We describe a method used to calibrate the position- and time-dependent response of the MicroBooNE liquid argon time projection chamber anode wires to ionization particle energy loss. The method ...makes use of crossing cosmic-ray muons to partially correct anode wire signals for multiple effects as a function of time and position, including cross-connected TPC wires, space charge effects, electron attachment to impurities, diffusion, and recombination. The overall energy scale is then determined using fully-contained beam-induced muons originating and stopping in the active region of the detector. Using this method, we obtain an absolute energy scale uncertainty of 2% in data. We use stopping protons to further refine the relation between the measured charge and the energy loss for highly-ionizing particles. This data-driven detector calibration improves both the measurement of total deposited energy and particle identification based on energy loss per unit length as a function of residual range. As an example, the proton selection efficiency is increased by 2% after detector calibration.
Liquid argon time projection chambers (LArTPCs) are now a standard detector technology for making accelerator neutrino measurements, due to their high material density, precise tracking, and ...calorimetric capabilities. An electric field (E-field) is required in such detectors to drift ionization electrons to the anode where they are collected. The E-field of a TPC is often approximated to be uniform between the anode and the cathode planes. However, significant distortions can appear from effects such as mechanical deformations, electrode failures, or the accumulation of space charge generated by cosmic rays. The latter effect is particularly relevant for detectors placed near the Earth's surface and with large drift distances and long drift time. To determine the E-field in situ, an ultraviolet (UV) laser system is installed in the MicroBooNE experiment at Fermi National Accelerator Laboratory. The purpose of this system is to provide precise measurements of the E-field, and to make it possible to correct for 3D spatial distortions due to E-field non-uniformities. Here we describe the methodology developed for deriving spatial distortions, the drift velocity and the E-field from UV-laser measurements.
We report on a flux-integrated multi-differential measurement of charged-current muon neutrino scattering on argon with one muon and one proton in the final state using the Booster Neutrino Beam and ...MicroBooNE detector at Fermi National Accelerator Laboratory. The data are studied as a function of various kinematic imbalance variables and of a neutrino energy estimator, and are compared to a number of event generator predictions. We find that the measured cross sections in different phase-space regions are sensitive to nuclear effects. Our results provide precision data to test and improve the neutrino-nucleus interaction models needed to perform high-accuracy oscillation analyses. Specific regions of phase-space are identified where further model refinements are most needed.
Color vision in
Drosophila relies on the comparison between two color-sensitive photoreceptors, R7 and R8. Two types of ommatidia in which R7 and R8 contain different rhodopsins are distributed ...stochastically in the retina and appear to discriminate short (p-subset) or long wavelengths (y-subset). The choice between p and y fates is made in R7, which then instructs R8 to follow the corresponding fate, thus leading to a tight coupling between rhodopsins expressed in R7 and R8. Here, we show that
warts, encoding large tumor suppressor (Lats) and
melted encoding a PH-domain protein, play opposite roles in defining the yR8 or pR8 fates. By interacting antagonistically at the transcriptional level, they form a bistable loop that insures a robust commitment of R8 to a single fate, without allowing ambiguity. This represents an unexpected postmitotic role for genes controlling cell proliferation (
warts and its partner
hippo and
salvador) and cell growth (
melted).
CONTEXT: Sexually transmitted diseases are increasing rapidly in China. Surveillance data imperfectly indicate current prevalence and risk factors. OBJECTIVES: To estimate the prevalence of genital ...chlamydial and gonococcal infections and to describe patterns of infection by subgroup and behavioral patterns. DESIGN, SETTING, AND PARTICIPANTS: A national stratified probability sample of 3426 Chinese individuals (1738 women and 1688 men) aged 20 to 64 years, who were interviewed between August 1999 and August 2000, completed a computer-administered survey, and provided a urine specimen (69% total participation rate). MAIN OUTCOME MEASURE: Positive test result for chlamydial or gonococcal infections. RESULTS: The overall prevalence per 100 population of chlamydial infection was 2.6 (95% confidence interval CI, 1.6-4.1) for women and 2.1 (95% CI, 1.3-3.3) for men. For gonococcal infection, the overall prevalence per 100 population was 0.08 (95% CI, 0.02-0.4) for women and 0.02 (95% CI, 0.005-0.1) for men. Risk factors for chlamydial infection among men aged 20 to 44 years were unprotected sex with a commercial sex worker (odds ratio OR, 8.24; 95% CI, 3.51-19.35), less education (OR, 7.20; 95% CI, 2.31-22.37), and recent sex with their spouse or other steady partner (OR, 7.73; 95% CI, 2.70-22.10). Among women aged 20 to 44 years, risk factors for chlamydial infection were having less education (OR, 2.82; 95% CI, 1.01-7.91) and living in a city (OR, 3.46; 95% CI, 1.67-7.18) or along the southern coast (OR, 2.16; 95% CI, 1.29-3.63) and having a spouse or other steady sexual partner who earned a high income (OR, 2.85; 95% CI, 1.11-7.29), who socialized often (OR, 2.79; 95% CI, 1.08-7.19), or who traveled less than 1 week per year (OR, 5.40; 95% CI, 1.44-20.3). CONCLUSIONS: The prevalence of chlamydial infection in China is substantial. The patterns of infection suggest potential avenues for intervention.
The MicroBooNE continuous readout stream is a parallel readout of the MicroBooNE liquid argon time projection chamber (LArTPC) which enables detection of non-beam events such as those from a ...supernova neutrino burst. The low energies of the supernova neutrinos and the intense cosmic-ray background flux due to the near-surface detector location makes triggering on these events very challenging. Instead, MicroBooNE relies on a delayed trigger generated by SNEWS (the Supernova Early Warning System) for detecting supernova neutrinos. The continuous readout of the LArTPC generates large data volumes, and requires the use of real-time compression algorithms (zero suppression and Huffman compression) implemented in an FPGA (field-programmable gate array) in the readout electronics. We present the results of the optimization of the data reduction algorithms, and their operational performance. To demonstrate the capability of the continuous stream to detect low-energy electrons, a sample of Michel electrons from stopping cosmic-ray muons is reconstructed and compared to a similar sample from the lossless triggered readout stream.
Cosmic ray (CR) interactions can be a challenging source of background for neutrino oscillation and cross-section measurements in surface detectors. We present methods for CR rejection in ...measurements of charged-current quasielastic-like (CCQE-like) neutrino interactions, with a muon and a proton in the final state, measured using liquid argon time projection chambers (LArTPCs). Using a sample of cosmic data collected with the MicroBooNE detector, mixed with simulated neutrino scattering events, a set of event selection criteria is developed that produces an event sample with minimal contribution from CR background. Depending on the selection criteria used a purity between 50 and 80% can be achieved with a signal selection efficiency between 50 and 25%, with higher purity coming at the expense of lower efficiency. While using a specific dataset and selection criteria values optimized for the MicroBooNE detector, the concepts presented here are generic and can be adapted for various studies of exclusive
ν
μ
CCQE interactions in LArTPCs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Neutrinos exist in one of three types or ‘flavours’—electron, muon and tau neutrinos—and oscillate from one flavour to another when propagating through space. This phenomena is one of the few that ...cannot be described using the standard model of particle physics (reviewed in ref. 1), and so its experimental study can provide new insight into the nature of our Universe (reviewed in ref. 2). Neutrinos oscillate as a function of their propagation distance (L) divided by their energy (E). Therefore, experiments extract oscillation parameters by measuring their energy distribution at different locations. As accelerator-based oscillation experiments cannot directly measure E, the interpretation of these experiments relies heavily on phenomenological models of neutrino–nucleus interactions to infer E. Here we exploit the similarity of electron–nucleus and neutrino–nucleus interactions, and use electron scattering data with known beam energies to test energy reconstruction methods and interaction models. We find that even in simple interactions where no pions are detected, only a small fraction of events reconstruct to the correct incident energy. More importantly, widely used interaction models reproduce the reconstructed energy distribution only qualitatively and the quality of the reproduction varies strongly with beam energy. Finally, this shows both the need and the pathway to improve current models to meet the requirements of next-generation, high-precision experiments such as Hyper-Kamiokande (Japan)3 and DUNE (USA)4.
Here, we report the first measurement of the (e, e' p) three-body breakup reaction cross sections in helium-3 (3He) and tritium (3H) at large momentum transfer ($\langle{Q^2}\rangle$ ≈ 1.9 (GeV/c)2) ...and xB > 1 kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta 40 ≤ pmiss ≤ 500 MeV/c that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon. The measured cross sections are compared with state-of-the-art ab-initio calculations. Overall good agreement, within ±20%, is observed between data and calculations for the full pmiss range for 3H and for 100 ≤ pmiss ≤ 350 MeV/c for 3He. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at pmiss > 250 MeV/c and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of 3He plus 3H, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire pmiss range. This validates current models of the ground state of the three-nucleon system up to very high initial nucleon momenta of 500 MeV/c.
We report the first measurement of the
(
e
,
e
′
p
)
three-body breakup reaction cross sections in helium-3 (
3
He
) and tritium (
3
H
) at large momentum transfer
⟨
Q
2
⟩
≈
1.9
(
GeV
/
c
)
2
...and
x
B
>
1
kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta
40
≤
p
miss
≤
500
MeV
/
c
that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon. The measured cross sections are compared with state-of-the-art ab initio calculations. Overall good agreement, within
±
20
%
, is observed between data and calculations for the full
p
miss
range for
3
H
and for
100
≤
p
miss
≤
350
MeV
/
c
for
3
He
. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at
p
miss
>
250
MeV
/
c
and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of
3
He
plus
3
H
, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire
p
miss
range. This validates current models of the ground state of the three-nucleon system up to very high initial nucleon momenta of
500
MeV
/
c
.
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