Comparison of calculated spectra for the interaction of photons in a liquid scintillator. Example of 54Mn 835keV emission

Cassette, P.; Ahn, Gilhwan; Alzitzoglou, T.; Aubineau-Lanièce, I.; Bochud, François; Torano, E. Garcia; Carles, A. Grau; Malonda, A. Grau; Kossert, Karsten; Lee, K.B.; Laedermann, Jean-Pascal; Simpson, B.R.S.; Wyngaardt, W.M. van; Zimmerman, Brian E.

doi:10.1016/j.apradiso.2006.02.080

Cited by 21 publications

(7 citation statements)

References 2 publications

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“…The case of the standardization of 54 Mn is a good example of this phenomenon. This radionuclide decays by electron capture originating subsequently an 835 keV photon emission [8]. The energy spectrum deposited by the gamma-ray into the scintillation cocktail and its probability of absorption must be calculated in order to estimate correctly the detection efficiency for this radionuclide.…”

Section: Jinst 12 P09021 3 Results and Discussionmentioning

confidence: 99%

“…The energy spectrum deposited by the gamma-ray into the scintillation cocktail and its probability of absorption must be calculated in order to estimate correctly the detection efficiency for this radionuclide. In view of this, a GEANT4 simulation of the 54 Mn measurement with a model of a 10 mL vial and the counting chamber similar to the one described in [8] was carried out. The simulated spectrum is shown in figure 8.…”

Section: Jinst 12 P09021 3 Results and Discussionmentioning

confidence: 99%

“…Recently, Monte Carlo codes have been utilized in order to simulate the physical processes related to the transport of particles and the corresponding generation of optical photons in the scintillation medium, thereby facilitating the calibration procedure for several nuclides and the optimization and design of diverse instruments [7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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GEANT4 simulation of the response of a liquid scintillation counter

Hurtado

2017

J. Inst.

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Liquid Scintillation Counting (LSC) is widely used as a very efficient technique for radioactivity quantification. LSC is a powerful tool applied as much in low level environmental radioactivity monitoring, as in radionuclide metrology for the activity standardization of electron capture, pure-beta, and alpha nuclides. In order to quantify the sample activity, the number of scintillation photons are counted by one or several PMTs. However, the scintillation count rate varies with the detection efficiency. As an alternative to traditional methods for the calculation of detection efficiency, a Monte Carlo approach based on GEANT4 toolkit is presented for the simulation of light emission inside a Quantulus 1220 liquid scintillation counter with two PMT photomultipliers tubes working in sum-coincidence mode. To this end, the GEANT4 simulation handles a variety of processes at optical wavelengths including refraction and reflection at medium boundaries, Rayleigh scattering and bulk absorption, and additional processes which produce optical photons such as Cherenkov effect, transition radiation and scintillation, and includes a description of optical properties associated with each material constituting the detection system. The objective is to simulate the propagation of optical photons from their creation in the liquid scintillation cocktail to the production of photoelectrons in the PMTs. In this paper, we report in detail the results of the proposed simulation (detection efficiency, and additionally wall effect and absorption probabilities of gamma-rays) for different radionuclides such as 14C, 3H, 54Mn and 90Y, and its validation through the comparison with the experimental measurements.

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Section: Jinst 12 P09021 3 Results and Discussionmentioning

confidence: 99%

Section: Jinst 12 P09021 3 Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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GEANT4 simulation of the response of a liquid scintillation counter

Hurtado

2017

J. Inst.

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“…The difficulties in calculating efficiencies for 64 Cu in particular were discussed by Kossert et al (2014) in their description of some extensions to the MICELLLE2 model. They noted that gamma- and x-ray scattering from the optical chamber can produce a non-negligible increase in the probability of interaction in the scintillant (as demonstrated by Cassette et al, 2006), that positron annihilation in flight—occurring with ≈ 0.6 % probability for 64 Cu positrons—reduces the energy deposited in the scintillant, and that screening and exchange effects may need to be considered in the calculation of the 64 Cu β +/− spectrum shapes. Kossert and Mougeot (2015) demonstrated the potential importance of screening and exchange corrections very clearly in the case of 63 Ni, and Kossert et al (2014) suggested they may also be important in the 64 Cu case.…”

Section: Discussionmentioning

confidence: 99%

Standardization of 64Cu activity

Bergeron

Cessna

Fitzgerald

et al. 2018

Applied Radiation and Isotopes

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The complex decay scheme that makes 64Cu promising as both an imaging and therapeutic agent in medicine also makes the absolute measurement of its activity challenging. The National Institute of Standards and Technology (NIST) has completed a primary activity standardization of a 64CuCl2 solution using the 4πβ(LS)-γ(NaI) live-timed anticoincidence (LTAC) counting method with a combined standard uncertainty of 0.51 %. Two liquid scintillation (LS) counting methods were employed for confirmatory measurements. Secondary measurements were made by high-purity germanium detectors, pressurized ionization chambers (IC), and a well-type NaI(Tl) counter. Agreement between the LTAC-based standard and standards from other laboratories was established via IC calibration factors. Poor agreement between methods and with theoretical IC responses may indicate a need for improved β+/− branching probabilities and a better treatment of β+/− spectra.

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“…La bande spectrale des photons simulés est limitée dans le domaine ultraviolet par la transmittance du flacon de verre (de l'ordre de 50 % à 290 nm) et par la réponse de la photocathode à basse fréquence (seuil de détection de l'ordre de 650 nm). -les dimensions du flacon sont tirées de la littérature [19] ; l'épaisseur de la paroi est de…”

Section: Description Du Modèle Rctd-geant4 Pour La Mesure D'activité unclassified

Approche stochastique du modèle RCTD pour la mesure de l’activité en Cherenkov et par scintillation liquide

Bobin¹,

Thiam²,

Chauvenet³

et al. 2013

R. franç. métrol.

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En métrologie de l'activité, la méthode RCTD (Rapport des Coïncidences Triples à Doubles) est une technique primaire fondée sur la scintillation liquide, utilisant une instrumentation spécifique à trois photomultiplicateurs. Le modèle RCTD statistique de l'émission lumineuse permettant le calcul des rendements de détection des coïncidences est étudié dans le cas de dépôts de basses énergies dans le liquide scintillant. Pour cela, l'indépendance stochastique entre les photomultiplicateurs est introduite comme condition préalable à l'écriture des relations classiques du modèle statistique. Deux phénomènes pouvant conduire à la non-validité de cette condition sont décrits. Mise en évidence expérimentalement avec la mesure d'activité du tritium (3 H), la dépendance stochastique de type temporel se manifeste par une perte systématique de coïncidences lorsque le temps de résolution est trop court comparé à la distribution temporelle des photons de scintillation. La dépendance stochastique de type géométrique est également étudiée en raison de la sensibilité du comptage des coïncidences selon le point d'origine de l'émission lumineuse dans le volume du liquide scintillant. Cette étude a été possible grâce au développement d'une nouvelle modélisation avec le code Monte-Carlo Geant4 intégrant la simulation de la propagation des photons optiques jusqu'à la production des photoélectrons dans le détecteur. Dans les deux cas de dépendance stochastique, l'influence sur le calcul des rendements de détection des coïncidences et par suite sur la détermination de l'activité est exposée. Le nouveau modèle RCTD-Geant4 intègre aussi l'émission de photons Cherenkov ; il a permis la confirmation de l'émission de lumière « parasite » sous forme de photons Cherenkov suite à la diffusion Compton dans les faces d'entrée des photomultiplicateurs. Une nouvelle technique primaire RCTD-Cherenkov a également été développée grâce au modèle RCTD-Geant4 ; elle a été notamment appliquée à la mesure d'activité du carbone-11 (radiopharmaceutique à durée de vie courte, T 1/2 de l'ordre de 20 min).

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Comparison of calculated spectra for the interaction of photons in a liquid scintillator. Example of 54Mn 835keV emission

Cited by 21 publications

References 2 publications

GEANT4 simulation of the response of a liquid scintillation counter

GEANT4 simulation of the response of a liquid scintillation counter

Standardization of 64Cu activity

Approche stochastique du modèle RCTD pour la mesure de l’activité en Cherenkov et par scintillation liquide

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