Ionizing Radiation Detector

Abstract

The invention concerns an ionizing radiation detector comprising a housing containing: an avalanche photodiode in contact, through its photosensitive face, with the scintillator material via optical coupling, a preamplifier of the electrical signal from the avalanche photodiode. This detector is compact, portable, and very robust. It detects X-rays or gamma rays with excellent resolution, which can be less than 3% at 662 keV.

1 . Ionizing radiation detector comprising a housing containing:
 a scintillator material,   an avalanche photodiode in contact, through its photosensitive face, with the scintillator material via optical coupling,   a preamplifier of the electrical signal from the avalanche photodiode.   
     
     
         2 . Detector according to the previous claim, characterized in that the scintillator material is covered with a light reflector. 
     
     
         3 . Detector according to one of the preceding claims, characterized in that the scintillator material is a rare-earth halide single crystal. 
     
     
         4 . Detector according to the preceding claim, characterized in that the single crystal is a cerium doped lanthanum bromide. 
     
     
         5 . Detector according to one of the preceding claims, characterized in that the volume of the housing is less than 300 cm 3 . 
     
     
         6 . Detector according to the preceding claim, characterized in that the volume of the housing is less than 60 cm 3 . 
     
     
         7 . Detector according to one of the preceding claims, characterized in that the scintillator material has a volume ranging from 1000 to 10000 mm 3 . 
     
     
         8 . Detector according to one of the preceding claims, characterized in that the housing comprises a metal. 
     
     
         9 . Detector according to one of the preceding claims, characterized in that the thickness of the optical coupling is less than 1 mm. 
     
     
         10 . Detector according to one of the preceding claims, characterized in that the optical coupling is an epoxy adhesive. 
     
     
         11 . Detector according to one of the preceding claims, characterized in that the refractive index of the optical coupling is between that of the scintillator material and that of the avalanche photodiode. 
     
     
         12 . Detector according to one of the preceding claims, characterized in that the thermal expansion coefficient of the optical coupling is between that of the scintillator material and that of the avalanche photodiode. 
     
     
         13 . Detector according to one of the preceding claims, characterized in that the scintillator material does not surround the photodiode but is completely contained in the half space delimited by the plane passing through the photosensitive face of the photodiode and not containing said photodiode. 
     
     
         14 . Detector according to one of the preceding claims, characterized in that the contact face area of the scintillator material is less than 1.5, and preferably less than 1.2 times, and even more preferably less than 1 times the contact face area of the avalanche photodiode. 
     
     
         15 . Detector according to the preceding claim, characterized in that the contact face area of the scintillator material is from 0.8 to 1 times the contact face area of the avalanche photodiode. 
     
     
         16 . Detector according to one of the preceding claims, characterized in that the contact face of the scintillator material and the contact face of the photodiode have the same form. 
     
     
         17 . Detector according to one of the preceding claims, characterized in that the contact face of the scintillator material is inscribed in the contact face of the avalanche photodiode. 
     
     
         18 . Detector according to one of the preceding claims, characterized in that every point of the edge of the contact face of the scintillator material is inside the contact face of the photodiode and at a distance of between 0.1 and 3 mm, and preferably between 0.2 and 0.7 mm, from the edge of the photodiode. 
     
     
         19 . Detector according to one of the preceding claims, characterized in that the avalanche photodiode works at a voltage of less than 450 volts. 
     
     
         20 . Detector according to one of the preceding claims, characterized in that there is an electromagnetic shielding element between the avalanche photodiode and the preamplifier. 
     
     
         21 . Detector according to one of the preceding claims, characterized in that the two closest points, one of the preamplifier and the other of the scintillator material, are less than 2 cm apart. 
     
     
         22 . Detector according to one of the preceding claims, characterized in that its resolution at 662 keV is less than 3.5% and even less than 3%. 
     
     
         23 . Detector according to the preceding claim, characterized in that its resolution at 662 keV is less than 2.9%. 
     
     
         24 . Detector according to one of the preceding claims, characterized in that the detection threshold measured with an americium 241 source is less than 15 keV and preferably less than 12 keV. 
     
     
         25 . Detector according to the preceding claim, characterized in that the detection threshold measured with an americium 241 source is less than 11 keV. 
     
     
         26 . Detector according to one of the preceding claims, characterized in that the preamplifier gain is between 0.1V/pC and 10 V/pC. 
     
     
         27 . Detector according to one of the preceding claims, characterized in that it does not comprise a cooling system. 
     
     
         28 . Detector according to one of the preceding claims, characterized in that it comprises a temperature stabilization system, the housing is placed in a casing, a Peltier module being placed between said housing and said casing. 
     
     
         29 . Method of detecting X-rays or gamma rays using the detector of one of the preceding claims. 
     
     
         30 . Method according to the preceding claim, without collimation of the radiation.