[en] The authors present data for the electroproduction of K⁺Λ and K⁺Σ states at beam energies of 2.4 and 4.0 GeV. The data were taken with the CLAS spectrometer, a large-acceptance detector housed in Hall B at CEBAF. They show plots of particle mass calculated from momentum and time-of-flight as well as missing mass plots of recoiling hyperons. They conclude by plotting event yields that demonstrate the large acceptance of the CLAS spectrometer, and briefly discuss prospects for further analysis

[en] We present data for the electroproduction of K⁺ Λ and K⁺ Σ states at beam energies of 2.4 and 4.0 GeV. The data were taken with the CLAS spectrometer, a large-acceptance detector housed in Hall B at CEBAF. We show plots of particle mass calculated from momentum and time-of-flight as well as missing mass plots of the recoiling hyperons. We conclude by plotting event yields that demonstrate the large acceptance of the CLAS spectrometer, and briefly discuss prospects for further analysis

[en] The authors review the status of inclusive electron-proton scattering F₂ structure function data in both the nucleon resonance region and the deep inelastic region, at momentum transfers below 5 (GeV/c)². From these data they construct moments of F₂, down to momentum transfers of Q²∼0.1(GeV/c)². The second moment is only slowly varying with Q² down to Q²∼1, which is a reflection of duality. Below Q² of 1 (GeV/c)², the Q² dependence of the moments is predominantly governed by the elastic contribution, whereas the inelastic channels still seem governed by local duality

[en] Using data from a recent reanalysis of neutron structure functions extracted from inclusive proton and deuteron deep-inelastic scattering (DIS), we re-examine the constraints on the shape of the $\stackrel{¯<!--\; ??\; -->}{d}-<!--\; ???\; -->\stackrel{¯<!--\; ??\; -->}{u}$ asymmetry in the proton at large parton momentum fractions x. A global analysis of the proton--neutron structure function difference from BCDMS, NMC, SLAC and Jefferson Lab, and Fermilab Drell-Yan lepton-pair production cross sections, suggests that existing data can be well described with $\stackrel{¯<!--\; ??\; -->}{d}>\stackrel{¯<!--\; ??\; -->}{u}$ for all values of x currently accessible. We compare the shape of the fitted $\stackrel{¯<!--\; ??\; -->}{d}-<!--\; ???\; -->\stackrel{¯<!--\; ??\; -->}{u}$ distributions with expectations from nonperturbative models based on chiral symmetry breaking, which can be tested by upcoming Drell-Yan data from the SeaQuest experiment at larger values of x.

[en] The ¹H(e,e'K⁺)Λ and ¹H(e,e'K⁺)Σ⁰ reactions were studied as a function of the squared four-momentum-transfer, Q², and the virtual photon polarization, ε, thus enabling the separation of the longitudinal and transverse parts of the cross section. The existence of a sizable longitudinal component for the ¹H(e,e'K⁺)Λ reaction seems to be indicated by these data. (orig.)

[en] We investigate the Q² dependence of inclusive electron-proton scattering F₂ structure function data in both the nucleon resonance region and the deep inelastic region, at momentum transfers below 5 (GeV/c)². From these data we construct moments of F₂, down to momentum transfers of Q²∼0.1 (GeV/c)². The second moment is only slowly varying with Q² down to Q²∼1 (GeV/c)², which is a reflection of duality. Below Q² of 1 (GeV/c)², the Q² dependence of the moments is predominantly governed by the elastic contribution, whereas the inelastic channels still seem governed by local duality

[en] We present measurements of the differential cross section and Lambda recoil polarization for the gamma p to K+ Lambda reaction made using the CLAS detector at Jefferson Lab. These measurements cover the center-of-mass energy range from 1.62 to 2.84 GeV and a wide range of center-of-mass K+ production angles. Independent analyses were performed using the K+ p pi- and K+ p (missing pi -) final-state topologies; results from these analyses were found to exhibit good agreement. These differential cross section measurements show excellent agreement with previous CLAS and LEPS results and offer increased precision and a 300 MeV increase in energy coverage. The recoil polarization data agree well with previous results and offer a large increase in precision and a 500 MeV extension in energy range. The increased center-of-mass energy range that these data represent will allow for independent study of non-resonant K+ Lambda photoproduction mechanisms at all production angles.

[en] The result of a feasibility study to measure the Λ polarization in associated K⁺-Λ electro-production is presented. This measurement was performed in the experimental Hall C at Jefferson Lab. The scattered electron was detected in the HMS spectrometer, and the electro-produced kaon and the proton from the Λ→pπ^- decay were both detected in the SOS spectrometer. This quantity is very sensitive to the elementary p(e,e'K)Λ process and gives information on resonance production, and Regge exchange, among others. The result presented was measured at Q²=1.50 (GeV/c)² and cosθ_Kγ^CM=14 deg. The limits of the Λ polarization, with respect to the p_γxp_K axis, were found to be -0.21 and +0.89 with a confidence level of 68%. The result is compared to theoretical predictions based on an effective hadronic field Lagrangian model and a Regge framework model

No abstract available

[en] Photomultiplier tubes continue to be a reliable, cost-effective means of detecting light produced by the interaction of subatomic particles with detectors. For detectors where the expected light yield is modest, characterizing the low light response of the tube is of paramount importance. Several phenomenological models addressing this issue exist. This paper presents side-by-side comparison between three such approaches as they arose from a large scale testing of tubes to be used by a Ring Imaging Cherenkov detector at Jefferson Lab. The main characteristics of the tubes, such as the gain, were found to be consistent within the expected uncertainties for all models considered. Leveraging the extensive nature of the study, a machine learning algorithm based on an artificial neural network capable of obtaining the tube characteristics directly from the raw ADC data was developed and trained. The trained neural network produced results fully compatible with the three models considered, with substantial savings in both computation time and experimenter overhead.