2,519 research outputs found
Planck LFI flight model feed horns
this paper is part of the Prelaunch status LFI papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jinst The Low Frequency
Instrument is optically interfaced with the ESA Planck telescope through 11
corrugated feed horns each connected to the Radiometer Chain Assembly (RCA).
This paper describes the design, the manufacturing and the testing of the
flight model feed horns. They have been designed to optimize the LFI optical
interfaces taking into account the tight mechanical requirements imposed by the
Planck focal plane layout. All the eleven units have been successfully tested
and integrated with the Ortho Mode transducers.Comment: This is an author-created, un-copyedited version of an article
accepted for publication in JINST. IOP Publishing Ltd is not responsible for
any errors or omissions in this version of the manuscript or any version
derived from it. The definitive publisher authenticated version is available
online at 10.1088/1748-0221/4/12/T1200
Milk acidity, curd firming time, curd firmness and protein and fat losses in the Parmigiano- Reggiano cheesemaking
The cheese yield depends on the milk casein content and on the fat to casein ratio. The efficiency of the milk transformation depends on curd particles ("curd fines") that remain in the cooked whey and on the losses of fat and casein as it is
Linear Ramps of Interaction in the Fermionic Hubbard Model
We study the out of equilibrium dynamics of the Fermionic Hubbard Model
induced by a linear ramp of the repulsive interaction from the metallic
state through the Mott transition. To this extent we use a time dependent
Gutzwiller variational method and complement this analysis with the inclusion
of quantum fluctuations at the leading order, in the framework of a slave
spin theory. We discuss the dynamics during the ramp and the issue of
adiabaticity through the scaling of the excitation energy with the ramp
duration . In addition, we study the dynamics for times scales longer
than the ramp time, when the system is again isolated and the total energy
conserved. We establish the existence of a dynamical phase transition analogous
to the one present in the sudden quench case and discuss its properties as a
function of final interaction and ramp duration. Finally we discuss the role of
quantum fluctuations on the mean field dynamics for both long ramps, where spin
wave theory is sufficient, and for very short ramps, where a self consistent
treatment of quantum fluctuations is required in order to obtain relaxation.Comment: v2: 19 pages, 14 figures, published versio
Comparing Catalysts of the Direct Synthesis of Hydrogen Peroxide in Organic Solvent: is the Measure of the Product an Issue?
The direct synthesis of hydrogen peroxide has been for about 20 years a hot topic in \u201cgreen\u201d catalysis. Several methods, which are well established to measure the concentration of hydrogen peroxide in water are also applied to the analysis of reaction mixtures from the direct synthesis of H2O2. However, this step could not be always straightforward, because these mixtures contain almost invariably organic solvents and, sometimes, selectivity enhancers which can interfere in some, at the least, of the most popular titrimetric methods. This work presents a comparative investigation of iodometry, cerimetry, permanganometry (titrimetric methods) and spectrophotometric analysis of TiIV/H2O2 adduct, as applied to analysis of hydrogen peroxide produced by its direct synthesis. They account for more than 90 % of the competent literature since 2000. Their pros and cons are highlighted to provide a guideline for the choice of the best possible method of analysis and for the comparison of catalytic results assessed in different ways in the context of the direct synthesis of hydrogen peroxide
The GRAAL high resolution BGO calorimeter and its energy calibration and monitoring system
We describe the electromagnetic calorimeter built for the GRAAL apparatus at
the ESRF. Its monitoring system is presented in detail. Results from tests and
the performance obtained during the first GRAAL experiments are given. The
energy calibration accuracy and stability reached is a small fraction of the
intrinsic detector resolution.Comment: 19 pages, 14 figures, submitted to Nuclear Instruments and Method
Planck-LFI radiometers' spectral response
The Low Frequency Instrument (LFI) is an array of pseudo-correlation
radiometers on board the Planck satellite, the ESA mission dedicated to
precision measurements of the Cosmic Microwave Background. The LFI covers three
bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central
frequency.
The characterization of the broadband frequency response of each radiometer
is necessary to understand and correct for systematic effects, particularly
those related to foreground residuals and polarization measurements. In this
paper we present the measured band shape of all the LFI channels and discuss
the methods adopted for their estimation. The spectral characterization of each
radiometer was obtained by combining the measured spectral response of
individual units through a dedicated RF model of the LFI receiver scheme.
As a consistency check, we also attempted end-to-end spectral measurements of
the integrated radiometer chain in a cryogenic chamber. However, due to
systematic effects in the measurement setup, only qualitative results were
obtained from these tests. The measured LFI bandpasses exhibit a moderate level
of ripple, compatible with the instrument scientific requirements.Comment: 16 pages, 9 figures, this paper is part of the Prelaunch status LFI
papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jins
High Performances Corrugated Feed Horns for Space Applications at Millimetre Wavelengths
We report on the design, fabrication and testing of a set of high performance
corrugated feed horns at 30 GHz, 70 GHz and 100 GHz, built as advanced
prototypes for the Low Frequency Instrument (LFI) of the ESA Planck mission.
The electromagnetic designs include linear (100 GHz) and dual shaped (30 and 70
GHz) profiles. Fabrication has been achieved by direct machining at 30 GHz, and
by electro-formation at higher frequencies. The measured performances on side
lobes and return loss meet the stringent Planck requirements over the large
(20%) instrument bandwidth. Moreover, the advantage in terms of main lobe shape
and side lobes levels of the dual profiled designs has been demonstrated.Comment: 16 pages, 7 figures, accepted for publication in Experimental
Astronom
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