I How Do Silicon Radiation Detectors Work in Detecting Beta and Gamma Radiations?

[C_Pu]

So we are doing Radioactivity lab at second year undergraduate. I am confused about the workings of the silicon radiation detects we are using even though the demonstrators tried to explain. We are detecting beta and gamma radiations by placing sources above a silicon detector that have a small area exposed.

According to the demonstrators, the detected signal represents all the energy deposited by the radiation. But wouldn't some energy go into the kinetic energies of the conducting electrons which would not be picked up as voltage?

Also, we see layers of discharge curves on the oscilloscope, how does the discharge work? They seem to have the same spread/period, are they timed? If it's just capacitor with same threshold, shouldn't all discharge occur at the same voltage?

 

[mfb]

The induced currents lead to net electron velocities of something like femtometers per second - how much energy do you expect?
In addition, this is a process that happens after all the energy got deposited, and you need a calibration of "energy per electron/hole pair" anyway because not all the energy is used to produce those pairs (most of it is lost as heat).

Also, we see layers of discharge curves on the oscilloscope, how does the discharge work? They seem to have the same spread/period, are they timed? If it's just capacitor with same threshold, shouldn't all discharge occur at the same voltage?

Is the energy the same every time?

 

[C_Pu]

The induced currents lead to net electron velocities of something like femtometers per second - how much energy do you expect?
In addition, this is a process that happens after all the energy got deposited, and you need a calibration of "energy per electron/hole pair" anyway because not all the energy is used to produce those pairs (most of it is lost as heat).Is the energy the same every time?

The energies from incoming beta electrons are different and energy deposited depends on the path in silicon too. We see many layers of discharge curve with different peaks but about same period.

 

[mfb]

and energy deposited depends on the path in silicon too

Depends on your sensor and the radiation.

We see many layers of discharge curve with different peaks but about same period.

Okay. What is unclear now?