P HI T S Setting of various source Part II Multi-Purpose Particle and Heavy Ion Transport code System Title1 May 2016 revised

Goal of this lecture Purpose2 Transport simulation using dump data as sources Simulation of radiation shielding using dump data, which were information on particles from a 60 Co source and were recorded at z=20cm.

sourceB.inp 3Check Input File Basic setup Projectile: Geometry: Tally: Geometry and 1.333MeV photons (from 60 Co) Water cylinder (10cm radius and 20cm thickness) [t-track] fluence distribution [t-cross] photon energy spectrum coming into water track_xz.epscross_eng.eps Water 60 Co

Table of Contents4 Table of contents 1.Source with dump data A)Making dump data file B)Transport simulation using dump data 2.Summary

Source with dump data 5 PHITS can perform two-step calculation using information on particles coming into specified regions. Dump data For example, to study shielding effect changing thickness of lead block. 60 Co Lead Water In the 1 st step, information on photons coming into the lead is recorded. Sources in the 2 nd step. You can perform calculations of the 2 nd step many times changing the thickness of the lead block.

6 1.In the [t-cross], [t-product], or [t-time] tally, set dump parameters. 2.Execute PHITS calculation of the 1 st step. 3.A data file named as ******_dmp.out is made (****** is specified by “file=“). This file contains information on the tallied particles. 4.In the [source] section, set s-type=17 with dump parameters. 5.The old [source] section and old tally, which were used in the 1 st step, should be invalid by “off”. 6.Execute PHITS calculation of the 2nd step. Dump data [ T - C r o s s ] ・ ・ ・ file = ******.out dump = dump parameters (1 st step) [source] section with dump parameters (2 nd step) [ S o u r c e ] s-type = 17 file = ******_dmp.out dump = The number of the data item. (If positive, the data file is made as binary. If negative, the file is made as ASCII data.) sameformat How to use

7Dump data dump = Using dump parameters, you can set the data item and their order to output in the dump data file. You can change this order IDphysical quantitiesIDphysical quantities 1kf: kind of particle11c1: value of counter 1 2x: x-coordinate12c2: value of counter 2 3y: y-coordinate13c3: value of counter 3 4z: z-coordinate14sx: x-component of spin 5u: x-component of velocity15sy: y-component of spin 6v: y-component of velocity16sz: z-component of spin 7w: z-component of velocity17name: collision number 8e: energy18nocas: history number 9wt: weight19nobch: batch number 10time: time20no: cascade ID ID number of dump data

Notes about dump data 8 (1 st step) set the dump region, where particle information is recorded, to be outer void, in order to avoid a double-count of particles passing through the region. (1 st step) set dump ID 18 and 19 (nocas and nobch) in the dump definition to take account of particle correlations in the 1 st step. (1 st step) tally the energy spectrum of the dump data and then confirm whether the data are large enough to be used as source or not. (2 nd step) the calculation using dump data gives results in the local area. (The result of the 1 st step is not included.) Dump data When the dump ID 18 and 19 are recorded, the correlations between particles in the calculation of the 1 st step are taken into account in the statistical processing with “idmpmode=1”*. (If the ID 18 and 19 are not recorded in the dump data, the old statistical process which ignores the correlations is applied.) *From PHITS2.80, this parameter is valid.

9 To record information on particles passing through the water as dump data, set outer void behind the water (positive side of z-axis). Dump region (defined as outer void) Set a cylindrical region (cell number is 102) with 10cm radius and 5cm thickness as outer void behind the water (positive side of z-axis). In the [cell] section, outer void is defined by setting its material number = -1 (density is not needed). Dump data *To check the geometry, set icntl=0 (perform normal transport calculation), because PHITS doesn’t show the outer void when icntl=8. Exercise 1

10Dump data SourceB.inp [ S u r f a c e ] 10 so cz pz pz pz 25. [ C e l l ] #101 #102 track_xz.eps Particle transport is not performed in the outer void. Answer 1 To record information on particles passing through the water as dump data, set outer void behind the water (positive side of z-axis).

11 Record information on photons from the 60 Co source, passing through the water as dump data. Dump region (cell 102) By copying the [t-cross] section, make the 2 nd [t-cross] section. (The 1 st one is used to make dump data, and the 2 nd one is used to check the energy spectrum of the dump data.) Add dump parameters (from 1 to 9, 18, and 19) to the 1 st [t-cross]. In the 1 st [t-cross], change cell numbers so that this tally counts the number of photons moving from cell 101 to 102. Furthermore, set “file= cross_photon.out” and “epsout=0” In the 2 nd [t-cross], add one condition to count the number of photons moving from cell 101 to 102 (set its area to be  10 2 ). Dump data Water (cell 101) Record photons moving from 101 to 102. Exercise 2

12 SourceB.inp The data are not enough to be used as sources, because this result should be continuum spectrum. [ T - C r o s s ] ・ ・ ・ ・ ・ ・ ne = 200 unit = 1 axis = eng file = cross_photon.out output = flux part = photon epsout = 0 dump = [ T - C r o s s ] ・ ・ ・ reg = 2 non r-in r-out area ・ ・ ・ cross_eng.eps (2 nd page) Dump data Answer 2 Record information on photons, come from 60 Co source, passing through the water as dump data.

13 Make large dump data can be used as source. Increase “maxcas” to obtain large data. cross_eng.eps(2 nd page) Result with maxcas=1000 not ehough Dump data Exercise 3 Result with maxcas=10000

14 The result becomes continuum spectrum. This can be used as source. (Note that the relative errors are %) Dump data Make large dump data can be used as source. Answer 3 Result with maxcas= cross_eng.eps(2 nd page)

Table of Contents15 Table of contents 1.Source with dump data A)Making dump data file B)Transport simulation using dump data 2.Summary

16 Perform the transport simulation using dump data. Create the new [source] section with s-type=17. (Set the old [source] section to be invalid by “off”.) Set cell 102 to be void (its material number is 0) Set the [t-cross] section with dump parameters to be invalid by “off”. [ S o u r c e ] s-type = 17 file = cross_photon_dmp.out dump = Both two files, cross_photon_dmp.out and cross_photon.out, are needed. * Dump data *When the dump ID 18 and 19 are included in the dump data, “maxcas” and “maxbch” of the 1 st step written in “cross_photon.out” are used. (“maxcas” and “maxbch” in the input file of the 2nd step are ignored.) Exercise 4 [source] section with dump parameters (2 nd step)

17Dump data [ S o u r c e ] off totfact = 2.0 ・ ・ ・ [ S o u r c e ] s-type = 17 file = cross_photon_dmp.out dump = SourceB.inp [ C e l l ] #101 #102 [ T - C r o s s ] off ・ ・ ・ dump = track_xz.eps Particles included in dump data are generated behind the water. Perform the transport simulation using dump data. Answer 4

18 Put a lead block behind the water. Dump data Isotope ratio of lead 204Pb Pb Pb Pb cell 102 (lead) cell 101 (water) cell 103 (void) 1cm Exercise 5 Change the material of cell 102 to lead with the isotope ratio (see the right table) and the density of 11.34g/cm 3. (Change some parameters in [material] and [cell].) In order to study an effect of the shielding, define a new cell 103 (a cylindrical region with 10cm radius and 1cm thickness). In the 2 nd [t-cross], add one condition to count the number of photons moving from cell 102 to 103 (set its area to be  10 2 ).

19Dump data SourceB.inp [ S u r f a c e ] ・ ・ ・ 13 pz pz pz 26. [ C e l l ] #101 #102 #103 [ M a t e r i a l ] mat[1] 1H 2 16O 1 mat[2] 204Pb Pb Pb Pb [ T - C r o s s ] ・ ・ ・ reg = 3 non r-in r-out area ・ ・ ・ track_xz.eps The particle fluence is reduced in the lead region. Put a lead block behind the water. Answer 5

20Dump data The lead block reduces the strength of and 1.333MeV photons to 1/100. (Investigate the thickness of the lead so that the strength becomes 1/1000.) cross_eng.eps(3 rd page) Energy spectrum of photons coming into the lead region Put a lead block behind the water. Answer 5

Table of Contents21 Table of contents 1.Source with dump data A)Making dump data file B)Transport simulation using dump data 2.Summary

Summary22 We can perform two step simulation using dump data. A correct statistical process using “idmpmode=1” can be applied by recording dump ID 18 and 19. (From PHITS2.80) Notes about idmpmode=1 “totfact” in [source] is ignored in the calculation of the 2 nd step using dump data. ⇒ set “totfact” in the 1 st step (at the time of making dump data) The option “idmpmode=1” is incompatible with multi-source. (Use sumtally option) In the 2 nd step, “istdev<0” (restart calculation) or “dumpall=1” in [parameters] cannot be used. If you use the old statistical process of PHITS, use dump data without the dump ID 18 and 19, or set “idmpmode=0”. The option “dmpmulti” controls the number of re-use of the dump file. (dmpmulti=2.0 is 2 times) Acknowledgement The option “idmpmode=1” and re-used calculation using the option “dmpmulti” were introduced by referring to the presentation “Estimation of uncertainty in multi-step Monte Carlo calculation”(N50) by Dr. Y. Namito et al. at the 2015 annual meeting of AESJ (Hitachi, Japan). Summary

Homework23 Estimate effective dose in the region behind the lead block, when the 134 Cs source is put on the 10cm square centered at x=0, y=0, z=-0.5cm. Lead Water Energies[MeV] and ratio[%] of photons (ratio is per decay) 134 Cs source (use s-type=5) Calculate effective dose here. (Use conversion coefficients incorporated in PHITS. [See H10multiplier.inp of recommendation]) Stop transport of electron and positron by setting emin because the coefficients for photons include contribution of the secondary electron and positron. Homework

24 Note that the conversion coefficient were estimated with a condition of Antero-Posterior geometry (AP) irradiation. 1 st step 2 nd step dmpmulti=1.0 dmpmulti=10.0 Homework (example of answer) Distribution of the effective dose when the thickness of the lead is 5cm.