Dear Qurat,

It is actually quite simple. SRIM gives you the total number of vacancies per incident ion per cm (averaged over many ion trajectories). That is equivalent to the total number of displacements per incident ion per unit penetration. To express that in dpa you need to divide by the atomic density and multiply times the flux:

dose rate (dpa/s) == 𝛄 ɸ / ρ == (vacancies/ion/cm) (ion/s/cm2) (cm3/atoms) == vacancies/atom/s == displacements per tom per second.

 The flux (ions per second per unit area) should be an input of your problem (e.g. ion beam flux, neutron flux in a nuclear reactor, etc), and the atomic density you can get easily for almost all materials.

What I describe here is the general calculation. Of course, the problem is that the number of vacancies per ion per unit depth changes as a function of depth 𝛄=𝛄(x) . Then you have to transform the above formula into an integral, i.e.:

dose rate = (1/d) ∫ [𝛄(x) ɸ / ρ] dx

where the integral extends from zero to the end of the Bragg peak (d).

Hope this helps.

Jaime

Displacements per ion you can find in Damage Events window (Distributions).

Fluence (or ion dose) you define by youself.

a few numerical example to help you solve your proble. I hope it helps, if not then do let me know. Cheers

http://fti.neep.wisc.edu/neep423/FALL97/lecture42.pdf    

Hi,

My suggestion:

It may be measured by giving "HIGH VIBRATION PERIODIC LOADING" to material.

Dear Qurat,

It is actually quite simple. SRIM gives you the total number of vacancies per incident ion per cm (averaged over many ion trajectories). That is equivalent to the total number of displacements per incident ion per unit penetration. To express that in dpa you need to divide by the atomic density and multiply times the flux:

dose rate (dpa/s) == 𝛄 ɸ / ρ == (vacancies/ion/cm) (ion/s/cm2) (cm3/atoms) == vacancies/atom/s == displacements per tom per second.

 The flux (ions per second per unit area) should be an input of your problem (e.g. ion beam flux, neutron flux in a nuclear reactor, etc), and the atomic density you can get easily for almost all materials.

What I describe here is the general calculation. Of course, the problem is that the number of vacancies per ion per unit depth changes as a function of depth 𝛄=𝛄(x) . Then you have to transform the above formula into an integral, i.e.:

dose rate = (1/d) ∫ [𝛄(x) ɸ / ρ] dx

where the integral extends from zero to the end of the Bragg peak (d).

Hope this helps.

Jaime

For neutron fluence, you need to know the primary knock on atom (PKA) spectum as input to SRIM. PKA spectra per neutron can be obtained from NJOY. Check out my recent work for further details. http://www.kns.org/jknsfile/v46/3-13-51.pdf

thank you Sir Jonghwa Chang !

i want to calculate proton fluence beacause i am doing proton irradiation. and i want to calculate vacancy density as a function of proton fluence. but in SRIM we can input energy and angle of incident ion not the fluence of ion. so how can i calculaye fluence and change fluence in SRIM in order to calculate corresponding vacancy density.thanks in advance for your help

SRIM will calculate the number of defects for given number of incident ions with given energy. Fluence is just number of ions (protons) per unit area.

dpa is just proportional to the fluence.

You could consider using FLUKA particle physics Monte Carlo package (www.fluka.org), which can compute fluence and DPA.

What I think is you just need to pause at desired time duration. Then you can see no of incident ions in that much interaction time. So by changing exposing time you can change the fluence. If someone has better solution please let us know.

hello, I have the same question. Have you already solved it? Please tell me, thank u!