MARS15 Developments Related to Beam- Induced Effects in Targets N. Mokhov, V. Pronskikh, I Rakhno, S. Striganov and I. Tropin (Fermilab) 6 th High-Power Targetry Workshop Merton college, Oxford, UK April 11-15, 2016

Outline Implementation of a TENDL-based event generator at MeV for improved neutronics, radioactivation, DPA, as well as H and He gas production that accelerates radiation damage at high energies Improvements and extensions of the DPA model RaDIATE examples FoM for Target Materials Other developments and applications 04/12/16N. Mokhov | MARS15 developments | HPTW20162

Neutron Production at T p < MeV MeV Problem 04/12/16N. Mokhov | MARS15 developments | HPTW20163 Nowadays, everything is fine in FLUKA, MARS15 and (more and more) in Geant4 for nuclear interactions up to a multi-TeV region, except for the outstanding problem in intranuclear cascade models for projectile protons at energies below MeV. Specifically with CEM and LAQGSM used in MARS15

TENDL at 1 to 120 MeV 04/12/16N. Mokhov | MARS15 developments | HPTW20164 Cascade-evaporation Monte Carlo event generators used in all the modern particle interaction/transport codes (CEM & LAQGSM in MARS15) fail to properly describe particle production at proton energies < MeV We have recently switched in MARS15 to TENDL (TALYS-based evaluated nuclear data library) below 120 MeV TENDL is maintained by the Nuclear Research and Consultancy Group (NRG) from Petten, the Netherlands. The development team consists of 16 people from NRG and other universities/laboratories The library contains data for direct use in both basic physics and applications, and it is updated annually starting from 2008 The evaluations were performed for practically entire periodic table except for H and He as targets, for ~2400 isotopes, at projectile (p, , d, t, 3 He and 4 He) kinetic energies from 1 MeV up to 200 MeV Implemented in MARS15 (2016)

Comparison to Experimental Data 04/12/16N. Mokhov | MARS15 developments | HPTW20165 TENDL Solid lines: TENDL

6 Atomic displacement cross section N d – number of stable defects produced, E d –displacement threshold, dσ/dT r - recoil fragment energy (T r ) distribution Non-ionizing energy loss (NIEL) N – number of atoms per unit volume T d - damage energy=total energy lost in non-ionizing process (atomic motion) 04/12/16N. Mokhov | MARS15 developments | HPTW20166 Atomic Displacement Cross-Section and NIEL

M.J. Norgett, M.T. Robinson, I.M. Torrens Nucl. Eng. Des 33, 50 (1975) T r, Z r, A r - recoil fragment energy=primary knock-on (PKA) energy, charge and atomic mass Z t, A t - charge and atomic mass of irradiated material Nuclear physics (T r, T d ) + solid state physics (N d ) NRT-DPA is successfully applied to correlate data from many studies involving direct comparison from different irradiation environments 04/12/16N. Mokhov | MARS15 developments | HPTW20167 NRT “Standard” Model to Calculate a Number of Frenkel Pairs and Damage Energy

Corrections to NRT to Account for Atom Recombination in Elastic Cascading in MARS15 (2016) 04/12/16N. Mokhov | MARS15 developments | HPTW Stoller: Database based on MD simulations. Its parametrization, efficiency function ξ(T), is used for several years in MARS15 (=1 if >1 in 2016 version) and FLUKA 2. Nordlund: Recently modified NRT with efficiency function )

DPA Model in MARS15 (2016) 04/12/16N. Mokhov | MARS15 developments | HPTW20169 Energy of recoil fragments and new charge particles in (elastic and inelastic) nuclear interactions is used to calculate atomic displacement cross sections using NRT model – with and w/o damage efficiency – for a number of stable defects Atomic screening parameters are calculated using the Hartree-Fock form-factors and recently suggested corrections to the Born approximation NJOY99+ENDF-VII database for 393 nuclides is used for neutrons from eV to 150 MeV In the same run/output, atomic displacement x-sections and resulting DPA in regions of interest are calculated in three ways: pure NRT and those for surviving defects with Nordlund and Stoller efficiency functions ξ(T)

Jung et al, Greene et al and Iwamoto measured electrical resistivity change due to protons, electrons, light ions, fast and low-energy neutrons at low temperatures and low doses. It is connected to displacement cross section σ d ρ F is a resistivity per unit concentration of Frenkel defects. This constant cannot be accurately calculated and is determined from measurements. Jung and Greene groups choose different ρ F (μΩm/u.c.) for the same material Konobeev, Broeders and Fisher (IOTA) note that Greene’s choice for W seems questionable taking into account later analysis Note: Recent Kyoto data at KUR and instrumented superconducting coils in Mu2e JungGreeneIwamoto Cu2.5 ± ± 1 W27 ± /12/16N. Mokhov | MARS15 developments | HPTW Experimental Data Relevant to DPA Analysis

Comparing MARS15 with IOTA and Experimental Data 04/12/16N. Mokhov | MARS15 developments | HPTW Notes: 1.There are some issues with TENDL based recoils in MARS for tungsten at 25 < E p < 60 MeV 2.At E p > 0.5 GeV, IOTA BCA-MD defect production efficiency is a factor of higher than Stoller and Nortlund ξ(T) at T d = keV Al Cu W

RaDIATE Example with MARS15 04/12/16N. Mokhov | MARS15 developments | HPTW MeV proton beam (Gaussian  x =  y = 2 cm) on 1-mm thick and 6-cm in radius Be and W discs 30-kW beam: 1 mA, 6.24×10 15 p/s, 1.97×10 23 p/yr

DPA/yr in Be and W with 3 DPA Models in MARS15 04/12/16N. Mokhov | MARS15 developments | HPTW201613

Light Nuclide Production in Be and W at 0 < r < cm 04/12/16N. Mokhov | MARS15 developments | HPTW Elemen t ZProduction H12.309E-04 H21.818E-04 H32.136E-05 He32.229E-05 He43.160E-04 He61.623E-09 Li66.268E-05 Li72.615E-05 Li84.696E-06 Li94.685E-09 Be72.387E-05 Be82.583E-06 Be92.017E-05 Be E-07 Be E-09 B82.329E-06 B91.476E-05 B E-07 B E-08 B E-09 C E-09 C E-08 ElementZProduction H11.202E-03 H25.821E-06 H37.623E-07 He31.687E-08 He44.268E-06 Be W Hydrogen and helium production can lead to significant changes in material properties such as embrittlement an swelling.

H 1 -Production/DPA in Be and W with 3 DPA Models in MARS15 04/12/16N. Mokhov | MARS15 developments | HPTW201615

He 4 -Production/DPA in Be and W with 3 DPA Models in MARS15 04/12/16N. Mokhov | MARS15 developments | HPTW201616

Figure of Merit for Target Materials 04/12/16N. Mokhov | MARS15 developments | HPTW201617

Other MARS15 Recent Developments 04/12/16N. Mokhov | MARS15 developments | HPTW New module for air activation 1-MeV equivalent neutron fluence for radiation damage to electronics Two new modules for residual dose calculations in enclosures: Decay Generator and CORD (Calculator Of Residual Dose), both are in beta- tests Several corrections and refinements to the nuclide library for DeTra used in MARS15 nuclide inventory and activity analysis Further improvements to the ROOT and hybrid geometry module; enhanced MAD-MARS15 coupling; successful instances of using CAD input in STEP format

New Module for Air Activation 04/12/16N. Mokhov | MARS15 developments | HPTW Default MARS15 generation of radiation-induced nuclides in air is CPU- time consuming and has some simplifications for low-energy neutron interactions To improve the code reliability and predictive power, a new module has been created and implemented It is based on convolution of MARS15-calculated energy spectra in the air regions of interest and x-sections for radionuclide production from C, N, O and Ar The x-section library was created at CERN by Mika Huhtinen et al for hadron energies from a few TeV down to thermal neutron energy The new module in MARS15 is fast and easy to use Results calculated with the new module were benchmarked against recent measurements at NuMI target station

Examples of HE N 7 Be and LE X-sections 04/12/16N. Mokhov | MARS15 developments | HPTW MeV

Air Activation at NuMI Neutrino Production Facility 04/12/16N. Mokhov | MARS15 developments | HPTW201621

Absorbed Dose and 1-MeV Neutron Equivalent in Mu2e Tracker and Calorimeter Electronics 04/12/16N. Mokhov | MARS15 developments | HPTW Z (mm)

Muon Fluxes in an Accident Upstream LBNF Target Station and Pion/Kaon Fluxes in Optimized Target/Horn 04/12/16N. Mokhov | MARS15 developments | HPTW201623

Power Density Contributors in LBNF Target 04/12/16N. Mokhov | MARS15 developments | HPTW201624

Delivering Beam to a Generic Target: Tracking Model Update Concept of steppers is introduced in MARS15/ROOT TGEO library. A stepper is attributed to a volume. It defines rules how to make a step requested by MARS under a possible effect of magnetic field, boundary crossing algorithm and actions performed when boundary is crossed. Generic stepper is a C++ class derived from ROOT classes. A set of steppers are implemented according to developed interface: 1) Linear stepper. 2) Helix stepper – default stepper to make a step in magnetic field. 3) Special stepper to transport primary beam particles inside the admittance: 8 th order Runge-Kutta algorithm with error estimation and adaptive step size. Stepper has interface with MAD-X, takes into account thin multipoles when boundary is crossed. Excellent agreement with PTC in multiturn tracking in Recycler collimation system design and ESS beam loss and radiation studies. Accurate modeling of acceleration in RF cavities. 04/12/16N. Mokhov | MARS15 developments | HPTW201625

ESS 600-MeV Linac in MARS15 04/12/16N. Mokhov | MARS15 developments | HPTW In perfect agreement with industry standard ASTRA

MARS15 Modeling of Beam Loss and Radiation Fields in ESS 04/12/16N. Mokhov | MARS15 developments | HPTW201627