Investigating SEU in a Silicon Component Irradiation

[Firben]

Homework Statement

[/B]
A silicon component is irradiated in an accelerator. The oxygen ion beam is pointed in the direction of the shortest dimension of the sensitive volume of the device. The energy required for producing an electron/hole pair in silicon is 3.6 eV. It is found that the highest energy for which SEU (Single-Event Upsets or “soft errors”) is observed is 10 MeV/nucleon. Assume that the shortest dimension of the sensitive volume is 2 µm and that ion energies do not change during traveling.

Homework Equations

E_c = ρ_Si*d*LET_m,th

Figure:
http://s716.photobucket.com/user/Pitoraq/media/LET_zpsqdevvbpw.png.html

The Attempt at a Solution

ρ_Si = 2.33 g/cm^2
d = 2μm

I have trouble to read of the diagram of what LET_Th is. If the energy is 10 Mev and if i draw a straight line upward i got the value of 10^0 or 1 LET (Mev * cm^2/mg). In the solution manual the LET_Th value is 0.85 why ?

E_c = 2.33*0.0002*0.9/10^-3 = 0.391 Mev
[/B]

 

[mfb]

I have trouble to read of the diagram of what LETTh is. If the energy is 10 Mev and if i draw a straight line upward i got the value of 10^0 or 1 LET (Mev * cm^2/mg).

I get a smaller value, even a bit below 0.85.

 

[Firben]

If i draw the line upward from 10 Mev/u to oxygen and from there a horizontal line to the left. Then i got the value 10^0 or 1.

My line of sight:
http://s716.photobucket.com/user/Pitoraq/media/LET_zpsnurvavvp.png.html

 

[mfb]

Using your pixel values for the positions, I get about 0.87. I put it one pixel lower which gave 0.82. It is a log scale, so 15% difference is not much.