Re: [fluka-discuss]: Using info. from USRBIN

From: Mina Nozar <nozarm_at_triumf.ca>
Date: Tue, 20 May 2014 17:10:58 -0700

thank you Francesco,

Yes, taking into account the difference in the volumes (almost a factor
of 6), and calculating the total power dep. from the dat file of USRBIN,
I do get something that is consistent with the total power deposition in
the actual volume as reported by SCORE.


Mina


On 14-05-14 12:24 AM, Francesco Cerutti wrote:
>
> Dear Mina,
>
>> So in principle, I should be able to add up all the values in the
>> data file from the 1-D projection, multiply the total by (0.013) and
>> get the total energy deposition in the upstream window (or close to
>> it - cylindrical binning would have been a better choice). The slice
>> widths in X and Y are both 1 cm. I get 203 Watts! So I am not
>> converging to the total energy deposition I see via the simple SCORE
>> card (58.34 Watts).
>> Am I doing something wrong?
>
> yes, your calculation is not consistent with what yourself wrote
> upward in your message and turns out to be wrong by a factor of 13.
> Either you multiply the *average* energy density (sum over bins --->
> divided by number of bins) by the *total* volume (0.013 cm3) or -
> which obviously is in fact the same thing - you integrate by adding up
> the energy densities and multiplying by the *single bin volume* (0.001
> cm3).
> So you have now the opposite problem: you get an underestimation of
> the energy deposition in the window, that might be easily explained by
> the fact that you integrate over a transverse area of 1cm2 whereas
> your window has a surface almost 6 times larger (according to the
> radius you reported).
> As reassuring principle for any - always useful - crosscheking, SCORE
> values are certainly identical to the ones obtained by a suitable
> USRBIN mesh.
>
> Ciao
>
> Francesco
>
> **************************************************
> Francesco Cerutti
> CERN-EN/STI
> CH-1211 Geneva 23
> Switzerland
> tel. ++41 22 7678962
> fax ++41 22 7668854
>
> On Wed, 14 May 2014, Mina Nozar wrote:
>
>> Hello everyone,
>>
>> I have an inconsistency which I have not been able to resolve.
>> I score deposited energy distribution using USRBIN and plot the 2-D
>> or the 1-D projections and extract the corresponding data files.
>>
>> If I plot the 2-D projection, deposited energy is averaged in the
>> third dimension (over the chosen slice, if any), so to get the total
>> deposited energy in some region, I would need to multiply the value
>> in a given bin by the slice width and the widths of the bin for that
>> value, correct?
>>
>> And if I plot the 1-D projection, deposited energy is averaged in the
>> other two dimensions (over the slices I have chosen), so to get the
>> total deposited energy in some region, I would need to multiply the
>> value in a given bin by the width of the bin and widths of the slices
>> in the other two dimensions.
>>
>> I am looking at the power deposition in the entrance and exit windows
>> (0.013 cm or 130 microns, so very thin) of a Rb target. The windows
>> are discs with a radius of 1.35 cm. The beam is 110.5 MeV protons.
>>
>>
>> I look at the 1D projection of the deposited energy as a function of
>> depth or Z (i.e. longitudinal direction or direction of the beam). I
>> choose a 1 cm slice in X and Y. I am attaching the figure
>> (STF-PD_TopView_Z_lin.jpg). Results are based on 200 M primaries. The
>> red lines are drawn at the entrance and exit windows and the Rb
>> target sits in B/N. Bin width is 1 mm. I can see the Bragg peak in
>> the water but do not understand the 'saw-thooth or step-like
>> behaviour' of the energy deposition inside the target region. I see
>> the same behavior if I look at the proton fluence as a function of
>> proton energy inside the target (can send out that figure if anyone
>> is interested).
>>
>> Suppose I wanted to find the total deposited energy in the upstream
>> window. So I take the value at the first red line (entrance window),
>> i.e. 1034.5 Watts/cm^3 and multiply it by (1cm x 1cm x 0.1 cm) =
>> 103.45 Watts.
>>
>> But when I look at the output files for total deposited energy in
>> different volumes, I see: 58.34 Watts in the upstream window. The
>> reason I am off here by almost a factor of two has to do with the
>> coarse USBRIN binning, i.e. 1mm in the Z direction (while the window
>> thickness is 0.13 mm) so I am looking at a larger volume than the
>> volume of the window.
>>
>> I defined another usrbin card with finer binning along Z (0.001 cm
>> bin size) in the upstream window region. X and Y slices are still 1
>> cm wide each. I set the max. step size to 0.01 cm. I plot the 1D
>> projection as a function of Z. I have attached the figure
>> (STF-PD_usW_Z.jpg).
>>
>> So in principle, I should be able to add up all the values in the
>> data file from the 1-D projection, multiply the total by (0.013) and
>> get the total energy deposition in the upstream window (or close to
>> it - cylindrical binning would have been a better choice). The slice
>> widths in X and Y are both 1 cm. I get 203 Watts! So I am not
>> converging to the total energy deposition I see via the simple SCORE
>> card (58.34 Watts).
>>
>> Am I doing something wrong?
>>
>> I am also attaching a side-view of the geometry showing target
>> region. From left to right, you'll see the beam pipe, the beam pipe
>> exit window, air gap, water jacket entrance window, water, target
>> entrance window (too thin to see), target, target exit window (too
>> thin to see), Target container box, Graphite.
>>
>>
>> Thanks and best wishes,
>> Mina
>>
>>
>>
>>
>
Received on Wed May 21 2014 - 03:13:10 CEST

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