Detection of relativistic neutrons by baf2 scintillators simulation on mcnpx
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Detection of relativistic neutrons by BaF2 scintillators Simulation on MCNPX. Nuclear Physics Institute. Doctor V. Wagner Mitja Majerle Antonin Krasa Ondrej Svoboda. Ludovic BATTISTA. SETUP. 25 cm. 5.9 cm. view pz=3. view : py=0. Aluminium Separation. Description of the beam.

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Detection of relativistic neutrons by baf2 scintillators simulation on mcnpx

Detection of relativistic neutrons by BaF2 scintillators

Simulation on MCNPX

Nuclear Physics Institute

Doctor V. Wagner

Mitja Majerle

Antonin Krasa

Ondrej Svoboda

Ludovic BATTISTA


Setup
SETUP

25 cm

5.9 cm

view pz=3

view : py=0



Description of the beam
Description of the beam

sdef erg 600 dir 1 vec 0. 0. 1. x=d1 y=d2 z=-3.95 par n ccc=2

si1 h -10 10

sp1 d 0 1

si2 h -10 10

sp2 d 0 1

OR

sdef erg 600 dir 1 vec 0. 0. 1. rad d1 pos 0.0 0.0 -3.95 par n ccc=20

si1 h 0 3.5

sp1 -21 1


Tally selection
TALLY Selection

  • F6 :Energy deposition over a cell (in MeV/g)

    secondary particles are not taken into account.

  • *F8 : energy deposition created in a detector (in MeV)

    not a spectra

  • F8 : Energy distribution of pulses, created in a detector by radiation (in pulses)

    Take into account secondary particles.


Determination of the amount of neutron passing through the detector without depositing energy

2,95cm

25 cm

Determination of the amount of neutron passing through the detector without depositing energy

σ =

σ = 77,8 %


Determination of the amount of neutron passing through the detector without depositing energy1
Determination of the amount of neutron passing through the detector without depositing energy

tally type 1 number of neutrons crossing a surface 4.

energy e11 0 499.999999 500

0.0000E+00 0.00000E+00 0.0000 1.0000E-06 0.00000E+00 0.0000 4.9900E+02 4.13000E-02 0.0561 5.0000E+02 0.00000E+00 0.0000 5.0000E+02 1.00000E+00

tally type 1 number of neutrons crossing a surface 6.

energy e21 0 499.999999 500

0.0000E+00 0.00000E+00 0.0000 1.0000E-06 0.00000E+00 0.0000 4.9900E+02 1.66600E-01 0.0360 5.0000E+02 1.25400E-01 0.0264 5.0000E+02 2.79500E-01 0.0161

BaF2 Cylinder view : pz=3

σ ≈ 30 %

Set up view : py=0


Determination of the amount of neutron passing through the detector without depositing energy2
Determination of the amount of neutron passing through the detector without depositing energy

F1 : current integrated over a surface (in particles)

tally type 1 particle(s): neutron surface 31 energy e1 0 399.999999 400

0.0000E+00 0.00000E+00 0.0000 4.0000E+02 2.31560E-01 0.0130 4.0000E+02 1.00000E+00 0.0000

tally type 1 particle(s): neutron surface 311 energy e11 0 399.999999 400

0.0000E+00 0.00000E+00 0.0000 4.0000E+02 4.20900E-01 0.0079 4.0000E+02 3.02080E-01 0.0068

Setup view : py=0

σ≈30 %


Energy deposition on central module
Energy Deposition detector without depositing energyon Central Module

Shape of beam 400 MeV nps=5e5

SHAPE OBTAINED BY F8 TALLY IS ACCEPTED


Problem of normalization
Problem of Normalization ? detector without depositing energy

tally type 8 particle(s): neutron surface 311 energy e11 0 1e-6 400

0.0000E+00 0.00000E+00 0.0000 1.0000E-06 2.95440E-01 0.0069 4.0000E+02 6.93760E-01 0.0030

F8

tally type 1 particle(s): neutron surface 311 energy e11 0 399.999999 400

0.0000E+00 0.00000E+00 0.0000 4.0000E+02 4.20900E-01 0.0079 4.0000E+02 3.02080E-01 0.0068

F1

F8 tally DOES take into account particle passing through without depositing energy


Fig 5 f e kin l thr
Fig. 5 : detector without depositing energyε=f(EKIN,LTHR)

Neutron efficiency of the BaF2 cluster detector for various values of the electronic threshold LTHR as a function of EKIN

Script : beam for (i=200, i<=1500, i=i+50)

Code : F8:n,e,p,h,/ 1

E8: 0 1e-6 9 25 45 90 1500


Fig 6 f l thr e kin
Fig. 6 : detector without depositing energyε=f(LTHR,EKIN)

Neutron efficiency of the BaF2 cluster detector for various incident neutron kinetic energies EKINas a function of LTHR

Script : beam for (i=200, i<=1500, i=i+50)

Code : F8:n,e,p,h,/ 1

E8: 0 1e-6 9 25 45 90 1500


Fig 6 f l thr e kin1
Fig. 6 : detector without depositing energyε=f(LTHR,EKIN)


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Graph 20 : Exponential Regression of Fig. 6 for 23 different beams:

Exponential Regression

Exponential Regression of Fig. 6 for 23 different beams


Fig 4 f e kin
Fig. 4 : different beams:δ=f(EKIN)

Pulse height spectra measured with the BaF2 cluster detector for neutrons with kinetic energies EKIN =200, 300, 400, 800 MeV

Script :

beam for i in 200 300 400 800

Code : F8:n,e,p,h,/ 1

E8: 0 1e-6 80i 800

Shape of beam 400 MeV nps=5e4 -->


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Fig 4 different beams:

X2,29

X1,92

X1,43

X1,19

BERTINI

LCA J J J


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Fig 4 different beams:

X5,15

X3,15

X3,15

X1,82

X1,36

BERTINI

LCA J J J


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Pulse Height Spectra different beams:

using CEM2K model

Beam 600 MeV

Fig 4

CEM

LCA 8J 1


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Pulse Height Spectra using different beams:

PHYS:N J 100 3J -1

beam 600 MeV

Fig 4

In output file : warning. f8 tally unreliable since neutron transport nonanalog

manual extension

Coincidence counting of capture multiplicities and moments requires analog capture: CUT:N 2J

0 0. Calculations must be totally analog, with no variance reduction. Fission multiplicity also is

required: PHYS:N J 100 3J –1. An FT8 CAP tally in an input file automatically will set analog

capture, fission multiplicity, and exit with error messages if variance reduction is used. The

capture multiplicities and moments are stored in 80 cosine bins, which are printed out with the

F8 tally. A much more readable table of capture multiplicities and moments is given in Print

Table 118. The captures and moments can be compared with Print Table 117, which has the

spontaneous-fission source and induced-fission summaries of fission neutrons and moments

(Section 3.3.3).


Dealing with 2ndary particles
Dealing with 2ndary particles different beams:

BaF2 detector

Delimitation of free path

BaF2 detector 3x bigger

Neutron beam 800 MeV

Neutron beam 800 MeV



Adding the polyethylene box
Adding the polyethylene box different beams:

Graph 15 : set up with polyethylene box.

View pz = - 2.05

View py = 0



Fig 7 pulse height spectra observed in a central module b the all cluster
Fig 7 different beams::pulse height spectra observed in (a) central module (b) the all cluster

Central hits selected by the condition that the maximum signal occurs in the central module


Fig 7 200 mev
Fig 7 : 200 MeV different beams:

(a) central module (b) the whole cluster


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Fig 7 : 300 MeV different beams:

(a) central module (b) the whole cluster


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Fig 7 : 400 MeV different beams:

(a) central module (b) the whole cluster


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Fig 7 : 800 MeV different beams:

(a) central module (b) the whole cluster


Conclusions
Conclusions different beams:

  • MCNPX cannot describe “maximum signal occurs in the central module”

  • MCNPX code is designed for integral quantities determination , doesn’t take into account dead time of detector.