FLUKA is a general purpose Monte Carlo code able to describe the transport and interaction of any particle and nucleus type in complex geometries over an energy range extending from thermal neutrons ...to ultrarelativistic hadron collisions. It has many different applications in accelerator design, detector studies, dosimetry, radiation protection, medical physics, and space research. In 2019, CERN and INFN, as FLUKA copyright holders, together decided to end their formal collaboration framework, allowing them henceforth to pursue different pathways aimed at meeting the evolving requirements of the FLUKA user community, and at ensuring the long term sustainability of the code. To this end, CERN set up the FLUKA.CERN Collaboration
1
. This paper illustrates the physics processes that have been newly released or are currently implemented in the code distributed by the FLUKA.CERN Collaboration
2
under new licensing conditions that are meant to further facilitate access to the code, as well as intercomparisons. The description of coherent effects experienced by high energy hadron beams in crystal devices, relevant to promising beam manipulation techniques, and the charged particle tracking in vacuum regions subject to an electric field, overcoming a former lack, have already been made available to the users. Other features, namely the different kinds of low energy deuteron interactions as well as the synchrotron radiation emission in the course of charged particle transport in vacuum regions subject to magnetic fields, are currently undergoing systematic testing and benchmarking prior to release. FLUKA is widely used to evaluate radiobiological effects, with the powerful support of the Flair graphical interface, whose new generation (Available at
http://flair.cern
) offers now additional capabilities, e.g., advanced 3D visualization with photorealistic rendering and support for industry-standard volume visualization of medical phantoms. FLUKA has also been playing an extensive role in the characterization of radiation environments in which electronics operate. In parallel, it has been used to evaluate the response of electronics to a variety of conditions not included in radiation testing guidelines and standards for space and accelerators, and not accessible through conventional ground level testing. Instructive results have been obtained from Single Event Effects (SEE) simulations and benchmarks, when possible, for various radiation types and energies. The code has reached a high level of maturity, from which the FLUKA.CERN Collaboration is planning a substantial evolution of its present architecture. Moving towards a modern programming language allows to overcome fundamental constraints that limited development options. Our long term goal, in addition to improving and extending its physics performances with even more rigorous scientific oversight, is to modernize its structure to integrate independent contributions more easily and to formalize quality assurance through state-of-the-art software deployment techniques. This includes a continuous integration pipeline to automatically validate the codebase as well as automatic processing and analysis of a tailored physics-case test suite. With regard to the aforementioned objectives, several paths are currently envisaged, like finding synergies with Geant4, both at the core structure and interface level, this way offering the user the possibility to run with the same input different Monte Carlo codes and crosscheck the results.
The Antiproton Decelerator at the CERN Proton Synchrotron complex provides antiprotons at a kinetic energy of 5.3 Mev to several experiments. The stray radiation from antiproton annihilations is the ...most important radiation field for radiation protection in the Antiproton Decelerator experimental areas.
In August 2018, aluminium, bismuth and indium samples have been exposed to the annihilation stray radiation. The resulting induced radioactivity has been measured and compared to the predictions of FLUKA Monte Carlo simulations.
The observed agreement between the FLUKA predictions and the measured values is better than a factor of 2.
Background
Laser closure is a novel sphincter-saving technique for the treatment of anal fistula. The aim of this study was to report middle term results of laser treatment without closure of the ...internal orifice and to identify prognostic factors to improve selection criteria and maximize healing.
Methods
A retrospective observational study was conducted on patients treated with laser for transphinteric anal fistula. A diode laser emitting laser energy of 12W at a wavelength of 1470 nm was used. The relationship between fistula healing and age, sex, previous fistula surgery, location of fistula, and length of fistula tract was investigated. A successful outcome was defined by the complete healing of the surgical wound and external opening for at least 6 months.
Results
Thirty patients (16 males, median age 52 years, range 26–72 years) underwent laser fistula closure between January 2015 and December 2016. Cure was achieved in 10 patients (33.3%). The mean follow-up was 11.30 months (range 6–24 months). Patients with persistent or recurrent fistula were offered repeat surgery. Eventually 4 underwent laser treatment once more. Two patients were cured leading to an overall healing rate of 40% (12 out of 30). Only 4 minor complications occurred (13.3%). No worsening of anal continence was registered. Only fistula length had a statistically significant correlation with successful treatment. Fistula tracts shorter than 30 mm were associated with a primary healing rate of 58.3% while tracts longer than 30 mm were cured in only 16.6% of cases (
p
< 0.02).
Conclusions
Laser closure is a safe and effective treatment for transphinteric anal fistula. The fistula length is the only significant prognostic factor when closing anal fistulas exclusively with laser: shorter fistulas have a better outcome.
Rectal prolapse, rectal procidentia, “complete” prolapse or “third-degree” prolapse is the full-thickness prolapse of the rectal wall through the anal canal and has a significant impact on quality of ...life. The incidence of rectal prolapse has been estimated to be approximately 2.5 per 100,000 inhabitants with a clear predominance among elderly women. The aim of this consensus statement was to provide evidence-based data to allow an individualized and appropriate management and treatment of complete rectal prolapse. The strategy used to search for evidence was based on application of electronic sources such as MEDLINE, PubMed, Cochrane Review Library, CINAHL and EMBASE. The recommendations were defined and graded based on the current levels of evidence and in accordance with the criteria adopted by the American College of Gastroenterology’s Chronic Constipation Task Force. Five evidence levels were defined. The recommendations were graded A, B, and C.
During the operational life of a PET cyclotron, the concrete walls of the vault are activated by secondary neutrons. For the dismantling of such accelerator facilities, a considerable amount of low ...level solid radioactive waste has to be characterized and disposed. To decrease future dismantling costs and complexity, the amount of radioactive waste has to been prospectively evaluated in the design phase, then confirmed at the time of planning decommissioning. In this work, the Monte Carlo code Fluka was used for the assessment of the activation of the bunkers of two different facilities: the 16.5 MeV GE PETtrace at S. Orsola-Malpighi Hospital in Bologna and the 18 MeV IBA Cyclone 18/18 HC at the Bern University Hospital (Inselspital). The simulations were validated by means of experimental measurements performed in our previous works: non-destructive, in field measurements using a portable CZT detector were performed in Bologna; while core drilling samples were extracted from the bunker and measured in laboratory with an HPGe detector in Bern. The activity of the most important radionuclides in the concrete walls of the bunker, namely Eu-152, Mn-54, Co-60, Sc-46, Zn-65 and Cs-134 resulted within the range of 0.01 – 2 Bq/g. The consistency between Monte Carlo results and experimental measurements was within a factor 2 - 3 for most radionuclides, except for Eu-152, Sc-46, Zn-65. The activity concentrations estimated at each position considered exceeds the clearance levels of the new Directive 2013/59/Euratom.
The results of this work demonstrate that Monte Carlo simulations based on FLUKA are adequate to assess the residual activation levels, a fundamental information to foresee, plan and optimize the decommissioning of a cyclotron based PET centers.
•The activation in PET cyclotron bunkers was assessed via Monte Carlo simulations.•The Monte Carlo code used in this work was Fluka.•The model of a GE PETtrace and a IBA CYCLONE with their bunkers was implemented.•Monte Carlo simulation results were compared with experimental measurements.•The main long lived radionuclides produced were assessed.
The Monte Carlo toolkit Geant4 is used to simulate the production of a number of positron emitting radionuclides: 13N, 18F, 44Sc, 52Mn, 55Co 61Cu, 68Ga, 86Y, 89Zr and 94Tc, which have been produced ...using a 13MeV medical cyclotron. The results are compared to previous simulations with the Monte Carlo code FLUKA and experimental measurements. The comparison shows variable degrees of agreement for different isotopes. The mean absolute deviation of Monte Carlo results from experiments was 1.4±1.6 for FLUKA and 0.7±0.5 for Geant4 using TENDL cross sections with QGSP-BIC-AllHP physics. Both agree well within the large error, which is due to the uncertainties present in both experimentally determined and theoretical reaction cross sections. Overall, Geant4 has been confirmed as a tool to simulate radionuclide production at low proton energy.
•Geant4 useful tool for simulation of PET isotope production.•Geant4 and FLUKA results consistent.•Geant4 using TENDL cross sections with QGSP-AllHP model best compromise.•Model QGSP-BERT-HP and QGSP-BIC-HP do not produce all isotopes.
A new shape memory alloy (SMA)-based coupling system for ultra-high vacuum (UHV) applications in particle in accelerators is currently under investigation at the European organization for nuclear ...research (CERN). The use of such technology in some restricted-access radioactive areas within CERN accelerators could result in noticeable advantages, especially during maintenance operations. Bolt-free SMA couplers, can be activated remotely by temperature changes, resulting in significant reduction of the radiation doses collected by the technical personnel. The functional performance of SMA-based prototype systems, in terms of leak tightness, thermal mounting/dismounting and thermal outgassing properties, has been already verified. Radiation-induced microstructural damages usually cause losses in the mechanical properties, such as embrittlement in conventional engineering metals. The particle radiation effects on the functional characteristics of SMAs, in terms of microstructural transition mechanisms, represent a key issue for their application in critical accelerators areas. To this aim, specific research activities are being carried out at CERN for capturing the evolution of SMA mechanical and functional properties during and/or after particle irradiation. In this preliminary study, a few selected SMA-based prototype UHV chambers, have been exposed to a high-energy mixed particle field (up to ∼140 kGy of absorbed dose) at the CERN high-energy accelerator mixed-field (CHARM) facility. The results, in terms of post-irradiation measurements, have revealed that leak tightness and thermal dismounting are unaffected by irradiation.
The CERN High-Energy AcceleRator Mixed field (CHARM) facility provides a secondary particle field, produced by irradiating a thick target with 24 GeV/c protons supplied by the proton synchrotron. In ...order to investigate the thermalization process of secondary neutrons in the CHARM facility, we measured the thermal neutrons using the gold foil activation method. Bare and Cd-covered gold foils were placed at 35 positions to deduce the thermal neutron distribution in the CHARM facility. The 197Au(n, γ)198Au reaction rates and thermal neutron fluxes measured in this study were compared with the Monte Carlo simulation codes, PHITS, FLUKA, and MARS. The comparison between the measured and simulated values gives an agreement better than a factor of two. Besides, we investigated the simple empirical formula to estimate a thermal neutron flux in the accelerator room, ϕth = CQ/S, where Q is the neutron source intensity and S is the total surface area of a room. The coefficient C estimated in this study did not significantly depend on the incident proton beam energy.
The CERN High Energy AcceleRator Mixed field facility (CHARM) is located in the CERN Proton Synchrotron (PS) East Experimental Area. The facility receives a pulsed proton beam from the CERN PS with a ...beam momentum of 24 GeV/c with 5⋅1011 protons per pulse with a pulse length of 350 ms and with a maximum average beam intensity of 6.7⋅1010p/s that then impacts on the CHARM target.
The shielding of the CHARM facility also includes the CERN Shielding Benchmark Facility (CSBF) situated laterally above the target. This facility consists of 80 cm of cast iron and 360 cm of concrete with barite concrete in some places.
Activation samples of bismuth and aluminium were placed in the CSBF and in the CHARM access corridor in July 2015. Monte Carlo simulations with the FLUKA code have been performed to estimate the specific production yields for these samples. The results estimated by FLUKA Monte Carlo simulations are compared to activation measurements of these samples.
The comparison between FLUKA simulations and the measured values from γ-spectrometry gives an agreement better than a factor of 2.
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