Perspectives of Nuclear Physics in Europe: NuPECC Long Range Plan 2010

The goal of this European Science Foundation Forward Look into the future of Nuclear Physics is to bring together the entire Nuclear Physics community in Europe to formulate a coherent plan of the best way to develop the field in the coming decade and beyond.<p></p> The primary aim of Nuclear Physics is to understand the origin, evolution, structure and phases of strongly interacting matter, which constitutes nearly 100% of the visible matter in the universe. This is an immensely important and challenging task that requires the concerted effort of scientists working in both theory and experiment, funding agencies, politicians and the public.<p></p> Nuclear Physics projects are often “big science”, which implies large investments and long lead times. They need careful forward planning and strong support from policy makers. This Forward Look provides an excellent tool to achieve this. It represents the outcome of detailed scrutiny by Europe’s leading experts and will help focus the views of the scientific community on the most promising directions in the field and create the basis for funding agencies to provide adequate support.<p></p> The current NuPECC Long Range Plan 2010 “Perspectives of Nuclear Physics in Europe” resulted from consultation with close to 6 000 scientists and engineers over a period of approximately one year. Its detailed recommendations are presented on the following pages. For the interested public, a short summary brochure has been produced to accompany the Forward Look.<p></p&gt

Final report of the EURISOL Design Study (2005-2009) A Design Study for a European Isotope-Separation-On-Line Radioactive Ion Beam Facility

European Commission Contract N°515768 RIDS Published by GANI

Development of a Beam Profile Monitor/Time of Flight setup for HISPEC/DESPEC for FAIR

The Helmholtz Gesellschaft für Schwerionenforschung GmbH will be expanded by the Facility for Antiproton and Ion Research in upcoming years. Different, international collaborations have been formed in order to effectively use the accelerator facilities, which will become available. The collaboration Nuclear Structure, Astrophysics and Reactions deals with the usage of high energetic, radioactive ion beams for nuclear physics experiments. During such experiments it is possible to slow down these ions to energies of 5 to 10 MeV/u to open certain reaction channels. A problem with the slowing down is the introduction of additional energy and spatial straggling as well as a further fragmentation of the original ion beam. To be able to nevertheless select the desired ion, an additional detector is needed directly after the slowing down and before the target. Within the framework of this thesis, such a detector system has been developed and tested. One demand to such a system is a largest possible transparency, not to degrade or even stop the ion beam, which is to be examined. As a solution a design on the basis of an emissive foil has been chosen. Thereby electrons will be emitted out of a thin foil if passed by an ion. These so-called secondary electrons are then accelerated and confined by an electrostatic top-assembly towards the proper detector head where they are position sensitively registered. In this way the ions can be detected indirectly. Using two of such units, the flight path of a single ion can be reconstructed and discriminated against other kinds of ions, additionally. A first prototype was built and continuously developed further. By measurements with radioactive sources its efficiency, spatial and timing resolution was tested. The insights gained therefrom were used to develop a second prototype. With regards to the future use, an as compact as possible, integrated design has been focused on. To investigate the second prototype, a dedicated beamline for detector tests and the simulation of slowed down beams was built at the Cologne FN tandem accelerator. This testbed is open to the collaboration and has already been used successfully

Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process

Although the theory for the rapid neutron-capture process (r-process) was developed more than 55 years ago, the astrophysical site is still under a debate. Theoretical studies predict that the r-process path proceeds through very neutron-rich nuclei with very asymmetric protonto-neutron ratios. Knowledge about the properties of neutron-rich isotopes found in similarregions of the nuclear chart and furthermore suitable for r-process studies is still little or evennot existing. The basic nuclear properties such as binding energies, half-lives, neutron-inducedor neutron-capture reaction cross-sections, play an important role in theoretical simulations andcan vary or even drastically alternate results of these studies. Therefore, a considerable effortwas put forward to access neutron-rich isotopes at radioactive ion-beam facilities like ISOLDE at CERN. The goal of this PhD thesis is to describe the experimental work done for the precision mass measurements of neutron-rich cadmium (129-131Cd) and caesium (132,146-148Cs) isotopes. Measurements were done at the on-line radioactive ion-beam facility ISOLDE by using the fourtrap mass spectrometer ISOLTRAP. The cadmium isotopes are key nuclides for the synthesis of stable isotopes around the mass peak A = 130 in the Solar System abundance

Characterisation and functional test of the full readout chain of a microdosimeter using scintillating plastic optical fibres

Tese de Mestrado Integrado, Engenharia Física, 2022, Universidade de Lisboa, Faculdade de CiênciasInstruments with a high spatial resolution are necessary to measure dosimetric quantities at a cellular level in order to have a better delineation of treatment plans in radiotherapy. The work here described is within a project aiming to develop a new detector capable of measuring real time absorbed dose with sub-millimetre resolution. The device is constructed using juxtaposed scintillating plastic optical fibres (SPOF) readout by a multi-anode photomultiplier (MAPMT, Hamamatsu H8500D) and a data acquisition (DAQ) system. In this thesis a first validation of the full readout chain is done, going through the characterisation of the different elements composing this detector. Using a dedicated test bench SPOFS (Kuraray SCSF-78) of 1 mm and 0.5 mm were optically characterised, measuring basic properties, such as light yields and attenuation lengths, before measuring the crosstalk between juxtaposed optical fibres. Methods of analysis were designed to compare the signal from an isolated and ribbon SPOF. Next, the MAPMT’s key characteristics were studied using a UV-LED exciting SPOF, to guide the light to individual MAPMT cells, and a picoammeter as a readout system. Concerning the assembly of the MAPMT in a detector assembly, the ideal conditions to achieve a light tight setup were evaluated. The full readout chain was completed by including a costumed DAQ board. Pulsed LEDs were firstly used to evaluate main limitations in signal response of the readout chain. Radioactive sources were then used to test the sensibility to particles (betas, gammas and alphas). In terms of results, the crosstalk study needs further revision, specially quantifying its value. The MAPMT’s performance was characterised and validated, whereas the DAQ board observed saturation and response to particles needs more understanding. However, the integration of the three elements of the microdosimeter was achieved and could be implemented into a first prototype

Exploring magicity around N = 32 & 34 in Z >= 20 isotopes via precision mass measurements and developments with the TITAN MR-TOF mass spectrometer

The Nuclear Shell Model provided the first coherent description of the nucleus which accounted for a wide range of nuclear properties. The model originated from observations of particularly stable isotopes with certain numbers, known as `magic numbers’, of protons and neutrons. At the time it was developed, in the 1960s, observations were limited to naturally occurring, and therefore stable, isotopes. With the advent of radioactive beam facilities, new studies indicate that the magic numbers seem to evolve and model corrections are required. In this thesis, the TITAN Multiple-Reflection Time-Of-Flight Mass Spectrometer (MR-TOF-MS) was employed to study `new' magic numbers N=32,34 across a range of isotopic chains about the traditionally magic Z=20. This work includes a characterisation of the TITAN MR-TOF-MS and high-precision mass measurements of 54Ca, 54,55Sc, 54-56Ti, and 54-58V. Isotopes of neutron-rich Ca, Sc, Ti and V were produced at the TRIUMF-ISAC facility and transported to the TITAN facility for measurement. The results show magicity at N=32 is at a maximum in 52Ca, and the effects decrease with increasing Z across the isotopes measured, the effects are slightly weaker in 53Sc, and cease between 54Ti and 55V. This evolution is dramatically different due to the new measurements of 54,55Sc. The precision on the masses of all isotopes measured in the study is improved in comparison to the AME2016, and results include the first ever direct mass measurement of 58V. The evolution of N=32,34 magicity is explored via these new high-precision mass measurements

Monte Carlo modelling and radiation measurement with ATAGS, the XArray, and SATURN at CARIBU

The CAlifornium Rare Isotope Breeder Upgrade (CARIBU) at Argonne National Laboratory (ANL), USA allows access to, and measurement of, a broad range of neutron-rich nuclei with high intensities and purity. These nuclei are important test cases to expand our understanding of atomic nuclear structure, nuclear astrophysical processes and nuclear energy application. The thesis project encompasses the measurement of short-lived radioactive nuclei from CARIBU using various techniques, including Total Absorption Gamma-ray Spectroscopy (TAGS), gamma-ray coincidence spectroscopy and beta-decay spectroscopy. The two detectors used - the ATAGS spectrometer and the XArray and SATURN decay-spectroscopy station (called XSAT as a combined system) - required complex Monte Carlo radiation transport models in order to interpret the results of recent experiments. The TAGS technique was implemented at CARIBU by the recommissioning of a large, well-type NaI(Tl) scintillator detector. The detector performance was evaluated through testing of the well-known cases of 141Cs and 140Cs. This experimental program was extended to investigate the less-well-known beta-feeding intensities of 141Xe, 140Xe and 104mNb/104Nb. In addition, a Monte Carlo model of XSAT was constructed, validated and applied to the specific cases of 134Sb, 134mSb, 92Rb, 104Nb and 106Nb in this work. This enabled the determination of the 134mSb/134Sb branching ratio resulting from 252Cf decay, measurement of 92Rb decay with implications for the so-called 'anti-neutrino anomaly', and the interpretation of the complex spectroscopy following the beta-decay of 104Nb->104Mo and 106Nb->106Mo. This Monte Carlo modelling was a key element in obtaining and interpreting results from each of these three experiments

Titanium carbide-carbon porous nanocomposite materials for radioactive ion beam production:processing, sintering and isotope release properties

The Isotope Separator OnLine (ISOL) technique is used at the ISOLDE - Isotope Separator OnLine DEvice facility at CERN, to produce radioactive ion beams for physics research. At CERN protons are accelerated to 1.4 GeV and made to collide with one of two targets located at ISOLDE facility. When the protons collide with the target material, nuclear reactions produce isotopes which are thermalized in the bulk of the target material grains. During irradiation the target is kept at high temperatures (up to 2300 °C) to promote diffusion and effusion of the produced isotopes into an ion source, to produce a radioactive ion beam. Ti-foils targets are currently used at ISOLDE to deliver beams of K, Ca and Sc, however they are operated at temperatures close to their melting point which brings target degradation, through sintering and/or melting which reduces the beam intensities over time. For the past 10 years, nanostructured target materials have been developed and have shown improved release rates of the produced isotopes, due to the short diffusion distances and high porosities. In here a new Ti-based refractory material is developed to replace the currently used Ti-foils. Since nanometric TiC can't be maintained at high temperatures (T>1200 °C) due to sintering, a processing route was developed to produce TiC-C nanocomposites where the carbon allotropes used were either graphite, carbon black or multi wall carbon nanotubes (MWCNT). The developed nanocomposites sinterability was tested up to 1800 °C and they were characterized according to dimensional changes, relative density, mass losses, surface area, TiC particle size and microstructure morphology. All carbon allotropes had a significant effect on the stabilization of the nanometric TiC where the best result was obtained for a 1:1 volume ratio of TiC:carbon black at 1800 °C where TiC crystallite sizes were of 76 nm (from 51 nm in green) and density of 55 %, followed by TiC:MWCNT with TiC of 138 nm (58 % dense). The processing introduced a ZrO2 contamination from the milling media, forming ZrC that solubilizes in the TiC phase, increasing its lattice parameter. TiC sintering kinetics were studied through the master sintering curve and the activation energy determined for sintering, 390 kJ/mol, were close to the ones obtained in the literature. Using the same method, the calculated activation energy for TiC-carbon black was 555 kJ/mol resulting from the carbon which reduces the TiC sintering, reducing its coordination number. The nanocomposites referred (and the TiC) were irradiated and studied in terms of isotope (Be, Na, Mg, K, Sc and Ca) release, where the nanocomposite with the highest isotope released fraction, TiC-carbon black was selected for the final target material. To produce a full target the processing was scaled up and a target prototype was build and tested at ISOLDE. Li, Na and K isotope intensities and release time-structure were measured from the target prototype, where in comparison with Ti-based materials, Na and Li intensities were higher, K were slightly lower and Ca were lower. The target presents an apparently longer release time structure when comparing with standard materials, as seen in other nanomaterial targets, which is likely related with effusion of the isotopes in the material porosity. Furthermore, contrarily to the Ti-foil targets, the obtained intensities were stable over the full operation time. At the end of this thesis suggestions for a future work which include a second iteration of the TiC-C nanocomposite (already developed) and further modeling