When alpha particle interact with a scintillator materials such as ZnS(Ag), it generates electron hole pairs in the medium due to ionization. When these electrons combine at luminescent center it generate light.
My questions is whether these primary electrons are capable of generating secondary electrons or not? if yes how to quantify them and what is their contribution is radio-luminescence/ scintillation?
Thanks
Hi,
It is possible yes but it depend of the energy of your primary electron which is link to the energy of your alpha particle. What is this energy ? At low energy (around keV to some MeV) it should be very low maybe neblectable, at high energy, hundred of MeV, it can be very important.
To quantify the contribution of these electron it's very difficult. You can obtain information from simulation but it's a lot of work. If possible you can try to modify the initial energy of the alpha particle to measure inquire about the contribution of these electrons with the differences in your measurment.
Sincerly
Nicolas
In many media where the main effect of ionizing radiation is ionization, it is known that a small percentage of secondary electrons have enough energy to produce further ionization. They are often called "delta rays". Though not important in number, they can carry a very significant part (several 10%) of the energy lost by the primary particle (e.g. alpha particle) and are responsible for a significant part of the damage to biological tissues.
The situation is basically similar in crystals, where ionization is replaced by e-hole pair excitation. Many secondary electrons receive an energy above the threshold of e-hole production (this threshold is smaller than the ionization threshold), and the transfer of energy to e-hole pairs is often a multistep process. They do not contribue significantly to crystal damages.
Probably simulation codes can describe this in detail, but often the interest is centered on damages to the solids ,for which delta rays are not very interesting, or to the link between the total luminescence to the total energy lost by the primary particle, and this is generally established by an experimental calibration. In the case of ZnS, the intensity of the luminescence is often not analysed, and it is used as a counter of alpha particles, not a spectrometer.
Rem: It is better to use "primary" for the incoming particles, not for the electrons liberated in the medium.
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