1. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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2. |
- Ralet, D., et al.
(författare)
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Evidence of octupole-phonons at high spin in Pb-207
- 2019
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Ingår i: Physics Letters B. - : ELSEVIER. - 0370-2693 .- 1873-2445. ; 797
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Tidskriftsartikel (refereegranskat)abstract
- A lifetime measurement of the 19/2(-) state in Pb-207 has been performed using the Recoil Distance Doppler-Shift (RDDS) method. The nuclei of interest were produced in multi-nucleon transfer reactions induced by a Pb-208 beam impinging on a Mo-100 enriched target. The beam-like nuclei were detected and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt gamma rays were detected by the AGATA tracking array. The measured large reduced transition probability B(E3, 19/2(-) -> 13/2(+)) = 40(8) W.u. is the first indication of the octupole phonon at high spin in Pb-207. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured B(E3) value in Pb-207 is compatible with the contributions from single-phonon and single particle E3 as well as E3 strength arising from the double-octupole-phonon 6(+) state, all adding coherently. A crucial aspect of the coupling model, namely the strong mixing between single-hole and the phonon-hole states, is confirmed in a realistic shell-model calculation. Crown Copyright (C) 2019 Published by Elsevier B.V.
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3. |
- Rodriguez, D., et al.
(författare)
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MATS and LaSpec : High-precision experiments using ion traps and lasers at FAIR
- 2010
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Ingår i: The European physical journal. Special topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 183, s. 1-123
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Forskningsöversikt (refereegranskat)abstract
- Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. The mass and its inherent connection with the nuclear binding energy is a fundamental property of a nuclide, a unique ""fingerprint"". Thus, precise mass values are important for a variety of applications, ranging from nuclear-structure studies like the investigation of shell closures and the onset of deformation, tests of nuclear mass models and mass formulas, to tests of the weak interaction and of the Standard Model. The required relative accuracy ranges from 10(-5) to below 10(-8) for radionuclides, which most often have half-lives well below 1 s. Substantial progress in Penning trap mass spectrometry has made this method a prime choice for precision measurements on rare isotopes. The technique has the potential to provide high accuracy and sensitivity even for very short-lived nuclides. Furthermore, ion traps can be used for precision decay studies and offer advantages over existing methods. With MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly-charged ions) at FAIR we aim to apply several techniques to very short-lived radionuclides: High-accuracy mass measurements, in-trap conversion electron and alpha spectroscopy, and trap-assisted spectroscopy. The experimental setup of MATS is a unique combination of an electron beam ion trap for charge breeding, ion traps for beam preparation, and a high-precision Penning trap system for mass measurements and decay studies. For the mass measurements, MATS offers both a high accuracy and a high sensitivity. A relative mass uncertainty of 10(-9) can be reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-ICR) detection technique on single stored ions. This accuracy limit is important for fundamental interaction tests, but also allows for the study of the fine structure of the nuclear mass surface with unprecedented accuracy, whenever required. The use of the FT-ICR technique provides true single ion sensitivity. This is essential to access isotopes that are produced with minimum rates which are very often the most interesting ones. Instead of pushing for highest accuracy, the high charge state of the ions can also be used to reduce the storage time of the ions, hence making measurements on even shorter-lived isotopes possible. Decay studies in ion traps will become possible with MATS. Novel spectroscopic tools for in-trap high-resolution conversion-electron and charged-particle spectroscopy from carrier-free sources will be developed, aiming e. g. at the measurements of quadrupole moments and E0 strengths. With the possibility of both high-accuracy mass measurements of the shortest-lived isotopes and decay studies, the high sensitivity and accuracy potential of MATS is ideally suited for the study of very exotic nuclides that will only be produced at the FAIR facility. Laser spectroscopy of radioactive isotopes and isomers is an efficient and model-independent approach for the determination of nuclear ground and isomeric state properties. Hyperfine structures and isotope shifts in electronic transitions exhibit readily accessible information on the nuclear spin, magnetic dipole and electric quadrupole moments as well as root-mean-square charge radii. The dependencies of the hyperfine splitting and isotope shift on the nuclear moments and mean square nuclear charge radii are well known and the theoretical framework for the extraction of nuclear parameters is well established. These extracted parameters provide fundamental information on the structure of nuclei at the limits of stability. Vital information on both bulk and valence nuclear properties are derived and an exceptional sensitivity to changes in nuclear deformation is achieved. Laser spectroscopy provides the only mechanism for such studies in exotic systems and uniquely facilitates these studies in a model-independent manner. The accuracy of laser-spectroscopic-determined nuclear properties is very high. Requirements concerning production rates are moderate; collinear spectroscopy has been performed with production rates as few as 100 ions per second and laser-desorption resonance ionization mass spectroscopy (combined with beta-delayed neutron detection) has been achieved with rates of only a few atoms per second. This Technical Design Report describes a new Penning trap mass spectrometry setup as well as a number of complementary experimental devices for laser spectroscopy, which will provide a complete system with respect to the physics and isotopes that can be studied. Since MATS and LaSpec require high-quality low-energy beams, the two collaborations have a common beamline to stop the radioactive beam of in-flight produced isotopes and prepare them in a suitable way for transfer to the MATS and LaSpec setups, respectively.
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4. |
- Boj, Sylvia F, et al.
(författare)
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Organoid models of human and mouse ductal pancreatic cancer
- 2015
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Ingår i: Cell. - : Cell press. - 0092-8674 .- 1097-4172. ; 160:1-2, s. 324-338
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic cancer is one of the most lethal malignancies due to its late diagnosis and limited response to treatment. Tractable methods to identify and interrogate pathways involved in pancreatic tumorigenesis are urgently needed. We established organoid models from normal and neoplastic murine and human pancreas tissues. Pancreatic organoids can be rapidly generated from resected tumors and biopsies, survive cryopreservation, and exhibit ductal- and disease-stage-specific characteristics. Orthotopically transplanted neoplastic organoids recapitulate the full spectrum of tumor development by forming early-grade neoplasms that progress to locally invasive and metastatic carcinomas. Due to their ability to be genetically manipulated, organoids are a platform to probe genetic cooperation. Comprehensive transcriptional and proteomic analyses of murine pancreatic organoids revealed genes and pathways altered during disease progression. The confirmation of many of these protein changes in human tissues demonstrates that organoids are a facile model system to discover characteristics of this deadly malignancy.
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5. |
- Flanagan, K. T., et al.
(författare)
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Nuclear Spins and Magnetic Moments of Cu-71,Cu-73,Cu-75 : Inversion of pi 2p(3/2) and pi 1f(5/2) Levels in Cu-75
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 103:14, s. 142501-
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Tidskriftsartikel (refereegranskat)abstract
- We report the first confirmation of the predicted inversion between the pi 2p(3/2) and pi 1f(5/2) nuclear states in the nu g(9/2) midshell. This was achieved at the ISOLDE facility, by using a combination of in-source laser spectroscopy and collinear laser spectroscopy on the ground states of Cu-71,Cu-73,Cu-75, which measured the nuclear spin and magnetic moments. The obtained values are mu(Cu-71)=+2.2747(8)mu(N), mu(Cu-73)=+1.7426(8)mu(N), and mu(Cu-75)=+1.0062(13)mu(N) corresponding to spins I=3/2 for Cu-71,Cu-73 and I=5/2 for Cu-75. The results are in fair agreement with large-scale shell-model calculations.
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6. |
- Giot, L., et al.
(författare)
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Isotopic production cross sections of the residual nuclei in spallation reactions induced by 136Xe projectiles on proton at 500 A MeV
- 2013
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 899, s. 116-132
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Tidskriftsartikel (refereegranskat)abstract
- Around 270 medium-mass residual nuclei, formed in spallation reactions induced by 136Xe projectiles impinging on a liquid hydrogen target at 500 A MeV, have been unambiguously identified at GSI using the magnetic spectrometer FRS. The individual production cross sections and the longitudinal momentum distributions have been determined with high accuracy. These data represent an important constraint for theoretical models describing spallation reactions. © 2013 Elsevier B.V.
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7. |
- Paradela, C., et al.
(författare)
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Isotopic production cross sections of residual nuclei in the spallation reaction Xe-136 (200A MeV) + p
- 2017
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Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 95:4
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Tidskriftsartikel (refereegranskat)abstract
- The residual nuclei produced in the spallation reaction of Xe-136 nuclei at 200A MeV on protons have been studied by measuring the isotopic distributions for the elements from cadmium (Z = 48) to cesium (Z = 55) by using the fragment separator (FRS) spectrometer at GSI and the inverse kinematics technique. This is one of the few measurements performed at such a low projectile energy, close to the validity limit for intranuclear cascade models such as INCL or ISABEL. The experimental results have been compared to these intranuclear cascade codes coupled to the evaporation code ABLA. Both code combinations reproduce qualitatively the measured isotopic distributions; however, both underestimate the production of residues with mass numbers between 126 and 134. The measured cross sections are of interest for the planning of future radioactive beam or neutron source facilities.
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8. |
- Rodriguez, L. , V, et al.
(författare)
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Doubly-magic character of Sn-132 studied via electromagnetic moments of( 13)(3)Sn
- 2020
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 102:5
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Tidskriftsartikel (refereegranskat)abstract
- We report the first measurement of the magnetic dipole and electric quadrupole moment of the exotic nucleus Sn-133 by high-resolution laser spectroscopy at ISOLDE/CERN. These, in combination with state-of-the-art shell-model calculations, demonstrate the single-particle character of the ground state of this short-lived isotope and, hence, the doubly-magic character of its immediate neighbor Sn-132. The trend of the electromagnetic moments along the N = 83 isotonic chain, now enriched with the values of tin, are discussed on the basis of realistic shell-model calculations.
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9. |
- Törnqvist, Hans, 1985, et al.
(författare)
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Tilted foils polarization at REX-ISOLDE
- 2013
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 317:PART B, s. 685-688
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Tidskriftsartikel (refereegranskat)abstract
- The tilted-foils nuclear-spin polarization method has been evaluated using the REX-ISOLDE linear accelerator at the ISOLDE facility, CERN. A beam of 8Li delivered with an energy of 300 keV/u traversed through one Mylar foil to degrade the beam energy to 200 keV/u and consequently through 10 thin diamond-like carbon foils to polarize the nuclear spin. The attained nuclear spin polarization of 3.6±0.3% was measured with a β-NMR setup.
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10. |
- Vernon, A. R., et al.
(författare)
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Nuclear moments of indium isotopes reveal abrupt change at magic number 82
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 607:7918, s. 260-265
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Tidskriftsartikel (refereegranskat)abstract
- In spite of the high-density and strongly correlated nature of the atomic nucleus, experimental and theoretical evidence suggests that around particular ‘magic’ numbers of nucleons, nuclear properties are governed by a single unpaired nucleon1,2. A microscopic understanding of the extent of this behaviour and its evolution in neutron-rich nuclei remains an open question in nuclear physics3–5. The indium isotopes are considered a textbook example of this phenomenon6, in which the constancy of their electromagnetic properties indicated that a single unpaired proton hole can provide the identity of a complex many-nucleon system6,7. Here we present precision laser spectroscopy measurements performed to investigate the validity of this simple single-particle picture. Observation of an abrupt change in the dipole moment at N = 82 indicates that, whereas the single-particle picture indeed dominates at neutron magic number N = 82 (refs. 2,8), it does not for previously studied isotopes. To investigate the microscopic origin of these observations, our work provides a combined effort with developments in two complementary nuclear many-body methods: ab initio valence-space in-medium similarity renormalization group and density functional theory (DFT). We find that the inclusion of time-symmetry-breaking mean fields is essential for a correct description of nuclear magnetic properties, which were previously poorly constrained. These experimental and theoretical findings are key to understanding how seemingly simple single-particle phenomena naturally emerge from complex interactions among protons and neutrons. © 2022, The Author(s), under exclusive licence to Springer Nature Limited.
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11. |
- Gladnishki, KA, et al.
(författare)
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Angular Momentum Population in the Projectile Fragmentation of 238U at 750 MeV/nucleon
- 2004
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:2
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Tidskriftsartikel (refereegranskat)abstract
- A systematic study of the population probabilities of nanosecond and microsecond isomers produced following the projectile fragmentation of U-238 at 750 MeV/nucleon has been undertaken at the SIS/FRS facility at GSI. Approximately 15 isomeric states in neutron-deficient nuclei around A similar to 190 were identified and the corresponding. isomeric ratios determined. The results are compared with a model based on the statistical abrasion-ablation description of relativistic fragmentation and simple assumptions concerning gamma cascades in the final nucleus (sharp cutoff). This model represents an upper limit for the population of isomeric states in relativistic projectile fragmentation. When the decay properties of the states above the isomer are taken into account, as opposed to the sharp cutoff approximation, a good agreement between the experimental and calculated angular momentum population is obtained.
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12. |
- Mach, H., et al.
(författare)
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New structure information on Mg-30, Mg-31 and Mg-32
- 2005
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-601X .- 1434-6001. ; 25, s. 105-109
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Konferensbidrag (refereegranskat)abstract
- The fast timing beta gamma gamma(t) method was applied to investigate the level lifetimes in Mg-30,Mg-31,Mg-32. Levels in Mg have been populated in beta and beta-delayed neutron emission of Na, at the ISOLDE facility. From the gamma gamma coincidences a number of new states have been identified and new level schemes were constructed for 30 31,32 Mg. The following preliminary half lives have been determined: T-1/2 = 3.9(4) ns for the 1789 keV state in Mg-30, T-1/2 = 133(8) ps and 10.5(8) us for the 221 keV and 461 keV states in Mg-31, respectively, and T1/2 = 16(4) ps for the 885 keV level in 32Mg. The 1789 keV level was established as a candidate for the intruder 0(+) configuration in Mg-30 with a possible strong E0 branch to the ground state.
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13. |
- Olaizola, B., et al.
(författare)
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High-sensitivity study of levels in Al-30 following beta decay of Mg-30
- 2016
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Ingår i: PHYSICAL REVIEW C. - 2469-9985 .- 2469-9993. ; 94:5
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Tidskriftsartikel (refereegranskat)abstract
- gamma-ray and fast-timing spectroscopy were used to study levels in Al-30 populated following the beta(-) decay of Mg-30. Five new transitions and three new levels were located in Al-30. A search was made to identify the third 1(+) state expected at an excitation energy of similar to 2.5 MeV. Two new levels were found, at 3163.9 and 3362.5 keV, that are firm candidates for this state. Using the advanced time-delayed (ATD) beta gamma gamma (t) method we have measured the lifetime of the 243.8-keV state to be T-1/2 = 15(4) ps, which implies that the 243.8-keV transition is mainly of M1 character. Its fast B(M1; 2(+) -> 3(+)) value of 0.10(3) W.u. is in very good agreement with the USD shell-model prediction of 0.090 W.u. The 1801.5-keV level is the only level observed in this study that could be a candidate for the second excited 2(+) state.
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14. |
- Wraith, Calvin, et al.
(författare)
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Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers
- 2017
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 771, s. 385-391
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Tidskriftsartikel (refereegranskat)abstract
- Collinear laser spectroscopy was performed on Zn (Z = 30) isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N = 33–49, allowed the measurement of nuclear spins for the ground and isomeric states in odd-A neutron-rich nuclei up to N = 50. Exactly one longlived (>10 ms) isomeric state has been established in each 69–79Zn isotope. The nuclear magnetic dipole moments and spectroscopic quadrupole moments are well reproduced by large-scale shell–model calculations in the f5pg9 and fpg9d5 model spaces, thus establishing the dominant term in their wave function. The magnetic moment of the intruder Iπ = 1/2+ isomer in 79Zn is reproduced only if the νs1/2 orbital is added to the valence space, as realized in the recently developed PFSDG-U interaction.The spin and moments of the low-lying isomeric state in 73Zn suggest a strong onset of deformation at N = 43, while the progression towards 79Zn points to the stability of the Z = 28 and N = 50 shell gaps, supporting the magicity of 78Ni
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15. |
- Xie, L., et al.
(författare)
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Nuclear charge radii of Zn62-80 and their dependence on cross-shell proton excitations
- 2019
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 797
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear charge radii of Zn62-80 have been determined using collinear laser spectroscopy of bunched ion beams at CERN-ISOLDE. The subtle variations of observed charge radii, both within one isotope and along the full range of neutron numbers, are found to be well described in terms of the proton excitations across the Z = 28 shell gap, as predicted by large-scale shell model calculations. It comprehensively explains the changes in isomer-to-ground state mean square charge radii of Zn69-79, the inversion of the odd-even staggering around N = 40 and the odd-even staggering systematics of the Zn charge radii. With two protons above Z = 28, the observed charge radii of the Zn isotopic chain show a cumulative effect of different aspects of nuclear structure including single particle structure, shell closure, correlations and deformations near the proposed doubly magic nuclei, Ni-68 and Ni-78. (C) 2019 The Author(s). Published by Elsevier B.V.
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16. |
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