"Asimov" wrote in message
...
Hi,

Say, I've got a question about something I've read about the Swift
gamma ray detection satellite. It's detector consisted of an antenna
composed of 52,000 lead blocks arranged by computer generated
pseudo-random locations and glued to the back of a sheet of 4x8
plywood. The actual detectors where located in the spaces between the
blocks. It wasn't mentioned but I think these were probably crystals
which give off a pulse of electricity every time they are struck by a
gamma ray.

Anyways my question is, in your opinion, what is the purpose of the
pseudo random arrangement of this "apperture mask" antenna? I suspect
it has something statistical related to the nature of ambient noise
signals. I tried making a pc simulation of this but I get the same
answer whether the array is in rows or pseudo-random. I tried with
noise but I saw no reduction. I haven't tried adding a signal to the
noise in the simulation yet though...

A*s*i*m*o*v

.... Three types of lies: lies, damn lies, and statistics - Mark Twain.

Plywood on a satellite?

73 Roger ZR3RC

Roger Conroy wrote:

"Asimov" wrote in message
...
Hi,

Say, I've got a question about something I've read about the Swift
gamma ray detection satellite. It's detector consisted of an antenna
composed of 52,000 lead blocks arranged by computer generated
pseudo-random locations and glued to the back of a sheet of 4x8
plywood. The actual detectors where located in the spaces between the
blocks. It wasn't mentioned but I think these were probably crystals
which give off a pulse of electricity every time they are struck by a
gamma ray.

Anyways my question is, in your opinion, what is the purpose of the
pseudo random arrangement of this "apperture mask" antenna? I suspect
it has something statistical related to the nature of ambient noise
signals. I tried making a pc simulation of this but I get the same
answer whether the array is in rows or pseudo-random. I tried with
noise but I saw no reduction. I haven't tried adding a signal to the
noise in the simulation yet though...

A*s*i*m*o*v

... Three types of lies: lies, damn lies, and statistics - Mark Twain.

Plywood on a satellite?

73 Roger ZR3RC

Honeycomb composite, about 2" thick and about 1/4 the area of a sheet of
plywood.

http://swift.gsfc.nasa.gov/docs/swif.../bat_desc.html

According to the web page, the answer to the original question is the
geometry of the mask elements allows the telescope to maintain its field
of view and angular resolution in the event of a wide variety of
different sensor failures.

ac6xg