Large Electron–Positron Collider

The Large Electron–Positron Collider (LEP) was one of the largest particle accelerators ever constructed.

It was built at CERN, a multi-national centre for research in nuclear and particle physics near Geneva, Switzerland. LEP collided electrons with positrons at energies that reached 209 GeV. It was a circular collider with a circumference of 27 kilometres built in a tunnel roughly 100 m (300 ft) underground and passing through Switzerland and France. LEP was used from 1989 until 2000. Around 2001 it was dismantled to make way for the LHC, which re-used the LEP tunnel. To date, LEP is the most powerful accelerator of leptons ever built.

Collider Background

LEP was a circular lepton collider – the most powerful such ever built. For context, modern colliders can be generally categorized based on their shape (circular or linear) and on what types of particles they accelerate and collide (leptons or hadrons). Leptons are point particles and are relatively light. Because they are point particles, their collisions are clean and amenable to precise measurements; however, because they are light, the collisions cannot reach the same energy that can be achieved with heavier particles. Hadrons are composite particles (composed of quarks) and are relatively heavy; protons, for example, have a mass 2000 times greater than electrons. Because of their higher mass, they can be accelerated to much higher energies, which is the key to directly observing new particles or interactions that are not predicted by currently accepted theories. However, hadron collisions are very messy (there are often lots of unrelated tracks, for example, and it is not straightforward to determine the energy of the collisions), and therefore more challenging to analyze and less amenable to precision measurements.

Eta Leporis

Eta Leporis (Eta Lep, η Leporis, η Lep) is a F-type main sequence star in the constellation of Lepus. It has an apparent visual magnitude of approximately 3.719. Using the IRS instrument on the Spitzer Space Telescope, excess infrared emission has been observed from the star, which can be modelled by a dust disk extending from 1 to 16 astronomical units from the star.

References

Beta Leporis

Beta Leporis (Beta Lep, β Leporis, β Lep) is the second brightest star in the constellation of Lepus. It is also known as Nihal,"quenching their thirst". The occasional spelling Nibal appears to be due to a misreading.

Based on parallax measurements from the Hipparcos astrometry satellite, this star is located about 160 light-years (49 parsecs) from the Earth. It has an apparent visual magnitude of 2.84 and a stellar classification of G5 II. The mass of this star is 3.5 times the mass of the Sun and it is about 240 million years old, which is sufficient time for a star this massive to consume the hydrogen at its core and evolve away from the main sequence, becoming a G-type bright giant.

This is a double star system and may be a binary. Using adaptive optics on the AEOS telescope at Haleakala Observatory, the pair was found to be separated by an angle of 2.58 arcseconds at a position angle of 1.4°. Component B has been observed to fluctuate in brightness and is catalogued as suspected variable star NSV 2008.

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Recycle Sally

by: Lobo

I know she's gone again
I saw her walking up the track
God only knows when she will be back
The only thing I know as sure as
Morning starts the day
When she comes home again
This is what they'll all say.
Recycle Sally coming round again
Recycle Sally we all know where you've been
Recycle Sally why can't the fools see
Recycle Sally Recycle Sally Recycle Sally
That you recycle to me.
Now Sally ain't about to start to get settled down
She likes to circulate herself all around town
She might get abused and crushed all out of shape




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