•Two unblended alternative jet fuels were tested on a CFM56 jet engine.•Particle emission followed the hydrogen content of the fuels.•One ASTM non-compliant fuel led to a reduction of 70% in particle ...emission.•Different transient patterns were applied and compared to steady-state processes.
The emission of soot particles from aircraft jet engines is relevant due to their impact on contrail formation and local air quality in airport areas. The reduction of particle emission may be achieved by changes in jet engine design. This, however, will only affect new aircraft. Previous studies have shown that the use of alternative jet fuels feature a co-beneficial reduction of soot emission beside an improved carbon footprint. In the present study, a CFM56-5C4 engine was operated on a test rig with three different fuel types: one reference kerosene, a catalytic hydrothermolysis jet fuel (ReadiJet) and an unblended alcohol-to-jet (ATJ) fuel. Due to the absence of aromatics in the ATJ fuel, ASTM jet fuel requirements are not met, but the use of this fuel led to a reduction of 70% in particle mass compared to the reference fuel. The ReadiJet fuel has higher aromatic content, lower fuel hydrogen content and, thus, an increase in particle emission was observed. For the present engine, the highest soot reductions were observed at lower power settings. In accordance to previous studies, the soot emission showed a good correlation to the hydrogen content of the fuels and the emission reduction matches the estimations of the imFOX model. In order to compare test rig studies to field studies, transient processes must be considered because they govern take-off conditions. Four experiments with different transient thrust patterns were performed on the test rig with regular Jet A-1. If the thrust changes were not very rapid (e.g. 5 s to ~90% thrust) the results could be reproduced with a set of pseudo-stationary processes to a sufficient extend. This emphasizes the relevance of test-rig studies for real in-field measurements and local air quality studies.
Modeling of GERDA Phase II data Agostini, M.; Bakalyarov, A. M.; Balata, M. ...
The journal of high energy physics,
03/2020, Letnik:
2020, Številka:
3
Journal Article
Recenzirano
Odprti dostop
A
bstract
The GERmanium Detector Array (Gerda) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double-beta (0
νββ
) decay of
76
Ge. The technological ...challenge of Gerda is to operate in a “background-free” regime in the region of interest (ROI) after analysis cuts for the full 100 kg
·
yr target exposure of the experiment. A careful modeling and decomposition of the full-range energy spectrum is essential to predict the shape and composition of events in the ROI around
Q
ββ
for the 0
νββ
search, to extract a precise measurement of the half-life of the double-beta decay mode with neutrinos (2
νββ
) and in order to identify the location of residual impurities. The latter will permit future experiments to build strategies in order to further lower the background and achieve even better sensitivities. In this article the background decomposition prior to analysis cuts is presented for Gerda Phase II. The background model fit yields a flat spectrum in the ROI with a background index (BI) of
16.04
−
0.85
+
0.78
·
10
−
3
cts/(keV
·
kg
·
yr) for the enriched BEGe data set and
14.68
−
0.52
+
0.47
·
10
−
3
cts/(keV
·
kg
·
yr) for the enriched coaxial data set. These values are similar to the one of Phase I despite a much larger number of detectors and hence radioactive hardware components.
Pulse shape analysis in Gerda Phase II Agostini, M.; Araujo, G.; Bakalyarov, A. M. ...
The European physical journal. C, Particles and fields,
04/2022, Letnik:
82, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The GERmanium Detector Array (
Gerda
) collaboration searched for neutrinoless double-
β
decay in
76
Ge using isotopically enriched high purity germanium detectors at the Laboratori Nazionali del ...Gran Sasso of INFN. After Phase I (2011–2013), the experiment benefited from several upgrades, including an additional active veto based on LAr instrumentation and a significant increase of mass by point-contact germanium detectors that improved the half-life sensitivity of Phase II (2015–2019) by an order of magnitude. At the core of the background mitigation strategy, the analysis of the time profile of individual pulses provides a powerful topological discrimination of signal-like and background-like events. Data from regular
228
Th calibrations and physics data were both considered in the evaluation of the pulse shape discrimination performance. In this work, we describe the various methods applied to the data collected in
Gerda
Phase II corresponding to an exposure of 103.7 kg year. These methods suppress the background by a factor of about 5 in the region of interest around
Q
β
β
=
2039
keV, while preserving
(
81
±
3
)
% of the signal. In addition, an exhaustive list of parameters is provided which were used in the final data analysis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The ability to detect liquid argon scintillation light from within a densely packed high-purity germanium detector array allowed the
Gerda
experiment to reach an exceptionally low background rate in ...the search for neutrinoless double beta decay of
76
Ge. Proper modeling of the light propagation throughout the experimental setup, from any origin in the liquid argon volume to its eventual detection by the novel light read-out system, provides insight into the rejection capability and is a necessary ingredient to obtain robust background predictions. In this paper, we present a model of the
Gerda
liquid argon veto, as obtained by Monte Carlo simulations and constrained by calibration data, and highlight its application for background decomposition.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
6.
Calibration of the Gerda experiment Agostini, M.; Araujo, G.; Bakalyarov, A. M. ...
European physical journal. C, Particles and fields,
08/2021, Letnik:
81, Številka:
8
Journal Article
Recenzirano
Odprti dostop
The GERmanium Detector Array (
Gerda
) collaboration searched for neutrinoless double-
β
decay in
76
Ge with an array of about 40 high-purity isotopically-enriched germanium detectors. The ...experimental signature of the decay is a monoenergetic signal at
Q
β
β
=
2039.061
(
7
)
keV in the measured summed energy spectrum of the two emitted electrons. Both the energy reconstruction and resolution of the germanium detectors are crucial to separate a potential signal from various backgrounds, such as neutrino-accompanied double-
β
decays allowed by the Standard Model. The energy resolution and stability were determined and monitored as a function of time using data from regular
228
Th calibrations. In this work, we describe the calibration process and associated data analysis of the full
Gerda
dataset, tailored to preserve the excellent resolution of the individual germanium detectors when combining data over several years.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ECHo-1K is an experiment designed to measure the electron neutrino mass from the spectrum of the electron capture on 163Ho using an array of 100 magnetic micro calorimeters each loaded with 10 Bq of ...163Ho. In this article, we present the results of our activities in the investigation of possible backgrounds to the electron capture spectrum using GEANT4 based Monte-Carlo simulations of the sources 166mHo, 40K, 210Pb and the 238U decay chain. For standard contaminations of the used materials, the contribution of the investigated sources is well below the background induced by the pile-up of 163Ho decays. Nonetheless, care has to be taken to avoid accidental contamination during the manufacturing and storage of the detectors, since a few mBq in total on the surface of all 100 detectors of either 40K (∼ 12 mBq) from residual potassium, or 210Pb (∼ 4 mBq) from radon emanation yield a background as large as the expected signal.
The GERmanium Detector Array (GERDA) experiment searched for the lepton-number-violating neutrinoless double-β (0νββ) decay of ^{76}Ge, whose discovery would have far-reaching implications in ...cosmology and particle physics. By operating bare germanium diodes, enriched in ^{76}Ge, in an active liquid argon shield, GERDA achieved an unprecedently low background index of 5.2×10^{-4} counts/(keV kg yr) in the signal region and met the design goal to collect an exposure of 100 kg yr in a background-free regime. When combined with the result of Phase I, no signal is observed after 127.2 kg yr of total exposure. A limit on the half-life of 0νββ decay in ^{76}Ge is set at T_{1/2}>1.8×10^{26} yr at 90% C.L., which coincides with the sensitivity assuming no signal.
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