Mon·Jul 3, 2017Monday·July 3, 2017

1. 01*

   Study of charged-particle multiplicities with ALICE

   Valentina Zaccolo (for the ALICE Collaboration)🇮🇹

   The multiplicity measurements include the pseudorapidity density, $\mathrm{d}{\mathrm{N}}_{\mathrm{ch}}/\mathrm{d}\eta$, and the probability distribution as a function of the number of charged particles, $\mathrm{P}({\mathrm{N}}_{\mathrm{ch}})$. ALICE has measured the multiplicities for three collision systems, for proton-proton, proton-lead and lead-lead collisions at Run 1 and 2 at the Large Hadron Collider. A selection of these results will be presented in these proceedings, concluding with an overview of new measurements planned.

   nucl-exNuovo Cim.C(2018)·0 citations
2. 02*

   Determination of the Proton Spin Structure Functions for 0.05 < Q^2 < 5 GeV^2 using CLAS

   Robert Fersch · Nevzat Guler · Peter Bosted · Alexandre Deur · Keith Griffioen · Christopher Keith · Sebastian Kuhn · Ralph Minehart · Yelena Prok · The CLAS Collaboration

   We present the results of our final analysis of the full data set of g_1^p(Q^2), the spin structure function of the proton, collected using CLAS at Jefferson Lab in 2000-2001. Polarized electrons with energies of 1.6, 2.5, 4.2 and 5.7 GeV were scattered from proton targets (15^NH_3 dynamically polarized along the beam direction) and detected with CLAS. From the measured double spin asymmetries, we extracted virtual photon asymmetries A_1^p and A_2^p and spin structure functions g_1^p and g_2^p over a wide kinematic range (0.05 GeV^2 < Q^2 < 5 GeV^2 and 1.08 GeV < W < 3 GeV), and calculated moments of g_1^p. We compare our final results with various theoretical models and expectations, as well as with parameterizations of the world data. Our data, with their precision and dense kinematic coverage, are able to constrain fits of polarized parton distributions, test pQCD predictions for quark polarizations at large x, offer a better understanding of quark-hadron duality, and provide more precise values of higher-twist matrix elements in the framework of the Operator Product Expansion.

   nucl-exPRC(2017)·73 citations
3. 03*

   The SeaQuest Spectrometer at Fermilab

   SeaQuest Collaboration: C. A. Aidala🇺🇸 · J. R. Arrington🇺🇸 · C. Ayuso🇺🇸 · B. M. Bowen🇺🇸 · M. L. Bowen🇺🇸 · K. L. Bowling🇺🇸 · A. W. Brown🇺🇸 · C. N. Brown🇺🇸 · R. Byrd🇺🇸 · R. E. Carlisle🇺🇸 · T. Chang🇹🇼 · W.-C. Chang🇹🇼 and 85 other authors

   The SeaQuest spectrometer at Fermilab was designed to detect oppositely-charged pairs of muons (dimuons) produced by interactions between a 120 GeV proton beam and liquid hydrogen, liquid deuterium and solid nuclear targets. The primary physics program uses the Drell-Yan process to probe antiquark distributions in the target nucleon. The spectrometer consists of a target system, two dipole magnets and four detector stations. The upstream magnet is a closed-aperture solid iron magnet which also serves as the beam dump, while the second magnet is an open aperture magnet. Each of the detector stations consists of scintillator hodoscopes and a high-resolution tracking device. The FPGA-based trigger compares the hodoscope signals to a set of pre-programmed roads to determine if the event contains oppositely-signed, high-mass muon pairs.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2019)·78 citations
4. 04*

   A Radial Time Projection Chamber for $\alpha$ detection in CLAS at JLab

   R. Dupré🇫🇷 · S. Stepanyan🇺🇸 · M. Hattawy🇺🇸 · N. Baltzell🇺🇸 · K. Hafidi🇺🇸 · M. Battaglieri🇮🇹 · S. Bueltmann🇺🇸 · A. Celentano🇮🇹 · R. De Vita🇮🇹 · A. El Alaoui🇨🇱 · L. El Fassi🇺🇸 · H. Fenker🇺🇸 and 8 other authors

   A new Radial Time Projection Chamber (RTPC) was developed at the Jefferson Laboratory to track low-energy nuclear recoils for the purpose of measuring exclusive nuclear reactions, such as coherent Deeply Virtual Compton Scattering and coherent meson production off ${}^4$He. In such processes, the ${}^4$He nucleus remains intact in the final state, however the CEBAF Large Acceptance Spectrometer (CLAS) cannot track the low energy $\alpha$ particles. In 2009, we carried out measurements using the CLAS spectrometer supplemented by the RTPC positioned directly around a gaseous ${}^4$He target, allowing a detection threshold as low as 12$\sim$MeV for ${}^4$He. This article discusses the design, principle of operation, calibration methods and the performances of this RTPC.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2018)·8 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.