排序方式: 共有12条查询结果,搜索用时 15 毫秒
1.
M. Brodeur T. Brunner S. Ettenauer A. T. Gallant V. V. Simon M. Smith A. Lapierre E. Man�� R. Ringle V. L. Ryjkov S. Bacca P. Delheij D. Lunney M. Pearson J. Dilling 《Hyperfine Interactions》2011,199(1-3):167-173
Precise atomic mass determinations play a key role in various fields of physics, including nuclear physics, testing of fundamental symmetries and constants and atomic physics. Recently, the TITAN Penning trap measured the masses of several neutron halos. These exotic systems have an extended, diluted, matter distribution that can be modelled by considering a nuclear core surrounded by a halo formed by one or more of loosely bound neutrons. Combined with laser spectroscopy measurements of isotopic shifts precise masses can be used to obtain reliable charge radii and two-neutron-seperation energies for these halo nuclei. It is shown that these results can be used as stringent tests of nuclear models and potentials providing an important metric for our understanding of the interactions in all nuclei. 相似文献
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Brodeur M Brunner T Champagne C Ettenauer S Smith MJ Lapierre A Ringle R Ryjkov VL Bacca S Delheij P Drake GW Lunney D Schwenk A Dilling J 《Physical review letters》2012,108(5):052504
The first direct mass measurement of {6}He has been performed with the TITAN Penning trap mass spectrometer at the ISAC facility. In addition, the mass of {8}He was determined with improved precision over our previous measurement. The obtained masses are m({6}He)=6.018?885?883(57) u and m({8}He)=8.033?934?44(11) u. The {6}He value shows a deviation from the literature of 4σ. With these new mass values and the previously measured atomic isotope shifts we obtain charge radii of 2.060(8) and 1.959(16) fm for {6}He and {8}He, respectively. We present a detailed comparison to nuclear theory for {6}He, including new hyperspherical harmonics results. A correlation plot of the point-proton radius with the two-neutron separation energy demonstrates clearly the importance of three-nucleon forces. 相似文献
4.
Z. Ke W. Shi G. Gwinner K. Sharma S. Toews J. Dilling V. L. Ryjkov 《Hyperfine Interactions》2006,173(1-3):103-111
We present simulations of electron and proton cooling of highly charged ions in a Penning trap, including the potentially
detrimental effects of radiative, dielectronic, and three-body recombination in electron cooling. We show a preliminary design
for a cooler trap accommodating both electron and proton cooling, which will be a component of the TITAN ion-trap facility
under construction at TRIUMF for precision mass measurements of short-lived radioactive nuclei.
相似文献
5.
G Fuchs K-H Müller J Freudenberger K Nenkov S-L Drechsler SV Shulga D Lipp A Gladun T Cichorek P Gegenwart 《Pramana》2002,58(5-6):791-797
The effect of substitutional disorder on the superconducting properties of YNi2B2C was studied by partially replacing yttrium and nickel by Lu and Pt, respectively. For the two series of (Y, Lu)Ni2B2C and Y(Ni, Pt)2B2C compounds, the upper critical field H
c2(T) and the specific heat c
p(T, H) in the superconducting mixed state have been investigated. Disorder is found to reduce several relevant quantities such
as T
c, the upper critical field H
c2(0) at T=0 and a characteristic positive curvature of H
c2(T) observed for these compounds near T
c. The H
c2(T) data point to the clean limit for (Y, Lu) substitutions and to a transition to the quasi-dirty limit for (Ni, Pt) substitutions.
The electronic specific heat contribution γ(H) exhibits significant deviations from the usual linear γ(H) law. These deviations reduce with growing substitutional disorder but remain even in the quasidirty limit which is reached
in the Y(Ni1−x
, Pt
x
)2B2C samples for x=0.1. 相似文献
6.
Sánchez R Nörtershäuser W Ewald G Albers D Behr J Bricault P Bushaw BA Dax A Dilling J Dombsky M Drake GW Götte S Kirchner R Kluge HJ Kühl T Lassen J Levy CD Pearson MR Prime EJ Ryjkov V Wojtaszek A Yan ZC Zimmermann C 《Physical review letters》2006,96(3):033002
The nuclear charge radius of 11Li has been determined for the first time by high-precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a 7Li-11Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free [FORMULA: SEE TEXT]transition. IS accuracy for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from 6Li to 9Li, and then increases from 2.217(35) to 2.467(37) fm for 11Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results. 相似文献
7.
Non-resonant microwave absorption (NRMA) studies of superconducting MgB2 and a sample containing ∼10% by weight of MgO in MgB2 are reported. The NRMA results indicate near absence of intergranular weak links in the pure MgB2 sample. A linear temperature dependence of the lower critical field H
c1 is observed indicating a non-s wave superconductivity. However, the phase reversal of the NRMA signal which could suggest d wave symmetry is also not observed. In the MgB2 + MgO sample, much larger low field dependent absorption is observed indicating the presence of intergranular weak links.
The hysteretic behavior of NRMA is compared and contrasted in the two samples. In the pure MgB2 sample, a large hysteresis is observed between the forward and the reverse scans of the magnetic field indicating strong
pinning of flux lines. This hysteresis saturates a few degrees below T
c while in the MgB2 + MgO sample, a much slower increase of hysteresis with decreasing temperature is observed, a signature of weaker pinning. 相似文献
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9.
P. Delheij L. Blomeley M. Froese G. Gwinner V. Ryjkov M. Smith J. Dilling 《Hyperfine Interactions》2006,173(1-3):123-131
The TITAN facility at TRIUMF-ISAC will use four ion traps with the primary goal of determining nuclear masses with high precision, particularly for short lived isotopes with lifetimes down to approximately 10 ms. The design value for the accuracy of the mass measurement is 1 ×10???8. The four main components in the facility are an RF cooler/buncher (RFCT) receiving the incoming ion beam, an electron beam ion trap (EBIT) to breed the ions to higher charge states, a cooler Penning trap (CPET) to cool the highly charged ions, and finally the measurement Penning trap (MPET) for the precision mass determination. Additional goals for this system are laser spectroscopy on ions extracted from the RFCT and beta spectroscopy in the EBIT (in Penning trap mode) on ions that are purified using selective buffer gas cooling in the CPET. The physics motivation for the mass measurements are manifold, from unitarity tests of the CKM matrix to nuclear structure very far from the valley of stability, nuclear astrophysics and the study of halo-nuclei. As a first measurement the mass of 11Li will be determined. With a lifetime of 8.7 ms and a demonstrated production rate of 4×104 ions/sec at ISAC the goal for this measurement at TITAN is a relative uncertainty of 5×10???8. This would check previous conflicting measurements and provide information for nuclear theory and models. 相似文献
10.
Rodolfo Sánchez Wilfried Nörtershäuser Andreas Dax Guido Ewald Stefan Götte Reinhard Kirchner H.-Jürgen Kluge Thomas Kühl Agnieszka Wojtaszek Bruce A. Bushaw Gordon W. F. Drake Zong-Chao Yan Claus Zimmermann Daniel Albers John Behr Pierre Bricault Jens Dilling Marik Dombsky Jens Lassen C. D. Phil Levy Matthew R. Pearson Erika J. Prime Vladimir Ryjkov 《Hyperfine Interactions》2006,171(1-3):181-188
We have determined the nuclear charge radius of 11Li by high-precision laser spectroscopy. The experiment was performed at the TRIUMF-ISAC facility where the 7Li-11Li isotope shift (IS) was measured in the 2s→3s electronic transition using Doppler-free two-photon spectroscopy with a relative accuracy better than 10−5. The accuracy for the IS of the other lithium isotopes was also improved. IS’s are mainly caused by differences in nuclear
mass, but changes in proton distribution also give small contributions. Comparing experimentally measured IS with advanced
atomic calculation of purely mass-based shifts, including QED and relativistic effects, allows derivation of the nuclear charge
radii. The radii are found to decrease monotonically from 6Li to 9Li, and then increase with 11Li about 11% larger than 9Li. These results are a benchmark for the open question as to whether nuclear core excitation by halo neutrons is necessary
to explain the large nuclear matter radius of 11Li; thus, the results are compared with a number of nuclear structure models. 相似文献