Radiation detector and radiation apparatus

Abstract

A practical semiconductor radiation detector capable of collecting electrons rapidly with a large volume is disclosed. A multiple layers of grid electrodes around an anode formed on a semiconductor element limits the generation of the induced charge signal for the anode to the space in the neighborhood of the anode, while at the same time making it possible to collect the electrons rapidly. As a result of limiting the space for generating the induced charge by the grid electrodes, the energy resolution is improved even for a thick semiconductor element. Also, the capability of rapidly collecting the electrons due to the high field strength generated by the grid electrodes makes a sensitive volume of the whole semiconductor and thus achieves a high radiation detection efficiency.

1 . A radiation detector comprising: 
 a semiconductor element irradiated for generating positive holes and electrons;    a cathode and an anode impressed with a voltage in such a manner as to form an electric field in said semiconductor element;    a first grid electrode impressed with a voltage not lower than said cathode voltage but not higher than said anode voltage and having the distance from said anode shorter than the distance from said cathode; and    a second grid electrode arranged on a side of said first grid electrode far from said anode and impressed with a voltage lower than said first grid electrode.    
   
   
       2 - 9 . (canceled)  
   
   
       10 . A radiation detector comprising 
 a semiconductor element irradiated for generating positive holes and electrons;    a cathode and an anode formed on the surface of said semiconductor element;    a first grid electrode arranged at a predetermined distance from said anode on the surface of said semiconductor element; and    a second grid electrode arranged at a predetermined distance from said first grid electrode on the part of the surface of said semiconductor element far from said anode, wherein the voltage of said anode is not lower than the voltage of said first grid electrode, the voltage of said first grid electrode is higher than the voltage of said second grid electrode, and the voltage of said second grid electrode is higher than the voltage of said cathode.    
   
   
       11 - 12 . (canceled)  
   
   
       13 . A radiation detector comprising: 
 a semiconductor element irradiated for generating positive holes and electrons;    a cathode and an anode formed on said semiconductor element; and    a plurality of grid electrodes formed on said semiconductor element at a predetermined distance from said anode, wherein a plurality of said grid electrodes can be impressed with a voltage independently of each other.    
   
   
       14 . A radiation detector comprising: 
 a semiconductor element irradiated for generating positive holes and electrons;    a cathode formed on one surface of said semiconductor element;    a plurality of anodes formed on a different surface of said semiconductor element; and    double grid electrodes surrounding each of said anodes, wherein each of said double grid electrodes can be impressed with a voltage independently of each other.    
   
   
       15 . A radiation detector comprising: 
 a semiconductor element irradiated for generating positive holes and electrons;    a cathode formed on one surface of said semiconductor element;    a plurality of anodes formed on another surface of said semiconductor element;    a plurality of grid electrodes surrounding said anodes, respectively, wherein a plurality of said grid electrodes are combined into a single grid electrode unit in such a manner as to be impressed with the same potential, each of said grid electrodes being configured to surround the corresponding one of said anodes without crossing the electrodes of other potentials.    
   
   
       16 - 17 . (canceled)  
   
   
       18 . A radiation detector comprising: 
 a semiconductor element irradiated for generating positive holes and electrons;    a cathode and an anode formed on said semiconductor element; and    a grid electrode formed on said semiconductor element at a predetermined distance from said anode, wherein said cathode, said anode and said grid electrode are combined to form a plurality of sets, the signals output from said anode and said cathode of each of said sets are sent to a signal reading circuit package board, and electric conduction is established by bump solder held between a plurality of reading portions in the detector and the reading portions of said signal reading circuit package board.    
   
   
       19 . A radiation detector comprising: 
 a substantially conical or substantially pyramidal semiconductor element irradiated for generating positive holes and electrons, wherein a plurality of said semiconductor elements are combined as a set, a cathode is formed on the bottom surface portion of each of said semiconductor elements, an anode is formed at the top portion of each of said semiconductor elements, a grid is formed at a predetermined distance from said anode of each of said semiconductor element, and said semiconductor elements are combined into a shape substantially similar to a sphere.    
   
   
       20 . A radiation apparatus comprising 
 a semiconductor element for generating positive holes and electrons by the radiation transmitted through a subject or generated from inside the subject;    a cathode and an anode impressed with a voltage in such a manner as to form an electric field in said semiconductor element;    a first grid electrode impressed with a voltage not lower than said cathode voltage but not higher than said anode voltage and having a distance from said anode shorter than the distance from said cathode;    a second grid electrode arranged on a side of said first grid electrode far from said anode and impressed with a voltage lower than the voltage of said first grid electrode; and    processing means for processing an image of said subject based on the signal from said anode.    
   
   
       21 . A radiation apparatus comprising 
 a semiconductor element for generating positive holes and electrons by the radiation transmitted through a subject or generated from inside the subject,    a cathode and an anode impressed with a voltage in such a manner as to form an electric field in said semiconductor element;    a first grid electrode;    a second grid electrode for forming an electric field with said first grid electrode; and    processing means for processing an image of said subject based on the signal from said anode.    
   
   
       22 . A radiation apparatus comprising 
 a semiconductor element for generating positive holes and electrons by the radiation transmitted through a subject or generated from inside the subject;    a cathode and an anode formed on the surface of said semiconductor element;    a first grid electrode formed at a predetermined distance from said anode on the surface of said semiconductor element; and    a second grid electrode formed at a predetermined distance from said first grid electrode on the part of the surface of said semiconductor element far from said anode, wherein the voltage of said anode is not lower than the voltage of said first grid electrode, the voltage of said first grid electrode is higher than the voltage of said second grid electrode, and the voltage of said second grid electrode is higher than the voltage of said cathode, said radiation apparatus further comprising processing means for processing an image of said subject based on the signal from said anode.