704 research outputs found
Measurement of Aerosols at the Pierre Auger Observatory
The air fluorescence detectors (FDs) of the Pierre Auger Observatory are
vital for the determination of the air shower energy scale. To compensate for
variations in atmospheric conditions that affect the energy measurement, the
Observatory operates an array of monitoring instruments to record hourly
atmospheric conditions across the detector site, an area exceeding 3,000 square
km. This paper presents results from four instruments used to characterize the
aerosol component of the atmosphere: the Central Laser Facility (CLF), which
provides the FDs with calibrated laser shots; the scanning backscatter lidars,
which operate at three FD sites; the Aerosol Phase Function monitors (APFs),
which measure the aerosol scattering cross section at two FD locations; and the
Horizontal Attenuation Monitor (HAM), which measures the wavelength dependence
of aerosol attenuation.Comment: Contribution to the 30th International Cosmic Ray Conference, Merida
Mexico, July 2007; 4 pages, 4 figure
Changes during storing and astringency removal of persimmon fruit Diospyros kaki L.
Physiological changes during ripening, storing and astringency removal of persimmon fruits were traced. The fruits were stored under normal (NA), controlled (CA) and vacuum atmospheres (VA). The fruits were stored for 100 days and analysed for firmness, acetaldehyde and ethanol content and soluble tannins, both before and after storing. The same analyses were done during the deastringency treatment carried out with a high CO2 concentration (99.99%) for 20 h at 20 °C. The persimmon fruits stored under NA, CA, VA or treated with high CO2 for 20 h accumulated acetaldehyde and ethanol in the fruit tissue. CA conditions caused the highest acetaldehyde accumulation; vacuum conditions the lowest. Ethanol content increased 20 fold during storage; the highest accumulation was observed in vacuum stored fruit followed by CA (3% CO2Ś2% O2 and 0.5% CO2Ś2% O2) conditions. Astringency removal treatment caused an immediate increase of acetaldehyde and ethanol, nearly to the same extent as in conventionally ripened or stored fruit. The amount of soluble tannins, the main cause of an astringent taste, decreased during storage, and it did much faster during deastringency removal at the same level. The sensory evaluation test revealed that fruit treated with high CO2 was preferred to conventionally ripened fruit
A study of the radiation tolerance of cvd diamond to 70 mev protons, fast neutrons and 200 mev pions
We measured the radiation tolerance of commercially available diamonds grown by the Chemical Vapor Deposition process by measuring the charge created by a 120 GeV hadron beam in a 50 ÎŒm pitch strip detector fabricated on each diamond sample before and after irradiation. We irradiated one group of samples with 70 MeV protons, a second group of samples with fast reactor neutrons (defined as energy greater than 0.1 MeV), and a third group of samples with 200 MeV pions, in steps, to (8.8±0.9) Ă 10 protons/cm, (1.43±0.14) Ă 10 neutrons/cm, and (6.5±1.4) Ă 1014 pions/cm, respectively. By observing the charge induced due to the separation of electronâhole pairs created by the passage of the hadron beam through each sample, on an event-by-event basis, as a function of irradiation fluence, we conclude all datasets can be described by a first-order damage equation and independently calculate the damage constant for 70 MeV protons, fast reactor neutrons, and 200 MeV pions. We find the damage constant for diamond irradiated with 70 MeV protons to be 1.62±0.07(stat)±0.16(syst)Ă 10â18 cm/(pÎŒm), the damage constant for diamond irradiated with fast reactor neutrons to be 2.65±0.13(stat)±0.18(syst)Ă 10â18 cm/(nÎŒm), and the damage constant for diamond irradiated with 200 MeV pions to be 2.0±0.2(stat)±0.5(syst)Ă 10â18 cm/(ÏÎŒm). The damage constants from this measurement were analyzed together with our previously published 24 GeV proton irradiation and 800 MeV proton irradiation damage constant data to derive the first comprehensive set of relative damage constants for Chemical Vapor Deposition diamond. We find 70 MeV protons are 2.60 ± 0.29 times more damaging than 24 GeV protons, fast reactor neutrons are 4.3 ± 0.4 times more damaging than 24 GeV protons, and 200 MeV pions are 3.2 ± 0.8 more damaging than 24 GeV protons. We also observe the measured data can be described by a universal damage curve for all proton, neutron, and pion irradiations we performed of Chemical Vapor Deposition diamond. Finally, we confirm the spatial uniformity of the collected charge increases with fluence for polycrystalline Chemical Vapor Deposition diamond, and this effect can also be described by a universal curve
A Study of the Radiation Tolerance of CVD Diamond to 70MeV Protons, Fast Neutrons and 200MeV Pions
Visual Anomaly Detection via Dual-Attention Transformer and Discriminative Flow
In this paper, we introduce the novel state-of-the-art Dual-attention
Transformer and Discriminative Flow (DADF) framework for visual anomaly
detection. Based on only normal knowledge, visual anomaly detection has wide
applications in industrial scenarios and has attracted significant attention.
However, most existing methods fail to meet the requirements. In contrast, the
proposed DTDF presents a new paradigm: it firstly leverages a pre-trained
network to acquire multi-scale prior embeddings, followed by the development of
a vision Transformer with dual attention mechanisms, namely self-attention and
memorial-attention, to achieve two-level reconstruction for prior embeddings
with the sequential and normality association. Additionally, we propose using
normalizing flow to establish discriminative likelihood for the joint
distribution of prior and reconstructions at each scale. The DADF achieves
98.3/98.4 of image/pixel AUROC on Mvtec AD; 83.7 of image AUROC and 67.4 of
pixel sPRO on Mvtec LOCO AD benchmarks, demonstrating the effectiveness of our
proposed approach.Comment: Submission to IEEE Transactions On Industrial Informatic
Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum
We report a first measurement for ultra-high energy cosmic rays of the
correlation between the depth of shower maximum and the signal in the water
Cherenkov stations of air-showers registered simultaneously by the fluorescence
and the surface detectors of the Pierre Auger Observatory. Such a correlation
measurement is a unique feature of a hybrid air-shower observatory with
sensitivity to both the electromagnetic and muonic components. It allows an
accurate determination of the spread of primary masses in the cosmic-ray flux.
Up till now, constraints on the spread of primary masses have been dominated by
systematic uncertainties. The present correlation measurement is not affected
by systematics in the measurement of the depth of shower maximum or the signal
in the water Cherenkov stations. The analysis relies on general characteristics
of air showers and is thus robust also with respect to uncertainties in
hadronic event generators. The observed correlation in the energy range around
the `ankle' at differs significantly from
expectations for pure primary cosmic-ray compositions. A light composition made
up of proton and helium only is equally inconsistent with observations. The
data are explained well by a mixed composition including nuclei with mass . Scenarios such as the proton dip model, with almost pure compositions, are
thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray
flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report
Numbe
Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter
An in-situ calibration of a logarithmic periodic dipole antenna with a
frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of
a radio station system used for detection of cosmic ray induced air showers at
the Engineering Radio Array of the Pierre Auger Observatory, the so-called
Auger Engineering Radio Array (AERA). The directional and frequency
characteristics of the broadband antenna are investigated using a remotely
piloted aircraft (RPA) carrying a small transmitting antenna. The antenna
sensitivity is described by the vector effective length relating the measured
voltage with the electric-field components perpendicular to the incoming signal
direction. The horizontal and meridional components are determined with an
overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} %
respectively. The measurement is used to correct a simulated response of the
frequency and directional response of the antenna. In addition, the influence
of the ground conductivity and permittivity on the antenna response is
simulated. Both have a negligible influence given the ground conditions
measured at the detector site. The overall uncertainties of the vector
effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in
the square root of the energy fluence for incoming signal directions with
zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is
unchanged with respect to v2. 39 pages, 15 figures, 2 table
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