Determination of electron lifetime in compressed Xe gas for gamma-spectroscopy

Abstract In the surveillance of bulk food produce by gamma ray spectroscopy for fission products, the activities of the commonly observed radionuclides are frequently in the magnitude of background inherent to the detection system. The problems of determining whether the sample is in fact contaminated, the lower limits of detecting the radionuclides, and the effect of compton smear on the lower limits are discussed. The discussions are based on the modified spectrum stripping method for quantitative analysis of gamma ray spectrum for the following radioisotopes: Cs-137, Zr-95/Nb-95, and K-40. A family of curves are shown for rapid determination of the minimum detectable true activity (AII) of Cs-137.

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Determination of the Electron Lifetime in Nanocrystalline Dye Solar Cells by Open-Circuit Voltage Decay Measurements

ChemPhysChem ◽

10.1002/cphc.200200615 ◽

2003 ◽

Vol 4 (8) ◽

pp. 859-864 ◽

Cited By ~ 970

Author(s):

Arie Zaban ◽

Miri Greenshtein ◽

Juan Bisquert

Keyword(s):

Solar Cells ◽

Open Circuit Voltage ◽

Open Circuit ◽

Electron Lifetime ◽

Voltage Decay ◽

Dye Solar Cells

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Prompt gamma spectroscopy for range control with CeBr3

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2017-0023 ◽

2017 ◽

Vol 3 (2) ◽

pp. 113-117 ◽

Cited By ~ 3

Author(s):

Paulo Magalhaes Martins ◽

Riccardo Dal Bello ◽

Andreas Rinscheid ◽

Katja Roemer ◽

Theresa Werner ◽

...

Keyword(s):

Bragg Peak ◽

Gamma Spectroscopy ◽

Signal To Noise Ratio ◽

Ion Beam ◽

Prompt Gamma ◽

Signal To Noise ◽

Particle Beams ◽

Therapy Center ◽

Flight Measurements

AbstractThe ultimate goal of radiotherapy using external beams is to maximize the dose delivered to the tumor while minimizing the radiation given to surrounding healthy critical organs. Prompt Gamma Spectroscopy (PGS) has been proposed for range control of particle beams along with the determination of the elemental composition of irradiated tissues. We aim at developing a PGS system for the German Cancer Research Center – DKFZ that takes advantage of the superior selectivity of Helium and Carbon beams accelerated at the Heidelberg Ion-Beam Therapy Center. Preliminary tests with protons accelerated with an IBA C230 cyclotron located at the Universitäts Protonen Therapie Dresden were performed at OncoRay – National Center for Radiation Re-search in Oncology. We present results obtained with a PGS system composed of CeBr3 detectors (Ø 2’’ × 2’’) and (Ø 1.5’’ × 3’’) coupled to a Hamamatsu R13089 photomulti-plier tube and plugged to a Target U100 Spectrometer. Such system provides accurate time-of-flight measurements to increase the signal-to-noise ratio relative to neutron-induced background. First measurements resulted from the irradiation of PMMA and water phantoms, and graphite and aluminum bricks. Several PG energy lines ranging from 0.511 MeV up to 8 MeV were identified and compared with reference re-sults. Two further experiments consisted in irradiating PMMA phantoms in a slit- and semi-collimated configuration with mono-energetic proton beams of 165 MeV and 224 MeV, respectively. Results acquired by means of trans-versal PGS at different phantom depths, ranging from 6 cm before the Bragg peak (BP) to 3.5 cm beyond the BP in 5 mm steps with a 1 cm slit collimation (tungsten) showed a slight decrease of PG yields after the BP. Similar measurements with a semi-opened collimation configuration demonstrated a steeper decrease of PG yields after the BP.

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Determination of radionuclides in Mytilus galloprovicialis by Alpha And Gamma-Spectroscopy

Mediterranean Marine Science ◽

10.12681/mms.216 ◽

2004 ◽

Vol 5 (1) ◽

pp. 117 ◽

Cited By ~ 3

Author(s):

H. FLOROU ◽

K. KEHAGIA ◽

CH. CHALOULOU ◽

V. KOUKOULIOU ◽

CH. LYKOMITROU

Keyword(s):

Mytilus Galloprovincialis ◽

Gamma Spectroscopy ◽

Natural Radionuclides ◽

Aegean Sea ◽

Radioactive Pollution ◽

Activity Concentrations ◽

North Aegean ◽

Concentration Factors ◽

North Aegean Sea

The natural radionuclides 238U ,234Th, 40K and the main man-made 137Cs, have been studied in Mytilus galloprovincialis (Lamarck, 1819) sampled in the Thermaikos gulf – North Aegean Sea, considered as a bioindicator for radiological assessment in the Mediterranean. The ratio 234U/238U has also been determined. In terms of 137Cs, the activity concentrations in seawater from the studied area have been measured as well, and the concentration factors of 137Cs in Mytilus galloprovincialis are given as a parameter of the organism response to radioactive pollution.

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A suitable time point for quantifying the radiochemical purity of 225Ac-labeled radiopharmaceuticals

EJNMMI Radiopharmacy and Chemistry ◽

10.1186/s41181-021-00151-y ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

James M. Kelly ◽

Alejandro Amor-Coarasa ◽

Elizabeth Sweeney ◽

Justin J. Wilson ◽

Patrick W. Causey ◽

...

Keyword(s):

Radiochemical Purity ◽

Gamma Spectroscopy ◽

Early Time ◽

Secular Equilibrium ◽

Data Set ◽

Testing Procedures ◽

Layer Chromatography ◽

High Resolution Gamma Spectroscopy ◽

Time Point

Abstract Background As 225Ac-labeled radiopharmaceuticals continue to show promise as targeted alpha therapeutics, there is a growing need to standardize quality control (QC) testing procedures. The determination of radiochemical purity (RCP) is an essential QC test. A significant obstacle to RCP testing is the disruption of the secular equilibrium between actinium-225 and its daughter radionuclides during labeling and QC testing. In order to accelerate translation of actinium-225 targeted alpha therapy, we aimed to determine the earliest time point at which the RCP of an 225Ac-labeled radiopharmaceutical can be accurately quantified. Results Six ligands were conjugated to macrocyclic metal chelators and labeled with actinium-225 under conditions designed to generate diverse incorporation yields. RCP was determined by radio thin layer chromatography (radioTLC) followed by exposure of the TLC plate on a phosphor screen either 0.5, 2, 3.5, 5, 6.5, or 26 h after the plate was developed. The dataset was used to create models for predicting the true RCP for any pre-equilibrium measurement taken at an early time point. The 585 TLC measurements span RCP values of 1.8–99.5%. The statistical model created from these data predicted an independent data set with high accuracy. Predictions made at 0.5 h are more uncertain than predictions made at later time points. This is primarily due to the decay of bismuth-213. A measurement of RCP > 90% at 2 h predicts a true RCP > 97% and guarantees that RCP will exceed 90% after secular equilibrium is reached. These findings were independently validated using NaI(Tl) scintillation counting and high resolution gamma spectroscopy on a smaller set of samples with 10% ≤ RCP ≤ 100%. Conclusions RCP of 225Ac-labeled radiopharmaceuticals can be quantified with acceptable accuracy at least 2 h after radioTLC using various methods of quantifying particle emissions. This time point best balances the need to accurately quantify RCP with the need to safely release the batch as quickly as possible.

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