排序方式: 共有37条查询结果,搜索用时 62 毫秒
1.
M. Mukherjee D. Beck K. Blaum G. Bollen J. Dilling S. George F. Herfurth A. Herlert A. Kellerbauer H. -J. Kluge S. Schwarz L. Schweikhard C. Yazidjian 《The European Physical Journal A - Hadrons and Nuclei》2008,35(1):1-29
ISOLTRAP is a Penning trap mass spectrometer for high-precision mass measurements on short-lived nuclides installed at the
on-line isotope separator ISOLDE at CERN. The masses of close to 300 radionuclides have been determined up to now. The applicability
of Penning trap mass spectrometry to mass measurements of exotic nuclei has been extended considerably at ISOLTRAP by improving
and developing this double Penning trap mass spectrometer over the past two decades. The accurate determination of nuclear
binding energies far from stability includes nuclei that are produced at rates less than 100 ions/s and with half-lives well
below 100ms. The mass-resolving power reaches 107 corresponding to 10keV for medium heavy nuclei and the uncertainty of the resulting mass values has been pushed down to below
10-8. The article describes technical developments achieved since 1996 and the present performance of ISOLTRAP. 相似文献
2.
Mukherjee M Kellerbauer A Beck D Blaum K Bollen G Carrel F Delahaye P Dilling J George S Guénaut C Herfurth F Herlert A Kluge HJ Köster U Lunney D Schwarz S Schweikhard L Yazidjian C 《Physical review letters》2004,93(15):150801
Mass measurements with a relative precision of better than 1.5 x 10(-8) were performed on 22Mg and its reaction partners 21Na and 22Na with the ISOLTRAP Penning trap mass spectrometer at CERN, yielding the mass excesses D(22Mg)=-399.92(27) keV, D(21Na)=-2184.71(21) keV, and D(22Na)=-5181.56(16) keV. The importance of these results is twofold. First, a comparative half-life (Ft value) has been obtained for the superallowed beta decay of 22Mg to further test the conserved-vector-current hypothesis. Second, the resonance energy for the 21Na proton capture reaction has been independently determined, allowing direct comparisons of observable gamma radiation in nova explosions with the yield expected from models. 相似文献
3.
4.
Fink D Barea J Beck D Blaum K Böhm Ch Borgmann Ch Breitenfeldt M Herfurth F Herlert A Kotila J Kowalska M Kreim S Lunney D Naimi S Rosenbusch M Schwarz S Schweikhard L Simkovic F Stanja J Zuber K 《Physical review letters》2012,108(6):062502
The 110Pd double-β decay Q value was measured with the Penning-trap mass spectrometer ISOLTRAP to be Q=2017.85(64) keV. This value shifted by 14 keV compared with the literature value and is 17 times more precise, resulting in new phase-space factors for the two-neutrino and neutrinoless decay modes. In addition a new set of the relevant matrix elements has been calculated. The expected half-life of the two-neutrino mode was reevaluated as 1.5(6)×10(20) yr. With its high natural abundance, the new results reveal 110Pd to be an excellent candidate for double-β decay studies. 相似文献
5.
A. Herlert L. Schweikhard M. Vogel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):65-68
Singly charged silver-cluster anions are produced in a laser vaporization source and transferred into a Penning trap. After
size selection the clusters are subjected to an electron bath in the trap, which results in the attachment of further electrons.
The relative abundance of dianions or trianions as a function of the clusters' size is analyzed by time-of-flight mass spectrometry.
Silver-cluster dianions are observed for sizes n≥ 24 and trianions for n > 100. In addition, a detailed study of the cluster sizes 24 ?n? 60 shows a pronounced resistance to electron attachment for singly charged anions Agn
- with a closed electronic shell, in particular Ag29
-, Ag33
-, and Ag39
-. Both the threshold size for the observation of dianionic silver clusters and the shell effects in the production yield correlate
favorably with previous theoretical investigations of the respective electron affinities.
Received 24 November 2000 相似文献
6.
M. Vogel K. Hansen A. Herlert L. Schweikhard 《Applied physics. B, Lasers and optics》2001,73(4):411-416
The pathway competition between neutral monomer and neutral dimer evaporation from optically excited odd-size gold cluster
ions Au+
n, n=7–15, has been investigated as a function of cluster size and excitation energy. Gold cluster ions of these sizes are
the only ones to show observable pathway competition while all other sizes exclusively evaporate either neutral monomers or
neutral dimers. The investigation has been performed by photoexcitation of stored size-selected gold cluster ions with a single
10-ns laser pulse. Subsequent time-resolved observation of the delayed dissociation allows us to quantitatively determine
the relative fragment yields of the respective decay channels as a function of excitation energy. Contrary to theoretical
expectations, the dimer-to-monomer branching ratio of evaporated particles is found to decrease monotonously with increasing
excitation energy for all cluster sizes under investigation. Possible explanations for this behaviour are discussed.
Received: 9 July 2001 / Revised version: 24 September 2001 / Published online: 15 October 2001 相似文献
7.
8.
L. Schweikhard K. Hansen A. Herlert G. Marx M. Vogel 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):137-143
Ion traps are wall-less containers which allow the
extended storage of selected species. During the storage various
interaction steps may be repeatedly applied. To this end no
further hardware has to be added - in contrast to beam
experiments. In this progress report two examples of recent
developments are presented: the experiments have been performed
with metal clusters stored in a Penning (ion cyclotron
resonance) trap. A new experimental scheme has been developed
which allows precision measurements of the dissociation energies
of polyatomic species. It has been triggered by investigations
on the delayed photodissociation of stored metal clusters.
However, the technique is also readily available for application
to a broad variety of different species and it is not even
restricted to trapping experiments. The second development is
more closely connected with ion storage in Penning traps: by
application of an electron bath singly charged anionic
clusters can be converted into multiply charged species.
Subsequently, they are charge selected and investigated with
respect to their reaction upon excitation. In particular,
preliminary results indicate that dianionic metal clusters emit
two electrons upon photoexcitation whereas the singly charged
species show dissociation. 相似文献
9.
Formation and stability patterns of silver dianionic and gold trianionic clusters are investigated with Penning-trap experiments and a shell-correction method including shape deformations. The theoretical predictions pertaining to the appearance sizes and electronic shell effects are in remarkable agreement with the experiments. Decay of the multiply anionic clusters occurs predominantly by electron tunneling through a Coulomb barrier rather than via fission, leading to appearance sizes unrelated to those of multiply cationic clusters. 相似文献
10.
M. Vogel K. Hansen A. Herlert L. Schweikhard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):73-76
The decay pathway competition between monomer and dimer evaporation of photoexcited cluster ions Au
+
n, n = 2-27, has been investigated by photodissociation of size-selected gold clusters stored in a Penning trap. For n > 6 the two decay pathways are distinguished by their experimental signature in time-resolved measurements of the dissociation.
For the smaller clusters, simple fragment spectra were used. As in the case of the other copper-group elements, even-numbered
gold cluster ions decay exclusively by monomer evaporation, irrespective of their size. For small odd-size gold clusters,
dimer evaporation is a competitive alternative, and the smaller the odd-sized clusters, the more likely they decay by dimer
evaporation. In this respect, Au
+
9 shows an anomalous behavior, as it is less likely to evaporate dimers than its two odd-numbered neighbors, Au
+
7 and Au
+
11. This nonamer anomaly is typical for copper-group cluster ions M
+
9 (M = Cu, Ag, Au) and a similar behavior is found in the anionic heptamers M
-
7. It is discussed in terms of the well-known electronic shell closing at n
e = 8 atomic valence electrons.
Received 2 November 2000 相似文献