Seasonal variation of background counting rates in liquid scintillation counting.

A liquid scintillation background sample was measured daily in a custom-built TDCR counter for more than 17 months. The double and triple coincidence counting rates exhibit an annual sinusoidal fluctuation with a maximum in winter and a minimum in summer. Possible correlations with air temperature, air humidity, radon concentration and secondary cosmic radiation were investigated.

Analysis of a neutron-induced conversion electron spectrum of gadolinium.

A 100-nm-thick gadolinium layer deposited on a pixelated silicon sensor was activated in a neutron field to measure the internal conversion electron (ICE) spectrum generated by neutron capture products of Gd and Gd. The experiment was performed at the ISIS neutron and muon facility, using a bespoke version of the HEXITEC spectroscopic imaging camera. Signals originating from internal conversion electrons, Auger electrons, x rays and gamma rays up to 150 keV were identified.

Air humidity and annual oscillations in Sr/Y and Co decay rate measurements.

Parkhomov published decay rate measurements of Sr/Y and Co beta decay sources with Geiger-Müller counters which showed annual cyclic deviations with less than 0.2% amplitude from a purely exponential slope. He investigated instrument instability induced by environmental parameters, yet did not find a clear coincidence with local temperature, atmospheric pressure, and relative humidity.

Measurement of the Sm half-life.

The half-life of Sm has been measured by means of the reference source method with a HPGe detector. The long-lived radionuclide Ti was mixed into the source for reference. The time-dependency of the Sm/Ti activity ratio was followed by assessing the count-rate ratio of their characteristic gamma-ray emissions at 61.

On the interpretation of annual oscillations in Si and Cl decay rate measurements.

The Si decay rate measurement data of Alburger et al. obtained in 1982-1986 at Brookhaven National Laboratory have been presented repeatedly as evidence for solar neutrino-induced beta decay. The count rates show an annual sinusoidal oscillation of about 0.

An international multi-center investigation on the accuracy of radionuclide calibrators in nuclear medicine theragnostics.

Background: Personalized molecular radiotherapy based on theragnostics requires accurate quantification of the amount of radiopharmaceutical activity administered to patients both in diagnostic and therapeutic applications. This international multi-center study aims to investigate the clinical measurement accuracy of radionuclide calibrators for 7 radionuclides used in theragnostics: Tc, In, I, I, I, Lu, and Y.

Methods: In total, 32 radionuclide calibrators from 8 hospitals located in the Netherlands, Belgium, and Germany were tested.

Derivation of an uncertainty propagation factor for half-life determinations.

An analytical equation is derived for the uncertainty propagation factor for a half-life determination from a least-squares fit to equidistant activity measurements performed with identical relative uncertainties. The obtained formula applies to a purely random statistical uncertainty component. It is equivalent to the solution published by Parker in Nucl.

Half-life determination and comparison of activity standards of Pa.

The results of an international comparison of activity measurements of a solution of Pa are reported and analysed. Prior to this, no known standardisation of Pa by activity measurement had been carried out. The comparison was run in 2017-2018 involving eight laboratories, and returned results with no identifiable inconsistencies between methods or laboratories.

Alpha-particle emission probabilities of Pa derived from first semiconductor spectrometric measurements.

The nuclide Pa is a member of the U decay chain. It is a complex alpha emitter with 25 identified alpha emissions. Formerly published alpha-particle emission probabilities were derived from measurements taken with magnetic spectrometers.

Conversion electron spectroscopy of the 59.54 keV transition in Am alpha decay.

A windowless Peltier-cooled silicon drift detector (SDD) was used to measure internal conversion electron (ICE) spectra of thin Am sources. The ICE peaks associated with the 59.54 keV gamma transition in Np were deconvoluted and relative ICE intensities were derived from the fitted peak areas.

Automated optical distance measurements for counting at a defined solid angle.

Two optical distance measurement devices have been compared for accurately defining the source-detector geometry of alpha-particle counters. The first consists of a travelling microscope with unifocal lens, to which a linear distance gauge is attached. The focusing is done by human eye.

The Fe half-life measured with a pressurised proportional counter.

The half-life of Fe has been measured accurately by following the decay curve of three sources with a large pressurised proportional counter. An argon(90%)-methane(10%) mixture was used as counter gas, at atmospheric pressure (∼1 × 10 Pa) and at enhanced pressures of 5 × 10 Pa and 8 × 10 Pa (for 1 source), respectively. The first measurements were performed in 2001, but the experiment was executed more systematically between 2005 and 2018, covering a period of about 5 half-lives.

Measurement of absolute γ-ray emission probabilities in the decay of Ac in equilibrium with its progeny.

The emission probabilities of γ rays produced in the Ac decay series were determined by high-resolution γ-ray spectrometry of sources with standardised activity. The sources were prepared quantitatively on glass discs by drop deposition of a solution with Ac in radioactive equilibrium with its daughter nuclides. Their activity was measured by a primary standardisation technique based on alpha-particle counting at a defined low solid angle.

Linearity check of an ionisation chamber through Tc half-life measurements.

The half-life of Tc was measured at the JRC using the ionisation chamber 'IC1' (type Centronic IG12). The result, T(Tc) = 6.00660 (18) h, is in good agreement with literature data.

Two-step transplantation with adipose tissue-derived stem cells increases follicle survival by enhancing vascularization in xenografted frozen-thawed human ovarian tissue.

Study Question: Do adipose tissue-derived stem cells (ASCs) enhance vascularization and follicle survival in xenografted ovarian tissue using a two-step transplantation approach?

Summary Answer: Higher rates of oxygenation and vascularization of ovarian tissue, as well as increased follicle survival rates, were detected in the early post-grafting period.

What Is Known Already: ASCs have multilineage differentiation potential, proangiogenic properties and enhance vascularization in a peritoneal grafting site. Some studies suggest that using ASCs may improve ovarian tissue quality by enhancing graft angiogenesis.

Intercomparison of Tc, F and In activity measurements with radionuclide calibrators in Belgian hospitals.

This study presents current status of performance of radiopharmaceutical activity measurements using radionuclide calibrators in Belgium. An intercomparison exercise was performed among 15 hospitals to test the accuracy of Tc, F and In activity measurements by means of radionuclide calibrators. Four sessions were held in different geographical regions between December 2013 and February 2015.

Measurement of absolute γ-ray emission probabilities in the decay of U.

Accurate measurements were performed of the photon emission probabilities following the α decay of U to Th. Sources of highly enriched U were characterised in terms of isotopic composition by mass spectrometry and their activities were standardised by means of alpha-particle counting at a low defined solid angle. The standardised sources were subsequently measured by high-resolution γ-ray spectrometry with calibrated high-purity germanium detectors to determine the photon emission probabilities.

Deconvolution of Pu conversion electron spectra measured with a silicon drift detector.

Internal conversion electron (ICE) spectra of thin Pu sources, measured with a windowless Peltier-cooled silicon drift detector (SDD), were deconvoluted and relative ICE intensities were derived from the fitted peak areas. Corrections were made for energy dependence of the full-energy-peak counting efficiency, based on Monte Carlo simulations. A good agreement was found with the theoretically expected internal conversion coefficient (ICC) values calculated from the BrIcc database.

Is decay constant?

Some authors have raised doubt about the invariability of decay constants, which would invalidate the exponential-decay law and the foundation on which the common measurement system for radioactivity is based. Claims were made about a new interaction - the fifth force - by which neutrinos could affect decay constants, thus predicting changes in decay rates in correlation with the variations of the solar neutrino flux. Their argument is based on the observation of permille-sized annual modulations in particular decay rate measurements, as well as transient oscillations at frequencies near 11 year and 12.

Direct measurement of alpha emission probabilities in the decay of Ra.

High-resolution alpha-particle spectrometry was performed to determine the main alpha-particle emission probabilities in the decay of Ra. Thin, homogeneous sources were prepared by electrodeposition on stainless steel disks. Alpha spectra with an energy resolution of 20keV were obtained in three laboratories and analysed with different deconvolution algorithms.

Advancements in NORM metrology - Results and impact of the European joint research project MetroNORM.

The results of the three years European Metrology Research Programme's (EMRP) joint research project 'Metrology for processing materials with high natural radioactivity' (MetroNORM) are presented. In this project, metrologically sound novel instruments and procedures for laboratory and in-situ NORM activity measurements have been developed. Additionally, standard reference materials and sources for traceable calibration and improved decay data of natural radionuclides have been established.

Evidence against solar influence on nuclear decay constants.

The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations.