Mechanism and kinetics of a mineral transformation under hydrothermal conditions: Calaverite to metallic gold

No abstract availabl

Precise activity measurements of medical radionuclides using an ionization chamber: a case study with Terbium-161.

<sup>161</sup> Tb draws an increasing interest in nuclear medicine for therapeutic applications. More than 99% of the emitted gamma and X-rays of <sup>161</sup> Tb have an energy below 100 keV. Consequently, precise activity measurement of <sup>161</sup> Tb becomes inaccurate with radionuclide dose calibrators when using inappropriate containers or calibration factors to account for the attenuation of this low energy radiation. To evaluate the ionization chamber response, the sample activity must be well known. This can be performed using standards traceable to the Système International de Référence, which is briefly described as well as the method to standardize the radionuclides. In this study, the response of an ionization chamber using different container types and volumes was assessed using <sup>161</sup> Tb. The containers were filled with a standardized activity solution of <sup>161</sup> Tb and measured with a dedicated ionization chamber, providing an accurate response. The results were compared with standardized solutions of high-energy gamma-emitting radionuclides such as <sup>137</sup> Cs, <sup>60</sup> Co, <sup>133</sup> Ba and <sup>57</sup> Co. For the glass vial type with an irregular glass thickness, the <sup>161</sup> Tb measurements gave a deviation of 4.5% between two vials of the same type. The other glass vial types have a much more regular thickness and no discrepancy was observed in the response of the ionization chamber for these type of vials. Measurements with a plastic Eppendorf tube showed stable response, with greater sensitivity than the glass vials. Ionization chamber measurements for low-energy gamma emitters (< 100 keV), show deviation depending on the container type used. Therefore, a careful selection of the container type must be done for activity assessment of <sup>161</sup> Tb using radionuclide dose calibrators. In conclusion, it was highlighted that appropriate calibration factors must be used for each container geometry when measuring <sup>161</sup> Tb and, more generally, for low-energy gamma emitters

Determination of ¹⁶¹Tb half-life by three measurement methods.

The radiolanthanide <sup>161</sup> Tb is being studied as an alternative to <sup>177</sup> Lu for targeted radionuclide tumor therapy. Both β <sup>-</sup> -particle emitters show similar chemical behavior and decay characteristics, but <sup>161</sup> Tb delivers additional conversion and Auger electron emissions that may enhance the therapeutic efficacy. In this study, the half-life of <sup>161</sup> Tb was determined by a combination of three independent measurement systems: reference ionization chamber (CIR, chambre d'ionization de référence), portable ionization chamber (TCIR) and a CeBr <sub>3</sub> γ-emission detector with digital electronics. The half-life determined for <sup>161</sup> Tb is 6.953(2) days, showing a significant improvement in the uncertainty, which is one order of magnitude lower, with a deviation of 0.91% from the last nuclear data reference value. The previous large uncertainty of the half-life had a direct impact on activity measurements. Now it is no more an obstacle to a primary standardization

First-in-Humans Application of Tb-161:A Feasibility Study Using Tb-161-DOTATOC

(161)Tb has decay properties similar to those of (177)Lu but, additionally, emits a substantial number of conversion and Auger electrons. The aim of this study was to apply (161)Tb in a clinical setting and to investigate the feasibility of visualizing the physiologic and tumor biodistributions of (161)Tb-DOTATOC. Methods: (161)Tb was shipped from Paul Scherrer Institute, Villigen-PSI, Switzerland, to Zentralklinik Bad Berka, Bad Berka, Germany, where it was used for the radiolabeling of DOTATOC. In 2 separate studies, 596 and 1,300 MBq of (161)Tb-DOTATOC were administered to a 35-y-old male patient with a metastatic, well-differentiated, nonfunctional malignant paraganglioma and a 70-y-old male patient with a metastatic, functional neuroendocrine neoplasm of the pancreatic tail, respectively. Whole-body planar γ-scintigraphy images were acquired over a period of several days for dosimetry calculations. SPECT/CT images were reconstructed using a recently established protocol and visually analyzed. Patients were observed for adverse events after the application of (161)Tb-DOTATOC. Results: The radiolabeling of DOTATOC with (161)Tb was readily achieved with a high radiochemical purity suitable for patient application. Planar images and dosimetry provided the expected time-dependent biodistribution of (161)Tb-DOTATOC in the liver, kidneys, spleen, and urinary bladder. SPECT/CT images were of high quality and visualized even small metastases in bones and liver. The application of (161)Tb-DOTATOC was well tolerated, and no related adverse events were reported. Conclusion: This study demonstrated the feasibility of imaging even small metastases after the injection of relatively low activities of (161)Tb-DOTATOC using γ-scintigraphy and SPECT/CT. On the basis of this essential first step in translating (161)Tb to clinics, further efforts will be directed toward the application of (161)Tb for therapeutic purposes

A New Boson with a Mass of 125 GeV Observed with the CMS Experiment at the Large Hadron Collider

The Higgs boson was postulated nearly five decades ago within the framework of the standard model of particle physics and has been the subject of numerous searches at accelerators around the world. Its discovery would verify the existence of a complex scalar field thought to give mass to three of the carriers of the electroweak force-the W+, W-, and Z(0) bosons-as well as to the fundamental quarks and leptons. The CMS Collaboration has observed, with a statistical significance of five standard deviations, a new particle produced in proton-proton collisions at the Large Hadron Collider at CERN. The evidence is strongest in the diphoton and four-lepton (electrons and/or muons) final states, which provide the best mass resolution in the CMS detector. The probability of the observed signal being due to a random fluctuation of the background is about 1 in 3 x 10(6). The new particle is a boson with spin not equal to 1 and has a mass of about 1.25 giga-electron volts. Although its measured properties are, within the uncertainties of the present data, consistent with those expected of the Higgs boson, more data are needed to elucidate the precise nature of the new particle

Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC

The article is the pre-print version of the final publishing paper that is available from the link below.Results are presented from searches for the standard model Higgs boson in proton–proton collisions At √s = 7 and 8 TeV in the Compact Muon Solenoid experiment at the LHC, using data samples corresponding to integrated luminosities of up to 5.1 fb−1 at 7TeV and 5.3 fb−1 at 8 TeV. The search is performed in five decay modes: γγ, ZZ, W+W−, τ+τ−, and bb. An excess of events is observed above the expected background, with a local significance of 5.0 standard deviations, at a mass near 125 GeV, signalling the production of a new particle. The expected significance for a standard model Higgs boson of that mass is 5.8 standard deviations. The excess is most significant in the two decay modes with the best mass resolution, γγ and ZZ; a fit to these signals gives a mass of 125.3±0.4(stat.)±0.5(syst.) GeV. The decay to two photons indicates that the new particle is a boson with spin different from one