86 research outputs found
Test of Lorentz Symmetry by using a 3He/129Xe Co-Magnetometer
To test Lorentz symmetry we used a 3He/129Xe co-magnetometer. We will give a
short summary of our experimental setup and the results of our latest
measurements. We obtained preliminary results for the equatorial component of
the background field interacting with the spin of the bound neutron: b_n < 3.72
x 10^(-32) GeV (95 C.L.).Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28 - July 2, 201
Potential of interdigitated back contact silicon heterojunction solar cells for liquid phase crystallized silicon on glass with efficiency above 14
Liquid phase crystallization of silicon LPC Si on glass is a promising method to produce high quality multi crystalline Si films with macroscopic grains. In this study, we report on recent improvements of our interdigitated back contact silicon heterojunction contact system IBC SHJ , which enabled open circuit voltages as high as 661 mV and efficiencies up to 14.2 using a 13 m thin n type LPC Si absorbers on glass. The influence of the BSF width on the cell performance is investigated both experimentally and numerically. We combine 1D optical simulations using GenPro4 and 2D electrical simulations using Sentaurus TCAD to determine the optical and electrical loss mechanisms in order to estimate the potential of our current LPC Si absorbers. The simulations reveal an effective minority carrier diffusion length of 26 m and further demonstrate that a doping concentration of 4 1016 cm 3 and a back surface field width of 60 m are optimum values to further increase cell efficiencie
Limit on Lorentz and CPT violation of the bound Neutron Using a Free Precession 3He/129Xe co-magnetometer
We report on the search for Lorentz violating sidereal variations of the
frequency difference of co-located spin-species while the Earth and hence the
laboratory reference frame rotates with respect to a relic background field.
The co-magnetometer used is based on the detection of freely precessing nuclear
spins from polarized 3He and 129Xe gas samples using SQUIDs as low-noise
magnetic flux detectors. As result we can determine the limit for the
equatorial component of the background field interacting with the spin of the
bound neutron to be bn < 3.7 x 10^{-32} GeV (95 C.L.).Comment: 5 pages, 4 figure
Silicon solar cells on glass with power conversion efficiency above 13 at thickness below 15 micrometer
Liquid phase crystallized silicon on glass with a thickness of 10 40 amp; 956;m has the potential to reduce material costs and the environmental impact of crystalline silicon solar cells. Recently, wafer quality open circuit voltages of over 650 mV and remarkable photocurrent densities of over 30 mA cm 2 have been demonstrated on this material, however, a low fill factor was limiting the performance. In this work we present our latest cell progress on 13 amp; 956;m thin poly crystalline silicon fabricated by the liquid phase crystallization directly on glass. The contact system uses passivated back side silicon hetero junctions, back side KOH texture for light trapping and interdigitated ITO Ag contacts. The fill factors are up to 74 and efficiencies are 13.2 under AM1.5 g for two different doping densities of 1 10 17 cm 3 and 2 10 16 cm 3 . The former is limited by bulk and interface recombination, leading to a reduced saturation current density, the latter by series resistance causing a lower fill factor. Both are additionally limited by electrical shading and losses at grain boundaries and dislocations. A small 1 0.1 cm 2 test structure circumvents limitations of the contact design reaching an efficiency of 15.9 clearly showing the potential of the technolog
An Improved Neutron Electric Dipole Moment Experiment
A new measurement of the neutron EDM, using Ramsey's method of separated
oscillatory fields, is in preparation at the new high intensity source of
ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland
(PSI). The existence of a non-zero nEDM would violate both parity and time
reversal symmetry and, given the CPT theorem, might lead to a discovery of new
CP violating mechanisms. Already the current upper limit for the nEDM
(|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model.
The new experiment aims at a two orders of magnitude reduction of the
experimental uncertainty, to be achieved mainly by (1) the higher UCN flux
provided by the new PSI source, (2) better magnetic field control with improved
magnetometry and (3) a double chamber configuration with opposite electric
field directions.
The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL
group's apparatus (which has produced the current best result) moved from
Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further
step with a new spectrometer, presently in the design phase.Comment: Flavor Physics & CP Violation Conference, Taipei, 200
Ultra-sensitive magnetometry based on free precession of nuclear spins
We discuss the design and performance of a very sensitive low-field
magnetometer based on the detection of free spin precession of gaseous, nuclear
polarized 3He or 129Xe samples with a SQUID as magnetic flux detector. The
device will be employed to control fluctuating magnetic fields and gradients in
a new experiment searching for a permanent electric dipole moment of the
neutron as well as in a new type of 3He/129Xe clock comparison experiment which
should be sensitive to a sidereal variation of the relative spin precession
frequency. Characteristic spin precession times T_2 of up to 60h could be
measured. In combination with a signal-to-noise ratio of > 5000:1, this leads
to a sensitivity level of deltaB= 1fT after an integration time of 220s and to
deltaB= 10^(-4)fT after one day. Even in that sensitivity range, the
magnetometer performance is statistically limited, and noise sources inherent
to the magnetometer are not limiting. The reason is that free precessing 3He
(129Xe) nuclear spins are almost completely decoupled from the environment.
That makes this type of magnetometer in particular attractive for precision
field measurements where a long-term stability is required
SME insolvency, bankruptcy, and survival: an examination of retrenchment strategies
A key assertion in the turnaround literature is that when survival is threatened, it is necessary to undertake asset and cost retrenchment strategies that stabilise the performance decline and provide a base for survival and recovery. Correcting for methodological weaknesses in the literature, this study of Spanish SMEs finds that retrenchment of inventory and employees is associated with liquidation. Furthermore, neither intangible asset nor tangible asset retrenchment is associated with survival. Only retrenchment of debt is associated with survival. These results challenge conventional wisdom on retrenchment in turnaround situations. Automatic, across-the-board retrenchment is not a universal panacea to achieve turnaround and should not be implemented as a reflex response to insolvency. Instead, managers of insolvent firms should focus on liquidity and operational improvements, which result in debt reduction. Great care should be taken with the need for, and the extent of, retrenchment in inventory and employees
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