An ultra-stable, high-power cw Nd:YAG laser system, developed for the ground-based gravitational wave detector Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory), was comprehensively ...characterized. Laser power, frequency, beam pointing and beam quality were simultaneously stabilized using different active and passive schemes. The output beam, the performance of the stabilization, and the cross-coupling between different stabilization feedback control loops were characterized and found to fulfill most design requirements. The employed stabilization schemes and the achieved performance are of relevance to many high-precision optical experiments.
The theory of general relativity describes macroscopic phenomena driven by the influence of gravity while quantum mechanics brilliantly accounts for microscopic effects. Despite their tremendous ...individual success, a complete unification of fundamental interactions is missing and remains one of the most challenging and important quests in modern theoretical physics. The spacetime explorer and quantum equivalence principle space test satellite mission, proposed as a medium-size mission within the Cosmic Vision program of the European Space Agency (ESA), aims for testing general relativity with high precision in two experiments by performing a measurement of the gravitational redshift of the Sun and the Moon by comparing terrestrial clocks, and by performing a test of the universality of free fall of matter waves in the gravitational field of Earth comparing the trajectory of two Bose-Einstein condensates of 85Rb and 87Rb. The two ultracold atom clouds are monitored very precisely thanks to techniques of atom interferometry. This allows to reach down to an uncertainty in the Eötvös parameter of at least 2 × 10−15. In this paper, we report about the results of the phase A mission study of the atom interferometer instrument covering the description of the main payload elements, the atomic source concept, and the systematic error sources.
Pregnancy-related venous thromboembolic events are important preventable causes of morbidity and mortality in South Africa. All pregnant patients should be evaluated for thrombotic risk at different ...stages of their pregnancy and appropriate preventive steps taken. Maternal and fetal wellbeing must be kept in mind, as well as physiological changes leading to altered drug pharmacokinetics. Managing the patient with thrombotic risk in pregnancy, diagnosing venous thromboembolism (VTE) during pregnancy and treatment of venous thromboembolic events should be managed by a team. Excellent recent reviews on this subject are available, including risk factor stratification in anticoagulant therapy; managing the patient at time of labour; diagnosing VTE; and managing neuraxial anaesthesia in the pregnant patient on anticoagulant therapy.
We present a high-performance Alexandrite laser for LIDAR applications with repetition rates up to 20 kHz in cavity-dumped Q-switched operation continuous-wave diode-pumped in the red spectral ...region. With a double-pass pump configuration, short pulses with 2.8 ns duration at repetition frequencies ranging from 1 kHz to 20 kHz could be demonstrated. At 5 kHz a - to our knowledge - record pulse energy of over 500 µJ could be achieved at 755 nm in TEM
. Furthermore, a stability measurement at an energy of around 350 µJ with 5 kHz showed no degradation over 150 Mega-shots. The influence of the crystal temperature on the laser performance is also investigated, first in continuous-wave and secondly in cavity-dumped Q-switched operation.
The detection of gravitational waves from compact binary mergers by LIGO has opened the era of gravitational wave astronomy, revealing a previously hidden side of the cosmos. To maximize the reach of ...the existing LIGO observatory facilities, we have designed a new instrument able to detect gravitational waves at distances 5 times further away than possible with Advanced LIGO, or at greater than 100 times the event rate. Observations with this new instrument will make possible dramatic steps toward understanding the physics of the nearby Universe, as well as observing the Universe out to cosmological distances by the detection of binary black hole coalescences. This article presents the instrument design and a quantitative analysis of the anticipated noise floor.
For more than 70 years the default therapy for anaemia and blood loss was mostly transfusion. Accumulating evidence demonstrates a significant dose-dependent relationship between transfusion and ...adverse outcomes. This and other transfusion-related challenges led the way to a new paradigm. Patient blood management (PBM) is the application of evidence-based practices to optimise patient outcomes by managing and preserving the patient’s own blood. ‘Real-world’ studies have shown that PBM improves patient outcomes and saves money. The prevalence of anaemia in adult South Africans is 31% in females and 17% in males. Improving the management of anaemia will firstly improve public health, secondly relieve the pressure on the blood supply, and thirdly improve the productivity of the nation’s workforce. While high-income countries are increasingly implementing PBM, many middle- and low-income countries are still trying to upscale their transfusion services. The implementation of PBM will improve South Africa’s health status while saving costs.
Proton-nucleus (p+A) collisions have long been recognized as a crucial component of the physics program with nuclear beams at high energies, in particular for their reference role to interpret and ...understand nucleus-nucleus data as well as for their potential to elucidate the partonic structure of matter at low parton fractional momenta (small-x). Here, we summarize the main motivations that make a proton-nucleus run a decisive ingredient for a successful heavy-ion program at the Large Hadron Collider (LHC) and we present unique scientific opportunities arising from these collisions. We also review the status of ongoing discussions about operation plans for the p+A mode at the LHC.
Proton-Lead Collisions at the CERN LHC Salgado, Carlos A; Wessels, Johannes P
Annual review of nuclear and particle science,
10/2016, Volume:
66, Issue:
1
Journal Article
Peer reviewed
Open access
The single proton-lead collision run performed at the LHC has had profound consequences for the entire field of hot and dense QCD. The prior, 20-year-long experimental exploration of high-energy ...nucleus-nucleus collisions indicated that a hot QCD medium is created in a very short time, a fast equilibration. The striking similarities found in these nucleus-nucleus data and the a priori simpler proton-lead collisions, where no hot medium was expected, are refining our understanding of the whole process of thermalization at the most fundamental level. We review the most relevant sets of data taken during the proton-lead collisions of Run 1 at the LHC and the implications they have for our understanding of the underlying physical mechanisms and characterization of hot and dense QCD systems.
In October this year, it will be seventy-five years since Helmut Hartert, at the University of Heidelberg, Germany, described a “new” method of detecting the changes in blood clotting from a viscous ...to a more elastic clot, known as “thrombus stressography.”1 The apparatus measured the changes in resistance when applying a continuous rotational force to whole blood. These changes in resistance were then transduced and presented graphically (Figure 1).
In this work, we studied the interlock requirements in a seed failure scenario for Er
3+
:Yb
3+
doped fiber amplifiers (EYDFAs) pumped with high intensities in the MWcm
−2
range at 9XX nm. We fed a ...time-dependent FEM-tool with the data from backwards directed amplified spontaneous emission (ASE) transients of different commercially available core-pumped single-mode fibers. In the FEM-tool, the Er
3+
:Yb
3+
system is defined as a bi-directional energy transfer process and described by the corresponding rate equations. The power evolution of the pump, seed, and ASE signal is computed by differential equations taking into account the transient population densities of the relevant energy levels. With the model, we computed the temporal evolution of the corresponding energy levels after a seeder failure to take place within tens to hundreds of µs and calculated the associated gain. The fibers under test provide a critical total gain of 30 dB after ∼ 80 µs within the Yb
3+
band and after ∼300 µs within the Er
3+
band. This time decreases with increasing pump power and doping concentration. The results can be extrapolated to high-power cladding-pumped EYDFAs to meet the challenging requirements of engineering-level systems.
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