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Question Neutron energy deposit on hafnium dioxide 

Forum: Biasing and Scoring
Date: 02 Oct, 2017
From: <jeonyboy@gmail.com>

Hello all,

I am trying to figure out neutron energy deposit for energies from low to high (1~200 MeV) in a hafnium dioxide box the size of 5x10x10 nm^3. I am using a B4d based program, however I get no energy deposits no matter what I try. I tried setting the set/cut to 1um but no changes still. Am I missing something?

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None Re: Neutron energy deposit on hafnium dioxide  by michel maire <michel maire>,   04 Oct, 2017
Re: Question Neutron energy deposit on hafnium dioxide
On Tue, 03 Oct 2017 03:22:57 GMT, jeonyboy wrote:
> Hello all,
> 
> I am trying to figure out neutron energy deposit for energies from low
> to high (1~200 MeV) in a hafnium dioxide box the size of 5x10x10 nm^3. I
> am using a B4d based program, however I get no energy deposits no matter
> what I try. I tried setting the set/cut to 1um but no changes still. Am
> I missing something?
> 

  Let me try to quantify what Michael said.
  In example Hadr03, I have defined hafnium dioxide material, and ran the attached macro.
 As you can see on output, the mean free path ( or interaction length) of neutron (10 MeV) is 4.68 cm.
 Therefore the probability to have one interaction within 10 nm is 10 nm/4.68 cm = ~2 10^-7

 In other words, you must have ~5 10^6 neutrons beam to get one interaction, or 5 10^9 neutrons to get 1000 interactions.
 Have you such a statistic ?

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/04/03.40-36421-hafnium.mac.txt
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/04/03.40-10094-hafnium.out.txt

None Re: Neutron energy deposit on hafnium dioxide  by <jeonyboy@gmail.com>,   07 Oct, 2017
Re: None Re: Neutron energy deposit on hafnium dioxide (michel maire)
On Wed, 04 Oct 2017 10:44:19 GMT, michel maire wrote:
> On Tue, 03 Oct 2017 03:22:57 GMT, jeonyboy wrote:
> 
> > Hello all,
> > 
> > I am trying to figure out neutron energy deposit for energies from low
> > to high (1~200 MeV) in a hafnium dioxide box the size of 5x10x10 nm^3. I
> > am using a B4d based program, however I get no energy deposits no matter
> > what I try. I tried setting the set/cut to 1um but no changes still. Am
> > I missing something?
> > 
> 
>   Let me try to quantify what Michael said.
>   In example Hadr03, I have defined hafnium dioxide material, and ran the attached macro.
>  As you can see on output, the mean free path ( or interaction length) of neutron (10 MeV) is 4.68 cm.
>  Therefore the probability to have one interaction within 10 nm is 10 nm/4.68 cm = ~2 10^-7
> 
>  In other words, you must have ~5 10^6 neutrons beam to get one interaction, or 5 10^9 neutrons to get 1000 interactions.
>  Have you such a statistic ?
> 
>    Attachment:
>       http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/04/03.40-36421-hafnium.mac.txt
>       http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/04/03.40-10094-hafnium.out.txt
> 

Hi, following your helpful and detailed explanation, I have upped the neutron particle shot from 2x10^6 to 2x10^8 but still energy deposits are being observed. Maybe because the B4d example I am basing has default cut range much greater than nm?

So I am trying run/setCut 1 nm in my executable file before running the macro file. It takes really long time for it to process, hopefully this will work. I really appreciate your help.

      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/07/05.00-73673-10MeVNeutron2x10_8.txt

None Re: Neutron energy deposit on hafnium dioxide  by michel maire <michel maire>,   09 Oct, 2017
Re: None Re: Neutron energy deposit on hafnium dioxide
On Sat, 07 Oct 2017 12:09:54 GMT, jeonyboy wrote:

> 
> Hi, following your helpful and detailed explanation, I have upped the
> neutron particle shot from 2x10^6 to 2x10^8 but still energy deposits
> are being observed. Maybe because the B4d example I am basing has
> default cut range much greater than nm?
> 
 1- It is not directly related. Kinetic energy of secondaries which are not generated (e.g. below threshold) are counted in the dE/dx of the primary particle. I would suggest to keep default cut ( ~ 1 mm). Playing with cuts will be a later refinement.

 2- Make sure that you have neutronHP in your physics list (compare with hafnium.out.txt).

 3- Around 1 eV, neutron capture dominates, cross section increases, mean free path is "only" ~0.5 mm
      Then ~10^7 events would allow to see few interactions.

 4- At most energies, elastic collisions may be important. The recoil nucleus contributes to energy deposition. But, for various reasons, this recoil nucleus is not generated by default.
 To create it, make sure that your physics list includes the statement  setCutValue(0*mm, "proton") 
 Instead, you can use the command /run/setCutForAGivenParticle  proton  0.  mm
 (if you do not understand well what I am speaking about, play with Hadr03 ...)

 5- I tried your exercice with Hadr07. I attach macro, output and plot. As you will see, there are 94 interactions  for 10^7 events.

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/09/09.47-57787-hafnium.out.txt
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/09/09.47-61635-hadr07.mac.txt
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/09/09.47-76278-hadr07.out.txt
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/09/09.47-48419-edep.gif

None Re: Neutron energy deposit on hafnium dioxide  by <jeonyboy@gmail.com>,   10 Oct, 2017
Re: None Re: Neutron energy deposit on hafnium dioxide (michel maire)
So I created executable file for Hadr07 and ran the identical macro file and I got zero energy deposits unlike your attached files. 0 entries at all actually. I checked and the cut value for proton is 0 mm like you suggested as well. Visual shows that the neutron is going through the absorber. Am I missing something?

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/10/08.03-36212-hafnium_neutron.PNG
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/10/07.58-82817-G4Data0.heprep
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/10/08.09-52436-hf.PNG

None Re: Neutron energy deposit on hafnium dioxide  by michel maire <michel maire>,   10 Oct, 2017
Re: None Re: Neutron energy deposit on hafnium dioxide
On Tue, 10 Oct 2017 15:10:01 GMT, jeonyboy wrote:
> So I created executable file for Hadr07 and ran the identical macro file
> and I got zero energy deposits unlike your attached files. 0 entries at
> all actually. I checked and the cut value for proton is 0 mm like you
> suggested as well. Visual shows that the neutron is going through the
> absorber. Am I missing something?
> 
  Could you send an output of your run ?

None Re: Neutron energy deposit on hafnium dioxide  by <jeonyboy@gmail.com>,   10 Oct, 2017
Re: None Re: Neutron energy deposit on hafnium dioxide (michel maire)
Here are my input and output files.

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/10/11.28-408-neutron.in
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/10/11.28-37749-neutron.outOn Tue, 10 Oct 2017 17:27:35 GMT, michel maire wrote:
> On Tue, 10 Oct 2017 15:10:01 GMT, jeonyboy wrote:
> > So I created executable file for Hadr07 and ran the identical macro file
> > and I got zero energy deposits unlike your attached files. 0 entries at
> > all actually. I checked and the cut value for proton is 0 mm like you
> > suggested as well. Visual shows that the neutron is going through the
> > absorber. Am I missing something?
> > 
>   Could you send an output of your run ?
> 

None Re: Neutron energy deposit on hafnium dioxide  by michel maire <michel maire>,   10 Oct, 2017
Re: None Re: Neutron energy deposit on hafnium dioxide
On Tue, 10 Oct 2017 18:29:44 GMT, jeonyboy wrote:
> Here are my input and output files.
> 
>    Attachment:
>       http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/10/11.28-408-neutron.in
>       http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/10/11.28-37749-neutron.out

  You did not build material HfO2 in DetectorConstruction.
  By default the absorber is G4_Si

None Re: Neutron energy deposit on hafnium dioxide  by <jeonyboy@gmail.com>,   09 Oct, 2017
Re: None Re: Neutron energy deposit on hafnium dioxide (michel maire)
On Mon, 09 Oct 2017 16:54:32 GMT, michel maire wrote:

>  1- It is not directly related. Kinetic energy of secondaries which are not generated (e.g. below threshold) are counted in the dE/dx of the primary particle. I would suggest to keep default cut ( ~ 1 mm). Playing with cuts will be a later refinement.
> 
>  2- Make sure that you have neutronHP in your physics list (compare with hafnium.out.txt).
> 
>  3- Around 1 eV, neutron capture dominates, cross section increases, mean free path is "only" ~0.5 mm
>       Then ~10^7 events would allow to see few interactions.
> 
>  4- At most energies, elastic collisions may be important. The recoil nucleus contributes to energy deposition. But, for various reasons, this recoil nucleus is not generated by default.
>  To create it, make sure that your physics list includes the statement  setCutValue(0*mm, "proton") 
>  Instead, you can use the command /run/setCutForAGivenParticle  proton  0.  mm
>  (if you do not understand well what I am speaking about, play with Hadr03 ...)
> 
>  5- I tried your exercice with Hadr07. I attach macro, output and plot. As you will see, there are 94 interactions  for 10^7 events.
> 

Wow thank you so much for your help. That is exactly what I wanted to see. I tried to replicate your simulation but I did not have hadr07 example because I am using 10.2 so I upgrade to 10.3 (Windows) but now I am having compiling error at ElectromagneticPhysics.cc where it says I am missing two members from G4EmParameters and indentifer "GetParticleIterator" being undefined.

I have updated all the data files as well and am downloading the G4TENDL1.3 just in case this data set is needed for Hadr07. I apologize if my questions are incredibly basic c++ language stuff. I am trying to google/search to find answers but running into walls.

Thank you again sincerely!

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2017/10/09/23.33-81709-hadr07.PNG

None Re: Neutron energy deposit on hafnium dioxide  by <jeonyboy@gmail.com>,   10 Oct, 2017
Re: None Re: Neutron energy deposit on hafnium dioxide
Scratch my last post please. I recompiled after getting rid of the 10.2 version of Geant4 and it went through without any coding issue. I will attempt running the neutron simulations now. Thank you!

If I may ask though what's so different about Hadr07 that it creates neutron energy deposition cases because neither Hadr06 or B4d example gave any returns and I was using the preconstructed physics such as FTFP_BERT_HP which is supposed to target neutron interaction?

Idea Re: Neutron energy deposit on hafnium dioxide  by Michael H. Kelsey <Michael H. Kelsey>,   02 Oct, 2017
Re: Question Neutron energy deposit on hafnium dioxide
On Tue, 03 Oct 2017 03:22:57 GMT, jeonyboy wrote:
> I am trying to figure out neutron energy deposit for energies from low
> to high (1~200 MeV) in a hafnium dioxide box the size of 5x10x10 nm^3. I
> am using a B4d based program, however I get no energy deposits no matter
> what I try. I tried setting the set/cut to 1um but no changes still. Am
> I missing something?

Neutrons themselves do not deposit energy (they're neutral particles, and energy deposits occur due to electromagnetic interactions). If you are doing something like a SteppingAction and only looking for hits from neutrons, you'll get zero. You need to accept energy deposit from _all_ particles (e.g., a neutron is captured on a nucleus, which subsequently emits gammas or electrons or whatever).

Is your box really just nanometers on a side? If the cross-sections for your desired interactions are large enough, then you might see hits, but with only a few hundred atoms in your box, it's likely that most of your simulation events are just "pass through", with no interactions. You may need to make your target larger to see anything.

  -- Michael Kelsey

Question Re: Neutron energy deposit on hafnium dioxide  by <jeonyboy@gmail.com>,   03 Oct, 2017
Re: Idea Re: Neutron energy deposit on hafnium dioxide (Michael H. Kelsey)
Hi thank you for your response. Yes I am aware that neutrons dont directly deposit energy since they are neutral in charge. From what I gathered hafnium dioxide has high neutron capture cross section which should result in charged secondary particles.

I am not too well versed in c++ language and so using example builds with minor revisions in it. Is example B4d not compatible for neutron secondary energy deposits? Can you recommend a code revision in scoring process or another example I may use for neutron simulations?

Thank you very much.

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