Features of PHITS3.20
PHITS development team, Mar. 2020

1Map of Models Recommended to Use in PHITS
NeutronProton, Pion(other hadrons)

NucleusLow ← Energy → High

1 TeV

e- / e+Photon
1 TeV

1 TeV/uIntra-nuclear cascade (JAM)+ Evaporation (GEM)

JAMQMD+ GEM

3.0 GeV

Intra-nuclear cascade (INCL4.6) d+t
Evaporation (GEM)
20 MeV

Muon

3He

Quantum
Molecular
Dynamics(JQMD)+ GEM

VirtualPhotoNuclear
JAM/
JQMD
+GEM
200 MeV

PhotoNuclear
EPDL97or
EGS5
EGS5JAM/
JQMD+GEM+JENDL+NRF

αNuclear
10 MeV/uATIMA
1 MeV+
Data Library
Original
Stopping power (ATIMA)(JENDL-4.0)
1 keVor track structure (KURBUC)
1 keV 1 keV+Muonic **TrackEGM
atom + structure *Only in water

0.01 meVCapture

1 meV

 Implement track structure mode for protons and ions based on KURBUC
 Implement reaction model for muon pair production by photon interaction

2Major Upgraded Features in ver. 3.17
Upgrade patch to 3.17 was released in Nov. 2019

Upgraded Points from ver. 3.10
 A model for estimating DNA damage based on track-structure mode and[t-userdefined] is developed Surface-type source distribution (s-type=26) becomes available
 A function to draw the variance of statistical errors is implemented
 Initial “counter” value can be specified for each multi-source A function to consider the reduction of target material due to nuclear
reactions is implemented in DCHAIN
 An option for excluding annihilation γ-ray from photon RI sources isintroduced

3

Major Upgraded Features in ver. 3.20
PHITS 3.20 was released in Apr. 2020

Upgraded Points from ver. 3.17
 A function to read the stopping power of each material from user-supplied
table is implemented
 A new section [Repeated Collisions] is implemented to improve thestatistics of rarely produced secondary particles*1)
 A pseudo random number generator based on xorshift64 is introduced
 Proton and carbon ion track structure code, KURBUC, is implemented*2)
 A function to estimate the systematic uncertainty based on ANOVA isdeveloped Muon-pair production from photon interaction can be considered*3)
 DCHAIN is improved and their libraries are updated*4)
 A function to read electro-magnetic field maps is developed Group-wised cross section data are acceptable in [frag data] section
Under support of *1) Dr. H. Iwamoto of JAEA, *2) Prof. H. Nikjoo & Dr. T. Liamsuwan,*3) Dr. Y. Sakaki of KEK, and *4) C. Konno of JAEA4

A model for estimating DNA damage
 DNA damage estimation based on track-structure mode and [t-userdefined] Output spatial patterns of interactions, analyze them, and obtain the yields※ Damage type： Single-Strand Break (SSB)・Double-Strand Break (DSB)[Output of interactions with etsmode]
cutoff（etsmin） = 1 eV
100 keV[Estimation of strand-break yields]

analyzing thespatial patternsof ionization andexcitation

Ionization
Excitation

Illustration of damage estimation

This simple model enables to reproduce in vitro experiments and other simulations
See phits/utility/usrtally/DNAdamage & Y. Matsuya et al., J. App. Phys. 126, 124701 (2019)5

Function to Read Stopping Power Table
Outline of the function

Dose (arbitrary unit)

100 MeV proton on water User can provide their own
stopping power tables

0.2

 Stopping power tables
developed by PSTAR andASTAR* are included in the
database folder data/dedx

0.1
Original (ATIMA)
dedxfile (PSTAR)
077.5
Depth in water (cm)

How to use
8

Depth-dose distributions calculated
by ATIMA and stopping power tabledeveloped by PSTAR(close-up view around Bragg Peak)Define dedxfile parameter in[material] section as written below[material]
m1 H 2.0 O 1.0
dedxfile = water_liquid.txt

Stopping power tables calculated by other codes can be used in PHITS* https://www.nist.gov/pml/stopping-power-range-tables-electrons-protons-and-helium-ions

6

Repeated Collisions
 [ Repeated Collisions ] is introduced → Similar to special in [t-yield]
 Repeat only nuclear reaction simulations to improve the statistical errors
 Numbers of iterations can be separately specified for direct andevaporation processes

Example for [t-deposit]
Example for [t-product]
Effective when low-probability but high-impact nuclear reaction
channels such as nuclear fission exist
7New pseudo-random number generator
Xorshift64 was implemented to obtain pseudo-random
numbers used in Monte Carlo calculations
Linear congruential generator• Recurrence relation: (former)
Xn+1=A*Xn mod M• Period length: 246• Serial correlation in n-dimensional
space (Not serious problem)

xorshift64 (new)• Shift-register generator
Xn+1=(I+La)(I+Rb)(I+Lc)Xn• Period length: 264-1• Fast because of bitwise operation

Figures of local coordinate spaces [0<x,y,z<10-5] with the points
defined as (x,y,z)=(r1,r2,r3),(r2,r3,r4),… by using random numbers ri:
linear congruential generator makes multi-planes (left panel).
 Xorshift64 is default (after 3.18). Old method is used by nrandgen=0
 Initial seed is changed by rseed= positive or negative real number Time dependent initial seed is used by setting itimrand=1
8

Proton and Carbon Ion Track Structure Mode
Implementation of KURBUC

30 keV proton trajectories calculated
1 MeV/n Carbon ion trajectory
calculated by TS modeby ATIMA (up) and TS mode (down)
 Activate by setting tsmax parameter Applicable only to proton (E < 300 MeV) and carbon ion (E < 10 MeV/n)
 Source code of KURBUC is not included in the package
Under support of Prof. Hooshang Nikjoo & Dr. Thiansin Liamsuwan

9ANOVA(analysis of variance)
Estimation of systematic uncertainty based on ANOVA
Effects caused by errors of PHITS input information can be estimated=Totaluncertainty+
Statistical error

Systematic uncertainty

1. Make a PHITS input file that avalue with errors is specified byci. (icntl=16 is set)
2. Make an input file for the script,
where information on variation ofci is written.
3. Execution of the script autorun
outputs total uncertainties,
systematic uncertainties, andstatistical errors.

Ex. case that density of water has error→specify the density value by ci in [cell]
100 MeVneutronConcrete + water

Effective doses in concrete material(error bars: total uncertainties)

phits/utility/autorun; S. Hashimoto and T. Sato, J. Nucl. Sci. Technol. 56, 345 (2019) 10

Photon-Induced Muon Pair Production
 Activate the model by setting
igmuppd = 1 in [parameters] Effective for shielding calculation for
high-energy electron accelerators
Secondary photon generates muon pairMuon can penetrate deeply

ElectronMuon fluence behind Fe target
irradiated by 18 GeV electrons

Model verification (angulardistributions of muon flux)Ref.) W. R. Nelson et al., Nucl. Instr. Meth., 120, 413 (1974).

Implemented model can reproduce the experimental data well
Under the support of Dr. Y. Sakaki of KEK

11

Improvements of DCHAIN & its Libraries
Rebranded from “DCHAIN-SP” to “DCHAIN-PHITS”
 A lot of selections in activation cross section and nuclear decay libraries
 Nuclide yield statistical uncertainties are now propagated to results
 Reduction of target nuclides can be considered → (default since ver. 3.20)
JEFF-3.1A(2007)JENDL/AD-2017
JENDL-4.0(2010)

Upgrade of Libraries← Neutron activation XS↓ Nuclear decay data

ENDF/B-VIII.0 (2018)

Various 1990s evaluations

ENDF/B-VII.1 (2011)

JENDL/DDF-2015

JEFF-3.3

ENDF/B-VIII.0 (2016)(2017)FENDL/A-3.0 (2012)JENDL + ENDF + ‘90s

EAF-2010

ENDF + JENDL + ‘90s

BROND-3.1(2016)

CENDL-3.1(2009)TENDL-2017

Under support ofC. Konno of JAEA

Comparison with new & old libraries
 Reaction library controlled with inxslib (+ hnxslib)
 Decay library controlled with idcylib

12Bug Fix & Default Changes in PHITS 3.17
Upgrade patch to 3.17 was released in Nov. 2019

Important changes since ver. 3.10
 Bug in EGS5 mode when it is combined with lattice or tetrahedral
structures is fixed （Only related to versions 3.08 ~ 3.14)
 Bug in the [t-deposit] calculation using EGS5 is fixed (Only related toversions 3.13 ~ 3.16)
 The default cut off energies of pions, muons and ions are decreased
from 1 MeV (or 1 MeV/n) to 1 keV (or 1 keV/n) The maximum number of multi-sources that can be written in aPHITS input file is increased from 200 to 500
 Bug in reading ionization potential in water, ih2o parameter, is fixed Bug that stdcut does not work in MPI version is fixed Bug that tetrahedral geometry cannot be read in MPI version is fixed13

Bug Fix & Default Changes in PHITS 3.20
PHITS 3.20 was released in Apr. 2020

Important changes since ver. 3.17
 Bug of providing particle energy in MeV/n instead of MeV/u with ATIMA isfixed Bug in generating the Maxwellian energy-spectrum source (e-type=3 & 7)
is fixed 2-dimensional geometry drawing function, gshow, has been improved toproperly depict complicated geometry defined by voxel or tetrahedron* The default cut off energy of proton is decreased down to 1 keV*ICRP voxel phantom depicted by gshow using PHITS 3.17 and 3.20

PHITS 3.17

PHITS 3.20
14

Upcoming Futures
We are planning to …

 Improve nuclear reaction model and data library Full set of JENDL-4.0/HE
 Adoption to the latest data format
 Fission & intral-nuclear cascade models
 Implement new functions
 track-structure mode to other ions & targets
 xyz-mesh for [t-dchain] Estimation of systematic uncertainties
 Improve user support functions
 Special editor for making PHITS input file15