49 research outputs found
A method for radiological characterization based on fluence conversion coefficients
No full textRadiological 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
CERN Summer Student Programme Report by Misael CALOZ
No full textThe aim of this report is to give an overview of my work during the summer student programme at CERN. My project was a work of 8 weeks (16/06 to 8/08 2014) in the Radiation Protection group of the Occupational Health & Safety and Environmental Protection Unit and was supervised by M. Robert Froeschl
Radiological characterization of TFA metallic tubes from CERN accelerator complex
No full textDissertação de mestrado em Engenharia Física, apresentada ao Departamento de Física da Universidade de CoimbraThe scope of this thesis consists in the radiological characterization of chilled water
pipes used for air-conditioning and exposed to ionizing radiation in the PS accelerator,
one of the CERN accelerators, for more than 40 years. Due to corrosion problems, the
1200 m of steel pipeline were removed from the PS tunnel during the long shutdowns
between the years 2000 to 2004. The radiological characterization, that included the
use of FLUKA Monte Carlo simulations and the JEREMY code, began in mid-2011 and
revealed a radionuclide inventory with the presence of 55Fe as dominant radionuclide
and 60Co as dominant g emitter. Due to operational reasons, only 5.5% of the pipeline
were characterized for validation. In the course of this work it was found that the
contribution of both aforementioned radionuclides corresponds to more than 90% of
the total computed IRAS factor (Indice Radiologique d’Acceptation en Stokage). Two
different methods were used for the characterization of the PS pipes, yielding two different
values of IRAS factor, very close to each other and both of them fulfilling the
radiological ANDRA acceptance criteria. Therefore, and as expected, the PS pipes will
be most probably eliminated, as soon as operationally possible, as radioactive waste
towards the French TFA (Très Faiblement Actif) final repository in the Aube district.O âmbito da presente tese assenta na caracterização radiológica de tubos de água
gelada usados no arrefecimento do ar e expostos a radiação ionizante no acelerador
PS, um dos aceleradores do CERN, durante mais de 40 anos. Devido a problemas
de corrosão, os 1200 m de conduta de aço foram removidos do túnel do PS durante
os períodos de paragem longos realizados entre os anos 2000 e 2004. A caracterização
radiológica, que incluiu o uso de simulações de Monte Carlo FLUKA e o código
JEREMY, foi iniciada em meados de 2011 e revelou a presença de 55Fe como o radionuclídeo
dominante e 60Co como o emissor g dominante. Devido a razões operacionais,
apenas 5,5% da tubagem foi caracterizada para validação. No decorrer deste trabalho
verificou-se que a contribuição de ambos os radionuclídeos acima mencionados corresponde
a mais de 90% do valor total calculado do factor IRAS (Indice Radiologique
d’Acceptation en Stokage). Dois métodos distintos foram usados na caracterização
dos tubos do PS, resultando em dois valores diferentes do factor IRAS, muito próximos
um do outro e ambos resultando no cumprimento dos critérios de aceitação da
ANDRA. Por conseguinte, e como esperado, os tubos do PS serão muito provavelmente
eliminados, tão depressa quão operacionalmente possível, como lixo radioactivo para
o repositório final TFA (Très Faiblement Actif) no distrito francês de Aube
The DORIAN code for the prediction and analysis of residual dose rates due to accelerator radiation induced activation
No full textThe 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
Retrospective clinical case series study in 2017 identifies Plasmodium knowlesi as most frequent Plasmodium species in returning travellers from Thailand to Germany
No full textFebrile illnesses are common in travellers returning from south-east Asia. However, malaria is a rare diagnosis in this population. A series of Plasmodium knowlesi infections was noted in German travellers returning from Thailand since 2012. Infectious disease and tropical medicine facilities registered by the German Society for Tropical Medicine and International Health were contacted in March 2017, and asked to report previous P. knowlesi cases. In addition, surveillance data from the Robert Koch-Institute were analysed. The facilities reported a total of six P. knowlesi-positive cases, all were returning travellers from Thailand. The P. knowlesi-positive cases made up 6/9 of all diagnosed malaria cases imported from Thailand in the time period 2012 to 2017. In 4/5 of cases where a malaria rapid diagnostic test had been applied it revealed a negative result. P. knowlesi is an important differential diagnosis in travellers returning from south-east Asia with itineraries that include Thailand. This study highlights the importance of this Plasmodium species in this patient subgroup. Whenever malaria is suspected in a returning traveller from Thailand, P. knowlesi should be taken into consideration and a differential PCR be executed as currently the unequivocal diagnosis of P. knowlesi is based on nuclear amplification techniques.Peer Reviewe
Radiological Characterization with a Fluence Conversion Coefficients–Based Method: A Practical Example of the Preparatory Studies to the Pilot Beam at the CERN Large Hadron Collider
No full textAt high-energy accelerator facilities like the ones that are part of the accelerator complex at the European Organization for Nuclear Research (CERN), Monte Carlo radiation transport codes are widely employed to face the challenges of estimating radionuclide production yields and activities with the aim of performing the radiological characterization of activated components. Indeed, it is of paramount importance to ensure adequate radiation protection during scheduled maintenance, transport, and handling of these components and to establish their proper disposal pathway once they ultimately reach the end of their useful life. This paper summarizes the principles of the fluence conversion coefficients method that was developed as a complementary approach for radiological characterization studies. Then, the Monte Carlo simulations in preparation to the pilot beam run at the Large Hadron Collider at CERN in 2021 are presented as a practical example of possible applications. Finally, the flexibility of the method and the most relevant operational radiation protection implications are discussed in relation to the provided example
Calibrating the CERN ATLAS Experiment with
No full textInside the ATLAS experiment two proton beams will collide with a center of mass energy of 14 TeV. These proton beams will be delivered with unprecedented high collision rates by the Large Hadron Collider (LHC) at the European Center of Particle Physics, CERN. For important parts of the physics program of ATLAS, e.g. the search for the Higgs boson, the performance of the electromagnetic calorimeter, whose primary task is to measure the energy of electrons and photons, is crucial. The main topic of this thesis is the intercalibration of the energy scale of the electromagnetic calorimeter and the momentum scale of the inner detector. This is an important consistency test for these two detectors. The intercalibration is performed by investigating the ratio E/p for electrons, i.e. the ratio of the energy E measured by the electromagnetic calorimeter and the momentum p measured by the inner detector. The starting point is the Combined Test Beam (CTB) 2004, where a segment of the ATLAS detector was exposed to different particle beams with different energies, ranging from 1 GeV to 350 GeV. First, I have investigated a calibration procedure using Monte Carlo simulation for the energy measured by the electromagnetic calorimeter for electrons. The performance of this procedure is presented for data taken in the CTB 2004. Second, I have developed a model for E/p which allows the disentanglement of the ratio of the two scales from tail ef fects from the different detector response functions of the inner detector and the electromagnetic calorimeter. The performance of this model for intercalibration is shown for the Monte Carlo simulation for the CTB 2004 and compared to data taken in the CTB 2004. Finally I have evaluated the performance of this method for the full ATLAS detector using Monte Carlo simulation. Although the energy scale of the electromagnetic calorimeter will ultimately be determined with electron/positron pairs from Z boson decays, the potential of the intercalibration method with initial data, and therefore limited statistics, is presented. With the presented intercalibration method the energy scale can also be determined for various electron energies, thereby measuring the linearity of the electromagnetic calorimeter in situ. This will only be limited by statistics, i.e. the number of electrons produced at high energies, and ultimately the capability of the inner detector to measure the momentum of charged particles at very high energies
Implementation of ICRP116 Fluence to Effective Dose Conversion Coefficients in a FLUKA user routine
No full textThe 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
Combined Studies of the EM Calorimeter and the Inner Detector in the 2004 ATLAS Combined Testbeam
No full textAdapting teaching and learning in times of COVID-19: a comparative assessment among higher education institutions in a global health network in 2020.
No full textFrom PubMed via Jisc Publications RouterHistory: received 2021-08-02, accepted 2022-06-15Publication status: epublishThis research examines the ways in which higher education institutions (HEIs) across the tropEd Network for Education in International Health (tropEd) began to adapt their teaching and learning approaches in response to the COVID-19 pandemic in 2020. Already during this early phase of the pandemic HEIs' responses demonstrate global health approaches emphasising cooperation and communication, rather than national health driven strategies that emphasise quarantine and control. Key lessons learnt for multiple dimensions of teaching and learning in global health are thus identified, and challenges and opportunities discussed. Data collection includes a cross-sectional online survey among tropEd member institutions (n = 19) in mid-2020, and a complementary set of open-ended questions generating free-text responses (n = 9). Quantitative data were analysed using descriptive statistics, textual data were analysed using a Framework Analysis approach. While early on in the pandemic the focus was on a quick emergency switch to online teaching formats to ensure short-term continuity, and developing the administrative and didactic competence and confidence in digital teaching, there is already recognition among HEIs of the necessity for more fundamental quality and longer-term reforms in higher education in global health. Alongside practical concerns about the limitations of digital teaching, and declines in student numbers, there is a growing awareness of opportunities in terms of inclusivity, the necessity of cross-border cooperation, and a global health approach. The extent to which the lack of physical mobility impacts HEI programmes in global health is debated. The COVID-19 pandemic has brought about preventive measures that have had a considerable impact on various dimensions of academic teaching in global health. Going forward, international HEIs' experiences and response strategies can help generate important lessons for academic institutions across different settings worldwide. [Abstract copyright: © 2022. The Author(s).
