Teknologi Penjelajahan Bulan

Edited and Added By:
Arip Nurahman Department of Physics, Faculty of sciences and Mathematics
Indonesia University of Education
&
Follower Open Course Ware at MIT-Harvard University, U.S.A.

NASA's blueprints for an outpost on the moon are shaping up. The agency's Lunar Architecture Team has been hard at work, looking at concepts for habitation, rovers, and space suits.

Image left: Concept of one potential design for a future lunar rover. Spacesuits would be attached to the exterior of the rover. Credit: NASA

NASA will return astronauts to the moon by 2020, using the Ares and Orion spacecraft already under development. Astronauts will set up a lunar outpost – possibly near a south pole site called Shackleton Crater – where they’ll conduct scientific research, as well as test technologies and techniques for possible exploration of Mars and other destinations.

Even though Shackleton Crater entices NASA scientists and engineers, they don’t want to limit their options. To provide for maximum flexibility, NASA is designing hardware that would work at any number of sites on the moon. Data from the Lunar Reconnaissance Orbiter mission, a moon-mapping mission set to launch in October 2008, might suggest that another lunar site would be best suited for the outpost.

First, astronauts on the moon will need someplace to live. NASA officials had been looking at having future moonwalkers bring smaller elements to the moon and assemble them on site. But the Lunar Architecture Team found that sending larger modules ahead of time on a cargo lander would help the outpost get up and running more quickly. The team is also discussing the possibility of a mobile habitat module that would allow one module of the outpost to relocate to other lunar destinations as mission needs dictate.

NASA is also considering small, pressurized rovers that could be key to productive operations on the moon’s surface. Engineers envision rovers that would travel in pairs – two astronauts in each rover – and could be driven nearly 125 miles away from the outpost to conduct science or other activities. If one rover had mechanical problems, the astronauts could ride home in the other.

Image left: Concept of one potential design for a future lunar rover. Spacesuits would be attached to the exterior of the rover. Credit: NASA

Astronauts inside the rovers wouldn't need special clothing because the pressurized rovers would have what's called a "shirt-sleeve environment." Spacesuits would be attached to the exterior of the rover (see images). NASA's lunar architects are calling them "step in" spacesuits because astronauts could crawl directly from the rovers into the suits to begin a moonwalk.

NASA is also looking to industry for proposals for a next-generation spacesuit. The agency hopes to have a contractor on board by mid-2008.

NASA will spend the next several months communicating the work of the Lunar Architecture Team to potential partners -- the aerospace community, industry, and international space agencies -- to get valuable feedback that will help NASA further refine plans for the moon outpost. The agency's goal is to have finalized plans by 2012 to get "boots on the moon" by 2020.

Semoga Bermanfaat!

Sumber:

http://www.nasa.gov/exploration/lunar_architecture.html

Arip Nurahman

Higgs Particels

Add and Edited By:
Arip Nurahman
Department of Physic
Faculty of Sciences and Mathematics
Indonesia University of Education





In particle physics, little Higgs is a refined version of the Higgs boson based on the idea that the Higgs boson is a pseudo-Goldstone boson arising from some global symmetry breaking at a TeV energy scale. The main goal of little Higgs theories was to have electroweak symmetry breaking be the result of strong dynamics in the spirit of pions in QCD. The idea was initially studied by Nima Arkani-Hamed, Andy Cohen, and Howard Georgi in the spring of 2001. The idea was explored further in a scientific paper by Nima Arkani-Hamed, Andy Cohen, Thomas Gregoire, and Jay Wacker in the spring of 2002. In the spring of 2002 several papers appeared that refined the ideas of little Higgs theories, most notably the Littlest Higgs by Nima Arkani-Hamed, Andy Cohen, Emmanuel Katz, and Ann Nelson.

Little Higgs theories were an outgrowth of dimensional deconstruction. In these theories, the gauge group has the form of a direct product of several copies of the same factor, for example SU(2)\times SU(2). Each SU(2) factor may be visualised as the SU(2) group living at a particular point along an additional dimension of space. Consequently, many virtues of extra-dimensional theories may be reproduced even though the little Higgs theory is 3+1-dimensional. The little Higgs models are able to predict a naturally-light Higgs particle.

The main idea behind the little Higgs models is that the one-loop contribution to the tachyonic Higgs boson mass coming from the top quark cancels. (The other one-loop contributions are small enough that they don't really matter; the top Yukawa coupling is huge and all the other Yukawa couplings and gauge couplings are small.) This protects the Higgs boson mass for about one order of magnitude, which is good enough to evade many of the precision electroweak constraints

Strong Force

Strong interaction

Add and Edited By:
Arip Nurahman Department of Physics, Faculty of Sciences and Mathematics
Indonesian University of Education
and

Follower Open Course Ware at Massachusetts Institute of Technology
Cambridge, USA
Department of Physics
http://web.mit.edu/physics/
http://ocw.mit.edu/OcwWeb/Physics/index.htm
&
Aeronautics and Astronautics Engineering
http://web.mit.edu/aeroastro/www/
http://ocw.mit.edu/OcwWeb/Aeronautics-and-Astronautics/index.htm

Physics Poster (CERN)

Strong force - Weak force Ref.: CERN-DI-9112020_1	History of the Universe Ref.: CERN-DI-9108002

Big Bang Ref.: CERN-DI-9112020_3	Quark gluon plasma Ref.: CERN-DI-9203073

From atom to quark Ref.: CERN-DI-9306017_1	Force carrying particles Ref.: CERN-DI-9306017_2

In particle physics, the strong interaction, or strong force, or color force, holds quarks and gluons together to form protons and neutrons. The strong interaction is one of the four fundamental interactions, along with gravitation, the electromagnetic force and the weak interaction. The word strong is used since the strong interaction is the most powerful of the four fundamental forces; its typical field strength is 100 times the strength of the electromagnetic force, some 10¹³ times as great as that of the weak force, and about 10³⁸ times that of gravitation.

The strong force is thought to be mediated by gluons, acting upon quarks, antiquarks, and the gluons themselves. This is detailed in the theory of quantum chromodynamics (QCD).

History

Before the 1970s, protons and neutrons were thought to be indivisible fundamental particles. It was known that protons carried a positive electrical charge, electric repulsion made same-charge particles repel each other, and multiple protons were bound together in the atomic nucleus. However, it was unknown what force held the like-charged protons together (with neutrons) in the nucleus.

Another, stronger, attractive force was postulated to explain how protons and neutrons were held together in the atomic nucleus, overcoming electromagnetic repulsion. For its high strength at short distances, it was dubbed the "strong" force. It was thought, at that time, this strong force was a fundamental force acting directly on the nuclear particles. Experiments suggested that the force acted equally between any nucleons, whether protons or neutrons.

It was later discovered this phenomenon was only a residual side-effect of another, truly fundamental, force acting directly on particles inside protons and neutrons, called quarks and gluons. This newly-discovered force was initially called the "color force." The name was chosen for convenience, and has no relation to visible color. ^[1]

Today, the term "strong force" is used for that strong nuclear force that acts directly on quarks and gluons. The original strong force that acts between nucleons (and also between particles made of quarks, or hadrons) is today called the nuclear force, or the "residual strong nuclear force."

Details

The behavior of the strong force

The contemporary strong force is described by quantum chromodynamics (QCD), a part of the standard model of particle physics. Mathematically, QCD is a non-Abelian gauge theory based on a local (gauge) symmetry group called SU(3).

Quarks and gluons are the only fundamental particles which carry non-vanishing color charge, and hence participate in strong interactions. The strong force itself acts directly only upon elementary quark and gluon particles.

All quarks and gluons in QCD interact with each other through the strong force. The strength of interaction is parametrized by the strong coupling constant. This strength is modified by the gauge color charge of the particle, a group theoretical property which has nothing to do with ordinary visual color.

The strong force acting between quarks, unlike other forces, does not diminish in strength with increasing distance, after a limit (about the size of a hadron) has been reached. It remains at a strength of about 10 newtons, no matter how far away from each other the particles are, after this limiting distance has been reached. In QCD, this phenomenon is called color confinement, implying that only hadrons can be observed; this is because the amount of work done against a force of 10 newtons is enough to create particle-antiparticle pairs within a very short distance of an interaction. Evidence for this effect is seen in many failed free quark searches.

The elementary quark and gluon particles affected are unobservable directly, but instead emerge as jets of newly created hadrons, whenever energy is deposited into a quark-quark bond, as when a quark in a proton is struck by a very fast quark (in an impacting proton) during an accelerator experiment. However, quark-gluon plasmas have been observed.

The behavior of the residual strong force (nuclear force)

A residual effect of the strong force is called the nuclear force. The nuclear force acts between hadrons, such as nucleons in atomic nuclei. This "residual strong force," acting indirectly, transmits gluons that form part of the virtual pi and rho mesons, which, in turn, transmit the nuclear force between nucleons.

The residual strong force is thus a minor residuum of the strong force which binds quarks together into protons and neutrons. This same force is much weaker between neutrons and protons, because it is mostly neutalized within them, in the same way that electromagnetic forces between neutral atoms (van der Waals forces) are much weaker than the electromagnetic forces that hold the atoms internally together.

Unlike the strong force itself, the nuclear force, or residual strong force, does diminish in strength, strongly with distance. The decrease is approximately as an negative exponential power of distance, though there is no simple expression known for this; see Yukawa potential. This fact, together with the less-rapid decrease of the disruptive electromagnetic force between protons with distance, causes the instability of larger atomic nuclei, such as all those with atomic numbers larger than 82.

See also

• Binding energy
• Color charge
• Coupling constant
• Internucleon force and Nuclear physics
• Nuclear force
• QCD matter
• Quantum field theory and Gauge theory
• Standard model of particle physics and Standard model (basic details)
• Weak interaction, electromagnetism and gravity

References

1. ^ Feynman, Richard (1985). "Loose Ends", QED: The Strange Theory of Light and Matter. Princeton University Press, p. 136. ISBN 0-691-08388-6. "The idiot physicists, unable to come up with any wonderful Greek words anymore, call this type of polarization by the unfortunate name of “color,” which has nothing to do with color in the normal sense."

Further reading

• Griffiths, David J. (1987). Introduction to Elementary Particles. John Wiley & Sons. ISBN 0-471-60386-4.
• Kane, Gordon L. (1987). Modern Elementary Particle Physics. Perseus Books. ISBN 0-201-11749-5.
• Morris, Richard (2003). The Last Sorcerers: The Path from Alchemy to the Periodic Table. Washington, D.C.: Joseph Henry Press. ISBN 0-309-50593-3.
• Halzen, Francis; Martin, Alan D. (1984), Quarks and Leptons: An Introductory Course in Modern Particle Physics, John Wiley & Sons, ISBN 0-471-88741-2

External links

• MISN-0-280: The Strong Interaction (PDF file) by J.R. Christman for Project PHYSNET.
• The Alice Experiment at CERN is the heavy ion collaboration that will investigate aspects of the Strong Nuclear Force upon the completion of the building of the Large Hadron Collider at CERN.
• The Star Experiment at the Relativistic Heavy Ion Collider at Brookhaven Nation Laboratory in New York, USA. Investigates many aspects of the Strong Nuclear Force including the theoretical Quark Gluon Plasma.

The Four Fundamental Interactions of Physics Strong interaction · Electromagnetism · Weak interaction · Gravitation

Retrieved from "http://en.wikipedia.org/wiki/Strong_interaction"

Categories: Fundamental physics concepts | Quantum chromodynamics | Particle physics | Nuclear physics