MGDRAW reaction analysis

Advanced Features and User Routines
1

Dear experts,

I performed a simulation with 15 MeV Deuteron beam on a thick (0.5 cm) Ta target. I used mgdraw.f to store the info related to generated particle and residue. During this study, I found the following observations:

  1. Query regarding ICODE 100: In the manual, ICODE 100 is referred as elastic interaction secondaries, hence I expected, it would be like 181Ta (d,d)181Ta, but when I checked the output, it was something like the following, why proton is generated? Is it because JTRACK =1 and LTRACK =2 i.e. the proton generated in the first generation is incident on the target and creating the elastic scattering?

=================================================
Event 437495 | ICODE 100 | REGION 3
JTRACK, LTRACK: 1 2

Secondaries:
No. Type ID Energy (MeV)
1 proton 1 0.9329E+01
Residual nucleus: A= 181 Z= 73

=================================================
Event 463774 | ICODE 100 | REGION 3
JTRACK, LTRACK: 1 2

Secondaries:
No. Type ID Energy (MeV)
1 proton 1 0.6832E+01
Residual nucleus: A= 181 Z= 73

=================================================

  1. For ICODE 101, I found very few numbers (3 - 4 no for 25E+7 histories) of the following reactions, where residual A = 179, which is inconsistent:

Event 485387 | ICODE 101 | REGION 3
JTRACK, LTRACK: -3 1

Secondaries:
No. Type ID Energy (MeV)
1 neutron 8 0.6616E+00
2 neutron 8 0.5148E+00
3 gamma 7 0.2022E+00
4 gamma 7 0.3409E+00
5 gamma 7 0.1548E+00
6 gamma 7 0.1771E+00
7 gamma 7 0.3574E+00
8 gamma 7 0.1200E+00
9 neutron 8 0.1550E+01
Residual nucleus: A= 179 Z= 74

=================================================
Event 251218 | ICODE 101 | REGION 3
JTRACK, LTRACK: -3 1

Secondaries:
No. Type ID Energy (MeV)
1 neutron 8 0.1369E+00
2 neutron 8 0.1182E+01
3 gamma 7 0.1200E+00
4 neutron 8 0.2383E+01
Residual nucleus: A= 179 Z= 74

=================================================
Event 283912 | ICODE 101 | REGION 3
JTRACK, LTRACK: -3 1

Secondaries:
No. Type ID Energy (MeV)
1 neutron 8 0.8969E+00
2 neutron 8 0.1083E+01
3 proton 1 0.3293E+01
Residual nucleus: A= 179 Z= 73

=================================================

  1. For ICODE 300, the description says 300: interaction secondaries, can you please explain what is the source of such neutrons?
  2. For ICODE 101, there are reactions like 181Ta (d, pn) 181Ta like the following output. Can we call this a break-up reaction of deuteron?

=================================================
Event 12 | ICODE 101 | REGION 3
JTRACK, LTRACK: -3 1

Secondaries:
No. Type ID Energy (MeV)
1 neutron 8 0.5935E+00
2 gamma 7 0.1072E+01
3 gamma 7 0.3691E+00
4 gamma 7 0.2215E+00
5 gamma 7 0.3591E+00
6 gamma 7 0.1362E+00
7 proton 1 0.8276E+01
Residual nucleus: A= 181 Z= 73

=================================================

Regards,

Riya

3

Hi Riya,

before I can give you a complete answer, could you provide the mgdraw.f file (and optionally also the .inp file) you used to produce these results?

Thank you,

Stefano

4

Dear @smarin ,

Please find the files for reference.

Regards,

Riya

mgdraw.f (4.6 KB)

D_on_Ta_15MeV.inp (1.6 KB)

5

Hello Riya,

to answer your questions:

  1. yes, that appears to be a proton generated as a secondary of an earlier deuteron run.

  2. if you are asking why when you sum together the reaction products and the residual you don’t get A = 183, it is because tantalum contains a small amount (0.012%) of 180Ta (specifically, a metastable state). So the events are most likely deuteron interacting with with 180Ta.

  3. neutrons can easily be generated by deuteron interactions at those energies, from stripping, breakup, evaporation etc.

  4. Looking at the energies of the proton and the neutron, I would suspect this is not a breakup reaction. The proton is carrying 8 MeV, ~50% of the total energy, while the neutrons is carrying a much lower energy. This indicates to me a two step process, first a proton stripping reaction, followed by an evaporation of neutron and gammas. The presence of other gammas further confirms this. If you want to see breakup reactions, you can enforce no gammas in the final state.

I hope this helps,

Stefano

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6

Dear @smarin ,

Thank you for the guidance, I completely forgot about the natural composition of Tantalum.

  1. Is there a way to check the isotopic details of the materials when we add them to material card in FLUKA?
  2. Regarding query no 3, what I wanted to mean is that 101 refers to inelastic interaction secondaries which will record neutrons from evaporation, stripping, breakup etc. reactions. Hence, what type of reactions are included for 300?
  3. For breakup, as you mentioned that I have to look for reactions with no gammas. I found such reactions in the output as given below. Here also, in the first example, the proton energy is very high as compared to neutron, but no gamma. Is it a breakup reaction then?

In 2nd output, the energies are 3 MeV and 5.7 MeV.

 ## =================================================
 Event     1605 | ICODE   101 | REGION     3
 JTRACK, LTRACK:     -3     1

 # Secondaries:
 No.   Type        ID   Energy (MeV)
 1  neutron       8    0.8732E+00
 2  proton        1    0.7686E+01
 Residual nucleus: A=  181 Z=   73
 ## =================================================


  =================================================
  Event     2530 | ICODE   101 | REGION     3
  JTRACK, LTRACK:     -3     1
  -------------------------------------------------
  Secondaries:
  No.   Type        ID   Energy (MeV)
    1  neutron       8    0.2946E+01
    2  proton        1    0.5733E+01
  Residual nucleus: A=  181 Z=   73
  =================================================
7

Hi Riya,

  1. yes, you will find the isotopic composition inside the .out file. Look for this header:

 *** Low energy neutron Point Wise materials
   ###  Material   Z   A m   T(K)/Abu   Dataset      Ver    Filename
    18  TANTALUM  73   0 0    296.0K    JEFF-3.3     1.1    
                     181 0    0.9999                        73_181_Tantalum
                     180 1    0.0001                        73_180m1_Tantalum

  1. ICODE 300 records interactions where the low-energy neutrons was the projectile (these are not included in the 101 case)

  2. The two events are likely to be breakup reactions, with the second much more likely. The proton still gets extra energy from the coulomb barrier repulsion, so it will tend to have more energy. If your EM thresholds are sufficiently low (~ <10 keV), gating on a clean n,p in the final state will give you predominantly elastic breakups.

Hope this helps,

Stefano

1 Like
8

Dear Stefano,

Thank you for the detailed explanation.

Regards,
Riya

1 Like