61 research outputs found
First Results from The GlueX Experiment
The GlueX experiment at Jefferson Lab ran with its first commissioning beam
in late 2014 and the spring of 2015. Data were collected on both plastic and
liquid hydrogen targets, and much of the detector has been commissioned. All of
the detector systems are now performing at or near design specifications and
events are being fully reconstructed, including exclusive production of
, and mesons. Linearly-polarized photons were
successfully produced through coherent bremsstrahlung and polarization transfer
to the has been observed.Comment: 8 pages, 6 figures, Invited contribution to the Hadron 2015
Conference, Newport News VA, September 201
Particle identification performance of a straw transition radiation tracker prototype
A 864 channel prototype of an integrated straw tracker and transition radiation detector for tracking and electron identification has been tested with and without magnetic field at the CERN SPS. The rejection against hadrons and converted photons has been measured and the dependence of the rejection power on detector parameters has been investigated. Tracking and hadron rejection were also studied in a high multiplicity environment. The results are compared with Monte-Carlo simulations. Wherever possible, conclusions are drawn concerning the performance of a full-scale detector at the future Large Hadron Collider
Artificial Intelligence for the Electron Ion Collider (AI4EIC)
The Electron-Ion Collider (EIC), a state-of-the-art facility for studying the
strong force, is expected to begin commissioning its first experiments in 2028.
This is an opportune time for artificial intelligence (AI) to be included from
the start at this facility and in all phases that lead up to the experiments.
The second annual workshop organized by the AI4EIC working group, which
recently took place, centered on exploring all current and prospective
application areas of AI for the EIC. This workshop is not only beneficial for
the EIC, but also provides valuable insights for the newly established ePIC
collaboration at EIC. This paper summarizes the different activities and R&D
projects covered across the sessions of the workshop and provides an overview
of the goals, approaches and strategies regarding AI/ML in the EIC community,
as well as cutting-edge techniques currently studied in other experiments.Comment: 27 pages, 11 figures, AI4EIC workshop, tutorials and hackatho
Measurement of the J/ photoproduction cross section over the full near-threshold kinematic region
We report the total and differential cross sections for
photoproduction with the large acceptance GlueX spectrometer for photon beam
energies from the threshold at 8.2~GeV up to 11.44~GeV and over the full
kinematic range of momentum transfer squared, . Such coverage facilitates
the extrapolation of the differential cross sections to the forward ()
point beyond the physical region. The forward cross section is used by many
theoretical models and plays an important role in understanding
photoproduction and its relation to the proton interaction. These
measurements of photoproduction near threshold are also crucial inputs
to theoretical models that are used to study important aspects of the gluon
structure of the proton, such as the gluon Generalized Parton Distribution
(GPD) of the proton, the mass radius of the proton, and the trace anomaly
contribution to the proton mass. We observe possible structures in the total
cross section energy dependence and find evidence for contributions beyond
gluon exchange in the differential cross section close to threshold, both of
which are consistent with contributions from open-charm intermediate states.Comment: 15 pages 18 figure
ATHENA detector proposal - a totally hermetic electron nucleus apparatus proposed for IP6 at the Electron-Ion Collider
ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity.This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges
First Measurement of Near-Threshold J /ψ Exclusive Photoproduction off the Proton
We report on the measurement of the γp→J/ψp cross section from Eγ=11.8 GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67±0.39 GeV-2 at 10.7 GeV average energy. The LHCb pentaquark candidates Pc+ can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions B(Pc+→J/ψp) and cross sections σ(γp→Pc+)×B(Pc+→J/ψp)
Measurement of Spin Density Matrix Elements in Λ(1520) Photoproduction at 8.2 GeV to 8.8 GeV
We report on the measurement of spin density matrix elements of the Λ(1520) in the photoproduction reaction γp → Λ(1520)K+, via its subsequent decay to K−p. The measurement was performed
as part of the GlueX experimental program in Hall D at Jefferson Lab using a linearly polarized
photon beam with Eγ = 8.2 GeV–8.8 GeV. These are the first such measurements in this photon
energy range. Results are presented in bins of momentum transfer squared, −(t − t0). We compare
the results with a Reggeon exchange model and determine that natural exchange amplitudes are
dominant in Λ(1520) photoproduction
Beam asymmetry Σ for the photoproduction of η and η′ mesons at Eγ = 8.8GeV
We report on the measurement of the beam asymmetry
Σ
for the reactions
→
γ
p
→
p
η
and
→
γ
p
→
p
η
′
from the GlueX experiment using an 8.2–8.8-GeV linearly polarized tagged photon beam incident on a liquid hydrogen target in Hall D at Jefferson Laboratory. These measurements are made as a function of momentum transfer
−
t
with significantly higher statistical precision than our earlier
η
measurements and are the first measurements of
η
′
in this energy range. We compare the results to theoretical predictions based on
t
-channel quasiparticle exchange. We also compare the ratio of
Σ
η
to
Σ
η
′
to these models as this ratio is predicted to be sensitive to the amount of
s
¯
s
exchange in the production. We find that photoproduction of both
η
and
η
′
is dominated by natural parity exchange with little dependence on
−
t
- …