[fluka-discuss]: RE: Thermal neutrons via Boron-10 not possible...

From: Anton Lechner <Anton.Lechner_at_cern.ch>
Date: Sat, 8 Feb 2014 09:59:51 +0000

Dear Georgios,

Looking at the EVENTBIN results I get with your input file, I see a large peak at ~2.3 MeV in the B10 region, which perfectly makes sense since it is the sum of the Li7 and alpha kinetic energies created in neutron interactions (n + B10 -> Li7 (~0.84MeV) + alpha (~1.47MeV) ). The key point is that many of them don't make it to another region due to their limited range and hence both deposit their energy in B10. Take into account that you have a 5 um layer of B10, which is roughly twice the range of the Li7 created in B10. Similarly, the range of the alphas is less than 5 um in B10 (I did some quick test with your geometry and only roughly 7% of Li7 and 16% of the alphas reach the gas volume).

The reason, you see a peak around the alpha energy for n ->Li6 is that the triton has a much larger range and hence more likely exits the Li6 layer while the alpha deposits its energy there (still, also the alphas have a larger range compared to the ones created in B10, hence also a good fraction of them leaves the Li6).

You may want to use different EVENTBINs with different AUXSCORE cards to restrict the scoring to a certain particle (e.g. alpha). This might give you some more insight.

Cheers, Anton





________________________________
From: owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] on behalf of Georgios Tsiledakis [Georgios.Tsiledakis_at_cern.ch]
Sent: 04 February 2014 10:56
To: fluka-discuss_at_fluka.org
Subject: [fluka-discuss]: Thermal neutrons via Boron-10 not possible...

Dear experts,

I would like to produce an alpha and 7Li ion pair from the
neutron interaction on 10B and transport them...
Please have a look at the input file attached...
In case I use Lithium-6, I am able to see the products via
the EVENTBIN card (energy deposition in the detector)
as you can see from the broad peak 2.05 (alpha) and 2.73 (3H) MeV
respectively (am I right?).
Looking at the out file is also pointed out that:
 Pointwise cross sections activated for Xsec mat: LITHIU-6

BUT what is wrong in case of BORON-10? How I could see alphas and
7Li's leaving the converter? I am totally puzzled...

I would be really glad to have your tips... I think I followed all feedback in the list
but in vein....

thanks a lot in advance

Georgios
Received on Sat Feb 08 2014 - 11:59:49 CET