1,781 research outputs found
Photodegradation Mechanisms of Tetraphenyl Butadiene Coatings for Liquid Argon Detectors
We report on studies of degradation mechanisms of tetraphenyl butadiene (TPB)
coatings of the type used in neutrino and dark matter liquid argon experiments.
Using gas chromatography coupled to mass spectrometry we have detected the
ultraviolet-blocking impurity benzophenone (BP). We monitored the drop in
performance and increase of benzophenone concentration in TPB plates with
exposure to ultraviolet (UV) light, and demonstrate the correlation between
these two variables. Based on the presence and initially exponential increase
in the concentration of benzophenone observed, we propose that TPB degradation
is a free radical-mediated photooxidation reaction, which is subsequently
confirmed by displaying delayed degradation using a free radical inhibitor.
Finally we show that the performance of wavelength-shifting coatings of the
type envisioned for the LBNE experiment can be improved by 10-20%, with
significantly delayed UV degradation, by using a 20% admixture of
4-tert-Butylcatechol.Comment: 12 pages, 9 figures. Submitted to JINS
Scintillator manufacture at Fermilab
A decade of research into plastic scintillation materials at Fermilab is reviewed. Early work with plastic optical fiber fabrication is revisited and recent experiments with large-scale commercial methods for production of bulk scintillator are discussed. Costs for various forms of scintillator are examined and new development goals including cost reduction methods and quality improvement techniques are suggested
Extruded scintillator for the Calorimetry applications
An extrusion line has been installed and successfully operated at FNAL (Fermi National Accelerator
Laboratory) in collaboration with NICADD (Northern Illinois Center for Accelerator and Detector
Development). This new Facility will serve to further develop and improve extruded plastic scintillator.
Recently progress has been made in producing co-extruded plastic scintillator, thus increasing the
potential HEP applications of this Facility. The current R&D work with extruded and co-extruded
plastic scintillator for a potential ALICE upgrade, the ILC calorimetry program and the MINERvA
experiment show the attractiveness of the chosen strategy for future experiments and calorimetry. We
extensively discuss extruded and co-extruded plastic scintillator in calorimetry in synergy with new
Solid State Photomultipliers. The characteristics of extruded and co-extruded plastic scintillator will be
presented here as well as results with non-traditional photo read-ou
Anti-N-Methyl-D-Aspartate Receptor Encephalitis: A New Challenging Entity for Consultation-Liaison Psychiatrist.
BACKGROUND: Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a relatively newly identified autoimmune neuropsychiatric disorder that predominantly affects children and young adults. Although psychiatric symptoms are highly prevalent and frequently severe, it has mainly been reported in neurological, but not psychiatric, literature. Understanding this form of encephalitis, its quick diagnosis and which treatment to provide are of utmost importance for consultation-liaison (C-L) psychiatrists. The aim of this paper was to describe a case of anti-NMDAR encephalitis with severe psychiatric manifestations, who showed impressive recovery but required intensive involvement of the C-L psychiatry team. We emphasise the behavioural aspects, psychiatric symptoms and challenges faced by the CL consultant across the different phases of the treatment.
METHODS: We report the different treatment phases for a young woman with anti-NMDAR encephalitis who developed severe neuropsychiatric symptoms, with a focus on the role and challenges faced by the C-L psychiatrist. The literature is reviewed for each of these challenges.
RESULTS: This case illustrated that even extremely severely affected patients may show impressive recovery, but require long lasting psychiatric care. C-L psychiatrists are faced with numerous challenges where only little literature is available.
CONCLUSION: C-L psychiatrists play a pivotal role throughout the multidisciplinary care of patients with anti-NMDAR encephalitis and should be informed about this entity
Enumerating Homomorphisms
The homomorphism problem for relational structures is an abstract way of formulating constraint satisfaction problems (CSP) and various problems in database theory. The decision version of the homomorphism problem received a lot of attention in literature; in particular, the way the graph-theoretical structure of the variables and constraints influences the complexity of the problem is intensively studied. Here we study the problem of enumerating all the solutions with polynomial delay from a similar point of view. It turns out that the enumeration problem behaves very differently from the decision version. We give evidence that it is unlikely that a characterization result similar to the decision version can be obtained. Nevertheless, we show nontrivial cases where enumeration can be done with polynomial delay
The Golden Channel at a Neutrino Factory revisited: improved sensitivities from a Magnetised Iron Neutrino Detector
This paper describes the performance and sensitivity to neutrino mixing
parameters of a Magnetised Iron Neutrino Detector (MIND) at a Neutrino Factory
with a neutrino beam created from the decay of 10 GeV muons. Specifically, it
is concerned with the ability of such a detector to detect muons of the
opposite sign to those stored (wrong-sign muons) while suppressing
contamination of the signal from the interactions of other neutrino species in
the beam. A new more realistic simulation and analysis, which improves the
efficiency of this detector at low energies, has been developed using the GENIE
neutrino event generator and the GEANT4 simulation toolkit. Low energy neutrino
events down to 1 GeV were selected, while reducing backgrounds to the
level. Signal efficiency plateaus of ~60% for and ~70% for
events were achieved starting at ~5 GeV. Contamination from the
oscillation channel was studied for the first
time and was found to be at the level between 1% and 4%. Full response matrices
are supplied for all the signal and background channels from 1 GeV to 10 GeV.
The sensitivity of an experiment involving a MIND detector of 100 ktonnes at
2000 km from the Neutrino Factory is calculated for the case of . For this value of , the accuracy in the
measurement of the CP violating phase is estimated to be , depending on the value of ,
the CP coverage at is 85% and the mass hierarchy would be determined
with better than level for all values of
A Novel Use of Light Guides and Wavelength Shifting Plates for the Detection of Scintillation Photons in Large Liquid Argon Detectors
Scintillation light generated as charged particles traverse large liquid
argon detectors adds valuable information to studies of weakly-interacting
particles. This paper uses both laboratory measurements and cosmic ray data
from the Blanche dewar facility at Fermilab to characterize the efficiency of
the photon detector technology developed at Indiana University for the single
phase far detector of DUNE. The efficiency of this technology was found to be
0.48% at the readout end when the detector components were characterized with
laboratory measurements. A second determination of the efficiency using cosmic
ray tracks is in reasonable agreement with the laboratory determination. The
agreement of these two efficiency determinations supports the result that
minimum ionizing muons generate photons/MeV as
they cross the LAr volume.Comment: Accepted version (without final editorial corrections
Changes in Topsoil Properties after Centennial Scots Pine Afforestation in a European Beech Forest (NE Spain)
In this work, we studied the effects of centenary Scots pine (Pinus sylvestris L.) afforestation on topsoil properties conducted in a deforested area that was previously occupied by a natural European beech (Fagus sylvatica L.) forest. Organic layers and topsoil Ah mineral horizons (0–10 cm) were sampled in the Scots pine and European beech forests of Moncayo Natural Park (north-eastern Spain). The physical (stoniness, aggregate stability, and water repellency persistence and intensity), chemical (total organic C, total N, C/N, pH, and exchangeable Ca2+, Mg2+, Na+, K+, Al3+, and Fe3+), and physicochemical (cation exchange capacity) properties of soil were analyzed. Total organic C and N were also obtained for litter samples. The studied topsoils shared a series of common properties, such as a high stoniness and aggregate stability, very low base content, high cation exchange capacity, and extreme acidity. Soils that developed under the pinewood showed a higher soil water repellency intensity. However, K+ content was significantly higher in the beechwood soil. In both forest types, total organic C and N were similar in topsoil and litter (Hemimoder type), although C and N were pooled in different O-layers. Results indicate that pine afforestation in a deforested area was an adequate measure for soil protection since it did not show significant differences in the long term (ca. 100 years) compared to the nearby natural beech stands
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