1,242 research outputs found
Metrological characterization of the pulsed Rb clock with optical detection
We report on the implementation and the metrological characterization of a
vapor-cell Rb frequency standard working in pulsed regime. The three main parts
that compose the clock, physics package, optics and electronics, are described
in detail in the paper. The prototype is designed and optimized to detect the
clock transition in the optical domain. Specifically, the reference atomic
transition, excited with a Ramsey scheme, is detected by observing the
interference pattern on a laser absorption signal.
\ The metrological analysis includes the observation and characterization of
the clock signal and the measurement of frequency stability and drift. In terms
of Allan deviation, the measured frequency stability results as low as
, being the averaging time, and
reaches the value of few units of for s, an
unprecedent achievement for a vapor cell clock. We discuss in the paper the
physical effects leading to this result with particular care to laser and
microwave noises transferred to the clock signal. The frequency drift, probably
related to the temperature, stays below per day, and no evidence of
flicker floor is observed.
\ We also mention some possible improvements that in principle would lead to
a clock stability below the level at 1 s and to a drift of few units
of per day
Present and Future Experiments with Stored Exotic Nuclei at Relativistic Energies
Recent progress is presented from experiments on masses and lifetimes of bare
and few-electron exotic nuclei at GSI.Comment: Proceedings of International Conference on "Frontiers in Nuclear
Structure, Astrophysics and Reactions", Kos, Greece, September 12-17, 200
An Atom Laser with a cw Output Coupler
We demonstrate a continuous output coupler for magnetically trapped atoms.
Over a period of up to 100 ms a collimated and monoenergetic beam of atoms is
continuously extracted from a Bose- Einstein condensate. The intensity and
kinetic energy of the output beam of this atom laser are controlled by a weak
rf-field that induces spin flips between trapped and untrapped states.
Furthermore, the output coupler is used to perform a spectroscopic measurement
of the condensate, which reveals the spatial distribution of the magnetically
trapped condensate and allows manipulation of the condensate on a micrometer
scale.Comment: 4 pages, 4 figure
On the transverse mode of an atom laser
The transverse mode of an atom laser beam that is outcoupled from a
Bose-Einstein condensate is investigated and is found to be strongly determined
by the mean--field interaction of the laser beam with the condensate. Since for
repulsive interactions the geometry of the coupling scheme resembles an
interferometer in momentum space, the beam is found show filamentation.
Observation of this effect would prove the transverse coherence of an atom
laser beam.Comment: 4 pages, 4 figure
Observation of Non-Exponential Orbital Electron Capture Decays of Hydrogen-Like Pr and Pm Ions
We report on time-modulated two-body weak decays observed in the orbital
electron capture of hydrogen-like Pr and Pm
ions coasting in an ion storage ring. Using non-destructive single ion,
time-resolved Schottky mass spectrometry we found that the expected exponential
decay is modulated in time with a modulation period of about 7 seconds for both
systems. Tentatively this observation is attributed to the coherent
superposition of finite mass eigenstates of the electron neutrinos from the
weak decay into a two-body final state.Comment: 12 pages, 5 figure
Isospin Dependence in the Odd-Even Staggering of Nuclear Binding Energies
The FRS-ESR facility at GSI provides unique conditions for precision
measurements of large areas on the nuclear mass surface in a single experiment.
Values for masses of 604 neutron-deficient nuclides (30<=Z<=92) were obtained
with a typical uncertainty of 30 microunits. The masses of 114 nuclides were
determined for the first time. The odd-even staggering (OES) of nuclear masses
was systematically investigated for isotopic chains between the proton shell
closures at Z=50 and Z=82. The results were compared with predictions of modern
nuclear models. The comparison revealed that the measured trend of OES is not
reproduced by the theories fitted to masses only. The spectral pairing gaps
extracted from models adjusted to both masses, and density related observables
of nuclei agree better with the experimental data.Comment: Physics Review Letters 95 (2005) 042501
http://link.aps.org/abstract/PRL/v95/e04250
Beam test results of silicon sensor module prototypes for the Phase-2 Upgrade of the CMS Outer Tracker
The start of the High-Luminosity LHC (HL-LHC) in 2027 requires upgrades to the Compact Muon Solenoid (CMS) Experiment. In the scope of the upgrade program the complete silicon tracking detector will be replaced. The new CMS Tracker will be equipped with silicon pixel detectors in the inner layers closest to the interaction point and silicon strip detectors in the outer layers. The new CMS Outer Tracker will consist of two different kinds of detector modules called PS and 2S modules. Each module will be made of two parallel silicon sensors (a macro-pixel sensor and a strip sensor for the PS modules and two strip sensors for the 2S modules). Combining the hit information of both sensor layers it is possible to estimate the transverse momentum of particles in the magnetic field of 3.8 T at the full bunch-crossing rate of 40 MHz directly on the module. This information will be used as an input for the first trigger stage of CMS.
It is necessary to validate the Outer Tracker module functionality before installing the modules in the CMS experiment. Besides laboratory-based tests several 2S module prototypes have been studied at test beam facilities at CERN, DESY and FNAL. This article concentrates on the beam tests at DESY during which the functionality of the module concept was investigated using the full final readout chain for the first time. Additionally the performance of a 2S module assembled with irradiated sensors was studied. By choosing an irradiation fluence expected for 2S modules at the end of HL-LHC operation, it was possible to investigate the particle detection efficiency and study the trigger capabilities of the module at the beginning and end of runtime of the CMS experiment.The start of the High-Luminosity LHC (HL-LHC) in 2027 requires upgrades to the Compact Muon Solenoid (CMS) experiment. In the scope of the upgrade program the complete silicon tracking detector will be replaced. The new CMS Trackerâwill be equipped with silicon pixel detectors in the inner layers closest to the interaction pointâand silicon strip detectors in the outer layers. The new CMS Outer Trackerâwill consist of two different kinds of detector modules called PS and 2S modules. Each module will be made of two parallel silicon sensors (a macro-pixel sensor and a strip sensor for the PS modules and two strip sensors for the 2S modules). Combining the hit information of both sensor layers, it is possible to estimate the transverse momentum of particles in the magnetic field of 3.8âT at the full bunch-crossing rate of 40âMHz directly on the module. This information will be used as an input for the first trigger stage of CMS. It is necessary to validate the Outer Trackerâmodule functionality before installing the modules in the CMS experiment. Besides laboratory-based tests several 2S module prototypes have been studied at test beam facilities at CERN, DESY and FNAL. This article concentrates on the beam tests at DESY during which the functionality of the module concept was investigated using the full final readout chain for the first time. Additionally the performance of a 2S module assembled with irradiated sensors was studied. By choosing an irradiation fluence expected for 2S modules at the end of HL-LHC operation, it was possible to investigate the particle detection efficiency and study the trigger capabilities of the module at the beginning and end of the runtime of the CMS experiment
Nuclear Physics Experiments with Ion Storage Rings
In the last two decades a number of nuclear structure and astrophysics
experiments were performed at heavy-ion storage rings employing unique
experimental conditions offered by such machines. Furthermore, building on the
experience gained at the two facilities presently in operation, several new
storage ring projects were launched worldwide. This contribution is intended to
provide a brief review of the fast growing field of nuclear structure and
astrophysics research at storage rings.Comment: XVIth International Conference on Electro-Magnetic Isotope Separators
and Techniques Related to their Applications, December 2--7, 2012 at Matsue,
Japa
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