396 research outputs found
Beta Irradiation of a Geometrically Metastable Superconducting Strip Detector with a Magnetic Flux Penetration Read-Out
Geometrical metastability, observed in superconducting type I tin flat
strips, has been previously proposed as a principle for particle detection. The
energy deposition of an incoming beta-particle induces the rupture of the
metastability and consequently the penetration of multiquantum flux tubes into
a superconducting tin strip. We present here the first absorption spectra from
two beta sources, which demonstrate the linearity and energy-resolution of
these detectors (presented at the 6th International Workshop on Low Temperature
Detectors for Dark Matter and Neutrinos (LTD-6), Interlaken, Switzerland, Sept.
1995)Comment: Compressed PostScript (filename.ps.Z), 8 pages, 2 figure
Diamagnetic interactions in superheated-superconducting microgranules under an external magnetic field
L'estudi de les transicions produïdes en conjunts de grànuls superconductors metastables té nterès tant per a la física fonamental com per a aplicacions com ara els detectors de partícules. L'estudi teòric d'aquest problema ha estat obstaculitzat per la dificultat del tractament de les interaccions diamagnètiques entre grànuls. En aquesta revisió descrivim el comportament d'aquests sistemes, desenvolupem el mètode numèric del tractament i presentem uns quants resultats experimentals i numèrics.The study of the phase transitions produced in ensembles of metastable superconducting granules by magnetic field variations is important both for fundamental physics and for applications in particle detectors. Theoretical study of the problem has long been hampered by the difficulty in dealing with the diamagnetic interactions between granules. In this review we describe the behaviour of such systems, develop numerical procedures to deal with them, and present some experimental and numerical results
S-35 Beta Irradiation of a Tin Strip in a State of Superconducting Geometrical Metastability
We report the first energy loss spectrum obtained with a geometrically
metastable type I superconducting tin strip irradiated by the beta-emission of
S-35. (Nucl. Instr. Meth. A, in press)Comment: Compressed PostScript (filename.ps.Z), 9 pages, 2 figure
Developing multiple regression models from the manufacturer's ground-source heat pump catalogue data.
The performance of ground-source heat pumps (GSHP), often expressed as Power drawn and/or the COP,depends on several operating parameters. Manufacturers usually publish such data in tables for certaindiscrete values of the operating fluid temperatures and flow rates conditions. In actual applications, suchas in dynamic simulations of heat pump system integrated to buildings, there is a need to determineequipment performance under operating conditions other than those listed. This paper describes asimplified methodology for predicting the performance of GSHPs using multiple regression (MR) modelsas applicable to manufacturer data. We find that fitting second-order MR models with eight statisticallysignificant x-variables from 36 observations appropriately selected in the manufacturer catalogue canpredict the system global behavior with good accuracy. For the three studied GSHPs, the external predictionerror of the MR models identified following the methodology are 0.2%, 0.9% and 1% for heatingcapacity (HC) predictions and 2.6%, 4.9% and 3.2% for COP predictions. No correlation is found betweenresiduals and the response, thus validating the models. The operational approach appears to be a reliabletool to be integrated in dynamic simulation codes, as the method is applicable to any GSHP cataloguedata
Response of parylene-coated NaI(Tl) scintillators at low temperature
Despite that it is widely used as a scintillator at room temperature, the hygroscopicity of NaI complicates its handling and limits its application for many purposes, for example as a cryogenic detector. To overcome this problem we study coating materials that can act as humidity barriers, in particular parylene, a polymer that can be deposited in very radiopure, thin and conformal layers. In this work, several NaI(Tl) samples coated with 2-5 µm parylene-C were tested at low temperature. Luminescence spectra under X-ray excitation are presented at several temperatures as well as the light output vs temperature at 1.5-300 K. Several thermoluminescence peaks were observed at around 60, 95 and 150 K during warm up to room temperature
The mechanical resistance of the coating under thermal cycles was also investigated, and we observed a degradation of the optical appearance and the light output after cooling down to about 100 mK, which compromises the reusability of the samples
Observation of exclusive DVCS in polarized electron beam asymmetry measurements
We report the first results of the beam spin asymmetry measured in the
reaction e + p -> e + p + gamma at a beam energy of 4.25 GeV. A large asymmetry
with a sin(phi) modulation is observed, as predicted for the interference term
of Deeply Virtual Compton Scattering and the Bethe-Heitler process. The
amplitude of this modulation is alpha = 0.202 +/- 0.028. In leading-order and
leading-twist pQCD, the alpha is directly proportional to the imaginary part of
the DVCS amplitude.Comment: 6 pages, 5 figure
Dependence of Quadrupole Strength in the Transition
Models of baryon structure predict a small quadrupole deformation of the
nucleon due to residual tensor forces between quarks or distortions from the
pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through
the dependence of the magnetic (), electric (), and
scalar () multipoles in the
transition. We report new experimental values for the ratios
and over the range = 0.4-1.8 GeV, extracted from
precision data using a truncated multipole expansion.
Results are best described by recent unitary models in which the pion cloud
plays a dominant role.Comment: 5 pages, 5 figures, 1 table. To be published in Phys. Rev. Lett.
(References, figures and table updated, minor changes.
A Kinematically Complete Measurement of the Proton Structure Function F2 in the Resonance Region and Evaluation of Its Moments
We measured the inclusive electron-proton cross section in the nucleon
resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2
with the CLAS detector. The large acceptance of CLAS allowed for the first time
the measurement of the cross section in a large, contiguous two-dimensional
range of Q**2 and x, making it possible to perform an integration of the data
at fixed Q**2 over the whole significant x-interval. From these data we
extracted the structure function F2 and, by including other world data, we
studied the Q**2 evolution of its moments, Mn(Q**2), in order to estimate
higher twist contributions. The small statistical and systematic uncertainties
of the CLAS data allow a precise extraction of the higher twists and demand
significant improvements in theoretical predictions for a meaningful comparison
with new experimental results.Comment: revtex4 18 pp., 12 figure
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
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