Alpha Magnetic Spectrometer set to sniff out strangelets
Mighty, antimatter-hunting machine attached to ISS
The crews of space shuttle Endeavour and the International Space Station have completed the installation of the Alpha Magnetic Spectrometer (AMS, or AMS-02) – the $2bn piece of kit designed to "advance knowledge of the universe and lead to the understanding of the universe's origin by searching for antimatter, dark matter and measuring cosmic rays".
Following a lengthy grapple this morning using the shuttle and ISS's robotic arms, the AMS now lies on the starboard side of the station's truss structure, ready to provide a continual flow of data to Earth-based operators during its nominal three-year mission.
The AMS boasts "a large permanent magnet to produce a strong, uniform magnetic field", which is "used to bend the path of charged cosmic particles as they pass through five different types of detectors".*
The device's most practical application will be measurement of cosmic rays, which represent "a significant obstacle to a manned space flight to Mars". NASA explains that "accurate measurements of the cosmic ray environment are needed to plan appropriate countermeasures", and the AMS will provide "an immense amount of accurate data and allowing measurements of the long term variation of the cosmic ray flux over a wide energy range, for nuclei from protons to iron".
While it's measuring cosmic radiation, the AMS will also sniff for rather more esoteric matter – antihelium nuclei, neutralinos, and strangelets.
Regarding antihelium, NASA elaborates: "Experimental evidence indicates that our Galaxy is made of matter; however, there are more than 100 hundred million galaxies in the universe and the Big Bang theory of the origin of the universe requires equal amounts of matter and antimatter.
"Theories that explain this apparent asymmetry violate other measurements. Whether or not there is significant antimatter is one of the fundamental questions of the origin and nature of the universe. Any observations of an antihelium nucleus would provide evidence for the existence of antimatter."
Neutralinos, meanwhile, are a theoretical candidate for dark matter, which along with dark energy is thought to make up 95 per cent of the universe's total mass. NASA says: "If neutralinos exist, they should be colliding with each other and giving off an excess of charged particles that can be detected by AMS-02. Any peaks in the background positron, anti-proton, or gamma flux could signal the presence of neutralinos or other dark matter candidates."
Finally, and just to make sure the AMS is earning its keep, it will be keeping a sharp eye out for the strangelet – a "a totally new form of matter" comprising three quarks (u, d and s), as opposed to our modest earthly matter, which has only two quarks (u and d).
The AMS will capture all this data at a rate of "7 Gigabits per second", which is "equivalent to filling a 1 Gigabyte USB memory stick every second!" as NASA excitedly puts it.
The agency explains: "Using sophisticated filtration and compression techniques, the advanced 600 computer processors located on AMS-02 are able to reduce the amount of data down by a factor of 3,000. This data is sent from the ISS to the ground where researchers around the globe will compile and analyze data."
*NASA specifies: "The Transition Radiation Detector (TRD) measures particles passing at speeds nearly that of the speed of light. The Time of Flight (TOF) measures the charge and velocity of passing particles. The Silicon Tracker measures the coordinates of charged particles in the magnetic field. The Ring Image Cerenkov Counter (RICH) measures both the velocity and charge of the particles and the Electromagnetic Calorimeter (ECAL) measures the energy and coordinates of electrons, positrons and gamma rays."
Yes, you behind the bikesheds! Stand still laddy!
"Strangelets – a "a totally new form of matter" comprising three quarks (u, d and s), as opposed to our modest earthly matter, which has only two quarks (u and d)."
Strangelets have a "strange" quark, so hadrons (3-quark units) like [up, down, strange] or mesons (2-quark units) like [up, strange] belong to that set.
Bog standard low-energy matter as we encounter everyday uses up and down exclusively so hadrons like the neutron [up, down, down] or mesons like [up, down] belong to that set.
Magnets - how do they work?
Specifically permanent magnets. They will pull things towards them. When they do, they've done work.
Where does the energy for the work come from?
Why doesn't/does the strength of the remaining magnetic field go down?
Do they wear out?
I'm sure this is GCSE physics but I'm buggered if I can remember it.
In principle, a magnetic field does not do work - it acts on moving charges only -- orthogonally to the vector of movement, thus FORCE dotproduct VELOCITY is zero. Ok, that doesn't help here.
Now, if your wrench is pulled towards the permanent magnet because the electrons have some correlation in their orbital movements [in the classical approach], then clearly work is being done. It must come from the potential energy inherent in the start configuration. Once the wrench is on the magnet, the total field magnetic should be reduced, as the wrench will start to behave like a magnet with inverse polarity.... that should be about it...
Anyway ... something for physicsexchange, I reckon.