X-Message-Number: 21001
Date: Wed, 29 Jan 2003 08:08:03 EST
Subject: Flea

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Flea is a project about using lasers for a quantum non-demolition x-rays 
brain reader.An industrial facility must be built to produce the hardware, 
one solution was to set it near Paris, another in the Sout-East part of 
France. The second option has been selected. Financing is by real estate 
operations, a pilot project is planned, because there are some autorizations 
to proceed, two options are under consideration. The hope is to have the 
paperwork ok for investment this summer.

The is some new shift in the technical definition. The first idea was to pump 
a nuclear laser with a dye optical laser, itself pumped by an ordinary laser 
of the metal vapour kind. At each step the energy coupling is very bad and 
more than 99% of the energy is lost. that translate into an enormous energy 
requirement at start.

A second option was about using two face to face interferometric mirrors to 
entangle a large number of optical photons so that a nuclear level pumping 
was done directly by the metal vapour laser. The problem was about thermal 
dissipation in the tick gelatin making up the holographic mirrors. No 
solution has been found and that way was turned down.

The current option is simpler on technological ground but more exotic. The 
dye laser is recovered but the metal vapour one is discarded. Pumping is by 
entangled radio waves in the centimeter range. The radio wave are produced in 
a klystron set and send between two mirrors. These have not to be of the 
interferometric kind, they are made from niobium alloys on a glass support. 
The output is a slit .1 micrometer wide, something that may be produced and 
controled with optical instruments. That setting will entangle one million 
radio wave photons, their collective absorption will pump the dye laser. 
Using that number of photons reduce the waveband by the square root of one 
million, that is one thousand.

The low conversion energy efficiency  of dye lasers comes from bad spectral 
fit. The pumping radiation is spread over a large spectrum when the dye sees 
only a narrow band. Using a large number of entangled photons reduce the 
pumping spectrum spread. Another useful tool is to send a sound wave in the 
dye so that different parts move at different speed. The resulting Doppler 
shift allows to scan the pump spectrum and so to collect more energy. The dye 
laser has a natural bent to work with  high modes producing up to 200 
entangled photons in up to 200 beams. In each beam a pair of liquid mirrors 
would further entangle some ten photons so that the final total energy of 
2000 UV photons would be in the 10keV range, sufficient to pump a 2 - 3 keV 
X-ray beam.

The big problem is with the coherence lenght of the x-rays, it must be more 
than 100 000 km, that is it must be produced by a metastabe energy level with 
half life at least 1/3 of a second long. this is not a problem in nuclear 
domain, but the waveband is exceedingly narrow, even by dye laser standards. 
Entanglement help to reduce the spectrum spread by 30 or so, but it will be 
necessary to vibrate the x-ray lasing medium so that the Doppler shift will 
give a better coverage of the pumping spectrum.

The next step is where to find the technology, if there is a requirement for 
unobtainium, the entire system fails. The radio power is produced by 
klystrons, that technology is used in particle accelerator physics so there 
is an industrial source for them. For tests, an organization such the CERN 
could sell back old klystrons at good price. A machine to make ultraflat 
mirrors has been found, cooling the mirrors so that they superconduct is not 
a big problem. That technology will solve all heat problems in the mirrors. 
High efficiency dye laser pumping looks as a readilly solvable problem.

The mirrors to entangle ten dye laser photons would use 3 liquid elements: 
mercury for the first mirror, a dense trensparent liquid to propagate the 
light, this product would be similar to those used in gem stones control. The 
second mirror would be made of oil with a reflecting coloidal load. A similar 
product has been used at the Laval University by E. Borra et al. in a liquid 
mirror. That technology must produce the ten nanometers wide exit slit 
without using interferometric mirrors. Pumping the x-ray laser would so be 
brought down to garage technology.

Yvan Bozzonetti.


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