ISSN:
1600-5767
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Geosciences
,
Physics
Notes:
Two novel detector concepts will be presented which together satisfy, in principle, most of the requirements of modern diffraction experiments with synchrotron radiation. One is based on a gaseous single photon counter with asynchronous read out and interpolating position encoding, combining the advantages of a pure pixel read out (high local and global rate capability) and of a projecting read out (small number of channels). In order to demonstrate the suitability of this detector for X-ray diffraction applications, measurements at the synchrotron radiation source Elettra (Trieste, Italy) have been performed with the prototype (140 x 140 pixels) recording diffraction patterns from different biological samples (a phospholipid and a protein crystal). These measurements have proven the good spatial resolution, the high intensity precision and the high local rate capability. Moreover, the single photon read out was utilized in order to perform highly time-resolved measurements in case of SAXS studies and to apply fine phi-slicing in case of protein crystallography. The other detector system is a highly segmented one-dimensional prototype ionization chamber with an active area of 5 * 30 mm2. Fast recording sequences in the order of 200 µs are ensured by a shielding grid, which is based on the principle of the recently invented MicroCAT structure. The grid enables new modes of operation such as gas amplification in combination with integration. In this fashion imaging on a sub photon noise level with respect to the integration time is possible. A continuous transition from integrating mode to single photon counting mode results in a huge dynamic range that covers at least 8 orders of magnitude. Preliminary experiments on biological samples will be presented.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0021889800001448
