PHITS

1
PHITS
Multi-Purpose Particle and Heavy Ion Transport
code System

• Basic Lecture III
• Parameter Setting

Feb. 2016 revised
title
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2
Purpose of This Lecture

• PHITS simulation is controlled by various
  parameters defined in Parameters section.
• Every parameter has its default value, and you do
  not have to change most of them.
• But you have to change some parameters to obtain
  appropriate results depending on the condition of
  the particle transport.

You will learn how to setup those parameters in
this lecture!
2
Introduction
3
Goal of This Lecture
Proton (up) and neutron (down) fluences
calculated by default settings for homework study
Proton (up) and neutron (down) fluences
calculated by appropriate settings for homework
study
You can obtain this kind of results at the end of
this lecture
Purpose
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4
Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
4
5
Selection of Calculation Mode
Particle Transport Simulation
Checking purpose
Geometry Visualization
Selection of Calculation Mode
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6
Geometry Visualization
Lets check the geometry using icntl11 3D-show
and icntl8 (gshow option)
Geometry Visualization
Geometry Visualization Mode
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3D-Show (icntl11)
T - 3 D s h o w output 3 material -1
6 x0 0 y0 0 z0
0 e-the 70 eye e-phi 20 e-dst
80 l-the 20 light l-phi 0
l-dst 100 w-wdt 50 window w-hgt
50 w-dst 25 heaven z line 1
shadow 2 file 3dshow.out title Check
onion structure using T-3dshow tally epsout
1
lec03.inp
file lec03.inp T i t l e P
a r a m e t e r s icntl 11 maxcas 100
maxbch 10 file(6) phits.out set c120
S o u r c e infl
onion.inp1-33
Activate t-3dshow
Onion structure
3dshow.eps
7
Geometry Visualization Mode
8
T-Track with gshow 1 (icntl8)
lec03.inp
file lec03.inp T i t l e P
a r a m e t e r s icntl 8 maxcas 100
maxbch 10 file(6) phits.out set c120
S o u r c e infl
onion.inp1-33
T - G s h o w mesh xyz x-type 2
nx 100 xmin -50. xmax 50.
y-type 1 ny 10 -25. -20. -15.
-10. -5. 0. 5. 10. 15. 20. 25. z-type
2 nz 100 zmin -50. zmax
50. axis xz output 6 file
gshow.out title Check onion structure using
T-gshow tally epsout 1
file lec03.inp T i t l e P
a r a m e t e r s icntl 11 maxcas 100
maxbch 10 file(6) phits.out set c120
S o u r c e infl
onion.inp1-33
Check cell ID and filled materials
Activate gshow option in t-track
gshow.eps
8
Geometry Visualization Mode
9
Check Sources (t-track)
lec03.inp
Change and Execute
T - T r a c k mesh xyz x-type 2
nx 100 xmin -50. xmax 50.
y-type 1 ny 1 -5.0 5.0
z-type 2 nz 100 zmin -50.
zmax 50. e-type 1 ne 1 0.
200. unit 1 axis xz file
track_xz.out title Check source direction
using T-track tally epsout 1
file lec03.inp T i t l e P
a r a m e t e r s icntl 5 maxcas 100
maxbch 10 file(6) phits.out
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10
Check Trajectory of Sources
track_xz.eps
No reaction and no ionization because all regions
are void. (You can confirm positions and
directions of sources.)
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Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
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Include File
You can include other files into PHITS input file
using infl command
lec03.inp
onion.inp
file lec03.inp T i t l e P
a r a m e t e r s icntl 7 maxcas 100
maxbch 10 file(6) phits.out set c120
S o u r c e infl
onion.inp1-33
file lec03.inp T i t l e P
a r a m e t e r s icntl 5 maxcas 100
maxbch 10 file(6) phits.out set c15 S
o u r c e infl onion.inp1-33
M a t e r i a l M a t N a m e
C o l o r S u r f a c e 10
so 500. 11 so 5. 12 so 10.
13 so 15. 14 so 20. 15 so
25. C e l l 100 -1 10 101 1
-19.32 -11 102 2 -1. 11
-12 103 3 -8.93 12 -13 104 4
-1. 13 -14 105 5 -0.9 14
-15 106 6 -1.20e-3 15 -10
You have to write file input file name at the
1st line when you use infl command
Replace this line by lines 1 to 33 in onion.inp
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Geometry Visualization Mode
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How to Use Variables
lec03.inp
You can use variables in PHITS input file.
Format set cix i integer (199) x
variable It is effective below the set command
file lec03.inp T i t l e P
a r a m e t e r s set c15 S
o u r c e totfact 1.0 s-type 2 proj
proton e0 150.0 x0 -c1 x1 c1 y0
-c1 y1 c1 z0 -30.0 z1 -30.0 dir
1.0
You can correlate between source area and tally
area etc.
You can use mathematic equations in PHITS input
file Format FORTRAN style e.g. exp(-2.0),
cos(pi/2), pic12 (pi is predefined constant to
3.141592)
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Source Check Mode
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Exercise 1
Extend the beam width so that the beam hits the
whole of the onion structure.

• Increase the variable c1

lec03.inp
rectangular (s-type2)
set c15 S o u r c e totfact 1.0
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
Source particles with their directions along the
z-axis are generated from a square with sides
10cm on xy-plane
track_xz.eps
Extend the width so that the beam covers a size
of a sphere with a radius of 25 cm.
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Answer 1
Extend the beam width so that the beam hits the
whole of the onion structure.
lec03.inp
rectangular (s-type2)
set c125 S o u r c e totfact 1.0
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
track_xz.eps
The beam generated from a square with sides 50cm
can cover the whole of the onion structure.
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Normalization
You have to normalize the PHITS results to your
requested quantities
lec03.inp

• Results of tally are outputted as values per
  generated source.
• (Precisely, weight of generated source.)
• To compare the results with measured values, the
  results have to be normalized by a production
  rate of the source, such as Bq and /cm2/s.
• Using a parameter totfact, you can directly
  obtain the results in a unit such as /cm2/s and
  mGy/h.

set c125 S o u r c e totfact 1.0
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
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Exercise 2
Increase the results of tally by 1,000 times.

• Set its multiplier to totfact in source section

lec03.inp
set c125 S o u r c e totfact 1.0
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
Increase the scale 10-3 to 1.
track_xz.eps
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Answer 2
Increase the results of tally by 1,000 times.
lec03.inp
set c125 S o u r c e totfact 1000
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
The scale increases by 1,000 times.
track_xz.eps
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Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
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Volume and Area Calculation
When you set regmesh in tallies, you have to
calculate volumes and surface areas of cells in
advance.
How much is the particle fluence per unit area in
the specified cell.
How much is the deposit energy per unit volume in
the specified cell.
When the cell is a simple object such as spheres
and cylinders, you can calculate analytically its
volume and surface area. However, complex
objects? ? Monte Carlo integration by PHITS!
You can set the volumes in volume section and
the surface areas in area column of t-cross
section.
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Monte Carlo Integration
Monte Carlo Integration is a numerical method to
obtain an approximate solution of definite
integrals using random numbers. This method
estimates the solution approximately by counting
the number of points inside a cell after marking
random points on a target. Its statistical error
depends on the history number.
a cm
Set a target of a square with side a cm, and then
mark points on it randomly. If the point is
inside the colored region, add 1 to the
score. In the left example, a probability
adding 1 is ½. Therefore, the total score
divided by the trial number approaches to ½ as
increasing the trial number. By multiplying its
result by a area of the target, a2, you can
obtain a area of the colored region approximately.
a cm
You can estimate approximately a specified area
by dividing the total score by the trial number,
and then by multiplying its result by the target
area. Furthermore, you can also estimate a volume
of a specified region by this method.
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Volume calculation by PHITS
PHITS can estimate an approximate value of the
volume by using a track length obtained by
t-track tally.
Volume of a cell cm3 Sum of red lines(total
score)cm of Line(trial number) Area of
source(area of target)cm2 Average track
lengthcmArea of source(area of target)cm2
Result of t-track (A factor of area of source
is included in the result by totfact)
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Exercise 3
Calculate volume of each cell in the onion
structure

• Set the source area to totfact by using c1
• Remove off in the right of t-track with
  filevolume.out

lec03.inp
set c125 S o u r c e totfact 1000
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
T - T r a c k off mesh reg reg
101 102 103 104 105
file volume.out
How much are the volumes of the cells?
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Answer 3
Calculate volume of each cell in the onion
structure
lec03.inp
T - T r a c k mesh reg reg 101
102 103 104 105
file volume.out
set c125 S o u r c e totfact
(c12)2 s-type 2 proj proton e0
150.0 x0 -c1 x1 c1 y0 -c1 y1
c1 z0 -30.0 z1 -30.0 dir 1.0

• To calculate volumes and areas of the geometry
• icntl5
• Area of source should be large enough to cover
  all objects

Open volume.out and then see the result of the
calculation!
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Results of Calculation
Volumes can be calculated by Monte Carlo
integration.
volume.out
num reg volume flux
r.err 1 101 1.0000E00
6.3277E02 0.1630 2 102 1.0000E00
3.6913E03 0.0897 3 103 1.0000E00
9.3260E03 0.0561 4 104 1.0000E00
1.8670E04 0.0361 5 105 1.0000E00
3.2614E04 0.0211

• Volume of each cell is
• 4p(5)3/3524 cm3
• 4p(10)3/3 - 5243665 cm3
• 4p(15)3/3 - 41899948 cm3
• 4p(20)3/3 - 1413719373 cm3
• 4p(25)3/3 - 3351031940 cm3

Differences become larger for inner spheres ?
Statistics are not enough!! ? How to increase the
statistics.
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Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
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Change History Number

• The accuracy of Monte Carlo simulation depends on
  the history number of the simulation
• You can obtain results with better statistics by
  increasing the history number

maxcas (D10) History number per 1 batch
maxbch (D10) Number of batch
rseed (D0.0) rseed lt 0 rseed 0 rseed gt 0 Initial random number option Get initial random number from starting time Default value Value of rseed is used as initial random number
irskip (D0) irskip gt 0 irskip lt 0 Random number control Begin calculation after skipping histories by irskip Begin calculation after skipping random number by irskip
maxcas maxbch total history number

• The same initial random number is used in default
  setting.
• If you want to obtain different results whenever
  you execute PHITS, set rseed lt 0.

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History and batch
Q. What is history number? Number of generated
source specified in source section ? number of
grapes Q. What is number of batch? A constant
history number (maxcas) is taken as a batch.
maxbch is the number of running PHITS
calculations. ? maxcas number of grapes per a
bunch maxbchnumber of bunch
Q. What does PHITS do at the end of each batch?
PHITS calculates results of tally and statistical
errors, and outputs them (by setting itall1).
?tasting harvested grapes
Q. Why does PHITS divide all calculations into
some batch? In the case that you run all
calculations at once, their results may come to
nothing if parameters in the calculations were
wrong. ?In the case that a farmer harvests all
grapes without tasting them, he may get a great
damage if he took a wrong time to do it. If the
above processing is performed each history, it
spends a computational time wastefully. ?If he
harvests with tasting each grapes, it takes a
very long time.
Adjust maxcas and maxbch in accordance with your
situation
e.g. set a computational time per one batch to be
2 or 3 minutes
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Exercise 4
Increase the history number to obtain results
with better statistics.
lec03.inp

• Increase maxcas to 1,000 or 10,000
• Confirm that statistical errors become small

P a r a m e t e r s icntl 5 maxcas
100 maxbch 10 file(6) phits.out set
c125 S o u r c e totfact (c12)2
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
statistical errors (relative errors)
volume.out
num reg volume flux
r.err 1 101 1.0000E00
6.3277E02 0.1630 2 102 1.0000E00
3.6913E03 0.0897 3 103 1.0000E00
9.3260E03 0.0561 4 104 1.0000E00
1.8670E04 0.0361 5 105 1.0000E00
3.2614E04 0.0211
How much do the statistical errors decrease when
the history number increases by 10 times?
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Answer 4
Increase the history number to obtain results
with better statistics.
lec03.inp
volume.out
num reg volume flux
r.err 1 101 1.0000E00
5.2586E02 0.0588 2 102 1.0000E00
3.6515E03 0.0279 3 103 1.0000E00
9.7779E03 0.0172 4 104 1.0000E00
1.9166E04 0.0111 5 105 1.0000E00
3.2095E04 0.0067
num reg volume flux
r.err 1 101 1.0000E00
5.2623E02 0.0187 2 102 1.0000E00
3.6038E03 0.0089 3 103 1.0000E00
9.8977E03 0.0054 4 104 1.0000E00
1.9304E04 0.0035 5 105 1.0000E00
3.2052E04 0.0021
num reg volume flux
r.err 1 101 1.0000E00
6.3277E02 0.1630 2 102 1.0000E00
3.6913E03 0.0897 3 103 1.0000E00
9.3260E03 0.0561 4 104 1.0000E00
1.8670E04 0.0361 5 105 1.0000E00
3.2614E04 0.0211
P a r a m e t e r s icntl 5 maxcas
100 maxbch 10 file(6) phits.out set
c125 S o u r c e totfact (c12)2
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
P a r a m e t e r s icntl 5 maxcas
1000 maxbch 10 file(6) phits.out set
c125 S o u r c e totfact (c12)2
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0
P a r a m e t e r s icntl 5 maxcas
10000 maxbch 10 file(6) phits.out set
c125 S o u r c e totfact (c12)2
s-type 2 proj proton e0 150.0 x0
-c1 x1 c1 y0 -c1 y1 c1 z0
-30.0 z1 -30.0 dir 1.0

• 4p(5)3/3524 cm3
• 4p(10)3/3 - 5243665 cm3
• 4p(15)3/3 - 41899948 cm3
• 4p(20)3/3 - 1413719373 cm3
• 4p(25)3/3 - 3351031940 cm3

exact solutions (analytical solutions)

• Relation between history number and statistical
  error
• The result become closer to the exact solution by
  increasing the history number.
• When the history number increases by 10 times,
  the statistical error becomes 1/v10.

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Restart Calculation mode
You can obtain the result with better statistics
by restart calculation adding a new result to the
past result.
lec03.inp
Add istdev-1, and then execute PHITS in restart
calculation mode.
P a r a m e t e r s icntl 5 maxcas
10000 maxbch 10 file(6) phits.out istdev
-1 set c125 S o u r c e totfact
(c12)2 s-type 2 proj proton e0
150.0 x0 -c1 x1 c1 y0 -c1 y1
c1 z0 -30.0 z1 -30.0 dir 1.0
In the restart calculation mode, a message is
shown in the console screen.
Information on each batch is also outputted.
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Concept of Batch

• Batch is a set of sources to be simulated in a
  single program run
• When the simulation of one batch is finished

• You can output the results still in progress by
  setting itall1 in the parameters section
• You can terminate the job manually by editting
  batch.now file

batch.now
If you change 1 to 0 at the first line and
save it, PHITS execution will be terminated when
the simulation of current batch is finished
1 lt--- 1continue, 0stop -----------------------
--------------------------------------------------
------ bat 560 ncas 560.
rijk 151264979546685. low neutron
0. ncall/s 4.000000000E00
cpu time 0.288 s. date 2012-05-02
time 15h 08m 25
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History Number
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Exercise 5
Terminate the job by batch.now
lec03.inp

• Comment out the line of istdev by marking . (Do
  not use restart calculation mode)
• Set itall1 to check the intermediate result.
• Increase maxbch to 100 to execute a long
  calculation.
• Terminate the job by batch.now.

file lec03.inp T i t l e P
a r a m e t e r s icntl 5 itall
maxcas 10000 maxbch 10 file(6)
phits.out istdev -1
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Answer 5
Terminate the job by batch.now
lec03.inp

1. Execute PHITS
2. Check that track_xz.eps is updated after the
   calculation of each batch
3. Terminate the job by changing the number in
   batch.now

file lec03.inp T i t l e P
a r a m e t e r s icntl 5 itall 1
maxcas 10000 maxbch 100 file(6)
phits.out istdev -1
batch.now
1 lt--- 1continue, 0stop -----------------------
--------------------------------------------------
------
0 lt--- 1continue, 0stop -----------------------
--------------------------------------------------
------
track_xz.eps
Check whether the job is properly terminated or
no by seeing phits.out
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Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
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36
Cut-off Energy
You can reduce your computational time by killing
the particles in which you are not interested, by
setting cut-off energy parameters
particle parameter Cut-off energy
proton emin(1) 1 MeV
neutron emin(2) 1 MeV
p, p0, p- emin(3), emin(4), emin(5) 1 MeV
m, m- emin(6), emin(7) 1 MeV
K, K0, K- emin(8), emin(9), emin(10) 1 MeV
electron, positron, photon emin(12), emin(13), emin(14) 109 MeV
d, t, 3He, a emin(15), emin(16), emin(17), emin(18) 1 MeV/u
nucleus emin(19) 1 MeV/u
Particles with energy below their emin parameters
are NOT traced by PHITS simulation
Cut-off Energy
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Transport calculation without setting of energy
cut-off
lec03.inp
Execute PHITS to confirm particle fluences in
cells of onion.
T - C r o s s off mesh reg reg
5 r-in r-out area 102 101 1.0
103 102 1.0 104 103 1.0 105 104
1.0 106 105 1.0 e-type 2 ne
100 emin 0. emax 200. axis
eng
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 file(6)
phits.out istdev -1
Change Execute
Remove off to use this tally.
Check the cells specified in this tally

• T-cross is tally to obtain particle fluence
  crossing at a certain surface.
• When meshreg, the tally counts crossing times
  from the cell of r-in to the cell of r-out.

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Transport calculation without setting of energy
cut-off
lec03.inp
Execute PHITS to confirm particle fluences in
cells of onion.
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 file(6)
phits.out istdev -1
cross.eps(the 3rd page)
The 3rd page shows energy distribution of
particles moving from the cell 104 to 103. The
protons below about 85MeV crosses the boundary
surface. See also the other pages.
track_xz.eps
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Exercise 6
By setting energy cut-off for neutrons, execute
PHITS without transport of neutrons below 50MeV.
lec03.inp
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) file(6)
phits.out istdev -1

• Set emin(2) in parameters section (neutrons ID
  is 2)

Confirm the fluences of the neutrons below 50MeV
by the set of the energy cut-off.
cross.eps(the 3rd page)
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Answer 6
By setting energy cut-off for neutrons, execute
PHITS without transport of neutrons below 50MeV.
lec03.inp
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 50
file(6) phits.out istdev -1
cross.eps(the 3rd page)
Neutron fluences below 50MeV disappears. ?The
neutrons dont fly.
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Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
41
42
What is data libraries?

• Because reaction cross sections of photons,
  electrons, positrons, and low-energy neutrons
  (below 20 MeV) have complex structures, normal
  reaction models cannot describe their behaviors.
  ? Data libraries are required.
• Cut-off energies of photons, electrons, and
  positrons are set to be high in default setting,
  because it may take a long time to execute PHITS
  considering their transports.

Some parameters ,such as emin, should be set in
parameters section to use data libraries.
Neutron reaction cross section on 113Cd
target(JENDL-4.0)
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How to Use Data Libraries

• Check nuclear data
• c/phits/XS/neu
• Check address (xsdir) file
• c/phits/data/xsdir.jnd
• Check the 1st line of the address file
• datapathc/phits/XS
• Set emin(i), dmax(i) and file(7) in the
  Parameters section

Neutron data library
Folder name where data libraries are included
This is Windows OS case. In Mac, correct a part
of in a directory of /Users/UserName/phits/
.
Nuclear Data Library
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Exercise 7
Perform the transport calculation of neutrons
below 0.1meV by using the neutron data library.
lec03.inp

• Set emin(2) to be 1.0e-10MeV.(10-10MeV0.1meV)
  
• Set dmax(2) to be 20MeV. (The neutron data up to
  20MeV are included in PHITS)
• Set file(7)c/phits/data/xsdir.jnd. (For Windows
  OS. Specify the full path of the address (xsdir)
  file.)
• Remove off in the right of t-track with
  filetrack_eng.out

P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 50
dmax(2) file(6) phits.out file(7)
istdev -1
T - T r a c k off mesh reg reg (101
102 103 104 105) e-type 2 axis
eng unit 1 part
proton neutron photon alpha file
track_eng.out epsout 1

• Average of the file regions by ().
• Use ( ) to sum up results for multiple regions

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Answer 7-1
Perform the transport calculation of neutrons
below 0.1meV by using the neutron data library.
lec03.inp
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 1.0e-10
dmax(2) 20 file(6) phits.out file(7)
c/phits/data/xsdir.jnd istdev -1
T - T r a c k mesh reg reg (101 102 103
104 105) e-type 2 axis eng
unit 1 part proton
neutron photon alpha file track_eng.out epsout
1
track_eng.eps
Energy spectra of the specified particles The
transport of neutrons below 1MeV is performed.
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Answer 7-2
Perform the transport calculation of neutrons
below 0.1meV by using the neutron data library.
lec03.inp
The last part of phits.out (around the 520 line)
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 1.0e-10
dmax(2) 20 file(6) phits.out file(7)
c/phits/data/xsdir.jnd istdev -1
--------------------------------------------------
------------- CPU time and number of event
called in PHITS ----------------------------------
-----------------------------
dklos 0.
hydro 288. n-data
42958. h-data 0.
p-data 0. e-data 0.
p-egs5 0. e-egs5
0.
T - T r a c k mesh reg reg (101 102 103
104 105) e-type 2 axis eng
unit 1 part proton
neutron photon alpha file track_eng.out epsout
1
Number of reactions using cross section data can
be confirmed in phits.out.
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Exercise 8
Perform the transport calculation of electrons,
positrons, and photons by using electron and
photon data libraries.
lec03.inp
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 1.0e-10
dmax(2) 20 emin(12) emin(13)
emin(14) dmax(12) dmax(13) dmax(14)
file(6) phits.out file(7)
c/phits/data/xsdir.jnd istdev -1

• Set cut-off energies of electron, positron, and
  photon, emin(12),emin(13),emin(14) to be 1MeV.
  (in order to avoid long computational time)
• Set their maximum energies for using their data
  libraries, dmax(12),dmax(13),dmax(14) to be
  1000MeV. (enough high for most cases)
• Note Please do not change emin(2) and dmax(2).

Execute PHITS, and then check photon energy
spectrum in track_eng.eps. Furthermore, check
values of p-data and e-data written in phits.out.
Additional exercise
Visualize fluences of electron, positron, and
photon by changing part parameter in
t-track(track_xz.out).
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Answer 8
Perform the transport calculation of electrons,
positrons, and photons by using electron and
photon data libraries.
lec03.inp
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 1.0e-10
dmax(2) 20 emin(12) 1.0 emin(13)
1.0 emin(14) 1.0 dmax(12)
1000.0 dmax(13) 1000.0 dmax(14)
1000.0 file(6) phits.out file(7)
c/phits/data/xsdir.jnd istdev -1
track_eng.eps
Photons below 10MeV are tallied.
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Exercise 9
Use EGS5 for electron photon transport.
lec03.inp
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 1.0e-10
dmax(2) 20 emin(12) 1.0 emin(13)
1.0 emin(14) 1.0 dmax(12)
1000.0 dmax(13) 1000.0 dmax(14)
1000.0 file(6) phits.out file(7)
c/phits/data/xsdir.jnd file(20) negs
istdev -1

• Set negs1.
• Set file(20)c/phits/XS/egs. (For Windows OS.
  Specify the full path of the folder for data
  library for EGS5.)

Execute PHITS. Check p-egs5 and e-egs5 in the
last part of phits.out.
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Answer 9
Use EGS5 for electron photon transport.
lec03.inp
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 1.0e-10
dmax(2) 20 emin(12) 1.0 emin(13)
1.0 emin(14) 1.0 dmax(12)
1000.0 dmax(13) 1000.0 dmax(14)
1000.0 file(6) phits.out file(7)
c/phits/data/xsdir.jnd file(20)
c/phits/XS/egs negs 1 istdev -1
The last part of phits.out. (around the 540 line)
--------------------------------------------------
------------- CPU time and number of event
called in PHITS ----------------------------------
-----------------------------
dklos
118. hydro 289. n-data
43949. h-data 0. p-data
0. e-data 0. p-egs5
1477. e-egs5 42529.

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Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
51
52
g-decay option
igamma Activate g-decay from residual nuclides
produced by nuclear reaction. (Default setting
does NOT produce g-rays)
igamma (D0) 0 1 2 3 g-decay option for residual nuclei Without g-decay With g-decay With g-decay based on EBITEM model With g-decay and isomer production based on EBITEM model
Recommended value is igamma2 from version 2.64.
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53
Option for beam transport analysis
nspred and nedisp Consider angular and energy
straggling of charged particle, respectively
(Important for beam transport analysis)
nspred (D0) 0 1 2 10 Option for Coulomb diffusion (angle straggling) Without Coulomb diffusion With Coulomb diffusion by the NMTC model With Coulomb diffusion by Lynchs formula With Coulomb diffusion by ATIMA
nedisp (D0) 0 1 10 Energy straggling option for charged particle Without energy straggling With energy straggling by Landau Vavilov model With energy straggling by ATIMA
Recommended values are nspred 2 nedisp 1.
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Switching Energy

• Several nuclear reaction models are implemented
  in PHITS
• You can switch the models in the parameters
  section

inclg (D1) Control parameter for use of INCL
ejamnu (D20.) Switching energy of nucleon-nucleus reaction calculation to JAM model (MeV)
ejampi (D20.) Switching energy of pion-nucleus reaction calculation to JAM model (MeV)
eqmdnu (D20.) Switching energy of nucleon-nucleus reaction calculation to JQMD model (MeV)
eqmdmin (D10.) Minimum energy of JQMD calculation (MeV/u)
ejamqmd (D3500.) Switching energy of nucleus-nucleus reaction from JQMD to JAMQMD (MeV/u)
incelf (D0) Control parameter for use of INC-ELF
dmax(i) (Demin(i)) Maximum energy of library use for i-th particle
Nuclear Reaction Model
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55
Map of Nuclear Reaction Models
(emin) dmax(i)
(1MeV) emin(i)
(3.0GeV) einclmax
Nucleon Library INCL (inclg1)
JAM
(1MeV) emin(i)
(3.0GeV) einclmax
Pion INCL (inclg1)
JAM
(10MeV/u) eqmdmin
(3.5GeV/u) ejamqmd
Nucleus JQMD
JAMQMD
(d, t, 3He, a) INCL (inclg1)
Kaon, Hyperon JAM
55
Nuclear Reaction Model
56
Event Generator Mode

• A nuclear reaction model for low-energy neutron
  interaction using nuclear data library combined
  with a special evaporation model
• Determine all ejectiles emitted from low-energy
  neutron interaction, considering the energy and
  momentum conservation

Event generator mode is effective in the case

• to know spectra of proton or alpha particles from
  reactions of low-energy neutrons.
• to obtain information on residual nuclei (e.g.
  recoil energies).
• to perform event-by-event analysis (e.g. response
  function calculation).

Event generator mode is NOT effective in the case

• to know information only on neutrons and photons
  (e.g. shielding).
• to calculate transmittance of neutrons.
• to know accurate behaviors of thermal-neutrons.

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57
How to Use EG Mode
Set e-mode 2 in the Parameters
section (igamma is automatically set to 2 when
you activate the event generator mode)
e-mode (D0) 0 1 2 Option for event generator mode Normal mode Event generator mode version 1 Event generator mode version 2
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Exercise 10
First, perform the transport calculation with
20MeV neutron sources not activating event
generator mode.
lec03.inp

• Set source particles to be 20MeV neutrons.

set c125 S o u r c e totfact
(c12)2 s-type 2 proj proton e0
150.0 x0 -c1 x1 c1 y0 -c1 y1
c1 z0 -30.0 z1 -30.0 dir 1.0
Confirm proton and alpha spectra by tallying
particle fluences in the whole sphere. (See
track_eng.eps)
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59
Answer 10
First, perform the transport calculation with
20MeV neutron sources not activating event
generator mode.
lec03.inp
set c125 S o u r c e totfact
(c12)2 s-type 2 proj neutron e0
20.0 x0 -c1 x1 c1 y0 -c1 y1 c1
z0 -30.0 z1 -30.0 dir 1.0
track_eng.eps

• Proton and alpha spectra are not shown!
• these particles are not generated by nuclear
  reactions of neutrons below 20MeV in the
  calculation without event generator mode.

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Exercise 11
Use event generator mode.
lec03.inp

• Set e-mode2.

P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 1.0e-10
dmax(2) 20 emin(12) 1.0 emin(13)
1.0 emin(14) 1.0 dmax(12)
1000.0 dmax(13) 1000.0 dmax(14)
1000.0 file(6) phits.out file(7)
c/phits/data/xsdir.jnd file(20)
c/phits/XS/egs negs 1 istdev -1 e-mode
Confirm proton and alpha spectra. (See
track_eng.eps)
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Answer 11
Use event generator mode.
lec03.inp
P a r a m e t e r s icntl 0 itall 1
maxcas 1000 maxbch 10 emin(2) 1.0e-10
dmax(2) 20 emin(12) 1.0 emin(13)
1.0 emin(14) 1.0 dmax(12)
1000.0 dmax(13) 1000.0 dmax(14)
1000.0 file(6) phits.out file(7)
c/phits/data/xsdir.jnd file(20)
c/phits/XS/egs negs 1 istdev -1 e-mode
2
track_eng.eps
Proton and alpha spectra are not shown!
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Important file Parameters
file(6) (Dphits.out) Summary output file name. If not specified, standard output.
file(7) (Dc/phits/data/xsdir.jnd) Address file for cross section data library.
file(15) (Ddumpall.dat) Dump file name for dumpall1 option.
file(18) (Dvoxel.bin) Binary file name for ivoxel1,2.
file(20) (Dc/phits/XS/egs/) Directory containing the library data for EGS5
file(21) (Dc/phits/dchain-sp/data/) Directory containing the library data for DCHAIN-SP
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63
Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
63
64
Exercise 12
Consider the case that the onion structure is
uniformly irradiated by 100MeV protons. The flux
is 1 particle per cm2 per second. How much energy
does it deposit in the cells of the onion, when
the irradiation time is 1 hour?
This is an exercise to convert results outputted
in the unit of MeV/source to values expressed
in MeV.

• 100MeV protons are produced from the same square
  with sides 50cm as before. (Dont change the
  source region.)
• Remove off in a t-deposit section with
  unit2. (When unit2, t-deposit tally outputs
  results in MeV/source)
• In source section, change source particle and
  its energy, and set totfact to convert values in
  MeV/source to those in MeV.

The onion is irradiated by 100MeV protons with
the flux of 1particle/cm2/s.
Note How many protons does the source of 1
particle/cm2/s produce for an hour from the
square with sides 50cm?
Open deposit_reg.out and then check the result.
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Answer 12
Consider the case that the onion structure is
uniformly irradiated by 100MeV protons. The flux
is 1 particle per cm2 per second. How much energy
does it deposit in the cells of the onion, when
the irradiation time is 1 hour?

• Calculation of totfact
• For 1 second, 5050 protons are produced from the
  square with sides 50cm because the beam fluence
  is 1 particle per 1cm2.
• 50503600 protons source are produced for an
  hour.
• Because t-deposit with unit2 outputs results
  in MeV/source, we can obtain values in MeV by
  multiplying 50503600 source with the set of
  totfact.

lec03.inp
S o u r c e totfact (c12)23600 s-type
2 proj proton e0 100.0 x0 -c1
T-deposit title Deposition
energy mesh reg reg 101 102 103 104
105 unit 2
remove off
deposit_reg.out
num reg volume dose
r.err 1 101 1.0000E00
8.9957E03 0.5393 2 102 1.0000E00
5.6722E04 0.3414 3 103 1.0000E00
5.1382E05 0.1583 4 104 1.0000E00
1.3005E08 0.0148 5 105 1.0000E00
5.5275E08 0.0062
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66
Contents of Lecture III

• Selection of Calculation Mode
• Convenient functions for input
• Setting for statistics
• Monte Carlo integration
• History Number and statistical error
• Setting for physics
• Cut-off Energy
• Nuclear Data Library
• Physical Models
• Exercise for normalization factor
• Summary

Contents
66
67
Summary

• Parameters section is used for controlling
  PHITS simulation procedure.
• You can select the calculation modes such as
  particle transport simulation, geometry and
  source check using icntl parameter.
• Statistical uncertainty of PHITS simulation
  depends on the history number (maxcas
  maxbch)
• You have to set cut-off energy emin of each
  particle to obtain good statistical data within a
  reasonable computational time
• Low-energy neutrons, as well as photons,
  electrons and positron must be transported using
  nuclear and atomic data libraries by setting
  dmax and file(7) parameter.
• You have to carefully select the physical models
  used in your simulation, such as the event
  generator mode

If you feel difficulties by selecting these
parameters, see recommendation folder and find
appropriate setting for your simulation
Summary
67
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Homework
Based on the homework condition

• Transport neutrons down to 10-10MeV using nuclear
  data library up to 20 MeV
• Activate event generator mode
• Obtain depth-dose distribution with relative
  error less than 2, by changing maxcas, istdev,
  batch.now etc.

Homework
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Example Answer
Proton (up) and neutron (down) fluences
Depth-dose distribution inside (up) and outside
(down) beam radius
Homework
69