The DORIAN code for the prediction and analysis of residual dose rates due to accelerator radiation induced activation

The estimation of residual dose rates at accelerator facilities is an important task for operational radiation protection. The DORIAN code, based on the FLUKA Monte Carlo simulation code, computes residual dose rates and allows in-depth analysis of the various contributions. In addition, the geometrical configuration can be changed after the irradiation has finished and the dose rate can be recalculated for any step-wise irradiation profile and any cooling time very quickly. Therefore, the DORIAN code is a powerful tool for the optimization of residual dose rates at accelerator facilities

A method for radiological characterization based on fluence conversion coefficients

Radiological characterization of components in accelerator environments is often required to ensure adequate radiation protection during maintenance, transport and handling as well as for the selection of the proper disposal pathway. The relevant quantities are typical the weighted sums of specific activities with radionuclide-specific weighting coefficients. Traditional methods based on Monte Carlo simulations are radionuclide creation-event based or the particle fluences in the regions of interest are scored and then off-line weighted with radionuclide production cross sections. The presented method bases the radiological characterization on a set of fluence conversion coefficients. For a given irradiation profile and cool-down time, radionuclide production cross-sections, material composition and radionuclide-specific weighting coefficients, a set of particle type and energy dependent fluence conversion coefficients is computed. These fluence conversion coefficients can then be used in a Monte Carlo transport code to perform on-line weighting to directly obtain the desired radiological characterization, either by using built-in multiplier features such as in the PHITS code or by writing a dedicated user routine such as for the FLUKA code. The presented method has been validated against the standard event-based methods directly available in Monte Carlo transport codes

Implementation of ICRP116 Fluence to Effective Dose Conversion Coefficients in a FLUKA user routine

The estimation of the effective dose from the prompt radiation of a high energy and mixed radiation field is an important aspect of radiation protection at accelerator facilities. At present, it is possible to estimate effective dose from external irradiation with the FLUKA Monte Carlo code using conversion coefficients as suggested by ICRP Publication 74 and as calculated by M. Pelliccioni. This Technical Note describes the methodology with which the latest sets of conversion coefficients from the ICRP Publication 116 for neutrons, protons, charged pions, muons, photons, electrons and positrons have been implemented in a FLUKA user routine for converting fluence to effective dose for different external irradiation geometries during radiation transport. The conversion coefficients for several other particles, e.g. kaons and sigmas, are approximated by the conversion coefficients for particles having a similar radiological effect, as it has been done in the past

Estimation of saturation activities for activation experiments in CHARM and CSBF using Fluence Conversion Coefficients

As summer student at CERN, I have been working in the Radiation Protection group for 10 weeks. I worked with the \textsc{Fluka} Monte Carlo simulation code, using Fluence Conversion Coefficients method to perform simulations to estimate the saturation activities for activation experiments in the \textsc{CSBF} and the \textsc{Charm} facility in the East Experimental Area. The provided results will be used to plan a Monte Carlo benchmark in the \textsc{CSBF} during a beam period at the end of August 2017

FLUKAVAL – A validation framework for the FLUKA radiation transport Monte Carlo code

The FLUKA general purpose radiation transport Monte Carlo code being developed and maintained by CERN (https://fluka.cern) has adopted modern software development standards including a formal quality assurance process. This includes the FLUKAVAL testing framework that takes into account the specific needs of testing a Monte Carlo radiation transport simulation code. FLUKAVAL allows to submit, process and validate a large number of test cases for a new FLUKA version and compare the results against previous versions and reference data. It produces a quantitative and qualitative comparison and compiles a summary report over all selected test cases, which is reviewed before the new FLUKA version is released. The overall validation requires only few manual steps and makes use of large computing clusters to run simulations in parallel

Correction factor for the number of incident protons using correlation between SEC1 and PMIEA822 radiation monitor in the CHARM during Run 2

In the CHARM facility, the beam intensity is obtained from the counts in the secondary emission chamber, denoted as SEC1. However, the SEC1 shows the nonlinear counting efficiency when the beam intensity was lower than around 1e11 proton per pulse. The beam intensity could be varied from 1e9 to 5e11 proton per pulse. Due to the nonlinearity of the SEC1 counting efficiency, the conversion to the number of incident protons is not applicable in the low beam intensity region around 1e9 protons per pulse. Thus, an air-filled plastic ionization chamber (PMIEA822 radiation monitor), which is installed in the irradiation room, is used to determine the correction factor that is used for compensating the nonlinear effect of the SEC1 for low-intensity proton beam. The correction factor was determined by checking the ratio of the readings from the PMIEA822 radiation monitor to the SEC1. In this report, the number of incident protons was analytically corrected with the correlation between SEC1 and PMIEA822 radiation monitor. The corrections were applied by multiplying the correction factors with the beam intensity determined by the SEC1 counts

Chapter 3: Design of the East Area facility after renovation

The PS primary proton beam is slowly extracted at 24 GeV/c towards the East Area with the help of the third- order resonance technique over a typical spill length of 350 to 450 ns within 2.4 s cycles. The number of East Area extractions is usually around five to six per overall PS super-cycle of typically 40 s and depends on both users and schedule constraints, respectively. After passing both magnetic septa SMH57 and SMH61 in the PS, the beam enters the F61 transfer line that transports the beam either to the so-called North Targets via the lines F62 and F63 or towards T08, which serves the irradiation facilities IRRAD and CHARM. During operation of primary ion beams, only these irradiation facilities can be operated. The principle of extraction by third-order resonance and the corresponding optical elements inside the PS, such as the magnetic septa, will be kept unchanged for the new East Area operation. Thus, only a replacement of the existing magnets by laminated versions with slight optimization of the optics was chosen as the renovation baseline for F61 with changes in the layout mostly due to integration constraints and considerations for improved radiation protection. In particular, all the main horizontal bends have been replaced by reliable and robust MCB magnets, which are available with sufficient spares and can be operated in pulsed mode. The splitting option, although more efficient for operation, was dropped in 2005 for technical reasons that were hard to overcome in a reliable manner. For further details on the recent operational history of F61 and the original ideas of the renovated East Area beams

FLUKA-Geant4 comparison for the muon flux experiment in the H4 beamline

The FLUKA - Geant4 comparison for the the muon flux experiment is reported. The experiment was performed in 2018 on the H4 400 GeV/c proton beamline to measure the muon flux emanating from a SHiP replica target. Good agreement between the two Monte Carlo simulations was found, in the low momentum and low transverse momentum range the agreement is at the level of 20%, while in the tails the disagreement is at maximum of a factor ∼3. These results suggest to reduce the safety factor for future BDF/SHiP facility radiation calculations from 5 (old recommended value) to 3 (new value)