Search results for "Stability"
showing 10 items of 3085 documents
Recent developments for high-precision mass measurements of the heaviest elements at SHIPTRAP
2013
Abstract Atomic nuclei far from stability continue to challenge our understanding. For example, theoretical models have predicted an “island of stability” in the region of the superheavy elements due to the closure of spherical proton and neutron shells. Depending on the model, these are expected at Z = 114, 120 or even 126 and N = 172 or 184. Valuable information on the road to the island of stability is derived from high-precision mass measurements, which give direct access to binding energies of short-lived trans-uranium nuclei. Recently, direct mass measurements at SHIPTRAP have been extended to nobelium and lawrencium isotopes around the deformed shell gap N = 152. In order to further …
Thermal relaxation of colour centres in LiBaF3crystals
2001
Abstract Processes in LiBaF3 crystals caused by the thermal decay of F-type centres created by X-irradiation at room temperature have been examined. It is shown that the thermal decay of F-type centres results in the formation of two kinds of electron centres peaking at 630 nm and 740 nm differing in thermal stability. Weak TSL intensity, accompanying the decay of F-centres, also observed as well as the low value of the process activation energy suggest that due to the presence of moving anion vacancies a random walk of the F-centres occur. We propose that in course of the random walk of the F-centres both the aggregate F-centres are created and the annihilation with some complementary radi…
High-resolution spectroscopy of gaseous $^\mathrm{83m}$Kr conversion electrons with the KATRIN experiment
2020
In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous $^\mathrm{83m}$Kr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The results obtained in this calibration measurement represent a major commissioning milestone for the upcoming direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the full KATRIN beamline. The KATRIN main spectrometer's excellent energy resolution of ~ 1 eV made it possible to determine the narrow K-32 and L$_3$-32 conversion electron line widths with an unprecedented precision of ~ 1 %.
Light-induced formation of metastable high-spin states in [Fe(mtz)6](CiO4)2
1988
[Fe(mtz)6](CiO4)2 (mtz=1-methyltetrazole) is a spin crossover compound with two different iron(II) lattice sites. Only one of them (lattice site A) shows thermally induced high spin (HS) ⇌ low spin (LS) spin transition. The LIESST effect (Light-Induced Excited Spin State Trapping) can be observed below 50 K. Complex molecules in B-sites remain in HS state at all temperatures. At ∼ 20 K irradiation with red light causes a partial conversion to another HS species, HS(C), with also practically infinite lifetime.
New time-differential Mössbauer emission measurements on the high-spin→low-spin relaxation in [57Co/Co(phen)3](ClO4)2
1990
Using our new spectrometer for time-differential Mossbauer emission spectroscopy we reinvestigated the high-spin→low-spin relaxation following the57Co(EC)57Fe process in [57Co/Co(phen)3](ClO4)2 (phen=1,10-phenanthroline). In contrast to former investigations we found a temperature dependent initial population less than 1 for the metastable high-spin states. The results and the data evaluation method are presented.
The electronion scattering experiment ELISe at the International Facility for Antiproton and Ion Research (FAIR) - A conceptual design study
2011
The electronion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented. © 2011 Elsevier B.V. All rights reserved.
Conversion electron spectroscopy at IGISOL
2012
Conversion elecron spectroscopy has been an important part of the nuclear spectrocopy research at the Department of Physics of the University of Jyv¨askyl¨a since the commissioning of the first cyclotron in the mid 1970s. At the IGISOL facility a specialiced conversion electron spectrometer ELLI was developed in the late 1980s. The first results with ELLI were obtained using the beams from the old MC-20 cyclotron to study newly discovered isotopes of refractory fission products. In the present K130 cyclotron laboratory ELLI has been utilized in many decay-spectroscopy experiments both neutron-deficient and neutron-rich side of the valley of stability. In the early 2000s the new JYFLTRAP ion…
Molecular Mobility in Glassy Bread: A Multispectroscopy Approach
1999
ABSTRACT The molecular mobility in low-moisture (<9%, web) white bread was studied as a function of temperature using pulsed-proton nuclear magnetic resonance (NMR), and dielectric and dynamic mechanical spectroscopies. The water was mobile, even in glassy samples. Different processes below glass transition temperature (sub-Tg) were observed, and a relaxation map of the studied system was drawn. These results have been interpreted and extrapolated to suggest that the Tg is not a universal predictive parameter for the physical stability of glassy food.
DETERMINATION OF NUCLEAR GROUND STATE PROPERTIES FAR FROM STABILITY BY OPTICAL PUMPING
1973
The possibilities of determining nuclear spin, moments and variation in charge volume by optical pumping of on line masseparated isotopes are described for the example of the isotopic chain lY1Hg-205Hg. The variation in nuclear charge volume (6 ) along this chain and in particular its abrupt change for the lightest Hg-isotopes, indicating a phase transition in nuclear structure, are discussed. 1. Introduction. - This talk is based on expe- riments (I), (2), (3) performed recently by a visiting team (*) at the ISOLDE facility at CERN with the members : J. Bonn, G. Huber, H.-J. Kluge, U. Kopf, L. Kugler, J. Rodriguez, and E. W. Otten. The investigation of the hyperfine structure (hfs) and iso…
About the Reliability of Extrapolation of Nuclear Structure Data for r-process Calculations
2002
Gross decay properties are the nuclear part of the input for calculations of elemental abundances. They depend, sometimes very sensitively, on details of nuclear structure. Models for predictions of nuclear masses and shapes have to be used for isotopes very far from stability. The reliability of extrapolations far from experimentally reachable nuclei is, however, not always granted due to singularities in the nuclear landscape. We review data on the region of the neutron-rich isotopes near A = 100, which is a region of especially dramatic changes.