Inter-comparison of Medium-Energy Neutron Attenuation in Iron and Concrete (8) H. Hirayama and Attenuation Length Sub-Working Group in Japan

From Inter-comparison at SATIF-9 Study the reason for the large difference in the attenuation length and dose between codes. It is desired to receive improved results from other groups. Study the reason of the different tendency of C/E values between codes. It is desired that other groups attend this inter comparisons.

Problems for an Inter-comparison (8) Problems are same with an inter-comparison (7) Neutron dose, spectrum inside 6m iron or 12m concrete plane for parallel beam of mono-energy neutrons (0.04-100GeV) and Secondary neutrons produced by protons (0.2- 24GeV) Comparison with the experimental results of AGS shielding experiments As the new item to be sent by participants, “ particles treated to obtain the results ” is added.

Summary of contributors for Neutron attenuation calculation Name of participants Name of Particles treated and organization computer code T. Koi and D. Wright Geant4 v9.3 All particles (SLAC National (2009 Dec. (Including recoil Accelerator Laboratory) released) nucleus) neutron, proton, Y. Uwamino (Riken) HETC-3STEP N. Matsuda (JAEA) and PHITS 2.24 all established K. Niita (RIST) hadoronic states S. Roesler (CERN) FLUKA 2008.3c. All hadrons which FLUKA can transport N.V. Mokhov and MARS15(2010) All elementary particles I.L. Rakhno (Fermilab) and heavy ions

400 ANISN(SATIF-6) 350 M ARS(SATIF-8) FLU KA(SATIF-10) -2 ) HE TC-3STEP(S ATIF-6) Attenuation Length (g cm 300 RO Z-6.6(SATIF-8) PH ITS(3m ,SATIF-10) PH ITS w ithout 0 (3m , SATIF-10) 250 GE AN T-4(SATIF-10) Geant-321(SATIF-8) M CN PX (SATIF-8) 200 150 100 50 0 4 5 10 100 1000 10 10 Source N eutron Energy (M eV) Fig. 1 Com parison of the neutron attem uation length of iron.

D ose Eqivalent rate (Sv per n/cm 2 ) -10 10 -12 10 -14 10 RO Z-6.6(SATIF-8) -16 10 FLUKA(SATIF-10) G EANT-4(SATIF-10) G EANT-321(SATIF-8) -18 MARS(SATIF-8) 10 PH ITS(SATIF-10) PH ITS(without 0 )(SA TIF-10) -20 10 0 100 200 300 400 500 600 Depthin Iron (cm ) Fig. 2 Dose distribution inside iron for 10 G eV protons.

1000 Include R OZ result MC results only MC results without PHIT S with Lab M ax./Min. dose ratio at 4m 100 10 1 4 5 10 100 1000 10 10 Source neutron energy (MeV) Fig. 4 Neutron dose difference at 4m inside iron betw een ROZ 6.6, FLUKA, M ARS, G EAN T4 and PHITS.

Iron for mono energy neutrons General tendency of the attenuation length is similar for all results except PHITS with 0 particle. Differences of dose itself are large. Difference between Monte Carlo results except PHITS with transport 0 particle is about 10. The effects of 0 particle in PHITS The effects can be seen from 3 GeV and maximum at 10 GeV and decrees at 50 and 100 GeV. 0 portion within produced particles except neutrons and protons emitted from 1cm diameter and 1cm iron and concrete by high energy neutrons becomes maximum at 20 GeV and decrease with increase of neutron energy.

-9 10 -11 10 Sv per n/cm 2 -13 10 3G eV 3 G eV without -15 0 10 5 G eV 5 G eV without 0 -17 10 G eV 10 10 G eV without 0 50 G eV -19 50 G eV without 0 10 100 G eV 100 G eV without -21 0 10 0 100 200 300 400 500 600 Depth in iron (cm ) Fig. 5 Dose distribution inside iron by PHITS.

0.03 0 /total (except neutron and proton) 0.025 0.02 0.015 0.01 Iron Concrete 0.005 0 4 5 10 10 Neutron Energy (MeV) Fig.6 0 portion w ithin produced particles except neutrons and protons from 1cm diam eter and 1cm length of iron or concrete.

0 contribution to neutron attenuation length Matsuda and Niita estimate the effect of 0 particle to the neutron attenuation length as follows: The 0 particle is one of the stable baryon, which life time is 2.6x10 10 sec and decayed to nucleon and pion. If the 0 particle is decayed very quickly after its production, as shown in Fig, 5, the additional contribution of 0 is disappeared. Therefore the additional contribution of the 0 particle is realized by the collisions of Lambda on material nucleus. The mass of the 0 particles is heavier than that of nucleon. Thus much larger energy can be transported by the Lambda particles. This is a reason, we suppose, that the attenuation through the Lambda particle is much flatter than that of not through the Lambda particle. General tendency of the attenuation length is similar for all results except PHITS with 0 particle. It is desired to check the contribution of 0 particle to the neutron attenuation by other codes and also to compare various particles production rates from small target..

200 -2 ) 150 A ttenuation Length (g cm 100 AN IS N(S ATIF-6) FLU KA(SATIF-10) HE TC-3STEP(S ATIF-8) RO Z-6.6(SATIF-8) 50 PH ITS(R=3m )(SATIF-8) GE AN T-4(S ATIF-10) GE AN T-321(SATIF-8) M CN PX (SATIF-8) M ARS(SATIF-8) 0 4 5 10 100 1000 10 10 Source Neutron Energy (M eV) Fig. 7 Com parison of the neutron attenuation length of concrete.

1000 Include ROZ result MC results only M ax./M in. dose ratio at 8m 100 10 1 0.1 1 10 100 Source neutron energy (GeV) Fig. 10 Neutron dose difference at 8m inside concrete betw een ROZ 6.6, FLUKA, M ARS, GEANT4 and PHITS.

Concrete for mono energy neutron General Tendencies are same with at SATIF-9. The differences between the attenuation lengths between each code are relatively small at low-energy region and increase with the increase of neutron energy. The attenuation length have the tendency to increase slightly with increase of neutron energy for 12 m slab. The dose differences at 8m are about 10 or less between Monte Carlo.

Secondary -1 (a) (b) 10 Hg-Target neutrons Inner Reflector -2 produced by 10 -1 protons - 2 M eV Moderator -3 10 Inner Outer Reflector (0.2-24GeV) Outer Z Reflector Z X Reflector X -4 Y=0 plane Y=15 plane 10 Neutrons cm (d) (c) -5 10 24GeV p: 90-105 deg. Inner Reflector 3 G eV p: 0-15 deg. -6 10 3 G eV p: 45-60 deg. Inner Moderator Reflector 3 G eV p: 90-105 deg. -7 10 Outer Outer Z 3 G eV p: 135-150 deg. Z X X Reflector Reflector Y=-15 plane Y=25 plane -8 10 4 (e) Inner 10 100 1000 10 Reflector Neutron Energy (MeV) Moderator Hg-Target H g Target M odel Secondary Neutron Spectrum from a H g Target Bom barded by 3 G eV Protons (by M CNPX) Y Outer X Reflector Z=0 plane and 24 G eV P rotons (by N M TC /JAM ).

160 Attenuation Length (g cm - 2 ) 120 G EANT-4(SAT IF-10) 80 AN ISN(S AT IF5) MARS(SATIF-8) PH ITS(R=3m )(SATIF-8) HE TC -3STEP (SATIF-6) RO Z-6.6(SATIF-8) 40 FLU KA(SATIF-10) G EANT-321(SATIF-8) IS IS Exp. LANSCE Exp. 0 4 100 1000 10 Proton Energy (MeV) Fig. 13 Com parison of the neutron attenuation length of iron for secondary neutrons em iited to 90 degrees from Fe and Hg (24GeV) targer w ith protons.

Comparison with Fe Target General Tendencies are same with at SATIF-9. All results show similar tendency to reach an almost constant value above 1 GeV protons.

Comparison with Experimental results at AGS

209 Bi(n,4n) 206 Bi 2.83GeV, Steel 2 MC NPX(SATIF-9) PHITS(SATIF-9) Geant4(SATIF-10) FLUKA(SATIF-10) 1.5 MARS(SAT IF-10) Calc./ Expt. Range of 1 Experim ental E rror 0.5 0 0 50 100 150 200 250 300 Steel Thickness (cm )

209 Bi(n,6n) 204 Bi 2.83GeV, Steel 2 MCN PX(SATIF -9) PHITS(SAT IF-9) Geant4(SATIF-10) FLUKA(SATIF-10) 1.5 MAR S(SATIF-10) Calc./ Expt. Range of 1 Experim ental Error 0.5 0 0 50 100 150 200 250 300 Steel Thickness (cm )

209 Bi(n,4n) 206 Bi 24GeV, Steel 2 M CNPX(SATIF-9) PHITS(SATIF-9) G eant4(SATIF-10) FLUKA(SATIF-10) 1.5 M ARS(SATIF-10) Calc./ Expt. Range of 1 Experim ental Error 0.5 0 0 50 100 150 200 250 300 Steel Thickness (cm )

209 Bi(n,6n) 204 Bi 24 GeV, Steel 2 MC NPX(SATIF-9) PHITS(SATIF-9) Geant4(SAT IF-10) FLUKA(SATIF-10) 1.5 MARS(SATIF-10) Calc./ Expt. Range of 1 Experim ental Error 0.5 0 0 50 100 150 200 250 300 Steel Thickness (cm )

Steel shield The calculated results are smaller than the measured ones in general. The calculated results for 2.83 GeV protons are agree each other. The C/E value differences for 24 GeV protons are larger than those for 2.83 GeV.

209 Bi(n,4n) 206 Bi 2.83 GeV, Concrete 2 M CNPX(SATIF-9) PHIT S(SATIF-9) G eant4(SATIF-10) FLUKA(SATIF -10) 1.5 M ARS(SATIF-10) Range of Calc./ Expt. Experim ental E rror 1 0.5 0 0 50 100 150 200 250 300 350 400 Concrete Thickness (cm )

209 Bi(n,6n) 204 Bi 2.83 G eV, Concrete 2 M CN PX(SATIF -9) PHITS(SAT IF-9) G eant4(SATIF-10) F LUKA(SATIF-10) 1.5 M AR S(SATIF-10) Range of Calc./ Expt. Experim ental Error 1 0.5 0 0 50 100 150 200 250 300 350 400 Concrete Thickness (cm )

209 Bi(n,4n) 206 Bi 24 G eV, Concrete 2 MC NPX(SATIF -9) PHITS(SATIF-9) Geant4(SATIF-10) FLUKA(SATIF-10) MAR S(SAT IF-10) 1.5 Range of Experim ental Error Calc./ Expt. 1 0.5 0 0 50 100 150 200 250 300 350 400 Concrete Thickness (cm )

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