# Efficiency of a NaI detector ( effect photoelectrics )

Please I need to know the scoring command that i will use in order to calculate " the efficiency of a NaI detector "
efficiency.inp (1.5 KB)

I am writing to seek guidance and assistance regarding the calculation of efficiency for a NaI detector. I have recently been tasked with evaluating the performance of a NaI detector and determining its efficiency in detecting photons via the photoelectric effect.

Specifically, I would like to calculate the ratio of Photons produced by the photoelectric effect to the total number of emitted photons incident on the detector. I am seeking guidance on the appropriate methodology, equations, and parameters required to accurately calculate the efficiency. ( SCORING command )

I would be grateful if the knowledgeable members of the Fluka Forum could offer their expertise in helping me understand the process involved in determining the efficiency of a NaI detector.

Dear @youssef.allay,

Please, avoid repeatedly posting your question. There is no point in doing it.
People reply on this forum on a best effort base, not as their main task.
Just be patient and wait for a reply.

In the meantime, you can get familiar with the various estimator that Fluka offers you, and try to understand which one is more suitable for your purposes.
Have a look at the scoring lecture from the last Fluka course.

Dear @youssef.allay,

• Just to be sure we are talking about the same thing, you want to calculate the ratio of electrons produced by the photoelectric effect to the total number of emitted photons incident on the detector (and not photons). Right?
• Is your geometry finished in the input file you shared? More specifically, your target should be made of a compound (Na-I) if I understood well.
• What is the energy distribution of your photons?

It might be useful for you to check the following ressources:

1 Like

Dear @ Samuel Niang
Thanks for your answer, I will try to clarify the issue further.

1- for calculation of efficiency for a NaI detector. I have a photon of energy 511 keV, which is going to make a reaction ( photoelectric effect or effect compton â€¦ ). i need to calculate the ratio of number of photons that performs just a photoelectric effect reaction / the total number of emitted photons incident on the detector .
2-yes, target should be made of a compound (Na-I)
3-i have 6 energy : 511, 662,835, 1173, 1275, and 1332 keV

Thank you

Dear amario
Iâ€™m not trying to repeat the question, I just made it clear more. Thank you for your answer. I checked the last Fluka course, but I did not find what I was looking for. The picture is not clear to me yet.

Thank you

Dear @youssef.allay,

One solution might be to use the mgdraw routine in the `USDRAW` entry (detailed example from the forum).

Here is a piece of code to insert in the routine which will write in a file some information only for photons inducing a photoelectric effect.

``````ENTRY USDRAW ( ICODE, MREG, XSCO, YSCO, ZSCO )
* if photoelectric effect
IF(ICODE.EQ.221) THEN
* we write id of the prim, the total energy, the part code of prim,
* the number of secondaries
WRITE (72,*) NCASE, ETRACK, JTRACK, NP
* for each secondary
DO I=1,NP
* we write the part code and the kinetic energy
WRITE(72,*) KPART(I), TKI(I)
END DO
END IF
RETURN
``````

You will find in attachment my input file and the modified routine (I tried it, it worked), I let you adapt them (especially concerning the primay and the material of the target) and then you will have to process the output file by yourself.

It is also important to specify in the EMF-cut card the energy theshold for EM particles when you want to track low energy particles.

2023_05_NaI.zip (5.7 KB)

Dear @sniang

Thank you, Samuel, for providing valuable assistance in explaining how to find a solution to the problem. Your guidance and explanations have been greatly appreciated.
but the input file you sent me i canâ€™t run it !!

Did you compile with the routine before trying to run? If not, check the course â€śsource routineâ€ť to see how to do it.
In particular for the compilation refer to the