Hello ... 
>   I am a materials physicist who uses synchrotron radiation for structural studies.
I am also interested to see some crystal structure analysis program(s) in debian.
>   cmpr: peak fitting and x-ray diffraction data viewer (OK for Debian)
Yes great program.
What about jana2000 (http://www-xray.fzu.cz/jana/Jana2000/J2000_main.html)
I am not sure about the licence the only thing I found was a line in the README:
-> JANA2000 is a  free software accessible by anonymous ftp from ftp.fzu.cz,
Somthing different which hasn't mentioned (?) are:
 libgpib*
 libcomedi*
and additional kernel patches for the hardware ...
By the way. Do anyone know some good library or program to comunicate with 
Eurotherm Modbus (rs232 rs485) temperature controllers.
              mfg
	              boris