0000000000177671
AUTHOR
B. Howard
Antiproton-proton annihilation at rest in H2 gas into π+ π− π0
Antiproton-proton annihilation at rest into π+ π− π0 has been studied by stopping antiprotons from LEAR in a H2 gas target at normal temperature and pressure. The reaction is observed in coincidence withL X-rays which are emitted in the cascade of\(\bar pp\) atoms. The X-rays populate one of the angular momentumL=1 states of a\(\bar pp\) atom which then annihilates. A spinparity analysis of the π+ π− π0 Dalitz plot gives contributions from the threeP states from which annihilation into three pions is allowed. The most striking features of the Dalitz plot are production of charged and neutral ϱ(770) and off2(1270) mesons. Production of ϱ(770) mesons proceeds via the isoscalar part of the1P1 …
Volume IV The DUNE far detector single-phase technology
This document was prepared by the DUNE collaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. The DUNE collaboration also acknowledges the international, national, and regional funding agencies supporting the institutions who have contributed to completing this Technical Design Report.
First results on ProtoDUNE-SP liquid argon time projection chamber performance from a beam test at the CERN Neutrino Platform
The ProtoDUNE-SP detector was constructed and operated on the CERN Neutrino Platform. We thank the CERN management for providing the infrastructure for this experiment and gratefully acknowledge the support of the CERN EP, BE, TE, EN, IT and IPT Departments for NP04/ProtoDUNE-SP. This documentwas prepared by theDUNEcollaboration using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. This work was supported by CNPq, FAPERJ, FAPEG and FAPESP, Brazil; CFI, IPP and NSERC, Canada; CERN; MSMT, Czech Republi…
Neutrino interaction classification with a convolutional neural network in the DUNE far detector
The Deep Underground Neutrino Experiment is a next-generation neutrino oscillation experiment that aims to measure CP-violation in the neutrino sector as part of a wider physics program. A deep learning approach based on a convolutional neural network has been developed to provide highly efficient and pure selections of electron neutrino and muon neutrino charged-current interactions. The electron neutrino (antineutrino) selection efficiency peaks at 90% (94%) and exceeds 85% (90%) for reconstructed neutrino energies between 2–5 GeV. The muon neutrino (antineutrino) event selection is found to have a maximum efficiency of 96% (97%) and exceeds 90% (95%) efficiency for reconstructed neutrino…
The ASTERIX spectrometer at LEAR
The ASTERIX spectrometer has been used to study the formation and the ground state of the pp atom and exclusive final states of pp annihilation at rest in a H2 gas target at NTP, using antiprotons from the Low Energy Antiproton Ring (LEAR) at CERN. The article describes the mechanical construction of the apparatus, the trigger logic, the chamber readout, and the data acquisition system. The detector calibration and the offline processing of the 55 million reconstructed events are illustrated. An overview is given about the new physics results obtained by the experiment.
Volume I. Introduction to DUNE
Journal of Instrumentation 15(08), T08008 (1-228) (2020). doi:10.1088/1748-0221/15/08/T08008
Antiproton-proton annihilation at rest intoπ + π − η ′ andπ + π − η from atomicS andP states
We have measured the branching ratios for\(\bar pp\) annihilation at rest intoπ+π−η andπ+π−η′ in hydrogen gas in two data samples that have different fractions ofS-wave andP-wave initial states. The branching ratios are derived from a comparison with the topological branching ratio for\(\bar pp\) annihilations into four charged pions of (49±4)% and the branching ratio intoπ+π−π+π−π0 of (18.7±1.6)%. We find a significant reduction of the branching ratios fromP-states for\(\bar pp \to \pi ^ + \pi ^ - \eta \) andπ+π−η′ in comparison toS-state annihilation. $$\begin{gathered} BR(S - wave \to \pi ^ + \pi ^ - \eta ) = (13.7 \pm 1.46) \cdot 10^{ - 3} \hfill \\ BR(P - wave \to \pi ^ + \pi ^ - \eta …
Observation and analysis ofE mesons in $$\bar p$$ p annihilation at rest in H2 gas
Antiproton-proton annihilation at rest in a gaseous H2 target at NTP into the final state π+ π−K± π∓ (K0) with an undetectedK0 or\(\bar K^0 \) has been investigated. We observe theE(1420) resonance in the invariant mass spectrum (K0)missK± π∓ with massME=1413±8 MeV/c2 and widthГE=62 ± 16MeV/c2 and find evidence for the production of thef1(1285). The absolute branching ratio of\(\bar p\)p → π+ π−E0,E0 →K0LK±π∓ at (61±6)%P wave annihilation is (3.0±0.9)·10−4 of all annihilations. The observed suppression of theE production fromP wave with respect to theS wave together with some simple selection rules suggest that the quantum numbers of theE(1420) areJpc=0−+ and not I++.
Volume III. DUNE far detector technical coordination
The preponderance of matter over antimatter in the early universe, the dynamics of the supernovae that produced the heavy elements necessary for life, and whether protons eventually decay-these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our universe, its current state, and its eventual fate. The Deep Underground Neutrino Experiment (DUNE) is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the st…