Submitted via IRC for SoyCow1984
The first full characterization measurement of an accelerator beam in six dimensions will advance the understanding and performance of current and planned accelerators around the world.
A team of researchers led by the University of Tennessee, Knoxville conducted the measurement in a beam test facility at the Department of Energy's Oak Ridge National Laboratory using a replica of the Spallation Neutron Source's linear accelerator, or linac. The details are published in the journal Physical Review Letters.
"Our goal is to better understand the physics of the beam so that we can improve how accelerators operate," said Sarah Cousineau, group leader in ORNL's Research Accelerator Division and UT joint faculty professor. "Part of that is related to being able to fully characterize or measure a beam in 6D space -- and that's something that, until now, has never been done."
Six-dimensional space is like 3D space but includes three additional coordinates on the x, y, and z axes to track motion or velocity.
"Right away we saw the beam has this complex structure in 6D space that you can't see below 5D -- layers and layers of complexities that can't be detangled," Cousineau said. "The measurement also revealed the beam structure is directly related to the beam's intensity, which gets more complex as the intensity increases."
Previous attempts to fully characterize an accelerator beam fell victim to "the curse of dimensionality," in which measurements in low dimensions become exponentially more difficult in higher dimensions. Scientists have tried to circumvent the issue by adding three 2D measurements together to create a quasi-6D representation. The UT-ORNL team notes that approach is incomplete as a measurement of the beam's initial conditions entering the accelerator, which determine beam behavior farther down the linac.
Source: https://www.sciencedaily.com/releases/2018/08/180810132608.htm
(Score: 1, Insightful) by Anonymous Coward on Monday August 13 2018, @12:21PM (2 children)
It's not 6 degrees of freedom, it's 3 degrees of freedom but 6D phase space.
In brief: if you want to solve for the motion of a Newtonian particle in 3D space, you have 3 2nd order equations for the position, therefore you need 6 initial conditions rather than just 3.
If you include rotations, you need 12 initial conditions (initial rotation, as well as initial rotation rate), and you have 6 2nd order equations.
(Score: 3, Informative) by PiMuNu on Monday August 13 2018, @12:58PM
This is correct, however in most particle accelerators the beam polarity is not important so measurement of particle spin is not required.
(Score: 2) by DeathMonkey on Monday August 13 2018, @05:42PM
It's not 6 degrees of freedom, it's 3 degrees of freedom but 6D phase space.
Ok, so put this in layman terms for me: Is Kevin Bacon involved or not?