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Submission + - Man Records TSA Ejection After Refusing Body Scan (signonsandiego.com) 3

bonch writes: A man refusing a full-body scan and 'groin check' was ejected from the San Diego International Airport by the TSA as he recorded the incident with a cell phone sitting on his luggage. John Tyner, who posted his account of events along with the video on his blog, refused to pass through a full-body scanner, citing privacy and health concerns. Tyner was escorted to a security area for a patdown but, after hearing a description of the procedure, told the agent, 'You touch my junk and I'm going to have you arrested.' This led to a series of encounters with supervisors as well as a visit from a local police officer. Tyner was told that he was not being detained against his will, but that if he left the area, he would be hit with a civil suit and a $10,000 fine. He walked out the airport anyway, posting his account two hours later. The new TSA procedures have generated criticism from both passengers and airline crew, and one activist has proposed a National Opt-Out Day.

Comment Re:Kinetic Energy? (Score 3, Informative) 163

Each particle has 5 TeV of kinetic energy.
There will be (roughly) 1e12 particles per bunch, and (roughly) 1e3 bunches per pulse.

This works out as ~800 MJ per pulse.

That is the same energy as a 1e6 kg train moving at ~80 mph, so the comparison is not as daft as it would seem.

(Note: Those numbers are all pretty rough, and I'm sure someone will be along soon to correct me soon, but the point is that the LHC beams store waaay more KE than you would imagine.)

Comment Re:engineers vs. scientists (Score 2, Informative) 338

That's not quite true.

Experimental accelerator physicists (not particle physicists) will come up with a conceptual design for the machine that fits the particle physicists requirements, and they will then work with engineers to design and build it.

Most of the designing and building is done by properly qualified engineers, not scientists.

Comment Re:The radio makes senes, but not the singer (Score 1) 645

But leave my goddamn radio at my desk alone.

If anyone else can hear that radio, I hope you've counted the number of "employee units" within earshot, and the number of half hour increments during which you play the radio, and paid the appropriate tariff.

http://www.prsformusic.com/SiteCollectionDocuments/PPS%20Tariffs/I-2009-03%20Tariff.pdf

*shakes head sadly*

I wish I was making this up.

Comment Re:t that's not damped detuning (Score 2, Informative) 191

FYI -- I work on this project, and I work with Roger Jones (the guy in the article), so I know a substantial amount about this.

Your definition of damping is quite right, but your definition of detuning is, in this case, not really what he means. What he means is taking a cavity, and changing its shape in order to "detune" some cells.

To explain:

The cavities are traditionally built in such a way that each cell rings (like a bell) at the design frequency of the accelerating rf. Since all of the cells are identical, the beam will excite exactly the same mode frequencies in each one (like a hammer hitting a bell). Since they are resonant with each other, they can and will ring coherently. Thus the amplitude of these modes will be proportional to N^2 (where N is the number of cells).

If they are made to have slight differences (detuned) that cause their resonant frequencies to be slightly different (but still within the bandwidth of each other due to their finite Q -- so they *can* excite one another), they will ring incoherently. This causes the mode amplitude to be proportional to N.

Thus, the amplitude of the incoherent ringing will be lower by a factor of N.

On top of this, they also add absorbing material to take out some of the power (the damping you refer to), and it is this that fits your guitar string analogy, not the detuning that Roger was referring to in the article. Absorbing material cannot change the frequency of the oscillation -- all it can do is remove energy from it, thus damping it's amplitude.

To go further, yes the differing stiffnesses of the springs under my car *does* look like a system of bells ringing at different frequencies. They are each ringing at a different "pitch" in order to detune any destructive vibrations. Your car analogy, including the absorbing rubber, is almost perfect! :)

I think the confusion is coming from the fact that this system can use both the absorbing material that fits your guitar string analogy, and the detuning technique that fit's Roger's bells. His analogy *does* describe the system very well, and I hope you can see that now.

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