# Using of estimators

hello dear expert. attached is my input file.
I designed this input file to calculate the depth dose profile, the neutron fluence between the vaccum and target and the LET of all particles between vaccum and target.
but the results obtained are not convincing and I see your points of view. to know if it is really this result that must obtain? did I define my estimators correctly?
Ps my target is a rectangular parallelogram 20cm wide, 20cm high and 40cm long irradiated by a mono energetic carbon beam of 400MeV.
my results are correct.
carbone400.inp (2.2 KB)

Dear Tomfey,

A remark for future posts, the figures have no axis label what makes difficult to understand what you are plotting unless one really goes into the input file. Please, next time include this info with the proper normalization on the Y-axis.

As a suggestion for the USRBIN card to get the dose distribution in depth, you may use a Cartesian mesh (X-Y-Z) to better cover the whole region instead of the cylindrical one.

Regarding the LET, you may correct several things on the USRYIELD card:

• The way of getting the LET is by setting W(6) of the USRYIELD second card to d2N/dx1dx2 (ixa=3), the plain double differential yield not the double differential weighted fluence cross section as you have now.

• Since the scoring is done at the surface between the vacuum region (where the beam do not loose energy) and your target, the energy of the impinging particle beam is very well defined (400 MeV per nucleon). Therefore, the LET distribution will be rather a delta. As the beam penetrates the media, it losses energy and the energy spread increases thus the LET becomes a distribution which values will depend on the energy of the particle beam at a given depth.

• Since the range of the LET do not cover several orders of magnitude, it is recommended
to score it with linear bins instead of log.

• Try not to restrict the second quantity (in this case the kinetic energy) since you have the risk of not getting all the information. At the moment you are setting the upper limit of the kinetic energy to 1 GeV which is below the actual energy of the beam (400 MeV per nucleon = 4.8 GeV).

A parallel note for clarification purposes, you have mentioned that the energy of the particle beam is 400 MeV. Be careful here, in the BEAM card when SDUM=HEAVYION, the energy specified is per nucleon while in the scoring cards the kinetic energy refers to the total kinetic energy of the beam.

Hope this helps.

@msabateg
Thank you dear experts. At the LET level I didn’t really understand. Can you correct my input file to really help me better understand my errors. For USRBIN. I understood but concerning the LET I hardly understand. Thanks in advance

For instance:

@msabateg
Thank you very much for your availability.