Abstract
Ionization electron diffusion in Liquid Argon Time
Projection Chambers (LArTPCs) has typically been considered at the
detector design stage, but little attention has been given to its
...effects on calibration and particle identification. We use a
GEANT4-based simulation to study how diffusion impacts these
techniques, and give consideration to how this effect is
simulated. We find that diffusion can cause a drift-dependent bias
to both the median and Most Probable Value (MPV) of
d
Q
/dx distributions. The bias is estimated to be
∼ 2.5% (median) and ∼ 5.0% (MPV) for typical maximum drift
times in currently running LArTPCs before adding detector specific
considerations such as electric field non-uniformities. This
indicates that these metrics should not be used for calibration
without care, contrary to the conventional wisdom. The impact of
diffusion on the ability of LArTPCs to separate muons and protons is
small, and not expected to pose any problems in future
detectors. Diffusion may however be a significant source of
systematic uncertainty when separating particles of more similar
masses (muons and pions, kaons and protons). Separation of such
populations may be improved by implementation of a drift-time
dependent particle identification.
Abstract
Metalenses and metasurfaces are promising emerging
technologies that could improve light collection in light collection
detectors, concentrating light on small area photodetectors such as
...silicon photomultipliers. Here we present a detailed method to
characterize metalenses to assess their efficiency at concentrating
monochromatic light coming from a wide range of incidence angles,
not taking into account their imaging quality.
The Liquid Argon Purity Demonstrator Adamowski, M; Carls, B; Dvorak, E ...
Journal of instrumentation,
07/2014, Letnik:
9, Številka:
7
Journal Article
Recenzirano
Odprti dostop
The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the ...cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.
Fermilab experiment E835 has measured the cross section for the reaction p̄p→e+e− at s=11.63, 12.43, 14.40 and 18.22 GeV2. From the analysis of the 66 observed events new high-precision measurements ...of the proton magnetic form factor are obtained.
CDF Run II silicon vertex detector annealing study Stancari, M.; Knoepfel, K.; Behari, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2014, Letnik:
743
Journal Article
Recenzirano
Odprti dostop
Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron collider delivered 12fb−1 of pp¯ collisions at s=1.96TeV to the Collider Detector at Fermilab ...(CDF). During that time, the CDF silicon vertex detector was subject to radiation doses of up to 12Mrad. After the end of operations, the silicon detector was annealed for 24days at 18°C. In this paper, we present a measurement of the change in the bias currents for a subset of sensors during the annealing period. We also introduce a novel method for monitoring the depletion voltage throughout the annealing period. The observed bias current evolution can be characterized by a falling exponential term with time constant τI=17.88±0.36(stat.)±0.25(syst.) days. We observe an average decrease of (27±3)% in the depletion voltage, whose evolution can similarly be described by an exponential time constant of τV=6.21±0.21days. These results are consistent with the Hamburg model within the measurement uncertainties.
The second workshop to discuss the development of liquid argon time projection chambers (LArTPCs) in the United States was held at Fermilab on July 8-9, 2014. The workshop was organized under the ...auspices of the Coordinating Panel for Advanced Detectors, a body that was initiated by the American Physical Society Division of Particles and Fields. All presentations at the workshop were made in six topical plenary sessions: i) Argon Purity and Cryogenics, ii) TPC and High Voltage, iii) Electronics, Data Acquisition and Triggering, iv) Scintillation Light Detection, v) Calibration and Test Beams, and vi) Software. This document summarizes the current efforts in each of these areas. It primarily focuses on the work in the US, but also highlights work done elsewhere in the world.
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The spin-exchange collision cross-section for hydrogen atoms has been measured for the first time in the low temperature range 40–100 K by using the polarized hydrogen gas target of the HERMES ...experiment at DESY (Hamburg, Germany). The results agree with a previous measurement in the overlapping temperature region 80–100 K, while seem to hint an increasing behaviour with temperature in the region 50–80 K.
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