112 research outputs found
The electron capture in Ho experiment – ECHo
No full textNeutrinos, and in particular their tiny but non-vanishing masses, can be considered one of the doors towards physics beyond the Standard Model. Precision measurements of the kinematics of weak interactions, in particular of theH β-decay and theHo electron capture (EC), represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture inHo experiment, ECHo, is designed to reach sub-eV sensitivity on the electron neutrino mass by means of the analysis of the calorimetrically measured electron capture spectrum of the nuclideHo. The maximum energy available for this decay, about 2.8 keV, constrains the type of detectors that can be used. Arrays of low temperature metallic magnetic calorimeters (MMCs) are being developed to measure theHo EC spectrum with energy resolution below 3 eV FWHM and with a time resolution below 1 μs. To achieve the sub-eV sensitivity on the electron neutrino mass, together with the detector optimization, the availability of large ultra-pureHo samples, the identification and suppression of background sources as well as the precise parametrization of theHo EC spectrum are of utmost importance. The high-energy resolutionHo spectra measured with the first MMC prototypes with ion-implantedHo set the basis for the ECHo experiment. We describe the conceptual design of ECHo and motivate the strategies we have adopted to carry on the present medium scale experiment, ECHo-1K. In this experiment, the use of 1 kBqHo will allow to reach a neutrino mass sensitivity below 10 eV/c. We then discuss how the results being achieved in ECHo-1k will guide the design of the next stage of the ECHo experiment, ECHo-1M, where a source of the order of 1 MBqHo embedded in large MMCs arrays will allow to reach sub-eV sensitivity on the electron neutrino mass
The SPES Laser Ion Source: Time Structure and Laser Enhancement Measurements with Sm+ beam
No full textA two-step resonance photo-ionization scheme has been used to ionize samarium atoms in the SPES tantalum hot-cavity ion source. The effect of the ion load on the ion beam time structure and the laser enhancement of the ion yield has been studied at different ion source temperatures. Generally, the introduction of more positive ions (ion load) affects negatively the overall confinement of the laser ions inside the volume of the ion source. Possible enhancement of the laser ion confinement through the introduction of neutrals is observed as well. The ion load is also observed to affect the confinement in the transfer line much more than in the hot cavity. Measurement of the time structure with inverted polarity of the cavity DC heating supply confirmed the significance of the longitudinal potential for ion extraction. The laser enhancements of the ion yield are found to be sensitive to the ion load at low operating temperature of the ion source i.e. 1800°C, whereas at 2050°C and 2200°C, they are relatively stable till an ion load value of 1.2 μA
The SPES laser ion source: Time structure, laser enhancement and efficiency measurements with gallium at ISOLDE Offline 2
No full textThe SPES laser ion source has been tested at ISOLDE Offline 2, CERN. A two-step single resonance photo-ionization scheme has been used to ionize gallium atoms in the SPES tantalum hot-cavity ion source. The ion beam time structure, laser enhancement of ion yield, and ionization efficiency are investigated in relation to the ion source temperature and ion load. From the time structures, it is inferred that a significant fraction of the extracted ions are generated in the transfer line rather than just in the hot cavity. The effect of the electrostatic axial field on the movement of ions inside the ion source is discussed. Generally, there is an inverse relationship between total ion load and the laser enhancement factor. This dependency is enhanced at lower operating temperature of the ion source. This is explained by the influence of thermionic electron emission and ion density on the transverse laser-ion confinement, and therefore the survival of ions as they drift towards the extraction region of the ion source. At 2200 °C, the nominal temperature for on-line operation of the ion source, the ratio of laser-ionized to surface-ionized gallium was stable around 55 during the measurement campaign, and independent of the total extracted ion current up to the measured value of 1.1 A. A resonance laser ionization efficiency value of 27.2% for gallium has been measured
Efficient Production of High Specific Activity Thulium-167 at Paul Scherrer Institute and CERN-MEDICIS
No full textThulium-167 is a promising radionuclide for nuclear medicine applications with potential use for both diagnosis and therapy (“theragnostics”) in disseminated tumor cells and small metastases, due to suitable gamma-line as well as conversion/Auger electron energies. However, adequate delivery methods are yet to be developed and accompanying radiobiological effects to be investigated, demanding the availability of 167Tm in appropriate activities and quality. We report herein on the production of radionuclidically pure 167Tm from proton-irradiated natural erbium oxide targets at a cyclotron and subsequent ion beam mass separation at the CERN-MEDICIS facility, with a particular focus on the process efficiency. Development of the mass separation process with studies on stable 169Tm yielded 65 and 60% for pure and erbium-excess samples. An enhancement factor of thulium ion beam over that of erbium of up to several 104 was shown by utilizing laser resonance ionization and exploiting differences in their vapor pressures. Three 167Tm samples produced at the IP2 irradiation station, receiving 22.8 MeV protons from Injector II at Paul Scherrer Institute (PSI), were mass separated with collected radionuclide efficiencies between 11 and 20%. Ion beam sputtering from the collection foils was identified as a limiting factor. In-situ gamma-measurements showed that up to 45% separation efficiency could be fully collected if these limits are overcome. Comparative analyses show possible neighboring mass suppression factors of more than 1,000, and overall 167Tm/Er purity increase in the same range. Both the actual achieved collection and separation efficiencies present the highest values for the mass separation of external radionuclide sources at MEDICIS to date.sponsorship: This research received funding from the Swiss National Science Foundation (SNF Grant Number: 200021_188495), the Research Foundation Flanders FWO (Belgium) under contracts FWO SBO Tb-IRMA-V No. S005019N and WO IRI ISOLDE No. I002619N, and the European Union's Horizon 2020 research and innovation programme under grant agreement No. 101008571 (PRISMAP - The European medical radionuclides programme). (Swiss National Science Foundation (SNF Grant)|200021_188495, Research Foundation Flanders FWO (Belgium)|S005019N, Research Foundation Flanders FWO (Belgium)|I002619N, European Union's Horizon 2020 research and innovation programme|101008571, Swiss National Science Foundation (SNF)|200021_188495)status: Publishe
Tunable spectral squeezers based on monolithically integrated diamond Raman resonators
No full textWe report on the generation and tuning of single-frequency laser light in a monolithic Fabry–Pérot diamond Raman resonator operating in the visible spectral range. The device was capable of squeezing the linewidth of a broad multi-mode nanosecond pump laser ([Formula: see text] 7.2 ± 0.9 GHz at [Formula: see text] 450 nm) to a nearly Fourier-limited single axial mode Stokes pulse ([Formula: see text] 114 ± 20 MHz at [Formula: see text] 479 nm). The tuning was achieved by precise adjustment of the resonator temperature, with a measured frequency-temperature tuning slope of [Formula: see text] −3 GHz/K, and a temperature dependence of the first-order Raman phonon line of [Formula: see text] +0.23 GHz/K. The Stokes center frequency was tuned continuously for over 20 GHz (more than twice the free spectral range of the resonator), which, in combination with the broad Ti:Sapphire laser spectral tunability, enables the production of Fourier-limited pulses in the 400–500 nm spectral range. The Stokes center-frequency fluctuations were 52 MHz (RMS) when the temperature of the resonator was actively stabilized. Moreover, the conversion efficiency was up to 30%, yielding an overall power spectral density enhancement of [Formula: see text] from pump to Stokes pulse
Resonance ionization scheme development for europium
No full textOdd-parity autoionizing states of europium have been investigated by resonance ionization spectroscopy via two-step, two-resonance excitations. The aim of this work was to establish ionization schemes specifically suited for europium ion beam production using the ISOLDE Resonance Ionization Laser Ion Source (RILIS). 13 new RILIS-compatible ionization schemes are proposed. The scheme development was the first application of the Photo Ionization Spectroscopy Apparatus (PISA) which has recently been integrated into the RILIS setup.</p
The CERN/ISOLDE Laser Ion Source
No full textLaser resonance photo-ionization an essential aspect of radioactive ion beam production for fundamental and applied physics research. The laser ion source of the ISOLDE facility, described here, is the most versatile of its type worldwide
Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE
No full textAt ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of–the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210–950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser–atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments
The identification of autoionizing states of atomic chromium for the resonance ionization laser ion source of the ISOLDE radioactive ion beam facility
No full textThis paper presents the results of an investigation into autoionizing states of atomic chromium, in the service of the resonance ionization laser ion source (RILIS): the principal ion source of the ISOLDE radioactive ion beam facility based at CERN. The multi-step resonance photo-ionization process enables element selective ionization which, in combination with mass separation, allows isotope specific selectivity in the production of radioactive ion beams at ISOLDE. The element selective nature of the process requires a multi-step “ionization scheme” to be developed for each element. Using the method of in-source resonance ionization spectroscopy, an optimal three-step, three-resonance photo-ionization scheme originating from the 3d5(6S)4s a7S3 atomic ground state has been developed for chromium. The scheme uses an ionizing transition to one of the 15 newly observed autoionizing states reported here. Details of the spectroscopic studies are described and the new ionization scheme is summarized
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