177 research outputs found
Reactive Desorption of CO Hydrogenation Products under Cold Pre-stellar Core Conditions
The astronomical gas-phase detection of simple species and small organic
molecules in cold pre-stellar cores, with abundances as high as
n, contradicts the generally accepted idea
that at K, such species should be fully frozen out on grain surfaces. A
physical or chemical mechanism that results in a net transfer from solid-state
species into the gas phase offers a possible explanation. Reactive desorption,
i.e., desorption following the exothermic formation of a species, is one of the
options that has been proposed. In astronomical models, the fraction of
molecules desorbed through this process is handled as a free parameter, as
experimental studies quantifying the impact of exothermicity on desorption
efficiencies are largely lacking. In this work, we present a detailed
laboratory study with the goal of deriving an upper limit for the reactive
desorption efficiency of species involved in the CO-HCO-CHOH
solid-state hydrogenation reaction chain. The limit for the overall reactive
desorption fraction is derived by precisely investigating the solid-state
elemental carbon budget, using reflection absorption infrared spectroscopy and
the calibrated solid-state band-strength values for CO, HCO and CHOH.
We find that for temperatures in the range of to K, an upper limit of
for the overall elemental carbon loss upon CO conversion into
CHOH. This corresponds with an effective reaction desorption fraction of
per hydrogenation step, or per H-atom induced
reaction, assuming that H-atom addition and abstraction reactions equally
contribute to the overall reactive desorption fraction along the hydrogenation
sequence. The astronomical relevance of this finding is discussed.Comment: 9 pages, 7 figure
On the existence of the second Dirac operator in Riemannian space
We describe a Riemannian space class where the second Dirac operator arises
and prove that the operator is always equivalent to a standard Dirac one. The
particle state in this gravitational field is degenerate to some extent and we
introduce an additional value in order to describe a particle state completely.
Some supersymmetry constructions are also discussed. As an example we study all
Riemannian spaces with a five-dimentional motion group and find all metrics for
which the second Dirac operator exists. On the basis of our discussed examples
we hypothesize about the number of second Dirac operators in Riemannian space.Comment: LaTex, 10 pages, no figure
JUNO Conceptual Design Report
The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine
the neutrino mass hierarchy using an underground liquid scintillator detector.
It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants
in Guangdong, China. The experimental hall, spanning more than 50 meters, is
under a granite mountain of over 700 m overburden. Within six years of running,
the detection of reactor antineutrinos can resolve the neutrino mass hierarchy
at a confidence level of 3-4, and determine neutrino oscillation
parameters , , and to
an accuracy of better than 1%. The JUNO detector can be also used to study
terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard
Model. The central detector contains 20,000 tons liquid scintillator with an
acrylic sphere of 35 m in diameter. 17,000 508-mm diameter PMTs with high
quantum efficiency provide 75% optical coverage. The current choice of
the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO
as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of
detected photoelectrons per MeV is larger than 1,100 and the energy resolution
is expected to be 3% at 1 MeV. The calibration system is designed to deploy
multiple sources to cover the entire energy range of reactor antineutrinos, and
to achieve a full-volume position coverage inside the detector. The veto system
is used for muon detection, muon induced background study and reduction. It
consists of a Water Cherenkov detector and a Top Tracker system. The readout
system, the detector control system and the offline system insure efficient and
stable data acquisition and processing.Comment: 328 pages, 211 figure
Grain Surface Models and Data for Astrochemistry
AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of âŒ25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions
Đ ĐČĐŸĐżŃĐŸŃŃ ĐŸ ĐČĐŸĐ·ĐŒĐŸĐ¶ĐœŃŃ ĐŒĐ”Ń Đ°ĐœĐžĐ·ĐŒĐ°Ń ĐŽĐ”ĐčŃŃĐČĐžŃ Đ°ĐșŃĐżŃĐœĐșŃŃŃŃ ĐżŃĐž лДŃĐ”ĐœĐžĐž Đ±ĐŸĐ»ŃĐœŃŃ Đ±ŃĐŸĐœŃ ĐžĐ°Đ»ŃĐœĐŸĐč Đ°ŃŃĐŒĐŸĐč
The acupuncture effect mechanisms (efficacy of a single procedure and a treatment course) have been thoroughly studied with due account of neirophysical, biochemical and energetic aspects. The study was based on an integral estimation assessment of patientsâ conditions (contemporary European and classic Chinese estimates) for 60 patients with a mild course of bronchial asthma and 30 patients with the pre-asthma state treated with acupuncture monotherapy.Specific aspects of the homeostasis adaptive correction have been defined. This makes it possible to recommend the acupuncture not only for treatment but for the bronchial asthma prophylaxis.ĐĐ”Ń
Đ°ĐœĐžĐ·ĐŒŃ ĐŽĐ”ĐčŃŃĐČĐžŃ Đ°ĐșŃĐżŃĐœĐșŃŃŃŃ (ŃŃŃĐ”ĐșŃŃ ĐŸĐŽĐœĐŸĐč ĐżŃĐŸŃДЎŃŃŃ Đž ĐșŃŃŃĐŸĐČĐŸĐłĐŸ лДŃĐ”ĐœĐžŃ) ОзŃŃалОŃŃ ĐșĐŸĐŒĐżĐ»Đ”ĐșŃĐœĐŸ (ĐœĐ”ĐčŃĐŸŃĐžĐ·ĐžĐŸĐ»ĐŸĐłĐžŃĐ”ŃĐșОД, Đ±ĐžĐŸŃ
ĐžĐŒĐžŃĐ”ŃĐșОД, ŃĐœĐ”ŃгДŃĐžŃĐ”ŃĐșОД Đ°ŃпДĐșŃŃ) ĐœĐ° ĐŸŃĐœĐŸĐČĐ” ĐžĐœŃДгŃĐ°Đ»ŃĐœĐŸĐč ĐŸŃĐ”ĐœĐșĐž ŃĐŸŃŃĐŸŃĐœĐžŃ (ŃĐŸĐČŃĐ”ĐŒĐ”ĐœĐœĐŸĐč Đ”ĐČŃĐŸĐżĐ”ĐčŃĐșĐŸĐč Đž ĐșлаŃŃĐžŃĐ”ŃĐșĐŸĐč ĐșĐžŃĐ°ĐčŃĐșĐŸĐč) Ń 60 Đ±ĐŸĐ»ŃĐœŃŃ
Ń Đ»Đ”ĐłĐșĐžĐŒ ŃĐ”ŃĐ”ĐœĐžĐ”ĐŒ бŃĐŸĐœŃ
ОалŃĐœĐŸĐč Đ°ŃŃĐŒŃ Đž 30 Đ±ĐŸĐ»ŃĐœŃŃ
Ń ŃĐŸŃŃĐŸŃĐœĐžĐ”ĐŒ ĐżŃДЎаŃŃĐŒŃ ĐČ ĐżŃĐŸŃĐ”ŃŃĐ” ĐŒĐŸĐœĐŸŃĐ”ŃапОО Đ°ĐșŃĐżŃĐœĐșŃŃŃĐŸĐč. ĐŁŃĐŸŃĐœĐ”ĐœŃ ĐŸŃĐŸĐ±Đ”ĐœĐœĐŸŃŃĐž Đ°ĐŽĐ°ĐżŃĐžĐČĐœĐŸĐč ĐșĐŸŃŃĐ”ĐșŃОО ĐłĐŸĐŒĐ”ĐŸŃŃĐ°Đ·Đ°, ĐżĐŸĐ·ĐČĐŸĐ»ŃŃŃОД ŃĐ”ĐșĐŸĐŒĐ”ĐœĐŽĐŸĐČĐ°ŃŃ Đ°ĐșŃĐżŃĐœĐșŃŃŃŃ ĐœĐ” ŃĐŸĐ»ŃĐșĐŸ ĐŽĐ»Ń Đ»Đ”ŃĐ”ĐœĐžŃ, ĐœĐŸ Đž ĐŽĐ»Ń ĐżŃĐŸŃОлаĐșŃĐžĐșĐž бŃĐŸĐœŃ
ОалŃĐœĐŸĐč Đ°ŃŃĐŒŃ
Identification and reconstruction of low-energy electrons in the ProtoDUNE-SP detector
Measurements of electrons from interactions are crucial for the Deep
Underground Neutrino Experiment (DUNE) neutrino oscillation program, as well as
searches for physics beyond the standard model, supernova neutrino detection,
and solar neutrino measurements. This article describes the selection and
reconstruction of low-energy (Michel) electrons in the ProtoDUNE-SP detector.
ProtoDUNE-SP is one of the prototypes for the DUNE far detector, built and
operated at CERN as a charged particle test beam experiment. A sample of
low-energy electrons produced by the decay of cosmic muons is selected with a
purity of 95%. This sample is used to calibrate the low-energy electron energy
scale with two techniques. An electron energy calibration based on a cosmic ray
muon sample uses calibration constants derived from measured and simulated
cosmic ray muon events. Another calibration technique makes use of the
theoretically well-understood Michel electron energy spectrum to convert
reconstructed charge to electron energy. In addition, the effects of detector
response to low-energy electron energy scale and its resolution including
readout electronics threshold effects are quantified. Finally, the relation
between the theoretical and reconstructed low-energy electron energy spectrum
is derived and the energy resolution is characterized. The low-energy electron
selection presented here accounts for about 75% of the total electron deposited
energy. After the addition of lost energy using a Monte Carlo simulation, the
energy resolution improves from about 40% to 25% at 50~MeV. These results are
used to validate the expected capabilities of the DUNE far detector to
reconstruct low-energy electrons.Comment: 19 pages, 10 figure
Low exposure long-baseline neutrino oscillation sensitivity of the DUNE experiment
The Deep Underground Neutrino Experiment (DUNE) will produce world-leading
neutrino oscillation measurements over the lifetime of the experiment. In this
work, we explore DUNE's sensitivity to observe charge-parity violation (CPV) in
the neutrino sector, and to resolve the mass ordering, for exposures of up to
100 kiloton-megawatt-years (kt-MW-yr). The analysis includes detailed
uncertainties on the flux prediction, the neutrino interaction model, and
detector effects. We demonstrate that DUNE will be able to unambiguously
resolve the neutrino mass ordering at a 3 (5) level, with a 66
(100) kt-MW-yr far detector exposure, and has the ability to make strong
statements at significantly shorter exposures depending on the true value of
other oscillation parameters. We also show that DUNE has the potential to make
a robust measurement of CPV at a 3 level with a 100 kt-MW-yr exposure
for the maximally CP-violating values \delta_{\rm CP}} = \pm\pi/2.
Additionally, the dependence of DUNE's sensitivity on the exposure taken in
neutrino-enhanced and antineutrino-enhanced running is discussed. An equal
fraction of exposure taken in each beam mode is found to be close to optimal
when considered over the entire space of interest
Impact of cross-section uncertainties on supernova neutrino spectral parameter fitting in the Deep Underground Neutrino Experiment
A primary goal of the upcoming Deep Underground Neutrino Experiment (DUNE) is
to measure the MeV neutrinos produced by a Galactic
core-collapse supernova if one should occur during the lifetime of the
experiment. The liquid-argon-based detectors planned for DUNE are expected to
be uniquely sensitive to the component of the supernova flux, enabling
a wide variety of physics and astrophysics measurements. A key requirement for
a correct interpretation of these measurements is a good understanding of the
energy-dependent total cross section for charged-current
absorption on argon. In the context of a simulated extraction of
supernova spectral parameters from a toy analysis, we investigate the
impact of modeling uncertainties on DUNE's supernova neutrino
physics sensitivity for the first time. We find that the currently large
theoretical uncertainties on must be substantially reduced
before the flux parameters can be extracted reliably: in the absence of
external constraints, a measurement of the integrated neutrino luminosity with
less than 10\% bias with DUNE requires to be known to about 5%.
The neutrino spectral shape parameters can be known to better than 10% for a
20% uncertainty on the cross-section scale, although they will be sensitive to
uncertainties on the shape of . A direct measurement of
low-energy -argon scattering would be invaluable for improving the
theoretical precision to the needed level.Comment: 25 pages, 21 figure
Snowmass Neutrino Frontier: DUNE Physics Summary
The Deep Underground Neutrino Experiment (DUNE) is a next-generation long-baseline neutrino oscillation experiment with a primary physics goal of observing neutrino and antineutrino oscillation patterns to precisely measure the parameters governing long-baseline neutrino oscillation in a single experiment, and to test the three-flavor paradigm. DUNE's design has been developed by a large, international collaboration of scientists and engineers to have unique capability to measure neutrino oscillation as a function of energy in a broadband beam, to resolve degeneracy among oscillation parameters, and to control systematic uncertainty using the exquisite imaging capability of massive LArTPC far detector modules and an argon-based near detector. DUNE's neutrino oscillation measurements will unambiguously resolve the neutrino mass ordering and provide the sensitivity to discover CP violation in neutrinos for a wide range of possible values of ÎŽCP. DUNE is also uniquely sensitive to electron neutrinos from a galactic supernova burst, and to a broad range of physics beyond the Standard Model (BSM), including nucleon decays. DUNE is anticipated to begin collecting physics data with Phase I, an initial experiment configuration consisting of two far detector modules and a minimal suite of near detector components, with a 1.2 MW proton beam. To realize its extensive, world-leading physics potential requires the full scope of DUNE be completed in Phase II. The three Phase II upgrades are all necessary to achieve DUNE's physics goals: (1) addition of far detector modules three and four for a total FD fiducial mass of at least 40 kt, (2) upgrade of the proton beam power from 1.2 MW to 2.4 MW, and (3) replacement of the near detector's temporary muon spectrometer with a magnetized, high-pressure gaseous argon TPC and calorimeter
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