Tim May wrote:
On Thursday, March 6, 2003, at 12:05 PM, Peter Fairbrother wrote:
Thomas Shaddack wrote:
FIPS-140 is your friend. They did the math. Cheers - Bill
fips140.c is a cool toy, thanks :) However, a bit unusable for my purposes; the tests I run on data from /dev/dsp always fail. (I am using the tuner card, tuned to between the channels; visual test (cat /dev/dsp) looks like a noise.)
About 1% of this noise is cosmic-ray background, caused by cosmic rays
hitting the atmosphere.
Unlikely in the extreme. Even galactic cosmic rays with TeV energies are unimpressive when dissipating their (paltry) energy over several hundred m^3, let alone over hundreds of km^3. The somewhat more common GeV-energy particles are literally inconsequential.
GeV = 10^9 eV TeV = 10^12 eV
One TeV in 10^-8 seconds is 10^12 {eV} x 10^8 {s^-1} / 6.12x10^18 {eV J^-1}
or 16 Watts. 16 watts 50 km away will register on an untuned (ie with
maximun gain) TV receiver.
First, dumping all the energy in 10 nanoseconds is implausible. Characteristic shower length, speed of light issues, etc. Get out your calculator. (Hint: Many of the shower products even reach mountain altitudes, sometimes even sea level.)
Second, even if somehow the energy of a TeV particle were to be localized and dumped in the time you specify, an antenna 50 km away would receive how much energy (power at source divided by roughly r cubed, but lasting only the 10 ns you assume). No resonant detector could see this, for obvious reasons of nonrepeatability, and no ultrawideband pulse detector could see this.
Galactic cosmic rays go up to 4x10^21 eV. That's ~60 Joules, in say 10^-8
seconds, or => 6 GW <=.
But so rare in any given region as to be notable events, which hardly fits with their being part of the background noise in a sea level RF detector.
Which is far more than any terrestrial TV transmitter I've ever heard of.
I might be wrong, I haven't experimented myself and was just repeating received wisdom. But not for that reason.
Get out your calculator. You're off by many, many orders of magnitude.
--Tim May
"Stupidity is not a sin, the victim can't help being stupid. But stupidity is the only universal crime; the sentence is death, there is no appeal, and execution is carried out automatically and without pity." --Robert A. Heinlein
