Primary beam stop

Abstract

An X-ray or neutron-optical system comprising an X-ray or neutron source ( 1 ) from which corresponding radiation is guided as a primary beam ( 2 ) to a sample ( 4 ) under investigation, with an X-ray or neutron detector ( 6 ) for receiving radiation diffracted or scattered from the sample ( 4 ), wherein the source ( 1 ), the sample and the detector are disposed substantially on one line (=z-axis) and wherein a beam stop ( 5; 31; 41 ) is provided between the sample and the detector whose cross-sectional shape is adjusted to the cross-section of the primary beam is characterized in that the beam stop is disposed to be displaceable along the z-direction for optimum adjustment of the amounts of useful and interfering radiation impinging on the detector. This protects the detector from the influence of the primary beam while allowing a maximum amount of diffracted or scattered radiation to reach the detector, wherein the beam stop can be easily adjusted to temporally changing properties of the beam optics.

We claim:  
     
         1 . An X-ray or neutron system for investigating a sample, the system comprising: 
 a source for directing a primary beam of radiation onto the sample;    a detector for receiving radiation from the sample;    a beam stop disposed between the sample and said detector, wherein said source, the sample, said beam stop, and said detector are substantially collinear along a z-axis, said beam stop having a cross-sectional shape transverse to said z-axis to intercept said primary beam; and    means, cooperating with said beam stop, for displacing said beam stop along said z-axis for optimal adjustment of amounts of useful and disturbing radiation impinging on said detector.    
     
     
         2 . The system of  claim 1 , wherein said radiation from the sample is X-ray or neutron radiation diffracted or scattered from the sample.  
     
     
         3 . The system of  claim 1 , wherein the system is designed to measure small-angle radiation.  
     
     
         4 . The system of  claim 3 , wherein said small-angle radiation is between 0.1° and 5°.  
     
     
         5 . The system of  claim 1 , wherein said beam stop can be adjusted in an xy-plane, perpendicular to said z-axis.  
     
     
         6 . The system of  claim 1 , wherein said beam stop has a round cross section.  
     
     
         6 . The system of  claim 1 , wherein said beam stop has a circular cross-section.  
     
     
         7 . The system of  claim 1 , wherein said beam stop has a shape similar to a truncated cone.  
     
     
         8 . The system of  claim 1 , wherein said beam stop is formed from a material with good radiation-absorbing properties.  
     
     
         9 . The system of  claim 1 , wherein said material comprises at least one of Au, Sb, Pb, W and Bi.  
     
     
         10 . The system of  claim 1 , wherein said displacing means comprises a motor.  
     
     
         11 . The system of  claim 10 , wherein the system can be automatically adjusted in accordance with predetermined criteria.  
     
     
         12 . The system of  claim 1 , wherein a surface of said beam stop facing said primary beam is concave.  
     
     
         13 . The system of  claim 1 , wherein said the detector is a one-element detector (zero-dimensional detector) which can scan a defined angular region about said z-axis.  
     
     
         14 . The system of  claim 1 , wherein said detector is a one-dimensional detector.  
     
     
         15 . The system of  claim 1 , wherein said detector is a two-dimensional area detector, wherein a detector surface is disposed substantially perpendicular to said z-axis.