scholarly journals Commissioning characterization and exploitation of the CERN Shielding Benchmark Facility (CSBF)

2018 ◽  
Author(s):  
Ελπίδα Ηλιοπούλου
Keyword(s):  
Monte Carlo ◽  
High Energy ◽  
Material Test ◽  
High Energy Accelerator ◽  
Test Location ◽  
Mixed Field ◽  
Shielding Material

Μία από τις κύριες εφαρμογές του κώδικα προσομοιώσεων FLUKA Monte Carlo, είναι ο σχεδιασμός νέων εγκαταστάσεων ιοντίζουσας ακτινοβολίας. Ένα αναπόσπαστο κομμάτι της διαδικασίας ανάπτυξης του κώδικα FLUKA, είναι η συγκριτική αξιολόγηση προγνωστικών για νέα χαρακτηριστικά έναντι πειραματικών δεδομένων, για παράδειγμα, συγκριτική αξιολόγηση της διείσδυσης σε βαθιά θωράκιση από σωματίδια που προέρχονται από επιταχυντή πρωτονίων υψηλής ενέργειας εν λειτουργία. Για το λόγο αυτό, το CERN High Energy Accelerator Mixed Field Facility (CHARM) και το CERN Shielding Benchmark Facility (CSBF) σχεδιάστηκαν ειδικά για την απόκτηση πειραματικών δεδομένων για μελέτες διείσδυσης σωματιδίων σε βαθιά θωράκιση. Οι κύριοι στόχοι αυτής της διατριβής, είναι ο σχεδιασμός και ο χαρακτηρισμός του CSBF, τόσο με προσομοιώσεις των φασμάτων ακτινοβολίας με FLUKA Monte Carlo, όσο και με την επικύρωση τους με πειράματα ενεργοποίησης. Το πρώτο πρωτότυπο του CSBF εγκαταστάθηκε, μαζί με ολόκληρη τη θωράκιση της εγκατάστασης CHARM, κατά τη διάρκεια του Long Shut-down 1 (LS1) το 2013/2014. Η εγκατάσταση CHARM λειτουργεί με δέσμη πρωτονίων 24GeV/c από τον Σεπτέμβριο του 2014. Ένας πρώτος χαρακτηρισμός της εγκατάστασης CSBF πραγματοποιήθηκε τον Ιούλιο του 2015, με την πραγματοποίηση πειραμάτων ενεργοποίησης ανιχνευτών βισμουθίου και αλουμινίου στο CSBF. Οι προσομοιώσεις Monte Carlo με τον κώδικα FLUKA, πραγματοποιήθηκαν για την εκτίμηση των αποδόσεων παραγωγής ισοτόπων βισμουθίου και νατρίου, για αυτά τα δείγματα. Οι αποδόσεις παραγωγής που εκτιμήθηκαν από τις προσομοιώσεις FLUKA Monte Carlo, συγκρίθηκαν με τις αποδόσεις παραγωγής που λήφθηκαν από τις μετρήσεις της γ-φασματοσκοπίας των δειγμάτων, λαμβάνοντας υπόψη το προφίλ της έντασης δέσμης. Με την εμπειρία που αποκτήθηκε κατά τη διάρκεια της εκστρατείας ενεργοποίησης το 2015, το CSBF αναβαθμίστηκε σημαντικά κατά τη διάρκεια της εκτεταμένης τεχνικής διακοπής στο τέλος του έτους 2016. Συνεπώς, τον Σεπτέμβριο του 2016 πραγματοποιήθηκε μια δεύτερη εκστρατεία πειραμάτων με ενεργοποίηση δειγμάτων βισμουθίου, αλουμινίου και ινδίου, που τοποθετήθηκαν στο CSBF, για να χαρακτηρίσουν την αναβαθμισμένη έκδοση του CSBF. Οι προσομοιώσεις Monte Carlo με τον κώδικα FLUKA, πραγματοποιήθηκαν για την εκτίμηση των ειδικών αποδόσεων παραγωγής των ισοτόπων βισμουθίου, νατρίου και ινδίου, για τα δείγματα αυτά, στη νέα εγκατάσταση και έπειτα συγκρίθηκαν με τις αποδόσεις παραγωγής που λήφθηκαν από τις μετρήσεις γ-φασματοσκοπίας των δειγμάτων, λαμβάνοντας υπόψη το προφίλ της έντασης δέσμης. Παράλληλα με την εκστρατεία ενεργοποίησης το 2016, πραγματοποιήθηκε μια σειρά μετρήσεων με θάλαμο ιονισμού υδρογόνου υπό υψηλή πίεση 20 bar, βαθμονομημένο για τη μέτρηση ρυθμού ισοδύναμης δόσης περιβάλλοντος, στo shielding material test location. Με τη σύγκριση του ρυθμού δόσης που μετρήθηκε σε διαφορετικές θέσεις, υπολογίζεται ο μέσος όρος του μήκους εξασθένησης φάσματος νετρονίων των διάφορων, συνήθως, χρησιμοποιούμενων υλικών θωράκισης. Τα αποτελέσματα που προέκυψαν για τις εκστρατείες ενεργοποίησης το 2015 και το 2016 έδειξαν ότι τα πεδία ακτινοβολίας στο CSBF είναι τώρα καλά κατανοητά και καλά περιγραφόμενα από την FLUKA. Αυτά τα αποτελέσματα μπορούν να χρησιμοποιηθούν ως κατευθυντήριες γραμμές για παρόμοιες μελέτες σε μελλοντικούς επιταχυντές πρωτονίων και σε ιατρικές εγκαταστάσεις.

Raman distributed temperature measurement at CERN high energy accelerator mixed field radiation test facility (CHARM)

2015 ◽  
Author(s):  
Iacopo Toccafondo ◽  
Tiziano Nannipieri ◽  
Alessandro Signorini ◽  
Elisa Guillermain ◽  
Jochen Kuhnhenn ◽  
...  
Keyword(s):  
Temperature Measurement ◽  
High Energy ◽  
Test Facility ◽  
High Energy Accelerator ◽  
Radiation Test ◽  
Field Radiation ◽  
Mixed Field

scholarly journals Single Event Effect cross section calibration and application to quasi-monoenergetic and spallation facilities

2018 ◽  
Vol 4 ◽  
pp. 1
Author(s):  
Rubén García Alía ◽  
Stefano Bonaldo ◽  
Markus Brugger ◽  
Salvatore Danzeca ◽  
Alfredo Ferrari ◽  
...  
Keyword(s):  
Monte Carlo ◽  
High Energy ◽  
Test Facility ◽  
Monte Carlo Code ◽  
Single Event ◽  
Single Event Effect ◽  
Monitoring Applications ◽  
Field Response ◽  
Broad Variety ◽  
Mixed Field

We describe an approach to calibrate Single Event Effect (SEE)-based detectors in monoenergetic fields and apply the resulting semi-empiric responses to more general mixed-field cases in which a broad variety of particle species and energy spectra are present. The calibration of the response functions is based both on experimental proton (30–200 MeV) and neutron (5–300 MeV) data and considerations derived from Monte Carlo simulations using the FLUKA Monte Carlo code. The application environments include the quasi-monoenergetic neutrons at RCNP, the atmospheric-like VESUVIO spallation spectrum and the CHARM high-energy accelerator test facility. The agreement between the mixed-field response and that predicted through the mono-energetic calibration is within ±30% for the broad variety of cases considered and thus regarded as highly successful for mixed-field monitoring applications.

Monte Carlo Modelling of Secondary Electron Yield from Rough Surfaces

1990 ◽  
Vol 48 (1) ◽  
pp. 422-423
Author(s):  
John C. Russ
Keyword(s):  
Monte Carlo ◽  
Energy Loss ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Analytical Calculation ◽  
Mean Free Path ◽  
Single Scattering ◽  
High Energy ◽  
Secondary Electron Yield ◽  
Electron Yield

Monte-Carlo programs are well recognized for their ability to model electron beam interactions with samples, and to incorporate boundary conditions such as compositional or surface variations which are difficult to handle analytically. This success has been especially powerful for modelling X-ray emission and the backscattering of high energy electrons. Secondary electron emission has proven to be somewhat more difficult, since the diffusion of the generated secondaries to the surface is strongly geometry dependent, and requires analytical calculations as well as material parameters. Modelling of secondary electron yield within a Monte-Carlo framework has been done using multiple scattering programs, but is not readily adapted to the moderately complex geometries associated with samples such as microelectronic devices, etc.This paper reports results using a different approach in which simplifying assumptions are made to permit direct and easy estimation of the secondary electron signal from samples of arbitrary complexity. The single-scattering program which performs the basic Monte-Carlo simulation (and is also used for backscattered electron and EBIC simulation) allows multiple regions to be defined within the sample, each with boundaries formed by a polygon of any number of sides. Each region may be given any elemental composition in atomic percent. In addition to the regions comprising the primary structure of the sample, a series of thin regions are defined along the surface(s) in which the total energy loss of the primary electrons is summed. This energy loss is assumed to be proportional to the generated secondary electron signal which would be emitted from the sample. The only adjustable variable is the thickness of the region, which plays the same role as the mean free path of the secondary electrons in an analytical calculation. This is treated as an empirical factor, similar in many respects to the λ and ε parameters in the Joy model.

Neutron dose evaluation of Elekta Linac at two energies (10 & 18 MV) by MCNP code and comparison with experimental measurements

2014 ◽  
Vol 6 (1) ◽  
pp. 1006-1015
Author(s):  
Negin Shagholi ◽  
Hassan Ali ◽  
Mahdi Sadeghi ◽  
Arjang Shahvar ◽  
Hoda Darestani ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Measurement Data ◽  
Calculated Data ◽  
High Energy ◽  
Neutron Dose ◽  
Dose Assessment ◽  
Photon Flux ◽  
Dose Equivalent ◽  
Monte Carlo Techniques ◽  
Neutron Dose Equivalent

Medical linear accelerators, besides the clinically high energy electron and photon beams, produce other secondary particles such as neutrons which escalate the delivered dose. In this study the neutron dose at 10 and 18MV Elekta linac was obtained by using TLD600 and TLD700 as well as Monte Carlo simulation. For neutron dose assessment in 2020 cm2 field, TLDs were calibrated at first. Gamma calibration was performed with 10 and 18 MV linac and neutron calibration was done with 241Am-Be neutron source. For simulation, MCNPX code was used then calculated neutron dose equivalent was compared with measurement data. Neutron dose equivalent at 18 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 3.3, 4, 5 and 6 cm. Neutron dose at depths of less than 3.3cm was zero and maximized at the depth of 4 cm (44.39 mSvGy-1), whereas calculation resulted  in the maximum of 2.32 mSvGy-1 at the same depth. Neutron dose at 10 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 2.5, 3.3, 4 and 5 cm. No photoneutron dose was observed at depths of less than 3.3cm and the maximum was at 4cm equal to 5.44mSvGy-1, however, the calculated data showed the maximum of 0.077mSvGy-1 at the same depth. The comparison between measured photo neutron dose and calculated data along the beam axis in different depths, shows that the measurement data were much more than the calculated data, so it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry in linac central axis due to high photon flux, whereas MCNPX Monte Carlo techniques still remain a valuable tool for photonuclear dose studies.

scholarly journals Analysis of Shielding Performance of Radiation-Shielding Materials According to Particle Size and Clustering Effects

2021 ◽  
Vol 11 (9) ◽  
pp. 4010
Author(s):  
Seon-Chil Kim
Keyword(s):  
Particle Size ◽  
Polymer Material ◽  
Energy Region ◽  
High Energy ◽  
Radiation Shielding ◽  
High Energy Region ◽  
Particle Structure ◽  
Effect Of Particle Size ◽  
Extensive Body ◽  
Shielding Material

In the field of medical radiation shielding, there is an extensive body of research on process technologies for ecofriendly shielding materials that could replace lead. In particular, the particle size and arrangement of the shielding material when blended with a polymer material affect shielding performance. In this study, we observed how the particle size of the shielding material affects shielding performance. Performance and particle structure were observed for every shielding sheet, which were fabricated by mixing microparticles and nanoparticles with a polymer material using the same process. We observed that the smaller the particle size was, the higher both the clustering and shielding effects in the high-energy region. Thus, shielding performance can be improved. In the low-dose region, the effect of particle size on shielding performance was insignificant. Moreover, the shielding sheet in which nanoparticles and microsized particles were mixed showed similar performance to that of the shielding sheet containing only microsized particles. Findings indicate that, when fabricating a shielding sheet using a polymer material, the smaller the particles in the high-energy region are, the better the shielding performance is. However, in the low-energy region, the effect of the particles is insignificant.

scholarly journals Monte Carlo Modeling and Design of Photon Energy Attenuation Layers for >10× Quantum Yield Enhancement in Si-Based Hard X-ray Detectors

Instruments ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 17
Author(s):  
Eldred Lee ◽  
Kaitlin M. Anagnost ◽  
Zhehui Wang ◽  
Michael R. James ◽  
Eric R. Fossum ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Quantum Yield ◽  
Photon Energy ◽  
High Efficiency ◽  
High Energy ◽  
Yield Enhancement ◽  
X Ray ◽  
Simulation Results ◽  
Conversion Efficiencies

High-energy (>20 keV) X-ray photon detection at high quantum yield, high spatial resolution, and short response time has long been an important area of study in physics. Scintillation is a prevalent method but limited in various ways. Directly detecting high-energy X-ray photons has been a challenge to this day, mainly due to low photon-to-photoelectron conversion efficiencies. Commercially available state-of-the-art Si direct detection products such as the Si charge-coupled device (CCD) are inefficient for >10 keV photons. Here, we present Monte Carlo simulation results and analyses to introduce a highly effective yet simple high-energy X-ray detection concept with significantly enhanced photon-to-electron conversion efficiencies composed of two layers: a top high-Z photon energy attenuation layer (PAL) and a bottom Si detector. We use the principle of photon energy down conversion, where high-energy X-ray photon energies are attenuated down to ≤10 keV via inelastic scattering suitable for efficient photoelectric absorption by Si. Our Monte Carlo simulation results demonstrate that a 10–30× increase in quantum yield can be achieved using PbTe PAL on Si, potentially advancing high-resolution, high-efficiency X-ray detection using PAL-enhanced Si CMOS image sensors.

scholarly journals High energy cosmic ray interactions and UHECR composition problem

2019 ◽  
Vol 210 ◽  
pp. 02001
Author(s):  
Sergey Ostapchenko
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
Hadronic Interactions ◽  
High Energy Cosmic Rays ◽  
Cosmic Ray Interactions ◽  
Composition Problem

The differences between contemporary Monte Carlo generators of high energy hadronic interactions are discussed and their impact on the interpretation of experimental data on ultra-high energy cosmic rays (UHECRs) is studied. Key directions for further model improvements are outlined. The prospect for a coherent interpretation of the data in terms of the UHECR composition is investigated.

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