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P HI T S Basic Lecture III: Parameter Setting Multi-Purpose Particle and Heavy Ion Transport code System title1 Mar revised

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

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Goal of This Lecture Purpose3 Proton (up) and neutron (down) fluences calculated by default settings for homework study You can obtain this kind of results at the end of this lecture Proton (up) and neutron (down) fluences calculated by appropriate settings for homework study

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Contents of Lecture III Contents4 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

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

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Geometry Visualization Mode6 Geometry Visualization Let’s check the geometry using icntl=11 [3D-show] and icntl=7 [t-gshow]

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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] 7 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 ・ ・ ・ 3dshow.eps Onion structure Activate [t-3dshow] [3D-Show] (icntl=11) Geometry Visualization Mode

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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] 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] [ T - G s h o w ] mesh = xyz x-type = 2 nx = 100 xmin = -50. xmax = 50. y-type = 1 ny = 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 8 lec03.inp gshow.eps Check cell ID and filled materials [T-gshow] (icntl=7) Activate [t-gshow] Geometry Visualization Mode

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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 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 = z-type = 2 nz = 100 zmin = -50. zmax = 50. e-type = 1 ne = unit = 1 axis = xz file = track_xz.out title = Check source direction using [T-track] tally epsout = 1 Check Sources ([t-track])

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10 Track-xz.eps No reaction and no ionization because all regions are void. （ You can confirm positions and directions of sources. ） Check Trajectory of Sources

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Contents of Lecture III Contents11 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

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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] 12 lec03.inp [ 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 so so so so so 25. [ C e l l ] e Replace this line by lines 1 to 33 in “onion.inp” onion.inp Include File You can include other files into PHITS input file using “infl” command You have to write “file = input file name” at the 1 st line when you use “infl” command Geometry Visualization Mode

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

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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 14 lec03.inp Mathematical equations You can use mathematical equations in FORTRAN format in PHITS input file 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 /cm 2 /s. Using a parameter “totfact”, you can directly obtain the results in a unit such as /cm 2 /s and mGy/h. In this case, the fluence on the sphere of the source are 1/πr 2 (/cm 2 /source) without normalization. Multiplying a factor of πr 2, the fluence on the sphere is 1(/cm 2 ). * Precisely, weight of generated source. The number π is denoted by pi. Exponentiation is denoted by **. Some functions, such as exp and cos, can also be used.

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Contents of Lecture III Contents15 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

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Volume and Area Calculation 16 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. Total track length in a cell [cm] = average track length [cm/source] x #Line [source] Density of line [1/cm 2 ] = average flux [1/cm 2 /source] x #Line [source] Volume of a cell [cm 3 ] You can obtain better statistics by increasing the history number = = Track length [cm/source] of particles calculated by [t-track] by setting icntl = 5 Expected flux [1/cm 2 /source] No Reaction, No Ionization Mode

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Volume and Area Calculation 17 Volume of a cell [cm 3 ] You can obtain better statistics by increasing the history number 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. by using isotropic irradiation source Expected flux in the sphere is 1/πr 2 (/cm 2 /source) and No Reaction, No Ionization Mode

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[ 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 ] mesh = reg reg = 5 r-in r-out area ( ) ( ) 1.0 ( ) ( ) 1.0 ( ) ( ) 1.0 ( ) ( ) 1.0 ( ) ( ) 1.0 ・ ・ ・ file = area.out 18 lec03.inp Change & Execute Exercise 1 No Reaction, No Ionization Mode Volume and area calculation To calculate volumes and areas of the geometry: icntl=5, s-type=9, r1=r2 （ size including the whole of the geometry ） dir=-all

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

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Contents of Lecture III Contents20 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

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maxcas(D=10)History number per 1 batch maxbch(D=10)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 21 maxcas ×maxbch ＝ total history number 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 The same initial random number is used in default setting. If you want to obtain different results whenever you execute PHITS, set rseed < 0.

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History and batch 22 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

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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 = lec03.inp volume.out ・ ・ ・ #num reg volume flux r.err E E E E E E E E E E area.out ・ ・ ・ #num area flux r.err E E E E E E E E E E 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 ・ ・ ・ #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 file = lec03.inp [ T i t l e ] ・ ・ ・ [ P a r a m e t e r s ] icntl = 5 maxcas = 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 area flux r.err E E E E E E E E E E Volume of each cell is… 4π(5) 3 /3=524 cm 3 4π(10) 3 / =3665 cm 3 4π(15) 3 / =9948 cm 3 4π(20) 3 / =19373 cm 3 4π(25) 3 / =31940 cm 3 Area of each surface is … 4π(5) 2 =314 cm 2 4π(10) 2 =1257 cm 2 4π(15) 2 =2827 cm 2 4π(20) 2 =5027 cm 2 4π(25) 2 =7854 cm 2 Volume and Area Calculation History Number

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24 lec03.inp Restart Calculation mode volume.out area.out file = lec03.inp [ T i t l e ] ・ ・ ・ [ P a r a m e t e r s ] icntl = 5 maxcas = 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 History Number istdev = -1 ・ ・ ・ #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 ・ ・ ・ #num area 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 area flux r.err E E E E E E E E E E

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25 lec03.inp Restart Calculation mode file = lec03.inp [ T i t l e ] ・ ・ ・ [ P a r a m e t e r s ] icntl = 5 maxcas = 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 History Number istdev = -1 In the restart calculation mode, a message is shown in the console screen. Information on each batch is also outputted.

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26 1 <--- 1:continue, 0:stop bat[ 560] ncas = 560. : rijk = low neutron = 0. : ncall/s = E+00 cpu time = s. date = time = 15h 08m 25 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 batch.now 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 History Number

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27 lec03.inp track_xz.eps 1 <--- 1:continue, 0:stop batch.now 0 <--- 1:continue, 0:stop Exercise 2 Execute a long calculation with a large maxbch. Set itall=1 to check the intermediate result. Terminate the job by batch.now. Check whether the job is properly terminated or not by seeing “phits.out” History Number file = lec03.inp [ T i t l e ] ・ ・ ・ [ P a r a m e t e r s ] icntl = 5 itall = 1 maxcas = maxbch = 100 file(6) = phits.out $ istdev = -1 Job Termination by “batch.now”

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Contents of Lecture III Contents28 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

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particleIDCut-off energy protonemin(1)1 MeV neutronemin(2)1 MeV π，μπ，μ emin(3~8)1 MeV electron ・ positron emin(12,13)10 9 MeV photonemin(14)10 9 MeV nucleusemin(15~19)1 MeV/u Cut-off Energy29 Particles with energy below their emin parameters are NOT traced by PHITS simulation 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

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30 [ P a r a m e t e r s ] icntl = 5 itall = 1 maxcas = 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 lec03.inp [ 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 Change & Execute Mono-energetic proton 150MeV incidence source-energy.eps [ 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 Tally inward fluxes between the constitution cells of onion Cut-off Energy gshow.eps Cut-off Energy

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31 lec03.inp [ 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 Neutron fluxes below 50 MeV disappears. cross.eps Cut-off Energy

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Contents of Lecture III Contents32 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

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What is data libraries? 33 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 113 Cd target （ JENDL-4.0 ）

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Nuclear Data Library34 How to Use Data Libraries 1.Check nuclear data c:/phits/XS/neu 2.Check address (xsdir) file c:/phits/data/xsdir.jnd 3.Check 1 st line of the address file datapath=c:/phits/XS 4.Set “emin(i)”, “dmax(i)” and “file(7)” in the [Parameters] section Neutron data library Folder name where data libraries are included

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35 lec03.inp [ 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 phits.out CPU Summary ・ ・ ・ dklos = 0. hydro = 379. n-data = h-data = 0. p-data = 0. e-data = 0. p-egs5 = 0. e-egs5 = 0. ・ ・ ・ Exercise 3 Use data library for neutrons below 20 MeV (Check emin < dmax) Folder & file name of the address file Nuclear Data Library Use neutron data library

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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 36Nuclear Data Library Check ‘e-data’ and ‘p-data’ written in ‘phits.out’ Execute PHITS Visualize electron, positron and photon fluences by changing ‘part’ parameter in [t-track] Exercise Exercise 4 Use photon & electron data libraries

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37 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) = 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 Use EGS5 phits.out CPU Summary ・ ・ ・ dklos = 103. hydro = 377. n-data = h-data = 0. p-data = 0. e-data = 0. p-egs5 = e-egs5 = ・ ・ ・ Folder for data library for EGS5 Exercise 5 Use EGS5 for photon & electron transport

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Contents of Lecture III Contents38 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

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39 igamma(D=0) = 0 = 1 = 2 = 3 -decay option for residual nuclei Without -decay With -decay With -decay based on EBITEM model With -decay and isomer production based on EBITEM model igamma: Activate -decay from residual nuclides produced by nuclear reaction. (Default setting does NOT produce -rays) decay option Recommended value is igamma=2 from version 2.64.

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40 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(D=0) = 0 = 1 = 10 Energy straggling option for charged particle Without energy straggling With energy straggling by Landau Vavilov model With energy straggling by ATIMA Option for beam transport analysis nspred and nedisp: Consider angular and energy straggling of charged particle, respectively (Important for beam transport analysis) Recommended values are nspred = 2 & nedisp = 1.

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Nuclear Reaction Model41 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(D=20.)Switching energy of pion-nucleus reaction calculation to JAM model (MeV) eqmdnu(D=20.)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

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

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43 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. 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

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44 e-mode(D=0) = 0 = 1 = 2 Option for event generator mode Normal mode Event generator mode version 1 Event generator mode version 2 How to Use EG Mode 1.Set “e-mode = 2” in the [Parameters] section (“igamma” is automatically set to 2 when you activate the event generator mode)

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45 lec03.inp Change & Execute [ 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 ( ). [ 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 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. Exercise 6 [ 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 Use event generator mode

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

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Important “file” Parameters 47 File(6)(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

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Contents of Lecture III Contents48 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

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49 [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 Summary If you feel difficulties by selecting these parameters, see “recommendation” folder and find appropriate setting for your simulation

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Homework50 Transport neutrons down to MeV 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 Based on the homework condition …

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Homework51 Depth-dose distribution inside (up) and outside (down) beam radius Example Answer Proton (up) and neutron (down) fluences

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