Analysis of CLAS data on double charge pion electroproduction

Recent developments in phenomenological analysis of the CLAS data on 2$\pi$ electroproduction are presented. The contributions from isobar channels and $P_{11}(1440)$, $D_{13}(1520)$ electrocouplings at $Q^{2}$ from 0.25 to 0.6 GeV$^2$ were determined from the analysis of comprehensive data on differential and fully integrated 2$\pi$ cross sections. Experiment Numbers: E94-005 Group: Hall BComment: Paper compiled for NSTAR2007 meetin

Studies of light liner compression dynamics in plasma focus

The study is devoted to the investigation of plasma focus systems as a driver for magnetic compression of liners. The experiments on the comparative analyse of the foam and multiwired liners compression were done on the Filippov-type plasma focus facility PF-3. The compression of the light (linear mass 0.3-0.6 mg/cm) liners with velocity (2-3).10⁶ cm/s was obtained. It is shown that under conditions of considerable radiation fluxes at the usage of strongly-radiating working gases a preliminary heating of the target can be attained. This results in acceleration of the transition of initially – condensed substance into plasma state, that assists in overcoming “cool start” problem.Робота присвячена дослідженню плазмового фокусу (ПФ) в ролі драйверa для магнітного обтиснення лайнерів. Проведено експерименти з порівняльного аналізу стиснення пінних й багатодротових лайнерів на установці типу Філіппова ПФ-3. Отримано стиснення лайнерів з погонною масою 0.3-0.6 мг/см зі швидкостями (2-3).10⁶ см/с при амплітуді розрядного струму 2 МА. Показано, що в умовах значних радіаційних потоків при використанні сильновипромінюючих робочих газів може бути здійснений попередній нагрів мішені. Це призводить до прискорення переходу первісно конденсованої речовини у плазмовий стан, що дає змогу подолати проблему «холодного старту».Работа посвящена исследованию плазменного фокуса (ПФ) в качестве драйвера для магнитного обжатия лайнеров. Проведены эксперименты по сравнительному анализу сжатия пенных и многопроволочных лайнеров на установке типа Филиппова ПФ-3. Получено сжатие лайнеров с погонной массой 0.3-0.6 мг/см со скоростями (2-3).10⁶ см/с при амплитуде разрядного тока 2 МА. Показано, что в условиях значительных радиационных потоков при использовании сильноизлучающих рабочих газов может быть осуществлен предварительный нагрев мишени. Это приводит к ускорению перехода первоначально конденсированного вещества в плазменное состояние, что способствует преодолению проблемы “холодного старта ”

Quasi-elastic and inelastic inclusive electron scattering from an oxygen jet target

The results of an experiment on inclusive electron scattering from an oxygen jet target, performed in a wide range of energy and momentum transfer covering both quasi-elastic and $\Delta$(1232) resonance regions, are reported. In the former region the theoretical predictions, obtained including effects of nucleon-nucleon correlations in both initial and final states, give a good description of the experimental data. In the inelastic region a broadening as well as a damping of the resonant part of the cross section with respect to the free nucleon case is observed. The need of more detailed calculations including nuclear structure effects on the electroproduction cross section of nucleon resonances is highlighted.Comment: to appear in Nucl. Phys.

Evaluation of the polarization observables I^S and I^C in the reaction gamma p --> pi^0 eta p

We evaluate the polarization observables I^S and I^C for the reaction gamma p --> pi^0 eta p, using a chiral unitary framework developed earlier. The I^S and I^C observables have been recently measured for the first time by the CBELSA/TAPS collaboration. The theoretical predictions of I^S and I^C, given for altogether 18 angle dependent functions, are in good agreement with the measurements. Also, the asymmetry dSigma/dcos(theta) evaluated here agrees with the data. We show the importance of the Delta(1700)D33 resonance and its S-wave decay into eta Delta(1232). The result can be considered as a further confirmation of the dynamical nature of this resonance. At the highest energies, deviations of the predictions from the data start to become noticeable, which leaves room for additional processes and resonances such as a Delta(1940)D33. We also point out how to further improve the calculation.Comment: Version accepted for publication by the European Physical Journal A, 9 pages, 7 figure

Measurements of the γvp→p′π+π- cross section with the CLAS detector for 0.4 GeV2<Q2<1.0 GeV2 and 1.3 GeV<W<1.825 GeV

New results on the single-differential and fully integrated cross sections for the process γvp→p′π+π- are presented. The experimental data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the kinematic region of the reaction invariant mass W from 1.3 to 1.825 GeV and the photon virtuality Q2 from 0.4 to 1.0 GeV2. The cross sections were obtained in narrow Q2 bins (0.05 GeV2) with the smallest statistical uncertainties achieved in double-pion electroproduction experiments to date. The results were found to be in agreement with previously available data where they overlap. A preliminary interpretation of the extracted cross sections, which was based on a phenomenological meson-baryon reaction model, revealed substantial relative contributions from nucleon resonances. The data offer promising prospects to improve knowledge on the Q2 evolution of the electrocouplings of most resonances with masses up to ∼1.8 GeV

Monte Carlo code for simulation of the large angle electromagnetic shower calorimeter for class detector

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Stochastic description of internal target effects on electron rings

The effects of internal targets on the beam accumulated in electron storage rings are studied with a linear stochastic model which describes the beam emittance and the beam phase-space growth and provides simple formulae for the longitudinal and transverse beam emittance. The description of facilities with and without beam damping is carried out in a consistent way. The obtained results are comparable to those obtained with other models and numerical simulations

Measurement of the response of long plastic scintillator bars for the large angle electromagnetic shower calorimeter for CLAS

The behaviour of plastic scintillator bars with length up to 450 cm, designed for the CLAS large angle electromagnetic shower calorimeter, is considered in relation to the overall calorimeter response function. In particular methods adopted to measure the light emission yield and transmission efficiency are described and the influence of the scintillator bar properties on the calorimeter energy read-out and timing is discussed. We found that the new scintillator NE110A manufactured by NE Technology Ltd. showed the best agreement with our demands. The effect of wrapping materials on the scintillator bar properties has been studied considering also the temperature variations expected in Hall B at CEBAF

Performance of the new plastic scintillator NE110A for the CLAS large angle calorimeter

The performance of the new NE110A plastic scintillator has been measured in connection with the construction of the AIACE large angle electromagnetic calorimeter for the CLAS detector at CEBAF. Measurements concerning 2128 scintillator bars 15 mm thick, roughly 10 cm wide and up to 450 cm length are reported. The results show an attenuation length of the order of 400 cm, a light output of 6540 photoelectrons/MeV and a uniformity >98%