| 1. |
- Hyldegaard, S., et al.
(författare)
-
R-matrix analysis of the beta decays of 12N and 12B
- 2010
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 81:2
-
Tidskriftsartikel (refereegranskat)abstract
- The β decays of 12N and 12B have been studied at KVI and JYFL to resolve the composition of the broad and interfering 0+ and 2+ strengths in the triple-α continuum. For the first time a complete treatment of 3α decay is presented including all major breakup channels. A multilevel, many-channel R-matrix formalism has been developed for the complete description of the breakup in combination with the recently published separate analysis of angular correlations. We find that, in addition to the Hoyle state at 7.65 MeV, more than one 0+ and 2+ state is needed to reproduce the spectra. Broad 03+ and 22+ states are found between 10.5 and 12 MeV in this work. The presence of β strength up to the 12N Q-value window suggests the presence of additional 0+ and 2+ components in the 12C structure at energies above 12.7 MeV.
|
|
| 2. |
- Fynbo, H. O. U., et al.
(författare)
-
The β-decay approach for studying 12C
- 2008
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 111:1
-
Tidskriftsartikel (refereegranskat)abstract
- The β-decays of the mirror nuclei 12B and 12N both populate states in 12C and they are therefore a precious source of information about this nucleus. Due to the selection rules of β-decay only 0+, 1+ and 2+ states are populated. This allows a very clean study of unbound states just above the 3α-threshold with those spin and parities. This probe has been applied in two experiments using two complementary experimental techniques: in the first the three α-particles emitted after β-decay are measured in coincidence in separate detectors using the ISOL method, while in the second method 12B and 12N are implanted in a detector and the summed energy of the three α-particles is measured directly. Preliminary results from the two approaches are presented. © 2008 IOP Publishing Ltd.
|
|
| 3. |
- Hyldegaard, S., et al.
(författare)
-
Precise branching ratios to unbound 12C states from 12N and 12B [beta]-decays
- 2009
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 678:5, s. 459 - 464
-
Tidskriftsartikel (refereegranskat)abstract
- Two complementary experimental techniques have been used to extract precise branching ratios to unbound states in 12C from 12N and 12B [beta]-decays. In the first the three [alpha]-particles emitted after [beta]-decay are measured in coincidence in separate detectors, while in the second method 12N and 12B are implanted in a detector and the summed energy of the three [alpha]-particles is measured directly. For the narrow states at 7.654 MeV (0+) and 12.71 MeV (1+) the resulting branching ratios are both smaller than previous measurements by a factor of [similar, equals]2. The experimental results are compared to no-core shell model calculations with realistic interactions from chiral perturbation theory, and inclusion of three-nucleon forces is found to give improved agreement.
|
|
| 4. |
|
|
| 5. |
- Kirsebom, O. S., et al.
(författare)
-
Measurement of the 2+→0+ ground-state transition in the β decay of F 20
- 2019
-
Ingår i: Physical Review C. - 2469-9985. ; 100:6
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first detection of the second-forbidden, nonunique, 2+→0+, ground-state transition in the β decay of F20. A low-energy, mass-separated F+20 beam produced at the IGISOL facility in Jyväskylä, Finland, was implanted in a thin carbon foil and the β spectrum measured using a magnetic transporter and a plastic-scintillator detector. The β-decay branching ratio inferred from the measurement is bβ=[0.41±0.08(stat)±0.07(sys)]×10-5 corresponding to logft=10.89(11), making this one of the strongest second-forbidden, nonunique β transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on Ne20 is now known to within better than 25% at the relevant temperatures and densities.
|
|
| 6. |
- Kirsebom, O. S., et al.
(författare)
-
Precise and accurate determination of the B-8 decay spectrum
- 2011
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 83:6
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate measurements of the B-8 neutrino spectrum are important for the interpretation of solar neutrino data. Experimentally, the B-8 neutrino spectrum can be obtained from the measurement of the beta-delayed alpha spectrum. We report on an alpha-alpha coincidence measurement performed at the IGISOL facility in Jyvaskyla, Finland. Our measurement allows extensive cross-checks to be performed and gives a more intense neutrino spectrum at high energies compared to the present standard. The deviation reaches 4% at the end point of the spectrum. Below 11 MeV, the deviation is less than 1%.
|
|
| 7. |
|
|
| 8. |
- Lorenz, Ch, et al.
(författare)
-
β Decay of 127Cd and Excited States in 127In
- 2019
-
Ingår i: Physical Review C. - 2469-9985. ; 99:4
-
Tidskriftsartikel (refereegranskat)abstract
- A dedicated spectroscopic study of the β decay of 127Cd was conducted at the IGISOL facility at the University of Jyväskylä. Following high-resolution mass separation in a Penning trap, β-γ-γ coincidences were used to considerably extend the decay scheme of 127In. The β-decaying 3/2+ and 11/2- states in 127Cd have been identified with the 127Cd ground state and the 283-keV isomer. Their respective half-lives have been measured to 0.45(+12-8)s and 0.36(4) s. The experimentally observed β feeding to excited states of 127In and the decay scheme of 127In are discussed in conjunction with large-scale shell-model calculations.
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Sarmiento Pico, Luis, et al.
(författare)
-
Elucidating the nature of the proton radioactivity and branching ratio on the first proton emitter discovered 53mCo
- 2023
-
Ingår i: Nature Communications. - 2041-1723. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- The observation of a weak proton-emission branch in the decay of the 3174keV 53mCo isomeric state marked the discovery of proton radioactivity in atomic nuclei in 1970. Here we show, based on the partial half-lives and the decay energies of the possible proton-emission branches, that the exceptionally high angular momentum barriers, lp = 9 and lp = 7, play a key role in hindering the proton radioactivity from 53mCo, making them very challenging to observe and calculate. Indeed, experiments had to wait decades for significant advances in accelerator facilities and multi-faceted state-of-the-art decay stations to gain full access to all observables. Combining data taken with the TASISpec decay station at the Accelerator Laboratory of the University of Jyväskylä, Finland, and the ACTAR TPC device on LISE3 at GANIL, France, we measured their branching ratios as bp1 = 1.3(1)% and bp2 = 0.025(4)%. These results were compared to cutting-edge shell-model and barrier penetration calculations. This description reproduces the order of magnitude of the branching ratios and partial half-lives, despite their very small spectroscopic factors.
|
|
| 13. |
|
|
| 14. |
- Hyldegaard, S., et al.
(författare)
-
Branching ratios in the beta decays of N-12 and B-12
- 2009
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 80:4
-
Tidskriftsartikel (refereegranskat)abstract
- Absolute branching ratios to unbound states in C-12 populated in the beta decays of N-12 and B-12 are reported. Clean sources of N-12 and B-12 were obtained using the isotope separation on-line (ISOL) method. The relative branching ratios to the different populated states were extracted using single-alpha as well as complete kinematics triple-alpha spectra. These two largely independent methods give consistent results. Absolute normalization is achieved via the precisely known absolute branching ratio to the bound 4.44 MeV state in C-12. The extracted branching ratios to the unbound states are a factor of three more precise than previous measurements. Branching ratios in the decay of Na-20 are also extracted and used to check the results.
|
|
| 15. |
- Knudsen, H. H., et al.
(författare)
-
Beta-decay of 13O
- 2005
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 72:4, s. 044312-
-
Tidskriftsartikel (refereegranskat)abstract
- The beta decay of O-13 has been studied at the IGISOL facility of the Jyvaskyla accelerator centre (Finland). By developing a low-energy isotope-separated beam of O-13 and using a modern segmented charged-particle detector array an improved measurement of the delayed proton spectrum was possible. Protons with energy up to more than 12 MeV are measured and the corresponding log(ft) values extracted. A revised decay scheme is constructed. The connection to molecular states and the shell model is discussed.
|
|
| 16. |
- Kolhinen, V. S., et al.
(författare)
-
Recommissioning of JYFLTRAP at the new IGISOL-4 facility
- 2013
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 317:Part B, s. 506-509
-
Tidskriftsartikel (refereegranskat)abstract
- The JYFLTRAP double Penning-trap system was moved to a new location along with the Ion Guide Isotope Separator On-line (IGISOL) facility at the Accelerator Laboratory of the University of Jyväskylä. The move made it possible to upgrade various parts of the facility. For example, separate beam lines for JYFLTRAP and the collinear laser spectroscopy station were constructed after the radio-frequency quadrupole cooler and buncher. In this contribution we give an overview of the new JYFLTRAP facility and results from the first stable ion-beam tests.
|
|
| 17. |
- Kraus, Ludwig, 1955-, et al.
(författare)
-
Self-exclusion from gambling : A toothless tiger?
- 2022
-
Ingår i: Frontiers in Psychiatry. - : Frontiers Media SA. - 1664-0640. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- While there is evidence for self-exclusion (SE) as an individual-level harm reduction intervention, its effects on reducing harm from gambling at the population level remain unclear. Based on a review of national legal frameworks and SE programs, including their utilization and enforcement in selected high-income societies, the present analysis aims to explore the reach and strengths of SE in the protection of gamblers in these jurisdictions. It places particular emphasis on SE programs' potential to prevent and minimize gambling harm at the population level. The overview examined SE in Finland, Germany, Italy, Massachusetts (USA), Norway, Sweden, and Victoria (Australia). These jurisdictions differ considerably in how gambling is regulated as well as in how SE is implemented and enforced. The reach and extent of enforcement of SE apparently vary with the polity's general policy balance between reducing gambling problems and increasing gambling revenue. But in any case, though SE may benefit individual gamblers and those around them, it does not appear to be capable of significantly reducing gambling harm at the population level. To render SE programs an effective measure that prevents gamblers and those linked to them from financial, social, and psychological harm, utilization needs to be substantially increased by reforming legal regulations and exclusion conditions.
|
|
| 18. |
- Lundgren, S, et al.
(författare)
-
Somatic mutations in lymphocytes in patients with immune-mediated aplastic anemia
- 2021
-
Ingår i: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 35:115, s. 1365-1379
-
Tidskriftsartikel (refereegranskat)abstract
- The prevalence and functional impact of somatic mutations in nonleukemic T cells is not well characterized, although clonal T-cell expansions are common. In immune-mediated aplastic anemia (AA), cytotoxic T-cell expansions are shown to participate in disease pathogenesis. We investigated the mutation profiles of T cells in AA by a custom panel of 2533 genes. We sequenced CD4+ and CD8+ T cells of 24 AA patients and compared the results to 20 healthy controls and whole-exome sequencing of 37 patients with AA. Somatic variants were common both in patients and healthy controls but enriched to AA patients’ CD8+ T cells, which accumulated most mutations on JAK-STAT and MAPK pathways. Mutation burden was associated with CD8+ T-cell clonality, assessed by T-cell receptor beta sequencing. To understand the effect of mutations, we performed single-cell sequencing of AA patients carrying STAT3 or other mutations in CD8+ T cells. STAT3 mutated clone was cytotoxic, clearly distinguishable from other CD8+ T cells, and attenuated by successful immunosuppressive treatment. Our results suggest that somatic mutations in T cells are common, associate with clonality, and can alter T-cell phenotype, warranting further investigation of their role in the pathogenesis of AA.
|
|
| 19. |
- Nesterenko, D. A., et al.
(författare)
-
High-precision mass measurements for the isobaric multiplet mass equation at A = 52
- 2017
-
Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 44:6
-
Tidskriftsartikel (refereegranskat)abstract
- Masses of 52Co, 52Com, 52Fe, 52Fem, and 52Mn have been measured with the JYFLTRAP double Penning trap mass spectrometer. The isobaric multiplet mass equation for the T = 2 quintet at A = 52 has been studied employing the new mass values. No significant breakdown (beyond the level) of the quadratic form of the IMME was observed (). The cubic coefficient was 6.0(32) keV (). The excitation energies for the isomer and the T = 2 isobaric analog state in 52Co have been determined to be 374(13) keV and 2922(13) keV, respectively. The measured mass values for 52Co and 52Com are 29(10) keV and 16(15) keV higher, respectively, than obtained in a recent storage-ring experiment, and significantly lower than predicted by extrapolations. Consequently, this has an impact on the proton separation energies for 52Co and 53Ni relevant for the astrophysical rapid proton capture process. The Q value for the proton decay from the isomer in 53Co has been determined with an unprecedented precision, keV.
|
|
| 20. |
|
|
| 21. |
|
|
| 22. |
- Ansell, Anna, et al.
(författare)
-
Molecular cross-talk between head and neck squamous cell carcinoma cells and cancer-associated fibroblasts
- 2013
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Cancer-associated fibroblasts (CAFs) are one of the main components of the tumor stroma and are known to increase tumor growth and stimulate invasion and metastasis. Increasing evidence suggests that CAFs may also be an important determinant of the response to various treatments. In this study we aimed to characterize the molecular cross-talk between CAFs and head and neck squamous cell carcinoma (HNSCC) cells.HNSCC cell lines were co-cultured with their patient-matched CAFs for seven days, after which the gene expression of tumor cells was investigated by Affymetrix microarray. 58 protein coding genes were found to be differentially expressed (Q≤0.05) in tumor cells cocultured with CAFs when compared to tumor cells cultured alone. The top functions of these genes were cancer, cellular movement, and embryonic development as analyzed by Ingenuity Pathway Analysis. Nine genes were upregulated by ≥1.5-fold while the expression of 35 genes was found to be reduced by ≤ 0.67-fold. Several of the differentially expressed genes have been associated with epithelial-to-mesenchymal transition (EMT). The change in the expression of POSTN, GREM1, COL1A2, VIM, and MMP7 was verified by qPCR analysis. Moreover, the influence of CAFs on the proliferation, migration and cetuximab sensitivity of tumor cells was investigated, and was found to vary among the tumor cell-CAF pairs.In conclusion, we demonstrate that CAF-derived signals cause changes in the expression of multiple genes, several of which are associated with an EMT phenotype of tumor cells. Furthermore, CAFs modulate the proliferation, migration and cetuximab treatment response of tumor cells.
|
|
| 23. |
- Diget, C. A., et al.
(författare)
-
Breakup channels for C-12 triple-alpha continuum states
- 2009
-
Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 80:3
-
Tidskriftsartikel (refereegranskat)abstract
- The triple-alpha-particle breakup of states in the triple-alpha continuum of C-12 has been investigated by way of coincident detection of all three alpha particles of the breakup. The states have been fed in the beta decay of N-12 and B-12, and the alpha particles measured using a setup that covers all of the triple-alpha phase space. Contributions from the breakup through the Be-8(0(+)) ground state as well as other channels-interpreted as breakup through excited energies in Be-8-have been identified. Spins and parities of C-12 triple-alpha continuum states are deduced from the measured phase-space distributions for breakup through Be-8 above the ground state by comparison to a fully symmetrized sequential R-matrix description of the breakup. At around 10 MeV in C-12, the breakup is found to be dominated by 0(+) strength breaking up through the ghost of the Be-8(0(+)) ground state with L = 0 angular momentum between the first emitted alpha particle and the intermediate Be-8 nucleus. For C-12 energies above the 12.7 MeV 1(+) state, however, L = 2 breakup of a C-12 2(+) state through the Be-8(2(+)) excited state dominates. Furthermore, the possibility of a 2(+) excited state in the 9-12 MeV region of C-12 is investigated.
|
|
| 24. |
- Gao, Zhihao, et al.
(författare)
-
Benchmark of a multi-physics Monte Carlo simulation of an ionguide for neutron-induced fission products
- 2022
-
Ingår i: European Physical Journal. - : Springer Nature. - 1286-0042 .- 1286-0050. ; 58:2
-
Tidskriftsartikel (refereegranskat)abstract
- To enhance the production of medium-heavy,neutron-rich nuclei, and to facilitate measurements of independentyields of neutron-induced fission, a proton-toneutronconverter and a dedicated ion guide for neutroninducedfission have been developed for the IGISOL facilityat the University of Jyväskylä. The ion guide holds thefissionable targets, and the fission products emerging fromthe targets are collected in helium gas and transported to thedownstream experimental stations.Acomputer model, basedon a combination of MCNPX for modeling the neutron production,the fission code GEF, and GEANT4 for the transportof the fission products, was developed. The model willbe used to improve the setup with respect to the productionand collection of fission products. In this paper we benchmarkthe model by comparing simulations to a measurementin which fission products were implanted in foils located atdifferent positions in the ion guide. In addition, the productsfrom neutron activation in the titanium foil and the uraniumtargets are studied. The result suggests that the neutron fluxat the high-energy part of the neutron spectrum is overestimatedby approximately 40%.However, the transportation offission products in the uranium targets agrees with the experimentwithin 10%. Furthermore, the simulated transportationof fission products in the helium gas achieves almost perfectagreement with the measurement. Hence, we conclude thatthe model, after correction for the neutron flux, is well suitedfor optimization studies of future ion guide designs.
|
|
| 25. |
- Gao, Zhihao, et al.
(författare)
-
Fission studies at IGISOL/JYFLTRAP : Simulations of the ion guide for neutron-induced fission and comparison with experimental data
- 2020
-
Ingår i: ND 2019. - : EDP Sciences. - 9782759891061
-
Konferensbidrag (refereegranskat)abstract
- For the production of exotic nuclei at the IGISOL facility, an ion guide for neutron-induced fission has been developed and tested in experiments. Fission fragments are produced inside the ion guide and collected using a helium buffer gas. Meanwhile, a GEANT4 model has been developed to simulate the transportation and stopping of the charged fission products. In a recent measurement of neutron-induced fission yields, implantation foils were located at different positions in the ion guide. The gamma spectra from these foils and the fission targets are compared to the results from the GEANT4 simulation.In order to allow fission yield measurements in the low yield regions, towards the tails and in the symmetric part of the mass distribution, the stopping and extraction efficiency of the ion guide has to be significantly improved. This objective can be achieved by increasing the size while introducing electric field guidance using a combination of static electrodes and an RF-carpet. To this end, the GEANT4 model is used to optimise the design of such an ion guide.
|
|
| 26. |
|
|
| 27. |
- Gorelov, D., et al.
(författare)
-
Measuring independent yields of fission products using a penning trap
- 2015
-
Ingår i: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 79:7, s. 869-871
-
Tidskriftsartikel (refereegranskat)abstract
- A new method for determining independent fission products is used in an experiment at the Accelerator Laboratory of the University of Jyväskylä. The method combines the chemical universality of the ion guide technique and the unique properties of the Penning trap. A beam of charged particles is formed by stopping fission products in gaseous helium. The Penning trap is employed as a highly accurate filter to identify particles by their mass. The yields of fission products are determined by the ion count downstream of the trap. The setup’s mass resolving power is on the order of 105 with a radio frequency excitation time of 400 ms. Such high mass resolution occasionally allows us not only to separate nuclides but to separate the isomeric and ground states of nuclei as well. Independent yields of fission products are measured in the fission reaction of the 232Th isotope by protons with an energy of 25 MeV. A short description of the method ae nd soexperimental data are supplememnted by the results fro theoretical calculations.
|
|
| 28. |
|
|
| 29. |
- Kirsebom, O. S., et al.
(författare)
-
Discovery of an Exceptionally Strong β -Decay Transition of F 20 and Implications for the Fate of Intermediate-Mass Stars
- 2019
-
Ingår i: Physical Review Letters. - 0031-9007. ; 123:26
-
Tidskriftsartikel (refereegranskat)abstract
- A significant fraction of stars between 7 and 11 solar masses are thought to become supernovae, but the explosion mechanism is unclear. The answer depends critically on the rate of electron capture on Ne20 in the degenerate oxygen-neon stellar core. However, because of the unknown strength of the transition between the ground states of Ne20 and F20, it has not previously been possible to fully constrain the rate. By measuring the transition, we establish that its strength is exceptionally large and that it enhances the capture rate by several orders of magnitude. This has a decisive impact on the evolution of the core, increasing the likelihood that the star is (partially) disrupted by a thermonuclear explosion rather than collapsing to form a neutron star. Importantly, our measurement resolves the last remaining nuclear physics uncertainty in the final evolution of degenerate oxygen-neon stellar cores, allowing future studies to address the critical role of convection, which at present is poorly understood
|
|
| 30. |
|
|
| 31. |
- Rakopoulos, Vasileios, et al.
(författare)
-
First isomeric yield ratio measurements by direct ion counting and implications for the angular momentum of the primary fission fragments
- 2018
-
Ingår i: Physical Review C. - : AMER PHYSICAL SOC. - 2469-9985 .- 2469-9993. ; 98:2
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first experimental determination of independent isomeric yield ratios using direct ion counting with a Penning trap, which offered such a high resolution in mass that isomeric states could be separated. The measurements were performed at the Ion Guide Isotope Separator On-Line (IGISOL) facility at the University of Jyvaskyla. The isomer production ratios of Ge-81, Y-96,Y-97 Sn-128(,1)30, and Sb-129 in the 25-MeV proton-induced fission of U-na(t) and Th-232 were studied. Three isomeric pairs (Ge-81, Y-96, and Sb-129) were measured for the first time for the U-na(t)(p, f) reaction, while all the reported yield ratios for the Th-232(p, f) reaction were determined for the first time. The comparison of the experimentally determined isomeric yield ratios with data available in the literature shows a reasonable agreement, except for the case of Sn-130 for unspecified reasons. The obtained results were also compared with the GEF model, where good agreement can be noticed in most cases for both reactions. Serious discrepancies can only be observed for the cases of Y-96(,)97 for both reactions. Moreover, based on the isomeric yield ratios, the root-mean-square angular momenta (J(r)(ms)) of the fission fragments after scission were estimated using the TALYS code. The experimentally determined isomeric yield ratios, and consequently the deduced J(rms), for Sn-130 are significantly lower compared to Sn-128 for both fissioning systems. This can be attributed to the more spherical shape of the fragments that contribute to the formation of Sn-130, due to their proximity to the N = 82 shell closure. The values of J(rms) for Sb-129 are higher than Sn-128 for both reactions, despite the same neutron number of both nuclides (N = 78), indicating the odd-Z effect where fission fragments with odd-Z number tend to bear larger angular momentum than even-Z fragments. The isomer production ratio for the isotopes of Sn is more enhanced in the U-na(t)(p, f) reaction than in Th-232(p, f). The opposite is observed for Y-96 and Y-97. These discrepancies might be associated to different scission shapes of the fragments for the two fission reactions, indicating the impact that the different fission modes can have on the isomeric yield ratios.
|
|
