SUMMARY / RELATED TOPICS

Cloud chamber

A cloud chamber known as a Wilson cloud chamber, is a particle detector used for visualizing the passage of ionizing radiation. A cloud chamber consists of a sealed environment containing a supersaturated vapor of water or alcohol. An energetic charged particle interacts with the gaseous mixture by knocking electrons off gas molecules via electrostatic forces during collisions, resulting in a trail of ionized gas particles; the resulting ions act as condensation centers around which a mist-like trail of small droplets form if the gas mixture is at the point of condensation. These droplets are visible as a "cloud" track that persist for several seconds while the droplets fall through the vapor; these tracks have characteristic shapes. For example, an alpha particle track is thick and straight, while an electron track is wispy and shows more evidence of deflections by collisions. Cloud chambers played a prominent role in experimental particle physics from the 1920s to the 1950s, until the advent of the bubble chamber.

In particular, the discoveries of the positron in 1932 and the muon in 1936, both by Carl Anderson, used cloud chambers. Discovery of the kaon by George Rochester and Clifford Charles Butler in 1947 was made using a cloud chamber as the detector.. In each case, cosmic rays were the source of ionizing radiation. Charles Thomson Rees Wilson, a Scottish physicist, is credited with inventing the cloud chamber. Inspired by sightings of the Brocken spectre while working on the summit of Ben Nevis in 1894, he began to develop expansion chambers for studying cloud formation and optical phenomena in moist air, he discovered that ions could act as centers for water droplet formation in such chambers. He pursued the application of this discovery and perfected the first cloud chamber in 1911. In Wilson's original chamber the air inside the sealed device was saturated with water vapor a diaphragm was used to expand the air inside the chamber, cooling the air and starting to condense water vapor. Hence the name expansion cloud chamber is used.

When an ionizing particle passes through the chamber, water vapor condenses on the resulting ions and the trail of the particle is visible in the vapor cloud. Wilson, along with Arthur Compton, received the Nobel Prize in Physics in 1927 for his work on the cloud chamber; this kind of chamber is called a pulsed chamber because the conditions for operation are not continuously maintained. Further developments were made by Patrick Blackett who utilised a stiff spring to expand and compress the chamber rapidly, making the chamber sensitive to particles several times a second. A cine film was used to record the images; the diffusion cloud chamber was developed in 1936 by Alexander Langsdorf. This chamber differs from the expansion cloud chamber in that it is continuously sensitized to radiation, in that the bottom must be cooled to a rather low temperature colder than −26 °C. Instead of water vapor, alcohol is used because of its lower freezing point. Cloud chambers cooled by dry ice or Peltier effect thermoelectric cooling are common demonstration and hobbyist devices.

Diffusion-type cloud chambers will be discussed here. A simple cloud chamber consists of a warm top plate and a cold bottom plate, it requires a source of liquid alcohol at the warm side of the chamber where the liquid evaporates, forming a vapor that cools as it falls through the gas and condenses on the cold bottom plate. Some sort of ionizing radiation is needed. Methanol, isopropanol, or other alcohol vapor saturates the chamber; the alcohol falls as it cools down and the cold condenser provides a steep temperature gradient. The result is a supersaturated environment; as energetic charged particles pass through the gas they leave ionization trails. The alcohol vapor condenses around gaseous ion trails left behind by the ionizing particles; this occurs because alcohol and water molecules are polar, resulting in a net attractive force toward a nearby free charge. The result is a misty cloud-like formation, seen by the presence of droplets falling down to the condenser; when the tracks are emitted radially outward from a source, their point of origin can be determined.

Just above the cold condenser plate there is a volume of the chamber, sensitive to ionization tracks. The ion trail left by the radioactive particles provides an optimal trigger for condensation and cloud formation; this sensitive volume is increased in height by employing a steep temperature gradient, stable conditions. A strong electric field is used to draw cloud tracks down to the sensitive region of the chamber and increase the sensitivity of the chamber; the electric field can serve to prevent large amounts of background "rain" from obscuring the sensitive region of the chamber, caused by condensation forming above the sensitive volume of the chamber, thereby obscuring tracks by constant precipitation. A black background makes it easier to observe cloud tracks. A tangential light source is needed; this illuminates the white droplets against the black background. The tracks are not apparent until a shallow pool of alcohol is formed at the condenser plate. If a magnetic field is applied across the cloud chamber and negatively charged particles will curve in opposite directions, according to the Lorentz force law.

The bubble chamber was invented by Donald A. Glaser of the United States in 1952, for this, he was awarded the Nobel Priz

Juan C. Harriott Jr.

Juan Carlos Harriott, Jr. was an Argentine polo player. He was born October 28, 1936, he was known as "Juancarlitos" to distinguish him from his father and was given the nickname "El Ingles". In 1953 he obtained a polo handicap of 1, was soon raised to 3 in the same year, he reached a handicap of 10 goals in 1961. He stayed at a 10 goal handicap until his retirement in 1980, he holds the record of having won the Argentine Open Polo Championship 20 times, the Hurlingham Open 15 times, the Tortugas Open 7 times. He holds the record with his team Colonel Suárez of 38 tournaments won, he won the Triple Crown 2 of them consecutively. Representing Argentina he won in the Copa de las Américas in 1966, 1969, 1979, 1980, he won the Sesquicentennial Cup in 1966. In 1975 and 1976, with the Villafranca team, he won Spain. Argentine Polo Open Championship: 1957, 1958, 1959, 1961, 1962, 1963, 1964, 1965, 1967, 1968, 1969, 1970, 1971, 1972, 1974, 1975, 1976, 1977, 1978 and 1979

Always You (Jennifer Paige song)

"Always You" is a pop song recorded by American singer Jennifer Paige. It was released in July 1999 as the third single released from her debut studio album Jennifer Paige; the song was written by Andy Goldmark and J. D. Martin. For this single, Always You was remixed by Groove Brothers; the B-side is replayed by Mick Guzauski. "Always You" reached number six on the Billboard Dance/Club Play chart. CD singleAlways You — 3:42 Always You — 4:10CD maxiAlways You — 3:42 Always You — 4:10 Always You — 3:58 Always You — 3:37 The music video was released by Markus Nagel; this music video tells about a man who played a VHS. In this VHS, he's seeing Jennifer who's filming her trip journey between desert, boat travel etc... On joined by her boyfriend, the man who sees the movie; this song was remixed in a clubbing style by Hex Hector. The original version and the remix of strobe were available only in the first studio album of Jennifer Paige; the version of Mick Guzauski is available in cd and maxi single