1.Accelerators
  • History-Why
  • Particle Sources
  • Acceleration stage
  • Space charge
  • Diagnostics
  • Application
        2. Detectors
    Gas-Filled Radiation Detectors        ionization chambers
                                          proportional counters
                                          Geiger-Muller counters
    Scintillation Detectors               Photomultiplier tube
    Semiconductor Detectors
    Personal Dosimeters                   photographic films 
                                          photographic emulsion plates
    Others                                Cloud and Bubble Chambers
    Particle identification                E-ΔE, TOF
    Measurement theory
    Detection Equipment
                         Ionization Chambers
  Key Components in a Simple Ionization Chamber
   Ionizing                        Battery                          the voltage must be 
   radiation                 +                                      sufficiently high for 
                                                                    effective collection of 
               –+–+–                                   Load         electrons. 
               +–+–+                                  resister
                              –
               Detector            Ampere-
               chamber              meter
                                                          The average energy required to 
  Current (A) is proportional to charges collected        ionize a gas atom  30 eV/ion.
                                                           If particles entering an air-filled
  on electrode in ionization chambers.                    detector deposit an average of 
                                                                   -1
  The current registered in the ionization chamber is     1 GeV S  in the gas, the 
  proportional to the number of ion pairs generated by    average current flowing through 
  radioactivity                                           the chamber
         How can the sensitivities of ionization chambers be improved?
         What happens when the voltage is increased? 
                                     Proportional Counters
                    Gas Multiplication                                           Key Components in a Simple Ionization Chamber
                                                                                 Ionizing                  Battery  X00 V
                                                                                 radiation             +
                                      –+                                                   –+–+–                            Load
                                                                                          +–+–+                           resister
                                                                                                       –
                                 –+–+–+                                                    Detector        Ampere-
                                                                                           chamber           meter
                                       
                –+–+–+–+–+–+–+–+–+                                             Proportional counters
                                       
          –+–+–+–+–+–+–+–+–+–+–+–                                              Gas multiplication due to 
        +–+–+–+–+–+–+–+–+–+–+–+–                                               secondary ion pairs when the 
        +–+–+–+–+–+–+–+–+–+–+–+–                                               ionization chambers operate at 
                                       +                                       higher voltage. 
      not only collect but also accelerate electrons                                                                              5
 It should be noted, however, that the small mass and high 
 energy of electrons make them drift 100,000 times faster 
 than ions. Thus, the current is mainly due to the drifting 
 electrons with only a small fraction due to the drift of ions.
 Despite the multiplication due to secondary ion pairs, the 
 ampere-meters register currents proportional to the numbers 
 of primary electrons caused by radiation entering the 
 detectors. Thus, currents of proportional chambers 
 correspond to amounts of ionization radiation entering the 
 proportional chamber.