# Questions about USRBIN and USRBDX

Dear FLUKA experts ,
I am a FLUKA beginer. I define an electron beam hitting two parallel aluminum plates (called tagert1 and target2) and use USRBIN and USRBDX to score it.

And my questions are:
(1) What’s the physics meaning of the USRBDX current scoring in the _sum.lis files?

The number of primary electrons in the card START is 3000. Does it mean that there are about 2286 electrons (3000*0.7622) going from target1 to void? If not, how can i get the exact number of electrons that are reflected by target1?

(2) I got a dose figure by USRBIN,how can I express it in Gy or kGy? How can I get the total absorbed dose of target1 or target2 ? (make a sum of target1, in Gy or kGy)

(3) I am also interested in the total net charge in target1 because it will be connected by measure circuit.But I can only get NET-CHRG figure by USRBIN.

As the charge of an electron is about 1.6*10^{-19} Coulomb,is there a way that I can get total net charge of target1? (express in Coulomb )

Thanks a lot for help.

Dear @shiqiang.pang,

1. All FLUKA scorings give the results per primary particle (except scorings used in activation calculations). You need to multiply this value with the real beam intensity, to get meaningful results.

Your assumption is correct, if you have 3000 primaries, ~2286 electrons (both primaries and produced secondaries) will leave target1 and enter VOID in every direction.

If you are only interested in the electrons leaving target1 only in the upstream direction, you need to construct you geometry accordingly. For example: you need to split the VOID region into different part, like VOID1 only touching the upstream part of target1, VOID2 on the downstream face, and VOID3 on the sides.

2. The unit of the Dose scoring is GeV/g per primary, to get Gy per primary you need to multiply it by 1.602176462E-7. You can apply this normalization factor during plotting using the Norm: field.

3. If you are interested in scoring values over a whole region, you can use the USRBIN scoring with Type Region.

Important: With this type of scoring, you need to normalize your result by the volume of the region as well to get the correct units.

Cheers,
David

There are still two points I would like to check:

(1) In comparison with the mass of the proton,the mass of the electron is considered negligible.
Is the way to get dose scoring results the same when protons are used? I mean,is that right to multiply the results by 3000,despite of the diffrence between proton and electron?

(2)I can only find boundary scorings in USRBDX,type Region doesn’t exist here.

Best regards,
shiqiang pang

Dear @shiqiang.pang,

1. The mass of the particles are taken into account by FLUKA, so the method of normalization is the same for electrons and protons.

2. I wanted to write USRBIN for the Region type scoring. Sorry about that.

Cheers,
David

2 posts were split to a new topic: USRBIN scoring per region: “R1from” and “R1to” fields meaning