94 research outputs found
Half-open Penning trap with efficient light collection for precision laser spectroscopy of highly charged ions
We have conceived, built and operated a 'half-open' cylindrical Penning trap
for the confinement and laser spectroscopy of highly charged ions. This trap
allows fluorescence detection employing a solid angle which is about one order
of magnitude larger than in conventional cylindrical Penning traps. At the same
time, the desired electrostatic and magnetostatic properties of a closed-endcap
cylindrical Penning trap are preserved in this congfiuration. We give a
detailed account on the design and confinement properties, a characterization
of the trap and show first results of light collection with in-trap produced
highly charged ions
Switchable Magnetic Bottles and Field Gradients for Particle Traps
Versatile methods for the manipulation of individual quantum systems, such as
confined particles, have become central elements in current developments in
precision spectroscopy, frequency standards, quantum information processing,
quantum simulation, and alike. For atomic and some subatomic particles, both
neutral and charged, a precise control of magnetic fields is essen- tial. In
this paper, we discuss possibilities for the creation of specific magnetic
field configurations which find appli- cation in these areas. In particular, we
pursue the idea of a magnetic bottle which can be switched on and off by
transition between the normal and the superconducting phase of a suitable
material in cryogenic environments, for example in trap experiments in moderate
magnetic fields. Methods for a fine-tuning of the magnetic field and its linear
and quadratic components in a trap are presented together with possible
applications
Trapped Ion Oscillation Frequencies as Sensors for Spectroscopy
The oscillation frequencies of charged particles in a Penning trap can serve as sensors for spectroscopy when additional field components are introduced to the magnetic and electric fields used for confinement. The presence of so-called “magnetic bottles” and specific electric anharmonicities creates calculable energy-dependences of the oscillation frequencies in the radiofrequency domain which may be used to detect the absorption or emission of photons both in the microwave and optical frequency domains. The precise electronic measurement of these oscillation frequencies therefore represents an optical sensor for spectroscopy. We discuss possible applications for precision laser and microwave spectroscopy and their role in the determination of magnetic moments and excited state life-times. Also, the trap-assisted measurement of radiative nuclear de-excitations in the X-ray domain is discussed. This way, the different applications range over more than 12 orders of magnitude in the detectable photon energies, from below μeV in the microwave domain to beyond MeV in the X-ray domain
g factor of lithiumlike silicon 28Si11+
The g factor of lithiumlike 28Si11+ has been measured in a triple-Penning
trap with a relative uncertainty of 1.1x10^{-9} to be g_exp=2.0008898899(21).
The theoretical prediction for this value was calculated to be
g_th=2.000889909(51) improving the accuracy to 2.5x10^{-8} due to the first
rigorous evaluation of the two-photon exchange correction. The measured value
is in excellent agreement with the state-of-the-art theoretical prediction and
yields the most stringent test of bound-state QED for the g factor of the
1s^22s state and the relativistic many-electron calculations in a magnetic
field
Expression Analysis of Fibronectin Type III Domain-Containing (FNDC) Genes in Inflammatory Bowel Disease and Colorectal Cancer
Background. Fibronectin type III domain-containing (FNDC) proteins fulfill manifold functions in tissue development and regulation of cellular metabolism. FNDC4 was described as anti-inflammatory factor, upregulated in inflammatory bowel disease (IBD). FNDC signaling includes direct cell-cell interaction as well as release of bioactive peptides, like shown for FNDC4 or FNDC5. The G-protein-coupled receptor 116 (GPR116) was found as a putative FNDC4 receptor. We here aim to comprehensively analyze the mRNA expression of FNDC1, FNDC3A, FNDC3B, FNDC4, FNDC5, and GPR116 in nonaffected and affected mucosal samples of patients with IBD or colorectal cancer (CRC). Methods. Mucosa samples were obtained from 30 patients undergoing diagnostic colonoscopy or from surgical resection of IBD or CRC. Gene expression was determined by quantitative real-time PCR. In addition, FNDC expression data from publicly available Gene Expression Omnibus (GEO) data sets (GDS4296, GDS4515, and GDS5232) were analyzed. Results. Basal mucosal expression revealed higher expression of FNDC3A and FNDC5 in the ileum compared to colonic segments. FNDC1 and FNDC4 were significantly upregulated in IBD. None of the investigated FNDCs was differentially expressed in CRC, just FNDC3A trended to be upregulated. The GEO data set analysis revealed significantly downregulated FNDC4 and upregulated GPR116 in microsatellite unstable (MSI) CRCs. The expression of FNDCs and GPR116 was independent of age and sex. Conclusions. FNDC1 and FNDC4 may play a relevant role in the pathobiology of IBD, but none of the investigated FNDCs is regulated in CRC. GPR116 may be upregulated in advanced or MSI CRC. Further studies should validate the altered FNDC expression results on protein levels and examine the corresponding functional consequences
A reservoir trap for antiprotons
We have developed techniques to extract arbitrary fractions of antiprotons
from an accumulated reservoir, and to inject them into a Penning-trap system
for high-precision measurements. In our trap-system antiproton storage times >
1.08 years are estimated. The device is fail-safe against power-cuts of up to
10 hours. This makes our planned comparisons of the fundamental properties of
protons and antiprotons independent from accelerator cycles, and will enable us
to perform experiments during long accelerator shutdown periods when background
magnetic noise is low. The demonstrated scheme has the potential to be applied
in many other precision Penning trap experiments dealing with exotic particles.Comment: Article by the BASE-collaboration at CERN. Results from the
Antiproton physics run 2014. Submitted to International Journal of Mass
Spectrometry, 8th of April 201
High-precision measurement of the atomic mass of the electron
The quest for the value of the electron's atomic mass has been subject of
continuing efforts over the last decades. Among the seemingly fundamental
constants which parameterize the Standard Model (SM) of physics and which are
thus responsible for its predictive power, the electron mass me plays a
prominent role, as it is responsible for the structure and properties of atoms
and molecules. This manifests in the close link with other fundamental
constants, such as the Rydberg constant and the fine-structure constant
{\alpha}. However, the low mass of the electron considerably complicates its
precise determination. In this work we present a substantial improvement by
combining a very accurate measurement of the magnetic moment of a single
electron bound to a carbon nucleus with a state-of-the-art calculation in the
framework of bound-state Quantum Electrodynamics. The achieved precision of the
atomic mass of the electron surpasses the current CODATA value by a factor of
13. Accordingly, the result presented in this letter lays the foundation for
future fundamental physics experiments and precision tests of the SM
Freeform terahertz structures fabricated by multi-photon lithography and metal coating
Direct-write multi-photon laser lithography (MPL) combines highest resolution on the nanoscale with essentially unlimited 3D design freedom. Over the previous years, the groundbreaking potential of this technique has been demonstrated in various application fields, including micromechanics, material sciences, microfluidics, life sciences as well as photonics, where in-situ printed optical coupling elements offer new perspectives for package-level system integration. However, millimeter-wave (mmW) and terahertz (THz) devices could not yet leverage the unique strengths of MPL, even though the underlying devices and structures could also greatly benefit from 3D freeform microfabrication. One of the key challenges in this context is the fact that functional mmW and THz structures require materials with high electrical conductivity and low dielectric losses, which are not amenable to structuring by multi-photon polymerization. In this work, we introduce and experimentally demonstrate a novel approach that allows to leverage MPL for fabricating high-performance mmW and THz structures with hitherto unachieved functionalities. Our concept exploits in-situ printed polymer templates that are selectively coated through highly directive metal deposition techniques in combination with precisely aligned 3D-printed shadowing structures. The resulting metal-coated freeform structures offer high surface quality in combination with low dielectric losses and conductivities comparable to bulk material values, while lending themselves to fabrication on planar mmW/THz circuits. We experimentally show the viability of our concept by demonstrating a series of functional THz structures such as THz interconnects, probe tips, and suspended antennas. We believe that our approach offers disruptive potential in the field of mmW and THz technology and may unlock an entirely new realm of laser-based 3D manufacturing
Trap-integrated fluorescence detection based on silicon photomultipliers in a cryogenic Penning trap
We present a fluorescence-detection system for laser-cooled 9Be+ ions based
on silicon photomultipliers (SiPM) operated at 4 K and integrated into our
cryogenic 1.9 T multi-Penning-trap system. Our approach enables fluorescence
detection in a hermetically-sealed cryogenic Penning-trap chamber with limited
optical access, where state-of-the-art detection using a telescope and
photomultipliers at room temperature would be extremely difficult. We
characterize the properties of the SiPM in a cryocooler at 4 K, where we
measure a dark count rate below 1/s and a detection efficiency of 2.5(3) %. We
further discuss the design of our cryogenic fluorescence-detection trap, and
analyze the performance of our detection system by fluorescence spectroscopy of
9Be+ ion clouds during several runs of our experiment.Comment: 12 pages, 11 figure
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