# Basic Lecture III: Parameter Setting

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Basic Lecture III: Parameter Setting
PHITS Multi-Purpose Particle and Heavy Ion Transport code System Basic Lecture III: Parameter Setting Mar revised title 1

You will learn how to setup those parameters in this lecture!
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 You will learn how to setup those parameters in this lecture! Introduction 2

You can obtain this kind of results at the end of this lecture
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 3

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 Summary Contents 4

Selection of Calculation Mode
Particle Transport Simulation Checking purpose Geometry Visualization Selection of Calculation Mode 5

Geometry Visualization
Let’s check the geometry using icntl=11 [3D-show] and icntl=7 [t-gshow] Geometry Visualization Geometry Visualization Mode 6

Geometry Visualization Mode
[3D-Show] (icntl=11) lec03.inp [ 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 ・ ・ ・ ・ ・ ・ 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: c1[20] [ S o u r c e ] infl: {onion.inp}[1-33] Activate [t-3dshow] Onion structure 3dshow.eps Geometry Visualization Mode 7

[T-gshow] (icntl=7) lec03.inp Geometry Visualization Mode 8 Activate
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: c1[20] [ S o u r c e ] infl: {onion.inp}[1-33] 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: c1[20] [ S o u r c e ] infl: {onion.inp}[1-33] [ T - G s h o w ] mesh = xyz x-type = 2 nx = 100 xmin = -50. xmax = 50. y-type = 1 ny = 10 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 Check cell ID and filled materials Activate [t-gshow] gshow.eps Geometry Visualization Mode 8

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 z-type = 2 nz = 100 zmin = -50. zmax = 50. e-type = 1 ne = 1 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 9

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.） 10

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 Summary Contents 11

Geometry Visualization Mode
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: c1[20] [ S o u r c e ] infl: {onion.inp}[1-33] 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: c1[20] [ S o u r c e ] infl: {onion.inp}[1-33] You have to write “file = input file name” at the 1st line when you use “infl” command [ 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 11 so 12 so 13 so 14 so 15 so [ C e l l ] e Replace this line by lines 1 to 33 in “onion.inp” Geometry Visualization Mode 12

How to Use Variables lec03.inp Source Check Mode 13
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: c1[10] [ S o u r c e ] s-type = 9 proj = proton x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = 1.0 e0 = 150 s-type=9, 10:　sphere or spherical shell source （x0, y0, z0）: center of the sphere r1: inner radius r2: outer radius Z You can use variables in PHITS input file. Format: set: ci[x] i: integer (1~99) x: variable It is effective below the “set” command r1 r2 Y （x0, y0, z0) X Source Check Mode 13

Mathematical equations
You can use mathematical equations in FORTRAN format in PHITS input file lec03.inp Normalization Results of tally are outputted as values per 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. In this case, the fluence on the sphere of the source are 1/πr2 (/cm2/source) without normalization. Multiplying a factor of πr2, the fluence on the sphere is 1(/cm2). set: c1[10] [ S o u r c e ] s-type = 9 proj = proton x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = 1.0 e0 = 150 totfact = pi*c1**2 The number π is denoted by pi. Exponentiation is denoted by **. Some functions, such as exp and cos, can also be used. *Precisely, weight of generated source. 14

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 Summary Contents 15

Volume and Area Calculation
Monte Carlo Integration is numerical integration using random number. Using this concept, the volume of each cell can be calculated from the average track length divided by the average flux inside the cell, by setting icntl = 5. = Volume of a cell [cm3] Total track length in a cell [cm] =　average track length [cm/source] x #Line [source] Density of line [1/cm2] = average flux [1/cm2/source] 　x #Line [source] = Track length [cm/source] of particles calculated by [t-track] by setting icntl = 5 You can obtain better statistics by increasing the history number Expected flux [1/cm2/source] No Reaction, No Ionization Mode 16

Volume and Area Calculation
Monte Carlo Integration is numerical integration using random number. Using this concept, the volume of each cell can be calculated from the average track length divided by the average flux inside the cell, by setting icntl = 5. Volume of a cell [cm3] by using isotropic irradiation source and You can obtain better statistics by increasing the history number Expected flux in the sphere is 1/πr2 (/cm2/source) No Reaction, No Ionization Mode 17

No Reaction, No Ionization Mode
Exercise 1 Volume and area calculation lec03.inp [ P a r a m e t e r s ] icntl = 5 maxcas = 100 maxbch = 10 file(6) = phits.out set: c1[30] [ S o u r c e ] s-type = 9 proj = proton x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = -all e0 = 150 totfact = pi*c1**2 [ T - T r a c k ] mesh = reg reg = ・ ・ ・ ・ ・ ・ file = volume.out [ T - C r o s s ] reg = 5 r-in r-out area ( ) ( ) 1.0 ( ) ( ) 1.0 ( ) ( ) 1.0 ( ) ( ) 1.0 ( ) ( ) 1.0 file = area.out Change & Execute To calculate volumes and areas of the geometry: icntl=5, s-type=9, r1=r2（size including the whole of the geometry） dir=-all No Reaction, No Ionization Mode 18

Results of Calculation
volume.out area.out ・ ・ ・ ・ ・ ・ #num reg volume flux r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num area flux 　　　　r.err E E E E E E E E E E Volume of each cell is… 4π(5)3/3=524 cm3 4π(10)3/ =3665 cm3 4π(15)3/ =9948 cm3 4π(20)3/ =19373 cm3 4π(25)3/ =31940 cm3 Area of each surface is… 4π(5)2=314 cm2 4π(10)2=1257 cm2 4π(15)2=2827 cm2 4π(20)2=5027 cm2 4π(25)2=7854 cm2 Differences become larger for inner spheres → Statistics are not enough !! No Reaction, No Ionization Mode 19

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 Summary Contents 20

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 (D=10) History number per 1 batch maxbch Number of batch rseed (D=0.0) rseed < 0 rseed = 0 rseed > 0 Initial random number option Get initial random number from starting time Default value Value of rseed is used as initial random number irskip (D=0) irskip > 0 irskip < 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 < 0. 21

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　　maxbch：number 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 itall=1). 　　→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 22

Volume and Area Calculation
lec03.inp volume.out file = lec03.inp [ T i t l e ] ・ ・ ・ ・ ・ ・ [ P a r a m e t e r s ] icntl = 5 maxcas = 10000 maxbch = 10 file(6) = phits.out set: c1[30] [ S o u r c e ] s-type = 9 proj = proton x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = -all e0 = 150 file = lec03.inp [ T i t l e ] ・ ・ ・ ・ ・ ・ [ P a r a m e t e r s ] icntl = 5 maxcas = 1000 maxbch = 10 file(6) = phits.out set: c1[30] [ S o u r c e ] s-type = 9 proj = proton x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = -all e0 = 150 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: c1[30] [ S o u r c e ] s-type = 9 proj = proton x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = -all e0 = 150 ・ ・ ・ ・ ・ ・ #num reg volume flux r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num reg volume flux r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num reg volume flux r.err E E E E E E E E E E Volume of each cell is… 4π(5)3/3=524 cm3 4π(10)3/ =3665 cm3 4π(15)3/ =9948 cm3 4π(20)3/ =19373 cm3 4π(25)3/ =31940 cm3 area.out ・ ・ ・ ・ ・ ・ #num area flux 　　　　r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num area flux 　　　　r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num area flux 　　　　r.err E E E E E E E E E E Area of each surface is … 4π(5)2=314 cm2 4π(10)2=1257 cm2 4π(15)2=2827 cm2 4π(20)2=5027 cm2 4π(25)2=7854 cm2 History Number 23

Restart Calculation mode
lec03.inp volume.out file = lec03.inp [ T i t l e ] ・ ・ ・ ・ ・ ・ [ P a r a m e t e r s ] icntl = 5 maxcas = 10000 maxbch = 10 file(6) = phits.out set: c1[30] [ S o u r c e ] s-type = 9 proj = proton x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = -all e0 = 150 ・ ・ ・ ・ ・ ・ #num reg volume flux r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num reg volume flux r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num reg volume flux r.err E E E E E E E E E E istdev = -1 area.out ・ ・ ・ ・ ・ ・ #num area flux 　　　　r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num area flux 　　　　r.err E E E E E E E E E E ・ ・ ・ ・ ・ ・ #num area flux 　　　　r.err E E E E E E E E E E History Number 24

Restart Calculation mode
lec03.inp In the restart calculation mode, a message is shown in the console screen. file = lec03.inp [ T i t l e ] ・ ・ ・ ・ ・ ・ [ P a r a m e t e r s ] icntl = 5 maxcas = 10000 maxbch = 10 file(6) = phits.out set: c1[30] [ S o u r c e ] s-type = 9 proj = proton x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = -all e0 = 150 istdev = -1 Information on each batch is also outputted. History Number 25

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 “itall=1” 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 <--- 1:continue, 0:stop bat[ ] ncas = : rijk = low neutron = : ncall/s = E+00 cpu time = s. date = time = 15h 08m 25 History Number 26

Exercise 2 Job Termination by “batch.now” lec03.inp History Number 27
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 Execute a long calculation with a large maxbch. Set itall=1 to check the intermediate result. Terminate the job by batch.now. track_xz.eps batch.now 0 <--- 1:continue, 0:stop 1 <--- 1:continue, 0:stop Check whether the job is properly terminated or not by seeing “phits.out” History Number 27

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 Summary Contents 28

Cut-off Energy Cut-off Energy 29
You can reduce your computational time by killing the particles in which you are not interested, by setting “cut-off energy” parameters particle ID Cut-off energy proton emin(1) 1 MeV neutron emin(2) π，μ emin(3~8) electron・positron emin(12,13) 109 MeV photon emin(14) nucleus emin(15~19) 1 MeV/u Particles with energy below their emin parameters are NOT traced by PHITS simulation Cut-off Energy 29

Cut-off Energy lec03.inp Cut-off Energy 30
Mono-energetic proton 150MeV incidence [ P a r a m e t e r s ] icntl = 0 　itall = 1 maxcas = 1000 maxbch = 10 file(6) = phits.out \$ istdev = -1 set: c1[30] [ S o u r c e ] s-type = 9 proj = proton ・ ・ ・ ・ ・ ・ dir = -all e0 = 150 [ P a r a m e t e r s ] icntl = 5 　itall = 1 maxcas = 10000 maxbch = 100 file(6) = phits.out \$ istdev = -1 set: c1[30] [ S o u r c e ] s-type = 9 proj = proton ・ ・ ・ ・ ・ ・ dir = -all e0 = 150 Change & Execute [ T - C r o s s ] off mesh = reg reg = 5 r-in r-out area e-type = 2 ne = 100 emin = 0. emax = 200. axis = eng unit = 1 output = flux file = cross.out epsout = 1 [ T - C r o s s ] mesh = reg reg = 5 r-in r-out area e-type = 2 ne = 100 emin = 0. emax = 200. axis = eng unit = 1 output = flux file = cross.out epsout = 1 source-energy.eps Tally inward fluxes between the constitution cells of onion gshow.eps Cut-off Energy 30

Cut-off Energy lec03.inp Cut-off Energy 31 Change & Execute cross.eps
[ P a r a m e t e r s ] icntl = 0 　itall = 1 maxcas = 1000 maxbch = 10 file(6) = phits.out \$ istdev = -1 set: c1[30] [ S o u r c e ] s-type = 9 proj = proton ・ ・ ・ ・ ・ ・ dir = -all e0 = 150 [ 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 set: c1[30] [ S o u r c e ] s-type = 9 proj = proton ・ ・ ・ ・ ・ ・ dir = -all e0 = 150 Change & Execute cross.eps Neutron fluxes below 50 MeV disappears. Cut-off Energy 31

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 Summary Contents 32

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） 33

How to Use Data Libraries
Check nuclear data c:/phits/XS/neu Check address (xsdir) file c:/phits/data/xsdir.jnd Check 1st line of the address file datapath=c:/phits/XS Set “emin(i)”, “dmax(i)” and “file(7)” in the [Parameters] section Neutron data library Folder name where data libraries are included Nuclear Data Library 34

Exercise 3 Use neutron data library lec03.inp Nuclear Data Library 35
phits.out [ P a r a m e t e r s ] icntl = 0 　itall = 1 maxcas = 1000 maxbch = 10 emin(1) = 50 emin(2)= 1.0e-10 dmax(2) = 20 file(6) = phits.out file(7) = c:/phits/data/xsdir.jnd \$ istdev = -1 CPU Summary ・ ・ ・ ・ ・ ・ dklos = hydro = n-data = h-data = p-data = e-data = p-egs5 = e-egs5 = Use data library for neutrons below 20 MeV (Check emin < dmax) Folder & file name of the address file Nuclear Data Library 35

Exercise 4 Use photon & electron data libraries
Set cut-off energies of electron, positron and photon: emin(12~14) = 1.0 → in order to avoid long computational time Set their maximum energies for using their data libraries: dmax(12~14) = → enough high for most cases Execute PHITS Check ‘e-data’ and ‘p-data’ written in ‘phits.out’ Exercise Visualize electron, positron and photon fluences by changing ‘part’ parameter in [t-track] Nuclear Data Library 36

Exercise 5 Use EGS5 for photon & electron transport lec03.inp 37
phits.out [ 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) = dmax(13) = dmax(14) = file(6) = phits.out file(7) = c:/phits/data/xsdir.jnd file(20) = c:/phits/XS/egs negs = 1 \$ istdev = -1 CPU Summary ・ ・ ・ ・ ・ ・ dklos = hydro = n-data = h-data = p-data = e-data = p-egs5 = e-egs5 = Folder for data library for EGS5 Use EGS5 37

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 Summary Contents 38

g-decay option Recommended value is igamma=2 from version 2.64. 39
igamma: Activate g-decay from residual nuclides produced by nuclear reaction. (Default setting does NOT produce g-rays) igamma (D=0) = 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 igamma=2 from version 2.64. 39

Option for beam transport analysis
nspred and nedisp: Consider angular and energy straggling of charged particle, respectively (Important for beam transport analysis) nspred (D=0) = 0 = 1 = 2 = 10 Option for Coulomb diffusion (angle straggling) Without Coulomb diffusion With Coulomb diffusion by the NMTC model With Coulomb diffusion by Lynch’s formula With Coulomb diffusion by ATIMA nedisp 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. 40

Nuclear Reaction Model
Switching Energy Several nuclear reaction models are implemented in PHITS You can switch the models in the [parameters] section inclg (D=1) Control parameter for use of INCL ejamnu (D=20.) Switching energy of nucleon-nucleus reaction calculation to JAM model (MeV) ejampi Switching energy of pion-nucleus reaction calculation to JAM model (MeV) eqmdnu Switching energy of nucleon-nucleus reaction calculation to JQMD model (MeV) eqmdmin (D=10.) Minimum energy of JQMD calculation (MeV/u) ejamqmd (D=3500.) Switching energy of nucleus-nucleus reaction from JQMD to JAMQMD (MeV/u) incelf (D=0) Control parameter for use of INC-ELF dmax(i) (D=emin(i)) Maximum energy of library use for i-th particle Nuclear Reaction Model 41

Map of Nuclear Reaction Models
(1MeV) emin(i) (=emin) dmax(i) (3.0GeV) einclmax Nucleon Library INCL (inclg=1) JAM (1MeV) emin(i) (3.0GeV) einclmax Pion INCL (inclg=1) JAM (10MeV/u) eqmdmin (3.5GeV/u) ejamqmd Nucleus JQMD JAMQMD (d, t, 3He, α) INCL (inclg=1) Kaon, Hyperon JAM Nuclear Reaction Model 42

Event Generator Mode Event generator mode is effective in the case
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. 43

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 (D=0) = 0 = 1 = 2 Option for event generator mode Normal mode Event generator mode version 1 Event generator mode version 2 44

Exercise 6 Use event generator mode lec03.inp 45
Change & Execute [ 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) = dmax(13) = dmax(14) = file(6) = phits.out file(7) = c:/phits/data/xsdir.jnd ... e-mode = 0 [ S o u r c e ] s-type = 9 proj = neutron x0 = 0. y0 = 0. z0 = 0. r1 = c1 r2 = c1 dir = -all e0 = 20.0 totfact = pi*c1**2 [ T - T r a c k ] mesh = reg reg = ( ) e-type = 2 ne = 100 emin = 0 emax = 20. axis = eng unit = 1 part = proton neutron photon alpha file = track_eng.out epsout = 1 If you want to output sum of results in several regions, use ( ). First, execute PHITS not activating event generator mode.（default setting） Set source particles to be 20 MeV neutrons. Confirm proton and alpha spectra by tallying particle fluences in the whole sphere. 45

Proton and alpha spectra are shown!
Exercise 6 Use event generator mode lec03.inp Change & Execute [ 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) = dmax(13) = dmax(14) = file(6) = phits.out file(7) = c:/phits/data/xsdir.jnd ... e-mode = 2 Track_eng.eps Proton and alpha spectra are shown! 46

Important “file” Parameters
(D=phits.out) Summary output file name. If not specified, standard output. File(7) (D=c:/phits/data/xsdir.jnd) Address file for cross section data library. File(15) (D=dumpall.dat) Dump file name for dumpall=1 option. File(18) (D=voxel.bin) Binary file name for ivoxel=1,2. File(20) (D=c;/phits/XS/egs/) Directory containing the library data for EGS5 File(21) (D=c:/phits/dchain-sp/data/) Directory containing the library data for DCHAIN-SP 47

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 Summary Contents 48

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 49

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. 宿題（3次元体系） Homework 50

Depth-dose distribution inside (up) and outside (down) beam radius
Example Answer Proton (up) and neutron (down) fluences Depth-dose distribution inside (up) and outside (down) beam radius Homework 51