Least fission fragment K.E needed for ionization

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Simulation Conditions and constraints

Detector Construction

The detector is designed based on example N03, a Ar/CO2 (90-10) layer absorber of thickness 10 cm, and has 1 atmospheric pressure and 300 K temperature.

Physics List

G4hIonization is the process under the generic ion, electrons are expected to scatter in all directions, only the Bremsstrahlung process is concerned.

Projectiles

From the mass distribution spectrum below, a peak exists for A=103 and another for A=83 for Th-232 fission reaction.

Energy 7.5 a biggerthan1.jpg

The same fragments are used as projectiles toward the absorber.

One of the element tested is O-17, the minimum energy to emit a tracked electron is 8 MeV, otherwise the table will mention hionization.

O-17 with K.E = 7 MeV

*********************************************************************************************************
* G4Track Information:   Particle = O17[0.0],   Track ID = 1,   Parent ID = 0
*********************************************************************************************************

Step#      X         Y         Z        KineE    dEStep   StepLeng  TrakLeng    Volume     Process
    0   -7.2 mm      0 fm      0 fm      7 MeV     0 eV      0 fm      0 fm        World    initStep
    1     -6 mm      0 fm      0 fm      7 MeV4.25e-16 eV    1.2 mm    1.2 mm        World  Transportation
    2      4 mm      0 fm      0 fm      7 MeV3.54e-15 eV      1 cm   1.12 cm        Layer  Transportation
    3   4.09 mm      0 fm      0 fm   6.87 MeV   125 keV  89.4 um   1.13 cm        ArCO2       hIoni
    4   4.11 mm      0 fm      0 fm   6.85 MeV  22.1 keV  21.8 um   1.13 cm        ArCO2       hIoni
    5   4.14 mm      0 fm      0 fm   6.82 MeV  37.2 keV  29.3 um   1.13 cm        ArCO2       hIoni
    6   4.41 mm      0 fm      0 fm    6.4 MeV   413 keV   272 um   1.16 cm        ArCO2       hIoni
    7   4.59 mm      0 fm      0 fm   6.17 MeV   231 keV   174 um   1.18 cm        ArCO2       hIoni
    8   6.65 mm      0 fm      0 fm    2.8 MeV  3.38 MeV  2.06 mm   1.39 cm        ArCO2       hIoni
    9   8.29 mm      0 fm      0 fm      0 eV    2.8 MeV  1.64 mm   1.55 cm        ArCO2       hIoni
---> End of event: 0
   Absorber: total energy:       7 MeV       total track length: 4.28725 mm 
        Gap: total energy:       0 eV        total track length:       0 fm 
Run terminated.
Run Summary
  Number of events processed : 1
  User=0s Real=0.09s Sys=0s

--------------------End of Run------------------------------

 mean Energy in Absorber : 7 MeV +- 0 eV 
 mean Energy in Gap      : 0 eV  +- 0 eV 

 mean trackLength in Absorber : 4.28725 mm  +- 0 fm 
 mean trackLength in Gap      : 0 fm  +- 0 fm 
------------------------------------------------------------

O-17 K.E = 8 MeV
*********************************************************************************************************
* G4Track Information:   Particle = O17[0.0],   Track ID = 1,   Parent ID = 0
*********************************************************************************************************

Step#      X         Y         Z        KineE    dEStep   StepLeng  TrakLeng    Volume     Process
    0   -7.2 mm      0 fm      0 fm      8 MeV     0 eV      0 fm      0 fm        World    initStep
    1     -6 mm      0 fm      0 fm      8 MeV4.04e-16 eV    1.2 mm    1.2 mm        World  Transportation
    2      4 mm      0 fm      0 fm      8 MeV3.37e-15 eV      1 cm   1.12 cm        Layer  Transportation
    3   4.13 mm      0 fm      0 fm   7.83 MeV   167 keV   129 um   1.13 cm        ArCO2       hIoni
    4   4.18 mm      0 fm      0 fm   7.76 MeV  69.4 keV  49.6 um   1.14 cm        ArCO2       hIoni
    :----- List of 2ndaries - #SpawnInStep=  1(Rest= 0,Along= 0,Post= 1), #SpawnTotal=  1 ---------------
    :   4.18 mm      0 fm      0 fm    994 eV         e-
    :----------------------------------------------------------------- EndOf2ndaries Info ---------------
    5   4.27 mm  -4.39 Ang -2.73 Ang  7.66 MeV   100 keV  88.3 um   1.15 cm        ArCO2       hIoni
    6   4.32 mm  -7.02 Ang -4.36 Ang  7.58 MeV  81.4 keV  52.8 um   1.15 cm        ArCO2       hIoni
    7   4.33 mm  -7.78 Ang -4.84 Ang  7.56 MeV  20.8 keV  15.2 um   1.15 cm        ArCO2       hIoni
    8   4.39 mm  -1.05 nm  -6.53 Ang  7.49 MeV  65.4 keV  54.7 um   1.16 cm        ArCO2       hIoni
    9   4.74 mm  -2.79 nm  -1.74 nm      7 MeV   499 keV   350 um   1.19 cm        ArCO2       hIoni
   10   4.81 mm  -3.14 nm  -1.95 nm   6.88 MeV   113 keV  68.8 um    1.2 cm        ArCO2       hIoni
   11   5.14 mm  -4.77 nm  -2.97 nm    6.4 MeV   477 keV   329 um   1.23 cm        ArCO2       hIoni
   12   6.15 mm  -9.79 nm  -6.09 nm   4.95 MeV  1.45 MeV  1.01 mm   1.33 cm        ArCO2       hIoni
   13   8.06 mm  -19.3 nm    -12 nm   1.61 MeV  3.34 MeV  1.91 mm   1.53 cm        ArCO2       hIoni
   14   9.53 mm  -26.7 nm  -16.6 nm      0 eV   1.61 MeV  1.47 mm   1.67 cm        ArCO2       hIoni

*********************************************************************************************************
* G4Track Information:   Particle = e-,   Track ID = 2,   Parent ID = 1
*********************************************************************************************************

Step#      X         Y         Z        KineE    dEStep   StepLeng  TrakLeng    Volume     Process
    0   4.18 mm      0 fm      0 fm    994 eV      0 eV      0 fm      0 fm        ArCO2    initStep
    1   4.19 mm   1.12 um    694 nm      0 eV    994 eV   57.2 um   57.2 um        ArCO2       eIoni
---> End of event: 0
   Absorber: total energy:       8 MeV       total track length: 5.59051 mm 
        Gap: total energy:       0 eV        total track length:       0 fm 
Run terminated.
Run Summary
  Number of events processed : 1
  User=0s Real=0.1s Sys=0s

--------------------End of Run------------------------------

 mean Energy in Absorber : 8 MeV +- 0 eV 
 mean Energy in Gap      : 0 eV  +- 0 eV 

 mean trackLength in Absorber : 5.59051 mm  +- 0 fm 
 mean trackLength in Gap      : 0 fm  +- 0 fm 
------------------------------------------------------------

Results and Conclusions

Based on the observation for O-17, for every hionization process we may consider minimum an electron released with a certain can be calculated if GEANT4 does not track the electron.

GEANT4 does not track the electron interaction after the ionization process, so may take the information given about any free electron then fire it again to record the processes occur in the medium or study just one process as bremsstrahlung.

Calculations and experiments related

Defination

The amount of energy expended in the gas per per ion pair produced will be represented by w. <ref name="Valentine">J.M. valentine, C.Curran, Reports on progress in phyiscs,21, 1 (1958) 1-29 </ref >


The energy needed to release a number of free electrons by ionization is basically depending on:<ref name="Valentine"/>

1- Gas nature

2- Ionizing particle energy and type.

References

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