Struggle

Her struggle restarted in 1906 with the death of her husband. She continued her work, but failed to get a position at the University of Paris, just because women were disallowed from such a position. She was, however, received with honour at Sorbonne, the first woman to hold the post of a professor.

She was attacked by her detractors and there were many when news about her alleged affair with Paul Langevin surfaced in 1910-11. In 1911, she received her second Nobel Prize this time in Chemistry and alone!

The 1911 Solvay conference, one of the most prestigious meetings of scientists in history. Seated, second from right is Madame Curie. Note the young Einstein standing on the right.

Legacy

She would die in 1936 due to the very radiation that made her a celebrity. She campaigned widely for more funding for radium research. She founded the Curie Institute, which produced more Nobel Laureates, including her daughter Irene Joliet-Curie and son-in law Frederic Joliot-Curie.

Madame Marie Curie is a symbol today, a reminder that science is not merely a great idea occurring inside the head of a genius. It’s a body of knowledge, requiring immense dedication, sometimes even courage, to acquire.

Madame Marie Curie, on your birthday, we salute you!

America Disarms Most Powerful Nuclear Bomb Ever Created

The US is burying the Cold War hatchet and doing so in style. It is dismantling the most powerful nuclear bomb ever created, believed to be over 500 times more powerful than the one dropped on Hiroshima. It was designed and armed in 1962, but, thankfully, never used. Named enigmatically as B53, it was to be carried by B-52 bombers and was capable of ripping apart even underground bunker facilities, should the Cold War have heated up.

The B53 at the Pantex Plant (Courtesy: Associated Press)

The B53

The B53 was a monster. It weighed in at 10,000 pounds (or 4.5 tonnes) and could release 9 megatons of TNT energy (or 38 PJ, 1 PJ = 1015 J a million billion joules)!! It formed a formidable arsenal, consisting of 340 individuals of its kind, built for B-47, B-52 and B-58 bomber planes. It used highly enriched Uranium (oralloy). It was meant to be used as a bunker buster a surface blast would send shockwaves that would shatter the Earth, enabling the underground parts to be exposed. Multiple strikes(!)  would eliminate technical facilities or even the leadership bunkered underground.

Disarmament

The disassembling process for the B53 arsenal began in 1980’s, but a few of them kept their place in the stockpile. In 1997, it was decided to retire them from the arsenal. The process took longer than expected, because the technology was old and most of the experts are either old or deceased. It took place at the Pantex plant at Amarillo, Texas, the only plant for disarmament in the US.

The disarmament is considered complete when the 300 pound explosive the fuse is separated from the highly fissile nuclear material. This nuclear material is known as the pit and is not heavy enough to detonate on its own (technically, it is of sub-critical mass). These pits are stored at the plant, then sanitized’ and disposed off.

The Pantex plant has served as a disarmament facility for a number of nuclear bombs. It will continue to do so!

Typhoon Roke Hits Japan, Moving Towards Fukushima And Tokyo

Typhoon Roke has just hit Japan! The first few news reports and photos are just coming out.  Typhoon Roke made landfall at Hamamatsu, just south east of the industrial city of Aichi, and this is its current location. It is on course for Fukushima, the city housing the troubled Daichi nuclear power plant. Tokyo might be hit too. Roke is expected to reach Fukushima in another two days time. The wind speed is 100 mph.  

We had warned about the approach of this storm in a previous post here.

Landfall and destruction

Unlike Irene, which fizzled out as it made landfall, Roke did not die. It has caused heavy rains on the coastal region. High speed winds have caused enough destruction on their own. All operations at sea have been discontinued for the coming days.

Sea surge caused due to Typhoon Roke (Courtesy: The Telegraph, Associated Press)

Initial reports indicate that at least 4 people have died in this initial spell of rain. This number, no doubt, will rise as more is known of the storm’s devastation. Aichi has been largely evacuated. The overflowing of the river that flows over Aichi has caused widespread flooding in the city.

Photos from the first few hours:  http://www.telegraph.co.uk/news/picturegalleries/worldnews/8778887/Typhoon-Roke-hits-Japan.html
The current position of the eye of Typhoon Roke, just south of the main island of Honshu. (Courtesy: The Weather Channel)

Fukushima and the Nuclear Worry

The biggest worry is Fukushima and the damaged nuclear power plant. Radioactive material will over flow into the sea and the surrounding areas due to the heavy downpour. Officials had begun preparations for the approach of the storm a few days back and are continuing to reinforce the defences of the nuclear power plant. Cables have been tied down and maximum effort is being put to ensure that no radioactive water leaks onto the habitable areas.

Dai’chi Plant Was Dumping Radioactive Waste Into Sea:  http://techie-buzz.com/science/japan-nuclear-radioactive-fears.html
Measuring Radiation: How Much Radiation is Too Much? :  http://techie-buzz.com/science/radiation-risks.html

The Japanese Meteorological Department has advised the highest level of caution to be used due to heavy rains, strong winds and high waves. Very heavy rains are expected in the coming days with as much as 5 cm in one hour!

These are just initial reports. We’ll continue tracking the storm, as it makes its way towards Fukushima with no expected loss in intensity.

We wish our beloved Japan the very best. It has been through worse in history, and it could fight back every single time. We know that this will be no exception.

Link to a previous post:  http://techie-buzz.com/science/typhoon-roke-japan.html

Discovered : A Belt of Antimatter Surrounding Earth

Anti-particles are not as exotic as many think and here’s further proof. The PAMELA spacecraft has detected a ring of anti-protons around the Earth, confined in that region by Earth’s magnetic field. These may be confined in that small region for hours before annihilating with matter and producing radiation.

This ground-breaking discovery was reported by PAMELA spacecraft recently. PAMELA, acronym for Payload for Anti-Matter Exploration and Light-nuclei Astrophysics, is a satellite that was launched to further cosmic ray astrophysics on 15th June 2006. It was specifically built to focus on the occurrence and interactions of positrons (anti-electrons) and anti-protons in the space around Earth.

The PAMELA spacecraft

Some theoretical considerations

Anti-matter is a theoretical necessity, which can be deduced from the symmetry of theories in physics. It was first predicted by the great Paul Dirac in 1931, following the interpretation of results given by his own equation (unsurprisingly called, the Dirac Equation) to describe the electron. His wild prediction of the positron was soon experimentally verified the following year by Carl Anderson, who detected it in his lab. (Remember, that the neutron was not yet known. It was also discovered in 1932 late in the year.) The scientific impact and importance can be gauged from the fact that Anderson went onto win the Nobel Prize in 1936, just four years after the discovery. Now, we know that every particle must have its anti-particle.

When particles and anti-particles collide, they annihilate producing (two) gamma rays. As always in physics, the reverse can also happen. Given certain conditions, a gamma ray can give rise to two particles a particle and an anti-particle obeying Einstein’s famous equation E=mc2. (Due to other strong constraints imposed by symmetries of physics, two particles or two anti-particles cannot be produced.)

The Van Allen Radiation Belts (Courtesy: Addison Wesley Longman)

In our atmosphere too, the same phenomenon happens. High energy cosmic rays bombard the Earth’s atmosphere producing matter and anti-matter particles. These can be kept separated out from each other due to the presence of Earth’s magnetic field, since moving particles of opposite charge behave very differently in magnetic fields. Furthermore, magnetic fields can confine these particles in pockets. They can remain stable for hours on average, before encountering matter particles and annihilating. Theoreticians have long predicted the presence of anti-protons in the Van Allen Belts (belts of charged particles surrounding Earth), in addition to positrons, because of the high energy of the bombarding cosmic rays. Anti-protons are much more massive than anti-electrons and thus require more energy to be produced. Most radiation can produce electron-positron pairs, but do not have enough energy to produce proton-antiproton pairs.

Enter PAMELA

PAMELA collected data over 850 days from the South Atlantic anomaly (a region over the South Atlantic ocean, where the Van Allen belts come closest to the Earth’s surface) and confirmed this theoretical prediction.

As this news spreads, there will be inevitable attempts at grabbing eyeballs by projecting this as the new cheap, easily available energy source. You can lend an ear to that at your own risk.

Radiation Risks: How much is too much?

Many people are scared stiff by the possibility of an explosion at the Japanese nuclear reactor. They believe that a nuclear fallout will affect life as we know it. Since, the radiation of radioactive substances takes a long time to die down to zero, and these substances can be carried by strong wind currents across large distances, the consequences might be catastrophic. Well, this is only partially correct.

First point to note – radiation from a radioactive source NEVER goes to zero. There is always something there, no matter how feeble. This is not a bad thing. This means that we already live in a bath of weak radiation. Radiation comes from various sources, like radon gas (the main source!), cosmic rays (which bombard atoms in the atmosphere), elements in soil and even food. This is completely harmless. Even we are radioactive just stand in front of a Geiger-Muller counter and hear the clicks due to the disintegration of atoms in your body! All of this constitutes the background. The crucial point here is that once the radiation from a source is close or below the background, it is harmless.

Sources of background radiation
Sources of background radiation and relative contribution

Next point, radiation flux decreases as inverse-square of the distance. Taking into account various ionization phenomenon, the decrease is even faster; making the decrease a power law in distance with some power higher than 2. This essentially means that radioactive samples high up in the atmosphere will have negligible effects on life on the ground.

 

Getting Quantitative:

For measurements, we need units. The standard units are the following:

  1. Gray (Gy): Unit of measurement of the amount of radiation incident on any body per unit area per unit time. 1 Gy = 1joule/1kg.
  2. Sievert (Sv): Unit of measurement of radiation incident on a human body per unit area, per unit time. 1 Sv = 1 Gy . W, where W=weight factor

The presence of the weight factor (W) in the definition of Sievert measures the damage done to a human body due to different types of radiation. For example, W=1 for electrons, muons, x-rays etc. These are less harmful than neutrons at 50 keV, which have W=10. Alpha particles from a close enough source can have W=20. (Higher weight=more damaging.) Weight factors also take into account the portion of the human body receiving the radiation. Bones have W=0.01, whereas gonads may have W=0.2.

1 Sv is a very high dose, so units like ‘rem’, (1 rem=0.01 Sv) or milli-Sievert (Sv) (1 mSv = 0.001 Sv) are used.

 

How much is safe?

There are Threshold Limit Values (TLV) lists available. These recommend that a person on average receive no more than 50 mSv per year, i.e. 5 rem. Over a five year period, a person shouldn’t receive more than 20 mSv (or 2 rem) per year. These estimates vary with location of a person and his/her occupation. Check values here.

These values are slightly misleading because it misses the important point that a large dose (say 50 mSv) delivered all at once much more damaging than the same amount of radiation spread over a long period of time, like a year.

A normal person, not working in or near a nuclear power plant, receives less than 10% of the allowed dose. So don’t worry about the radiation. It’s just not that dangerous.