排序方式: 共有25条查询结果,搜索用时 531 毫秒
11.
Premaditya Chhetri Dieter Ackermann Hartmut Backe Michael Block Bradley Cheal Christoph Emanuel Düllmann Julia Even Rafael Ferrer Francesca Giacoppo Stefan Götz Fritz Peter Heßberger Oliver Kaleja Jadambaa Khuyagbaatar Peter Kunz Mustapha Laatiaoui Felix Lautenschläger Werner Lauth Enrique Minaya Ramirez Andrew Kishor Mistry Sebastian Raeder Calvin Wraith Thomas Walther Alexander Yakushev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2017,71(7):195
12.
H. Backe Th. Blönnigen M. Dahlinger U. Doppler P. Graffé D. Habs M. Hies Ch. Illgner H. Kunz W. Lauth H. Schöpe P. Schwamb W. Theobald R. Zahn 《Hyperfine Interactions》1992,74(1-4):47-57
The feasibility of a hyperfine spectroscopy on242mAm fission isomers has been demonstrated at the low target production rate of 10/s. The experimental method employed is based
on resonance ionization spectroscopy in a buffer gas cell with detection of the ionization process by means of the fission
decay of the isomers. The resonance ionization has been performed in two steps, utilizing an excimer dye laser combination
with a repetition rate of 300 Hz. The first resonant step proceeds through theJ=7/2 term at 21440.35 cm−1, which has been excited with the tuncable dye laser beam of a wavelength of 466.28 nm, the second non-resonant step is achieved
with the 351 nm radiation of the excimer laser itself, running with XeF. The frequency scan of the tuneable dye laser exhibits
a broad resonance ionization signal, the width of which is most likely explained by the magnetic hyperfine interaction. 相似文献
13.
M. Laatiaoui H. Backe M. Block P. Chhetri F. Lautenschläger W. Lauth Th. Walther 《Hyperfine Interactions》2014,227(1-3):69-75
Strong efforts are undertaken at GSI in Darmstadt preparing for laser spectroscopy of the synthetic element nobelium. Several excimer- and dye lasers will be used in the forthcoming search for the $^1$P$_1$ -level in 254No. Based on the highly-efficient Radiation Detected Resonance Ionization Spectroscopy (RADRIS) technique, the identification of this excited state predicted around 3.8 eV becomes possible within a relatively short period of beam-time. This will form the basis for future studies of the atomic structure of the heaviest elements. 相似文献
14.
A. I. Sytov L. Bandiera D. De Salvador A. Mazzolari E. Bagli A. Berra S. Carturan C. Durighello G. Germogli V. Guidi P. Klag W. Lauth G. Maggioni M. Prest M. Romagnoni V. V. Tikhomirov E. Vallazza 《The European Physical Journal C - Particles and Fields》2017,77(12):901
We report the observation of the steering of 855 MeV electrons by bent silicon and germanium crystals at the MAinzer MIkrotron. Crystals with 15 \(\upmu \)m of length, bent along (111) planes, were exploited to investigate orientational coherent effects. By using a piezo-actuated mechanical holder, which allowed to remotely change the crystal curvature, it was possible to study the steering capability of planar channeling and volume reflection vs. the curvature radius and the atomic number, Z. For silicon, the channeling efficiency exceeds 35%, a record for negatively charged particles. This was possible due to the realization of a crystal with a thickness of the order of the dechanneling length. On the other hand, for germanium the efficiency is slightly below 10% due to the stronger contribution of multiple scattering for a higher-Z material. Nevertheless this is the first evidence of negative beam steering by planar channeling in a Ge crystal. Having determined for the first time the dechanneling length, one may design a Ge crystal based on such knowledge providing nearly the same channeling efficiency of silicon. The presented results are relevant for crystal-based beam manipulation as well as for the generation of e.m. radiation in bent and periodically bent crystals. 相似文献
15.
F. Grüner S. Becker U. Schramm T. Eichner M. Fuchs R. Weingartner D. Habs J. Meyer-ter-Vehn M. Geissler M. Ferrario L. Serafini B. van der Geer H. Backe W. Lauth S. Reiche 《Applied physics. B, Lasers and optics》2007,86(3):431-435
A recent breakthrough in laser-plasma accelerators, based upon ultrashort high-intensity lasers, demonstrated the generation
of quasi-monoenergetic GeV-electrons. With future Petawatt lasers ultra-high beam currents of ∼100 kA in ∼10 fs can be expected,
allowing for drastic reduction in the undulator length of free-electron-lasers (FELs). We present a discussion of the key
aspects of a table-top FEL design, including energy loss and chirps induced by space-charge and wakefields. These effects
become important for an optimized table-top FEL operation. A first proof-of-principle VUV case is considered as well as a
table-top X-ray-FEL which may also open a brilliant light source for new methods in clinical diagnostics.
PACS 41.60.Cr; 52.38.Kd 相似文献
16.
H. Backe P. Kunz W. Lauth A. Dretzke R. Horn T. Kolb M. Laatiaoui M. Sewtz D. Ackermann M. Block F. Herfurth F. P. Heßberger S. Hofmann R. Mann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(1):99-106
For the investigation of the atomic level structure of
heavy elements which can only be produced at on-line facilities
such as GSI, a novel experimental procedure has been developed. It
is based on Radiation Detected Resonance Ionization Spectroscopy
(RADRIS) and can be applied to elements like nobelium produced at
rates of a few ions per second. Fusion reaction products are
separated from the primary beam by the velocity filter SHIP at
GSI, stopped in a buffer gas cell, collected on a tantalum
filament and then re-evaporated as atoms. The ions produced by
resonance ionization with tunable laser beams are detected via
their characteristic α decay. First on-line experiments on
α-active 155Yb, which is supposed to have an atomic
level structure similar to nobelium, were performed. These test
experiments focused on the optimization of the collection and
re-evaporation process of the radioactive ions, the laser
ionization efficiency and the detection via α decay. An
overall efficiency for RADRIS of 0.8% with respect to the target
production rate was measured. While further improvements of this
efficiency are in progress it should already be sufficient for the
search for atomic levels in nobelium. 相似文献
17.
18.
19.
Backe H. Baum R. -R. Fricke B. Habs D. Hellmann K. Hies M. Illgner Ch. Krameyer Ch. Kunz H. Lauth W. Martin R. Schwamb P. Theobald W. Thörle P. Trautmann N. 《Hyperfine Interactions》1996,97(1):535-541
Istope shift and hyperfine structure measurements have been performed for the242fAm fission isomer with target production rates of only a few per second. The method is based on resonance ionization spectroscopy (RIS) in a buffer gas cell with radioactive decay detection of the ionization process (RADRIS). A relative isotope shift ratioX
exp=IS242f,241/ IS243,241=41.7±0.9 has been measured for the 500.02 nm transition corresponding to a nuclear parameter 242f,241=5.4±0.3 fm2. The analysis of the quadrupole moment based on the deformed Fermi-model of the nuclear charge distribution including second order corrections results inQ
20=38.2 ±1.4(
–0.8
+0.4
)model eb. The measurement of the hyperfine structure splitting of the transition at 466.28 nm yields a negativeg-factor and a nuclear spin ofI=2 orI=3.Work supported by the Bundesministerium für Bildung und Forschung under contract 06 MZ 5661. 相似文献
20.
J. Dilling D. Ackermann J. Bernard F.P. Hessberger S. Hofmann W. Hornung H. J. Kluge E. Lamour M. Maier R. Mann G. Marx R.B. Moore G. Münzenberg W. Quint D. Rodriguez M. Schädel J. Schönfelder G. Sikler C. Toader L. Vermeeren C. Weber G. Bollen O. Engels D. Habs P. Thirolf H. Backe A. Dretzke W. Lauth W. Ludolphs M. Sewtz 《Hyperfine Interactions》2000,127(1-4):491-496
SHIPTRAP is an ion trap facility which is being set up to deliver very clean and cool beams of singly-charged recoil ions
produced at the SHIP velocity filter at GSI Darmstadt. SHIPTRAP consists of a gas cell for stopping and thermalizing high-energy
recoil ions from SHIP, a rf ion guide for extraction of the ions from the gas cell, a linear rf trap for accumulation and
bunching of the ions, and a Penning trap for isobaric purification. The physics programme of the SHIPTRAP facility comprises
mass spectrometry, nuclear spectroscopy, laser spectroscopy and chemistry of transeinsteinium elements.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献